measured changes in c-band radar reflectivity of … technical paper 3671 measured changes in c-band...

NASA Technical Paper 3671

Measured Changes in C-Band RadarReflectivity of Clear Air Caused byAircraft Wake Vortices

Anne I. Mackenzie

Langley Research Center • Hampton, Virginia

National Aeronautics and Space AdministrationLangley Research Center • Hampton, Virginia 23681-2199

November 1997

https://ntrs.nasa.gov/search.jsp?R=19980000408 2018-07-13T03:44:43+00:00Z

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Contents

Symbols ............................................................................... v

Abstract ............................................................................... 1

1. Introduction .......................................................................... 1

2. Background .......................................................................... 2

3. Experimental Setup .................................................................... 3

3.1. Radar 5 .......................................................................... 3

3.2. C-130 Airplane .................................................................... 3

3.3. Scanning Strategies and Flight Patterns ................................................. 3

3.4. Weather and Local Geography ........................................................ 5

4. Signal Level Calculations ............................................................... 5

4.1. Recording Lag Correction ........................................................... 5

4.2. AGC to SNR Interpolation ........................................................... 5

4.3. Calibrated Sphere Track and Noise Calculation ........................................... 5

5. Clutter-Only Recordings ................................................................ 7

6. Vortex Data Analysis Method ............................................................ 8

6.1. Selection of Passes ................................................................. 8

6.2. Database and Programming Languages ................................................. 9

6.3. Criteria for Recognizing Wake Vortices ................................................ 9

6.4. Clutter Subtraction ................................................................ 10

6.5. Volume Reflectivity ............................................................... 10

7. Vortex Data Analysis Results ........................................................... 10

7.1. Data Plot Description .............................................................. 10

7.2. Screening for Airplane Detection ..................................................... 11

7.3. Evidence of Vortex Detection ....................................................... 11

7.4. Clutter Limitations to Vortex Detection ................................................ 12

8. Concluding Remarks and Recommendations ............................................... 12

Appendix A--Signal Level Plots and Track Plots ............................................. 13

Appendix B--Meteorological Data ........................................................ 59

Appendix C--Variability of Clutter Power at Various Time Lags ................................. 60

References ............................................................................ 74

!11

Symbols

B2

C n

C

D

G

k

L

lmN

n

Pt

P

R

S

T

r,t

V

IJ

£

0

G

x

radar receiver bandwidth

refractive index structure constant

speed of light

antenna diameter

antenna gain

Boltzmann' s constant

loss

Kolmogorov microscale

noise power

refractive index

peak transmitted power

pressure

range

signal power

temperature

system equivalent noise temperature

number of sample standard deviations away from mean, used in statistical calculations

where sample population is small enough that true standard deviation is unknown

range cell volume

kinematic viscosity

angular width of radar target

turbulent eddy dissipation rate

volume radar reflectivity

antenna two-sided 3-dB beamwidth

radar wavelength

radar cross section

range gate length

Abstract

Wake vortices from a Lockheed C-130 airplane were observed at the NASA

Wallops Flight Facility with a ground-based, monostatic C-band radar and anantenna-mounted boresight video camera. The airplane wake was viewed from a

distance of approximately 1 km, and radar scanning was adjusted to cross a pair ofmarker smoke trails generated by the C-130. For each airplane pass, changes in

radar reflectivity were calculated by subtracting the signal magnitudes during an ini-

tial clutter scan from the signal magnitudes during vortex-plus-clutter scans. The

results showed both increases and decreases in reflectivity on and near the smoke

trails in a characteristic sinusoidal pattern of heightened reflectivity in the center

and lessened reflectivity at the sides. Reflectivity changes in either direction varied

from -131 to -102 dBm-1; the vortex-plus-clutter to noise ratio varied from 20

to 41 dB. The radar recordings lasted 2.5 rain each; evidence of wake vortices was

found for up to 2 min after the passage of the airplane. Ground and aircraft clutter

were eliminated as possible sources of the disturbance by noting the occurrence of

vortex signatures at different positions relative to the ground and the airplane. This

work supports the feasibility of vortex detection by radar, and it is recommended that

future radar vortex detection be done with Doppler systems. (This paper was written

in January 1997.)

1. Introduction

From January through May 1995, the SensorsResearch Branch of Langley Research Center testedX-band and C-band radars to determine the characteris-

tics of ground-based wake vortex detection at those fre-

quencies. The Radar Wake Vortex Experiment is part ofthe NASA Reduced Spacing OperationlTerminal Area

Productivity (RSO/TAP) program, which seeks to

improve aircraft throughput at busy airports while main-

taining current safety standards. At present, aircraft,

when landing or taking off, are spaced at standard dis-

tances according to their relative sizes and weights to

prevent the upset or disturbance that can occur when one

aircraft flies through the wake vortices produced byanother. Radar is a sensor that can determine the pres-

ence, location, and longevity of vortices. With informa-

tion provided by such a sensor, air traffic controllers

could space aircraft according to the detected hazardrather than using standard separations which might be

longer than necessary.

In an effort to find the best frequency for all-weatherwake vortex detection, initial tests were conducted at

Wallops Island with a permanently installed C-band

radar in conjunction with an experimental X-band radar

connected to the inner portion of the nearby Wallops

ultrahigh-frequency (UHF) antenna. Because it had

already been well established that X-band radars could

detect rain by Rayleigh scattering, the Wallops tests were

performed in clear weather to test for detection of air tur-bulence by Bragg scattering.l The X-band radar system,

the principal one under test, was slaved to the C-band

radar antenna; therefore, data were acquired by both sys-

tems simultaneously. Both radars scanned across the

wake of a Lockheed C-130 airplane for about 2 min after

the passage of the airplane. The C-130 had been fitted

with smoke pods to give a visual indication of the posi-tion of the wake vortices. Although not designed for the

purpose of vortex detection, the C-band radar provided

auxiliary information that, it was hoped, would assist invalidation of the X-band detection of Bragg-scattered

signals from the aircraft-generated vortices.

Analysis of the C-band data, which consisted of sig-

nal magnitudes at one range gate selected for each pass,

showed an identifiable signature that lasted for up to

2 min after passage of the airplane. Particularly evident

during azimuth scans across the wake, the vortex-plus-

clutter signal magnitude consistently varied from the

clutter magnitude in a roughly sinusoidai pattern in the

immediate vicinity of the wake. Assuming that the

changes in magnitude were caused by vortex backscatter-

ing, one sees the vortex effect as an increase or decreasein reflectivity between - 131 and - 102 dBm-l, more typ-

ically between -120 and -110 dBm -1. The following

report is organized into sections on previous related work

at C-band frequencies, the experimental setup, radar cali-

brations, clutter tests, and the C-band analysis. Interest-

ing signal returns and simultaneous airplane tracks

relative to the radar, weather data, and plots of clutter-

variability data are provided in the appendices.

lln Rayleigh scattering, targets, such as raindrops, have well-defined boundaries and are much smaller than the electromagnetic

waves reflected from them. In Bragg scattering, a distributed target,such as turbulent air, reflects electromagnetic waves at half-waveintervals that sum coherently to produce a stronger signal than thereflections from other parts of the target.

2. Background

Since the 1930's, radar meteorologists have studied

clear-air turbulence as a natural, meteorological phenom-

enon (ref. 1). In recent years, some of the theory devel-

oped for meteorology has been applied to the study of

aircraft wake vortices. For example, Tatarski (ref. 2)

related the radar volume reflectivity of turbulent air to

the structure constant and the radar wavelength with the

equation

8 2- -1/3rI(K ) = 0.3 Cnk (1)

where

rl

C 2n

= volume radar reflectivity

= structure constant, a measure of variabilityof refractive index field within inertial

subrange

9_ = radar wavelength, _./2 being included in

inertial subrange

According to Kolmogorov's theory (ref. 3), for2

incompressible, locally isotropic fluids having a suffi-

ciently high Reynolds number, there exists an inertial

subrange of turbulent eddy sizes, defined as those sizesof eddies that break down into smaller eddies with no

loss of kinetic energy. The low end of the inertial sub-range, called the Kolmogorov microscale, is predicted as

Im = (2)

where

Im = Koimogorov microscale

v = kinematic viscosity

E = eddy dissipation rate

Equation (1) has been applied to the estimation of

radar reflectivity of aircraft-induced turbulence. Aircraft-2

wake-vortex-induced C n depends on such aircraft fac-tors as weight, velocity, and wingspan, as well as on such

meteorological factors as temperature (7), pressure (P),

partial pressure of water vapor, and prevailing winds.

Proctor (ref. 5) has adapted his two-dimensional terminal

area simulation system (TASS) to model wake vortices

over time, given initial aircraft and atmospheric condi-

tions. Currently this work is being expanded into a three-

dimensional model. Among the TASS outputs are T, P,

and E. Marshall and Scales (ref. 6) are using the TASS

outputs for various airplanes in varying weather condi-

tions together with Ottersten's theory (ref. 7) and equa-2

tion (1) to predict C n and 11. These estimates will be

2Turbulent airflow on scales of less than 2 km and close to the

ground can be considered incompressible (ref. 4).

2

improved as assumptions are validated with experimental

tests and the vortex atmospheric and radar models arerefined.

The two-dimensional TASS model 3 predicted that a

C-130 in a standard atmosphere with no crosswind

should produce a pair of vortices whose total spatial

extent is 80 m in width by 60 m in height 30 sec after

passage of the airplane. The core radius, that distancefrom one vortex center to the location of highest tangen-

tial velocity for that vortex, was calculated to be 5 m

(ref. 6). Marshall's current work (ref. 6) predicts that the

proper scales of turbulence and, therefore, sufficient

reflectivity should exist at C-band frequencies to allowwake vortex detection.

In the summer of 1990, W. H. Gilson of the

Massachusetts Institute of Technology Lincoln Labora-

tory conducted a series of clear-air wake vortex radar

tests (ref. 8) at Kwajalein Atoll in the Marshall Islands.

The experiment employed seven different radars, one of

which was the ALCOR C-band Doppler radar. ALCOR

transmitted 10-gsec pulses at 3-MW peak power, using a0.3 ° antenna beam. Viewing the wake of a Lockheed

C-5A cargo airplane at a look angle varying between 45 °

and 90 ° from the longitudinal wake axis, ALCOR suc-

cessfully detected and tracked the wake at ranges up to

17 km. From the ALCOR data, the calculated r' of thewake was -125 dBm -1 at 30 km (260 sec) bei::,',d the

C-5A and 1524 m (5000 ft) altitude. The 11 value

decreased 10 dB at 3048 m (10000 ft) altitude and

another 10 dB at 6401 m (21000 ft) altitude.

In early 1991, J. D. Nespor et al. (ref. 9) conductedfurther C-band, clear-air, wake vortex radar tests for

General Electric Company at White Sands Missile

Range, using the Multiple Object Tracking Radar

(MOTR). MOTR is a phased array, pulsed Doppler radar

that, during the tests, transmitted 1-gsec pulses at 1-MW

peak power in a 1° antenna beam. Nespor reported

detecting the wake from a Ling-Temco-Vought A-7

small attack jet, looking along the longitudinal wake axis

behind the airplane at a range of 2.7 km. Nespor calcu-

lated vortex Cn2 values ranging from -135.4 to -116.6

dB. According to equation (1), this calculation would

produce xI values in the range from -135.3 to -116.6dBm -1.

In view of these past experiments, it seemed reason-

able to expect that the Wallops R5 C-band radar woulddetect a C-130 wake at l-km range, using a 0.4 ° antenna

3TASS initialized its wake vortex calculations based on classic

elliptical theory (ref. 5). No provisions were made for aircraft flaps.Some of the initializing assumptions were that initial circulation =340 m2/sec, vortex core radius = 2 m, vortex height = 180 m, andvortex separation = 24 m.

beam and transmittingl-ktsecpulsesat 2.2-MWpeakpower.Basedon available C-band radar system

parameters, pre-experiment calculations indicated that

the radar would be able to detect wake turbulence having

a reflectivity of at least -143.6 dBm -1, obtaining a signal

to noise ratio (SNR) of 0 dB or greater.

3. Experimental Setup

3.1. Radar 5

The C-band radar that recorded the vortex data

described here is a type AN/FPQ-6 monostatic radar per-

manently located at Wallops Flight Facility and bearing

the Wallops designation R5. In past years, R5 has served

to observe meteorological phenomena; recently, it

tracked Spacc Shuttle craft and, at the time of these tests,

was configured for that use. The radar parameters for this

expcriment are compiled in table 1.

Table 1. C-Band Radar 5 Characteristics

Receiver and transmitter:Transmitted carrier frequency, MHz ................. 5765Peak transmitted power, MW ........................ 2.2Pulsc repetition frequency, Hz....................... 640Pulse length, ktsec ................................ 0.25Range gate length, lasec ............................ 0.75Measured noise 3-dB bandwidth, MHz ................ 4.36Noise level at the receiver, dBm ................... -100.6Number of range gates recorded ....................... 1Data recording rate, Hz ............................. 10

Antenna:

Beamwidth, deg ................................... 0.4Diameter, m ..................................... 8.84Gain, dB ......................................... 511st sidelobe height, dB ........................... - 16.5Polarization .................................. VerticalScanning rate, deg/sec ............................... 2Scanning direction ............................... Az-EITower height, m ................................. 14.98Two-way line loss, dB .............................. 4.9

R5 radiated sufficient power and measured atmo-

spheric reflections with sufficient spatial resolution todetect vortices. However, R5 recorded data in only one

112.5-m-long range cell per airplane pass, which meant

that, as the vortices drifted with the wind, rose, or fell,

they could be seen only occasionally in the data record,

when they happened to be in the correct range cell. The

receiver detected signal magnitudes only, without veloc-

ity information. Signal levels were recorded in the form

of automatic gain control (AGC) values; at the beginning

of each experiment day, the radar was calibrated to estab-

lish the correspondence between AGC level and SNR. A

calibrated sphere track test was performed once, and

from the results of that test, the radar system noise was

calculated and later multiplied by the SNR value to deter-

mine the absolute signal received. The signal data are

presented in appendix A in a two-dimensional format:

signal level versus scan angle at the fixed range for that

pass.

At the antenna scan rate of 2°/sec and the sample

recording rate of 10 samples/sec, each data point repre-

sented a spatial "smear" 0.2 ° in extent. According to the

pulse repetition rate of 640 pulses/sec, each sample was

obtained by integrating 64 pulses.

For the work described here, the actual vortex pair

width should be the same as the apparent width. Taking

into account the convolution of beam shape, AGC

response shape, and target shape, modeling shows that

targets I ° or more in width will appear at their true width,

while targets smaller than 1° will appear larger than their

true width. For example, targets 0.5 ° wide will appear to

be 0.7 ° wide and targets 0.2 ° or less wide will appear to

be 0.5 ° wide. When aircraft vortices are initially formed,

their combined width will be slightly larger than the air-craft wingspan. Because the aircraft wingspan at the

longest recorded range provides a lower bound of 1.6 °

for the true angular width, the vortex pair will occupy

more than 1° in any R5 scan.

3.2. C-130 Airplane

NASA 427, a research C-130 airplane, was selected

as the wake vortex generator. This airplane has a

wingspan of 40.4 m and, during experiment flights,

weighed between 64863 kg (143 000 Ib) and 48895 kg

(110000 lb), depending on how much fuel had been

burned. Typically, it flew at 64.3 m/sec (125 knots) air-

speed with gear and flaps up. Wing-tip-mounted smokegenerators were fueled by corvus oil from a tank in the

cargo section and were activated for approximately

30 sec as the airplane flew past the radar stations.

3.3. Scanning Strategies and Flight Patterns

The C-130 airplane flew in level, oval patterns pastR5 and the X-band radar, which was slaved to R5. These

two radars were sited 539 m apart. Appendix A contains

numerous plots of the airplane track that show its relation

to the R5 tower position and the radar scan. Data were

gathered with the following three antenna scanning strat-

egies depicted in figures 1, 2, and 3, respectively:

1. Head-on azimuth scans: The antenna scanned in

an azimuthal plane, keeping a fixed 20 ° elevation while

the airplane flew toward the antenna beam and over theantenna.

2. Tail-on azimuth scans: The antenna scanned in an

azimuthal plane, keeping a fixed 20 ° elevation while the

airplane flew over the antenna and away from theantenna beam.

View along flight line View across flight line

Figure 1. Head-on azimuth-scan configuration for airplane flying toward and over radar beam.


Figure 2. Tail-on azimuth-scan configuration for airplane flying over and away from radar beam.

__Elev_Ele_ ation \


Figure 3. Elevation-scan configuration for airplane flying along side and past radar.

3. Elevation scans: The antenna scanned in an eleva-

tion plane, keeping a fixed azimuth while the airplaneflew past the antenna to one side of the antenna tower.

The azimuth wake vortex scans provided a view that

was partly longitudinal and partly radial from below,

while the elevation scans provided a mostly lateral view.In order to accommodate the X-band radar, the airplane

flew past at close range, usually about 1 km away, at an

altitude of between 274 and 659 m (899 to 2161 ft) above

ground level. At 30 sec before the airplane passed, both

radars began data recording. The first scan was a long,

clutter scan of about 40 ° extent. Subsequent scans wereshorter, usually about 15° in extent. The antennas were

fitted with boresight videotape cameras to enable the

ground crew to view the smoke trails emanating from

wing-tip-mounted smoke pods on the C-130. The pilotflew along a requested line crossed by the initial antenna

scan;the R5 antennaoperatoradjustedthe scanningthroughouttheradarrecordingto continuecrossingthesmoketrailsastheydriftedacrossthesky.Datarecord-ingcontinueduntil2minaftertheairplanehadpassed.

At thesametimeastheweatherradarswererecord-ingthevortices,aC-bandtrackingradarwasrecordingthepositionof theairplane.UsuallythetrackingradarwasRI0,whichwaslocatedbetweenR5andtheX-bandradar.Theproximityof thetrackingradarto theflightlineresultedintheoccasionaltemporarylossoftheradarfix on theairplaneasit flewoverR10.OnoccasionswhenthemoredistanttrackingradarR18wasemployed,thetrackswereuninterrupted.

3.4. Weather and Local Geography

The vortex data presented here were recordedbetween January 5 and January 11, 1995. On these days,

the sky was blue and sunny, and light winds prevailed.Meteorological data, including temperature, pressure,

water vapor mixing ratio, and wind speed, were collected

every 2 hr. Those data recorded at the times closest to the

vortex radar data are presented in appendix B for an alti-

tude (400 m above ground level) that is representative of

the airplane passes.

The terrain of the Wallops Flight Facility, which

borders on the Atlantic Ocean, is fiat and very marshy. A

map of the area surrounding the radar test site is shown

in figure 4. C-band R5 is situated in a row of radars

which includes tracking Radar 10 and the X-band

radar that operated in conjunction with R5 during the

experiment. This group of radars is about 6 mi south ofthe airfield and tracking Radar 18 (not pictured in the fig-

ure). Within 1 km of the R5 tower, there are grassy

fields, numerous clumps of trees, a body of open waterbetween the mainland and the island, and occasional

metal towers and buildings housing other radar stations.Even in the absence of rain or wake vortices, substantial

variations (up to 18 dBm) were seen over time in thecombined radar reflections from the ground and atmo-

sphere when looking at the same point in space. There

were also signal variations of up to 30 dBm over angular

space from the varying ground clutter at different azi-muths and elevations.

4. Signal Level Calculations

4.1. Recording Lag Correction

Initial studies indicated that there was a consistent

lag between position and signal level recordings made by

R5 when the antenna was scanning. Comparison of the

apparent positions of a strong fixed target as the antenna

scanned upward and downward past it during elevation

scanning at the 2°/sec scan rate led to the deduction that

the recorded position was 0.5 ° "ahead" of the correct

position for the target. This error also occurred during

clockwise and counterclockwise azimuth scanning and

was corrected for by adding or subtracting 0.5 °, as appro-

priate, to the angular position at all recorded data points.

4.2. AGC to SNR Interpolation

Because the direct output of the recording systemwas AGC values, it was necessary to collect calibration

data to establish the relationship between AGC level andSNR. At least once on each experiment day, usually at

the beginning, the radar was calibrated with a series of

test signals from a nearby tower; the signal ranged in

5-dB steps from 0 to 65 dB above the radar noise levelobserved at the receiver. Thirty seconds worth of AGC

data were averaged at each SNR level. In postrecording

processing, SNR levels were determined for everyrecorded AGC data point by linear interpolation between

the appropriate SNR values. In general, most radarreturns lay within the calibrated region of the SNR scale.

The recorded signal level was observed to exceed the

scale only when the airplane was close to the radar and

the recorded range gate was centered at 814 m, one of the

closer recorded ranges.

4.3. Calibrated Sphere Track and NoiseCalculation

On May 1, 1995, a calibrated sphere track test was

performed to provide data for calculating the radar sys-

tem noise seen by the receiver. During the test, R5 wasconfigured in the same way it had been during the wake

vortex recordings. The receiver bandwidth was set at the

nominal value 4.8 MHz, for which the previously mea-sured noise bandwidth had been 4.36 MHz. A metallic

sphere with a radar cross section (RCS) of 0.0182 m 2

(6-in. diameter) was attached to a balloon and released

from the ground. As the balloon and sphere ascended, R5

tracked the sphere until it was 50 km away, recording

AGC level versus range. From these data, SNR versus

range was calculated. At each of three ranges,13.167 km, 26.335 km, and 45.720 kin, noise power was

calculated according to the radar equation

S Pt G2_'2_(3)

N 3 4(4/z) R L2_wayN

5

True North

WallopsIsland

Meteorological tower

Boresight tower

CausewayC-band radar 5

Camera station

Tracking radar 10

Camera station

Spandar radarSTIR antenna

30-see line

Water

Marsh _

Meters

0 1000 2000

I l 1 I I3000 4000

I I I I

Figure 4. Map of experiment site at Wallops Flight Facility, Wallops Island, Virginia. C-band Radar 5 is situated in a row of radars which

include tracking Radar 10 and the X-band radar that operated in conjunction with R5 during the experiment. This group of radars is about6 miles south of the airfield and tracking Radar 18 (not pictured). During azimuth-scan passes, the C-130 flew directly over the radars;during elevation-scan passes, the aircraft flew past the radars as pictured.

6

where

S/N = interpolated SNR

Pt = peak transmitted power

G = antenna gain

_. = radar wavelength

c = RCS

R = range

L2_way = 2-way line losses + atmosphericlosses = 4.9 dB + R - 0.015 dB/krn

The average of the three resulting noise values was

-100.58 dBm. Using B = 4.36 MHz in the equation

N = kTsB (4)

where k = Boltzmann's constant, 1.38 x 10 -23 J/K, one

obtains the resulting noise temperature 1454 K, which is

equivalent to a noise figure of 7.8 dB.

All experimental SNR values were multiplied by the

noise power to obtain the plotted power values seen atthe receiver.

5. Clutter-Only Recordings

Because the nonvortex returns varied so much over

time, it was infeasible to do clutter subtraction with a sin-

gle clutter map; instead, a clutter scan would be neededfor each pass. As used here, the term "clutter" includes

atmospheric and ground returns. It was decided thatsome statistical data on clutter collected in the absence of

aircraft would help in deciding which disturbances in thevortex data sets were the result of vortices. A data collec-

tion time was selected when the weather was clear and

the mean weather conditions were fairly constant. By the

time a clutter-only recording could be done using R5 on

such a day, it was November 28, 1995, 6 months after

the experiment. Several data sets were obtained withdifferent antenna scans, including the following whoseresults are discussed herein:

100 azimuth scans from 10 ° to 50 °, at 20 ° elevation

and 1369-m range

100 elevation scans from 20 ° to 50 °, at 141 ° azimuth

and 1409-m range

The other radar parameters were set, as before, accordingto table 1.

Because the vortex data would be considered on the

basis of signal level differences relative to one initialclutter scan per pass, the clutter itself was characterized

by finding the nonvortex signal level variations over time

at many antenna positions. The clutter signal levels were

calculated in mW and interpolated, together with their

detection times, at regular 0.25 ° intervals. At each angu-

lar position so determined, available pairs of dBm signal

powers and their corresponding detection times were

subtracted to produce sets of signal power difference val-

ues for various time intervals ranging from 2 sec to

8 min. For each set of between 46 and 98 signal power

difference samples representing a given time lag, the

average and standard deviation of all the signal powerdifferences were determined in dBm. A smoothed, abbre-

viated, wire mesh representation of the results is shown

in figures 5 and 6, including lag times up to 3 min, a time

period slightly longer than the flight passes. Tables C2

and C3 in appendix C contain the unsmoothed numerical

results together with the number of samples in each set

used to find the sample standard deviations.

At any one position and for a given time lag, the

distribution of signal power differences was roughly

Gaussian about a mean of no change. (The vortex data

sets showed that the mean clutter level varied very

greatly from day to day.) The clutter was particularly

variable at some positions (e.g., at 40.5 ° during the azi-

muth scans and 22.5 ° during the elevation scans). The

signal level changes also increased somewhat with

longer time lags, although the effect was much less strik-

ing than the change with position. For the azimuth scans,

the sample standard deviation of the signal level variedfrom 1.4 dBm (30.75 ° , 145 sec) to 3.7 dBm (40.5 °,

36 sec). For the elevation scans, the standard deviation

varied from 1.5 dBm (37.5 °, 25 sec) to 3.6 dBm (22.5 °,

149 sec).

One may determine the expected range of clutter

power variations at any particular position and time lag

by applying the t-test (ref. 10). For all the data in

tables C2 and C3, the smallest number of degrees of free-

dom is 46, which has a t.05 value of 1.68 (ref. 10). So, an

upper limit for the expected range of signal level varia-tions caused by change in clutter alone may be deter-

mined (with 95-percent confidence) at any position by

multiplying the standard deviation of the signal power

differences by 1.68. For example, at 25 ° azimuth and 20 °

elevation, there is a 95-percent chance that, after 36 sec,

the clutter power level will have changed less than4.9 dBm. At 35 ° azimuth and 20 ° elevation, there is a

95-percent chance that, after 36 sec, the clutter level will

have changed less than 3.6 dBm. At 141 ° azimuth and25 ° elevation, there is a 95-percent chance that, after

37 sec, the clutter power level will have changed lessthan 4.5 dBm.

Although these numbers represent only one range

gate on one day, they give an idea of the variability onecould encounter with such a radar. Clearly, the variability

at single points is quite large over a few minutes timeeven when no unusual disturbances, such as vortices, are

7

Standarddeviation of 2.5

A signal power,dBm

1.5

180

160

140

120

Time lag, sec 100

80

6O

40

20 3530

250 15 20

10 Antenna azimuth angle, deg

4045 50

Figure 5. Variability of received clutter power with azimuth direction; Wallops R5 elevation = 20 ° on 11/28/95 (data smoothed). At anygiven angular position and time lag, mean signal level change was negligible. Standard deviation of signal level change varied from 1.4 to3.7 dBm before smoothing.

encountered. As it turned out, the signal level changes

caused by vortices were often of the same order of mag-

nitude as the changes from unknown causes. For this rea-

son, it was decided to search for vortex patterns extended

over space, rather than for fluctuations at individual

points.

6. Vortex Data Analysis Method

6.1. Selection of Passes

Out of the 209 airplane passes for which azimuth-

scan or elevation-scan R5 recordings were available,

13 azimuth-scan passes and 10 elevation-scan passeswere chosen for detailed analysis for possible wake vor-

tex detection. Staring-mode passes were ignored because

vortex detection would be enabled by the signal level

contrasts seen spatially, as well as temporally, in

8

scanning mode. Where concurrent airplane tracking datawere available, flight paths of the C-130 were examined

in conjunction with the R5 scans to select passes where

the recorded volume was initially within about 50 m of

the airplane wake, in any direction. The passes were

further screened for proper functioning of the airplane

wing-tip smokers and availability of videotapes that

showed the smoke trails. Finally, it was desired, for eachpass, to have an initial clutter scan recorded at the same

positions as the vortex data of interest. Data from the 23

passes that met these criteria are shown in appendix A.

Appendix A contains one plot per pass of the air-

plane track and the radar range cell track across the

ground. At the top of the corresponding radar data plots

is additional information, such as radar range, airplane

altitude, and the time when the airplane flew over the

range cell track. This intersection was determined by

Standarddeviationof 2.5

A signal power,dBm

1.5

180

160

140

120

Time lag, sec 100

80

60

4G

3520 30

250 15 20

10 Antenna elevation angle, deg

4045 50

Figure 6. Variability of received clutter power with elevation direction; Wallops R5 at azimuth = 141° on 11/28/85 (data smoothed). At anygiven angular position and time lag, mean signal level change was negligible. Standard deviation of signal level change varied from 1.5 to3.6 dBm before smoothing.

graphic interpolation between the airplane tracking data

points, which were provided at l-sec intervals. Some of

the airplane track plots contain dotted lines where the

tracking information dropped out.

6.2. Database and Programming Languages

After the signal power values had been interpolatedfor each vortex data pass, they were loaded into adatabase created with Informix software on a Sun

SPARCstation 2, running Sun Operating System version

4.1.3_U1. Also in the database were radar-pointing and

aircraft-tracking data. Much of the initial sorting was

done with Informix-Sequel Query Language (ISQL) que-

ries and plots made by Tccplot. An ISQL-C program

allowed logarithmic and trigonometric calculations to be

done in C language on values selected by ISQL queries;

this program performed clutter subtraction and volume

reflectivity calculations. The clutter statistics were

calculated through the use of FORTRAN code on anASCII file that contained the radar clutter data.

6.3. Criteria for Recognizing Wake Vortices

In studying signal plots for evidence of vortex detec-

tion, a number of questions were asked.

1. Is the variation larger than that which would haveoccurred because of variations in atmospheric and

ground clutter alone?

2. Does the signal disturbance have a nonrandom

shape?

3. Is the signal disturbance coincident with thesmoke trails?

4. Does the disturbance appear at different positions

not associated with any particular ground clutter feature?

9

5. Doesthesignaldisturbance appear at different

times not tied to any particular position of the airplane?

6. Is the indicated physical size of the vortexreasonable?

7. Is the implied volume reflectivity of the vortex in

keeping with previous observations?

In the end, the answers to these questions were "not

necessarily" to the first question and "yes" to the others.

Because the clutter variability was so large and it was notknown in advance what a vortex would look like, the

vortex search was carried out visually by inspection of

signal level plots and videotapes of the smoke trails. Pos-

sible sideiobe detection of the airplane was a major con-

cern, so plots of the position of the airplane have been

included in this report with notations to show where the

airplane was at times of interest in the radar recordings.

6.4. Clutter Subtraction

In each vortex data pass, one antenna scan was des-

ignated as the clutter scan. This clutter scan was recorded

less than a minute before the passage of the airplane and

included those positions of interest during the rest of the

pass. In order to detect changes possibly caused by wake

vortices, the received signal levels in succeeding scans

were compared to the signal levels at the same positionsin the clutter scan. Both increases and decreases in signal

level were noted in the vicinity of the vortices.

6.5. Volume Reflectivity

Where deviations in signal level from the clutter

level were found, the change in reflectivity was calcu-lated as

[AS] (4_) 3R4L2-wayAq = (5)

PtG2_, 2V

where

Aq = change in volume reflectivity, RCS/volume 4

AS = change in received signal power

V = range cell volume

For R in the near field (less than 1266 m), the range

cell volume was calculated as that of a cylinder of diame-

ter equal to the antenna, so that

ltD2c'_ 3V - - 6905 m (6)

8

41n this report, rI is expressed in units of dB m-I . Another com-mon form of the unit is dB s m/rn 3.

10

where

D = antenna diameter

c = speed of light

x = range gate length

For R in the far field (greater than or equal to

1266 m), the volume was calculated as that of a conicsection, so that

_0 2 3 3

V = --_-(gfa r - gnear ) (7)

where

0 = 3-dB beamwidth (radians)

Rfa r = range at far edge of range cell

Rnear = range at near edge of range cell

During the majority of R5 vortex recordings, thevalue of V was the near-field value, 6905 m3; for the

entire experiment, the maximum value of V was8885 m 3. For the purpose of reflectivity calculation, it

was assumed that the vortices would fill one range cell.

For any one calculation, it was not known how much of

the radar range cell would be filled by the wake vortices;

however, it was expected that early in each pass record-

ing the range cell would be partly filled, while later in

that recording the range cell would be completely filled.

Therefore, Arl may at times be underestimated. The value

A11 has been calculated from the magnitude of the signal

change so that it is always a positive number ofm -1 and

can be expressed logarithmically. Because Ar I is lessthan 1 m -1, it is always a negative number of dBm -1.

However, one may deduce from the signal plots whetherthe reflectivity has increased or decreased, according to

whether the vortex-plus-clutter scan lies above or belowthe clutter scan.

7. Vortex Data Analysis Results

7.1. Data Plot Description

The vortex data analysis results are presented in

appendix A in the form of signal level plots and tracking

data plots. The plots are presented in order of airplane

pass numbers, which were assigned chronologically

throughout the testing.

For each pass included in this report, two or moreantenna scans of interest have been selected. Because

absolute signal power has been plotted, SNR may be

calculated at any point by adding 100.58 dB to the dBm

signal power value. Where the boresight videotape indi-

cated that the radar beam was crossing the smoke trails,

portions of the vortex-plus-clutter scans on or between

the two smoke trails of the airplane are represented as

solidcircles.In a fewcases,thesmokepositionis notmarkedbecausetherewasnovideotapeavailableshow-ingwhentheantennaboresightcrossedthesmoketrails.Placesofinterestareidentifiedwithanarrowpointingtoaparticulardatapoint;thetimeof day(hours,minutes,seconds)andchangein reflectivityaregivenforthatdatapoint.

In thetrackingdataplots,theaxesaremarkedindegreesof latitudeandlongitudeasif theywererectan-gularcoordinates,withthescalingdonesothatdegreesof latitudearethecorrect"length"relativeto degreeslongitudeforthatlocationin thecenterofthe"map."Thedirectionof flightof theairplanearoundits loop,indi-catedby an arrow,wascounterclockwiseexceptforpasses52,54,56,and64.Thetimesof interestmarkedonthesignallevelplotsarealsomarkedalongtheair-planetracks.Thedistancebetweenany twopointsinkilometersmaybeestimatedbyconvertingeach0.01oofthe distancemarkedoff alongthe latitudeaxis to1.11km.

7.2. Screening for Airplane Detection

It seemed quite possible that the airplane might inter-

fere with vortex detection by creating an extra unpredict-

able sidelobe target in the clutter scan or in the vortex-

plus-clutter scans. With this problem in mind, 10 head-on

and 10 tail-on clutter scans were compared to see if they

displayed substantially different features. Passes 99,

100, 103, and 104 were head-on passes recorded atR = 1364 m. Passes 106, 107, 108, 109, 117, and 118

were head-on passes recorded at R = 1111 m. Passes 51,

52, 54, 122, and 123 were tail-on passes recorded at R =1366 m. Passes 56, 60, 61, 64, and 127 were tail-on

passes recorded at R = 1110 m. Comparison of head-onand tail-on clutter scans recorded on the same day at the

same range revealed no obvious distinction in the fea-

tures. Therefore, it appeared that proximity of the air-

plane was not affecting the clutter scans. Because there

were very few days when good head-on and tail-on clut-

ter scans were both available for comparison, it was not

possible to establish a firm conclusion. It appeared thatthe date was much more important than the direction of

flight in determining the clutter signal levels. At the same

range, clutter recordings made on different days varied as

much as 18 dB in amplitude but showed similar features

(i.e., peaks at the same pointing angles). Of course, there

was a very noticeable difference both in the signal level

and in the general shape of clutter scans recorded at dif-

ferent ranges on the same day.

7.3. Evidence of Vortex Detection

The most convincing evidence of vortex detection

lay in passes where a signal disturbance could be seen

coincident with the smoke in several succeeding scans.

Such passes were 52, 54, 99, 100, 103, 104, 107, 108,117, 122, 123, 132, 137, and 141, which included both

azimuth-scan and elevation-scan passes. In the azimuth-

scan passes, the coincidence of the vortex signature withthe smoke trails as they drifted across the scan during the

pass indicated that the signal disturbance was not the

effect of ground clutter. At places of interest, the signal

disturbance represented a target of spatial extent consid-

erably more than the 0.5 ° resolution, the disturbance usu-

ally being between 100 and 150 m wide. This size is

consistent with the TASS-modeled vortex pair width of

80 m at 30 sec, assuming further expansion of the vorti-

ces after 30 sec. One may estimate the width of any fea-

ture in the scans as 2R tan(a/2), where ct is the angularextent of the feature.

The single-range-cell recording allowed a curved

strip image 112.5 m in depth, rather than a plan view pic-ture, to be created. Even if this strip passed through a

vortex, it did not show what was happening on all sides

of the vortex. Another difficulty was that, during the

recording, the vortices, as indicated by smoke trails, were

twisting around in the sky and could not be expected toform a neat radar image at all times. However, visual

inspection of many data plots often revealed a character-

istic sinusoidal pattern of the vortex-plus-clutter scan

about the clutter scan in the vicinity of the smoke trails.

Good examples of this shape may be seen in azimuth

scans, such as pass 56, scan 8; pass 100, scan 12;

pass 107, scans 5 and 22; pass 117, scan 19; pass 122,

scan 11; and pass 123, scan 4. Longer scans sometimes

showed a volume of increased reflectivity bounded by

two volumes of decreased reflectivity. In volumes of

increased reflectivity, the vortex-plus-clutter to noise

ratio was typically between 20 and 41 dB, while the vor-tex to clutter ratio was between 0.1 and 7.9 dB.

In these scans, the smoke trail was sometimes in the

portion of the scan where there was an increase in reflec-

tivity and sometimes in the portion showing a decrease in

reflectivity. The changes in reflectivity in either directionvaried from -131 to -102 dBm -|. The smoke trails fre-

quently remained quite close together, the distance

across both trails spanning as little as 40 or 50 m, which

is about the same as the expected initial distance acrossboth vortices from a C-130. This could mean either that

the vortices did not expand but did influence the reflec-

tivity of the air mass surrounding them or, more likely,that the vortex system expanded outside the smoke trails.

In the absence of a more complete spatial representation

or velocity information, it is not possible to say which

parts of the vortex system produced elevations in reflec-

tivity. In any case, it is safe to say that the smoke alone

did not change the reflectivity of the air.

11

Thetimelagsbetweenthepassageof theairplaneandtheexamplesofvortexdetectionshowninthisreportvaryfrom10.4to 120.1sec.Becausesignaldisturbanceswereseencoincidentwiththesmokeandirrespectiveofthepositionof theairplane,it isunlikelythatthedistur-banceswereinstancesof airplanedetection.

7.4. Clutter Limitations to Vortex Detection

In addition to signal level fluctuations in the vicinity

of the smoke trails, there were often equally large signalchanges in other regions of the scan. Sometimes, as in

pass 52, a nonrandom signal disturbance was noted, but

the vortex-plus-clutter scan power level never increasedabove the clutter scan power level. This clutter level fluc-tuation would make it difficult to write an automated

detection algorithm on the basis of signal magnitudes

alone, unless the clutter could be substantially reduced.

Currently, no evidence of vortex detection has been

found in the X-band data sets recorded at Wallops

concurrently with the R5 data. This result is thought to be

caused by the high sidelobe clutter power recorded bythat system.

8. Concluding Remarks and Recommendations

This study confirms the work of previous researchers

who reported that wake vortices could be detected with

C-band radars in clear air. Although the measured

vortex-induced changes in received signal level were

often similar to the expected clutter variation at individ-

ual points, the experimental data are convincing evidence

of wake detection because the signal level changed in anonrandom pattern at the locations of the smoke trails.

The wake was detected numerous times at a variety ofpositions relative to the airplane and radar, the calculated

size and increased reflectivity of the wake lying within

the ranges expected from previous experiments and

modeling.

To reiterate the essential characteristics of the radar,

R5 transmitted 2.2 MW and integrated over 64 pulses,recording noise at -100.58 dBm and vortex-plus-clutter

signals at 20 to 41 dB above the noise level. The results

of the research reported herein indicate that, by reducing

the receiver noise level and increasing the number of

pulses integrated, it should be possible to detect vortices

at the same range (1364 m) using much less power. For

example, the theoretical Swerling Case 1 target requires

a signal to noise ratio (SNR) of 7.2 dB for a probability

of detection of 0.9 and probability of false alarm of 10 -4

when 64 pulses are integrated. If 256 pulses are inte-

grated, the required SNR decreases to 3.8 dB, an

improvement of 3.4 dB. By reducing the receiver noise

by 8 dB and increasing the integration improvement fac-

tor by 3.4 dB, it should be possible to reduce the trans-

mitted power 27.6 dB to 3.8 kW and still obtain a SNR of3.8 dB.

Portions of the structure of the vortex system were

revealed by the limited recording of one range cell. It

appeared that there was a central volume of heightened

atmospheric reflectivity, with volumes of lessened atmo-

spheric reflectivity on each side. At present, it is not

known why some parts of the vortices in this experiment

showed decreased reflectivity. Although the vortex-plus-

clutter signals were visible above the clutter signals, it

would be of great value to reduce the proportion of

ground clutter level in the received signal by antenna

modification or pointing. This would make the patternsmore predictable, heighten the contrast between vortex

and nonvortex information, and improve the probabilityof vortex detection at low elevations. Detection of vorti-

ces by magnitude information alone required pattern rec-

ognition and a clutter map recorded as soon as possible

before the vortex recording.

For future work toward Reduced Spacing Operation/

Terminal Area Activity (RSO/TAP) program goals,

Doppler processing is undoubtedly necessary to sort out

clutter targets with confidence, to identify various parts

of the vortex system, and to quantify the hazard to

airplanes in terms derived from wind velocities. Spatial

resolution will have to be improved over the R5 systemso that the sample volumes are smaller than individual

vortices, on the order of 5 m in diameter. Keeping theprevious numerical example, the needed improvement in

resolution would be 13 dB, which could be achieved by

pulse compression and would require increasing the

transmitted power once again. Ultimately, a three-

dimensional target representation will be needed to

locate and track vortices from origin through decay; this

information must be obtained by scanning in both azi-

muth and elevation and by recording data from a range ofdistances.

NASA Langley Research CenterHampton, VA 23681-2199July 16, 1997

12

Appendix A

Signal Level Plots and Track Plots

This appendix presents the vortex data analysis results in the form of signal level plots and tracking data plots,

ordered according to pass numbers. Note that, above each signal level plot, text labels give additional R5 pointing infor-

mation and the time and airplane position when the airplane crossed the R5 recorded range cell track. All angles are

given relative to R5; times are given in coordinated universal time (UTC) code; altitude is given above ground level

(AGL).

Figures A1, A2, A3, and A4 contain three elevation scans and the ground tracks for pass 14. In scan 7, a signal

increase is seen just above the aircraft elevation, while a signal decrease is seen just below the aircraft elevation.

Between scans 7 and 18, the signal decrease has descended 4 ° or 89 m over a period of 95 sec.

-5o

Radar settings: R = 1268 m, Az = 145.0 °, El = scanning

Airplane crossing at time = 20:38:44.3, R = 1288 m, Az = 145.0 °, El = 30.0 °, Alt -- 659 m AGL

E

_D,v

-55

_50

_55

-70

-75

-80

-85

-9010

©

Scan l--clutter

Scan 7-vortex plus clutter (no video available)

I I

15 20

_-- 20:39:06.2, Arl = -123.9 dBm -1

, h _ L [ I I I

25 30 35 40

Elevation, deg

Figure A1. Total signal level vs. antenna elevation angle compared with clutter scan for pass t4, elevation scan 7, on

01-05-95.

13

E

e-

-50

-55

-60

-65

-70

-75

-80

-85

-9010


Airplane crossing at time = 20:38:44.3, R = 1288 m, Az = 145.0 °, El = 30.0 °, Alt = 659 m AGL

-- Scan 1--clutter


I A t i i i _ I i i

15 25

Elevation, deg

L 20:40:08.1, Arl = -123.1 dBm -1

20 30 35 40

Figure A2. As for figure A1, except for elevation scan 14.

E

oe_

"d

-50

-55

--60

-65

-70

-75

-80

-85

-9010


Airplane crossing at time = 20:38:44.3, R = 1288 m, Az = 145.0 °, E1 = 30.0 °, Alt = 659 m AGL

-- Scan 1-clutter


A

20:40:41.5, A'q = -115.8 dBm -1 _ °5_

I i _ i i t i _ L J I i _ i i I _ i i i I i i J _ I

15 20 25 30 35 40

Elevation, deg


14

-75.46

-75.48

,_ -75.50

g -75.52,.d

-75.54

-75.5637.94

North

20:40:08.0 _ Airplane track

c_ R5 range cell tracko R5 radar

U-...<°

v

37.92 37.90 37.88 37.86 37.84 37.82 37.80

Latitude, deg

Figure A4. Pass 14 airplane and Radar 5 ground tracks; lateral radar view of airplane wake.

15

Figures A5 and A6 contain one elevation scan and the ground tracks for pass 21. In scan 7, a signal increase is seen

just above the aircraft elevation, while a signal decrease is seen at and below the aircraft elevation.

-50

Radar settings: R = 1084 m, Az = 151.0 °, E1 = scanning

Airplane crossing at time = 21:44:23.9, R = 1133 m, Az = 151.0 °, E1 = 30.4 °, AIt = 588 m AGL

E

i..7

&

¢-

8r_

-55

-60

-65

-70

-75

-80

-85

-9010

Scan 1-clutter

o Scan 7-vortex plus clutter (no video available)

°___ "_ _:_Zq = -119.1 dBm -1

I I I I I , J , J I

15 20 25 30 35 40

Elevation, deg

Figure A5. Total signal level vs. antenna elevation angle compared with clutter scan for pass 21, elevation scan 7, on

01-05-95.

-75.46

-75.48

._ -75.50

2

_ -75.52

-75.54

-75.56

Figure A6.

/ 21:44:57.0

North

Airplane track

[] R5 range cell track

o R5 radar

,,, ...... l,,,x,,,*,l, ........ I,,,*,,,*,I ......... I,,***,,,,I ......... I

37.90 37.88 37.86 37.84 37.82 37.80 37.78 37.76

Latitude, deg

Pass 21 airplane and Radar 5 ground tracks; lateral radar view of airplane wake.

16

Figures A7, A8, and A9 contain two azimuth scans and the ground tracks for pass 52. During this pass, the signal

level was generally higher during the clutter scan than during any of the succeeding scans, implying possible contamina-

tion by the aircraft. Nevertheless, some local variation is visible around the smoke trails in scans 10 and 14; the contrast

between high and low points is more marked than in the clutter scan.

O

"5

e_

-5O

-55-60

_55

-70

-75

-80

-85

_90 J i i

15

Radar settings: R = 1366 m, Az = scanning, El = 20.0°Airplane crossing at time = 19:48:37.1, R = 1359 m, Az = 33.0 °, El = 19.4°, Alt = 467 m AGL

-- Scan 1-clutter

o Scan 10-vortex plus clutter. Scan 10-vortex plus clutter with smoke

.... - 108.0 dBm-

i I J i i , _ , , k i I i i , i I L L i i i I

20 25 30 35 40 45

Azimuth, deg

Figure A7. Total signal level vs. antenna azimuth angle compared with clutter scan for pass 52, azimuth scan 10, on01-09-95.

E

e_

"5

-50

-55

-60

-65

-70

-75

-80

-85

-9015

Radar settings: R = 1366 m, Az = scanning, El = 20.0 °

Airplane crossing at time = 19:48:37.1, R = 1359 m, Az = 33.0 °, El = 19.4 °, AIt = 467 m AGL

-- Scan l-clutter

Scan 14-vortex plus clutterScan 14-vortex plus clutter with smoke

_°_ _ 19:49:32.4, Arl = -107.9 dBm -1

20 25 30 35 40 45

Azimuth, deg

\

Figure A8. As for figure A7, except for azimuth scan 14.

17

-75.5637.92

19:49:32.0

19:49:22.0

Airplane track

D R5 range cell tracko R5 radar

37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg

Figure A9. Pass 52 airplane and Radar 5 ground tracks; tail-on radar view of airplane wake.

18

Figures AI0, A11, A12, and A13 contain three azimuth scans and the ground tracks for pass 54. In scans 8, 12,

and 14, a signal increase is seen at the location of the smoke trails. The signal increase is most obvious in scan 12, 63 sec

after the aircraft crosses the radar track.

Figure A 10.

01-09-95.

B

Oe-,

_0

-50

-55

-60

-65

-70

-75

-80

-85

-9010



20:00:45.4, Arl = -114.3 dBm -1

\

Scan l-clutter

o Scan 8-vortex plus clutter

• Scan 8-vortex plus clutter with smoke

15 20 25

Azimuth, deg

30 35

I

40

Total signal level vs. antenna azimuth angle compared with clutter scan for pass 54, azimuth scan 8, on

E

8.

_D

-5O

-55

-60

-65

-70

-75

-80

-85

-90I0



ooo i+1.Scan 1--clutter



15 20 25 30 35 40

Azimuth, deg


19

E

Oe_

erO1)

.,>

-50

-55

-60

-65

-70

-75

-80

-85

-90 ,10



20:01:11.1, Arl = -115.3 dBm -1 -7

©

©

i i i

-- Scan l-clutter

Scan 14-vortex plus clutter

Scan 14-vortex plus clutter with smoke

15 20 25

Azimuth, deg

, I i , , i I , i , , I

30 35 40


-75.46

-75.48

-75.50

_5

_= -75.52,.d

-75.54

20:01 : 11.0

20:01:02.0

J20:00:45.0

-75.56 ........ _ ......... E37.92 37.90 37.88

North

m Airplane track


o R5 radar

37.86 37.84 37.82 37.80 37.78

Latitude, deg


2O

Figures A14 and A15 contain one azimuth scan and the ground tracks for pass 56. In scan 8, a signal increase and a

signal decrease are seen side by side at the location of the smoke trails.

Figure A14.01-09-95.

-50


Airplane crossing at time = 20:11:18.5, R = 1167 m, Az = 33.0 °, El = 18.1% Alt = 373 m AGL

-55

-65e_

-70 •ed)

"_ -75 dBm-120:12:07.0, Arl = - 114.6>

8 -80,'_ -- Scan l-clutter

c> Scan 8-vortex plus clutter-85• Scan 8-vortex plus clutter with smoke

-90 _ i i i J )

10 15 20 25 30 35 40

Azimuth, deg


-75.44

-75.46

-_ -75.48

2

-75.50,...1

-75.52

-75.54

37.92

North

Airplane trackR5 range cell track

o R5 radar

/20:1 : .

, t n i h i L h J _ n i I i J t i , , I .... h , , , _ I I , t , a I I _ I ] t ..... k L i I , , i a i i , h t I ...... _ , , I

37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg


21

Figures A16 and A17 contain one azimuth scan and the ground tracks for pass 64. In scan 9, a signal increase is seen

at 29 ° azimuth, the location of the smoke trails. An equally large increase is seen at 35 ° .

Figure A 16.

01-09-95.

-50



Er_

O

ot_

O

-55

-60

-65

-70

-75

-80

-85

-9015

20:58:28.0, Arl = -118.2 dBm-_

-- Scan 1-clutter



20 25 30 35

Azimuth, deg

, I I

40 45


-75.44

-75.46

._ -75.48

_5

2

-75.50,.d

-75.52

-75.5437.92

North

Airplane track

D R5 range cell track

o R5 radar

- - - No tracking data

20:58:28.0

37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg


22

Figures A 18, A I 9, A20, and A21 contain three azimuth scans and the ground tracks for pass 99. In scans 4 and 1O, a

signal increase is seen at the location of the smoke trails. In scan 35, 120 sec after the aircraft crosses the radar track, the

signal increase is still present but the smoke has dissipated.

Figure A18.01-10-95.

-50

Radar settings: R = 1364 m, Az = scanning, El = 20.0°Airplane crossing at time = 19:47:17.7, R = 1296 m, Az = 24.6°, El = 21.5°, Alt = 490 m AGL

Ee_

.>.

r¢

-55

4i0

_5

-70

-75

-80

-85

-9010

i i i

O

Scan l-clutter


19'47'31 4 ArI --125 1 dBm-

, I , J _ , I , L L _ I

15 20 25 30 35 40

Azimuth, deg


E

Oe_

'7,

-50

-55

_0

4i5

-70

-75

-80

-85

-9010

Radar settings: R = 1364 m, Az = scanning, El = 20.0 °Airplane crossing at time = 19:47:17.7, R = 1296 m, Az = 24.6 °, El = 21.5°, Alt = 490 m AGL

Scan 1--clutter

o Scan lO-vortex plus clutter• Scan 10-vortex plus clutter with smoke

dBm -1

I I , , , , I _ _ Y I _ , L 1 , , , J I

15 20 25 30 35 40

Azimuth, deg


23

E

I..7

O

e-

r_

-50

-55

-60

-65

-70

-75

-80

-85

-9010



Scan l-clutter


_ 19:49:17.8, Arl = -122.5 dBm -1_ smoke no longer visible

@ o o

i i _ i I i n L n I i a i _ h _ n i , n J i

15 20 25 30 35 40

Azimuth, deg


-75.44

-75.46

._ -75.48

,.-i

g -75.50,..]

-75.52

-75.5437.92

19:49:18.0

1_48:35.0

i

t1

it

19:47:31.0///19:47:39.0

North

ni Airplane track

o R5 range cell track

o R5 radar

.... No tracking data

37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg

Figure A21. Pass 99 airplane and Radar 5 ground tracks; head-on radar view of airplane wake.

24

FiguresA22,A23,andA24containtwoazimuthscansandthegroundtracksforpass100.In scans6 and12,asignaldecreaseisseenatthelocationofthesmoke,whileasignalincreaseisseen4° or 95 m clockwise.

Figure A22.

01-10-95.

-5O


Airplane crossing at time = 19:51:55.8, R = 1365 m, Az = 30.1% El = 19.8 °, Alt = 478 m AGL

"o

o

tm

r¢

-55

-60

-65

-70

-75

-80

-85

-905

©

r,_Ll,,,,I

10 15

Scan l-clutter



19:52:16.2, Arl = -121.9 dBm -1

20 25 30 35

Azimuth, deg


E

oe.,

ta_

e¢

-50

-55

-60

-65

-70

-75

-80

-85

-905


Airplane crossing at time = 19:5l:55.8, R = 1365 m, Az = 30.1 °, El = 19.8 °, Alt = 478 m AGL

<3

i i i , I i , i , I , ,

10 15

Scan 1-clutter



19:52:36.5, Arl = -120.7 dBm -1 --_

20 25 30 35

Azimuth, deg


25

-75.44

-75.46

._ -75.48

= -75.50O

,.d

-75.52

-75.5437.94

North

1 Airplane track


o R5 radar


19:53:10.0

37.92 37.90 37.88 37.86 37.84 37.82 37.80

Latitude, deg


26

Figures A25, A26, A27, and A28 contain three azimuth scans and the ground tracks for pass 103. During this pass, a

crosswind was blowing the smoke trails across the field of view to the left. In scans 8, 17, and 23, a signal increase is

seen at or near the smoke trails.

Figure A25.

01-10-95.

-50



E

t.."

Ot_

t-

"7,

¢)

-55

-60

-65

-70

-75

-80

-85

-9010

, 1

15

-- Scan l-clutter



[-- 20:06:03.4, ArI = -123.1 dBm -1

%

L i L I

20 25 30 35 40

Azimuth, deg


E

e-,t;to

._>

-50

-55

-60

-65

-70

-75

-80

-85

-9010



%0

0

0

°@o

L L L

-- Scan 1-clutter



O

oe:!5_Sn_ ° _- 20:06:40.6, Arl = -123.5 dBm -I

I ,

15 20 25 30 35 40

Azimuth, deg


27

O

QJ

a_

-50

-55

-60

-65

-70

-75

-80

-85

-90lO



Scan l-clutter



r 20:07:14.0, Ar I =-124.3 dBm -1!

y

I I

15 20 25 30 35

Azimuth, deg


i

40

-75.44

-75.46

._ -75.48_5

.2

-75.5o

-75.52

-75.5437.94

Figure A28.

North

1 Airplane track

C _ 7114._ _ _adgarecell track

_ 20.06.41.0

20:06:03.0

37.92

,,, ii,l,l,l,,,i,I ill ii ,i,I I ,,I,l,ll ,iJI

37.90 37.88 37.86 37.84 37.82 37.80

Latitude, deg

Pass 103 airplane and Radar 5 ground tracks; head-on radar view of airplane wake.

28

FiguresA29,A30,A31,andA32containthreeazimuthscansandthegroundtracksfor pass104.In scans5, 11,and15,asignalincreaseisseen2° counterclockwisefromthesmoketrails.Thestrongestincreaseisseenin scan11,48secaftertheaircraftcrossestheradartrack.

FigureA29.01-10-95.

E

-50

-55

-60

-65

-70

Radarsettings:R=1364m,Az=scanning,El=20.0°Airplane crossing at time = 20:10:16.2, R = 1431 m, Az = 20.2 °, El = 19.4 °, Alt = 490 m AGL

Scan l-clutter



-75

-80

-85

-9010

, I

15

__Q:Dc_@_, I 20:10:35.9, AI]= -129.2 dBm -1

, ,

20 25 30 35 40

Azimuth, deg


'x3

Oe_

-50

Radar settings: R = 1364 m, Az = scanning, E1 = 20.0 °


-55

_50

_55

-70

-75

-80

-85

-9010

Scan l-clutter

o Scan 1I-vortex plus clutter

• Scan 1I-vortex plus clutter with smoke

[----- 20:! 1:04.3, Arl = -126.7 dBm-

1

0%%1 _ ,/

15 20 25 30 35 40

Azimuth, deg

Figure A30. As for figure A29, except for azimuth scan 1 1.

29

E

02

Qe_

e-

"5

o

o_

-50



-55

-60

_55

-70

-75

-80

-85

-9010

Scan 1-clutter



_- 20:11:21.8, An = -130.5 dBm -1

15 20 25 30 35 40

Azimuth, deg


-75.44

-75.46

-75.48_5

.2o= -75.50

-75.52

North

m Airplane track


o R5 radar


____20:11:22.0

,- 20:11:16.0///

20:10:36.0 fl

20:10:45.0

-75.54 ......... i ......... t ......... J ......... j ......... i ......... i ......... i37.94 37.92 37.90 37.88 37.86 37.84 37.82 37.80

Latitude, deg


30

FiguresA33, A34, A35, and A36 contain three azimuth scans and the ground tracks for pass 106. Following the

smoke trails from right to left, one sees a signal increase in scan 5, a decrease in scan 12, and an increase and a decrease

in scan 22.

Figure A33.

01-10-95.

-50



E

Oe_

t-

o_e¢

-55

-60

-65

-70

-75

-80

-85

--90

10

_ 20:20:09.0, Ar 1 = -120.0 dBm -1

-- Scan l-clutter



15 20 25 30 35 40

Azimuth, deg


_0

"5

-50



-55

-60

-65

-70

-75

-80

-85

-9010

-- Scan 1-clutter



°Qql_© o

--- 20:20:38.1, All = -121.3 dBm -1

, , _ , I , J I i I J

15 20 25 30 35 40

Azimuth, deg


31

Et_

O

e-

r,,

-50

Radar settings: R = 1111 m, Az = scanning, El = 20.0 °Airplane crossing at time = 20:19:45.25, R = 1110 m, Az = 26.4 °, El = 20.1 °, Alt = 396 m AGL

-55 -- 20:21:19.6, Arl = -114.1 dBm -1

-65t @-70

-75

-80-- Scan l-clutter

o Scan 22-vortex plus clutter-85• Scan 22-vortex plus clutter with smoke

--90 , , , , I , , , _ I , _ , , [ , , , , I _ , , , I , , , , I

10 15 20 25 30 35 40

Azimuth, deg


-75.42

-75.44

x_ -75.46G

g -75.48

-75.50

North

-75.5237.92

Airplane track

tJ R5 range cell track

o R5 radar


_ 20:21:20.0

''' _ 20:20:45.0/

20:20:05.0 _,1, , , ,, , ,I ....... I,l,,,,tL,,,I, ,,,, ,,,,I ........ 11 L,,, , ,t ,,I ,, , ...... I

37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg


32

Figures A37, A38, A39, and A40 contain three azimuth scans and the ground tracks for pass 107. In scan 5, a signal

decrease is seen at the location of the smoke trails, immediately adjacent to a signal increase. In scan 8, a signal decrease

is seen at the smoke trails. In scan 22, a signal increase is seen at the smoke trails, immediately adjacent to a signal

decrease. The videotape showed that, by this time, the shape of the smoke trail leftmost in the field of view had changed

from a straight line to a corkscrew pattern.

-50



-55 -- 20:25:08.0, A_q = -I 10.9 dBm -1

E_ _0

e_

-_ -70

"_ -75

_ -80,¢ -- Scan 1-clutter

o Scan 5-vortex plus clutter-85


-90 I _ _ , , I I , h , , I , , , , I _ , , , I

5 10 15 20 25 30 35

Azimuth, deg

Figurc A37. Total signal level vs. antenna azimuth angle compared with clutter scan for pass 107, azimuth scan 5, on

01-10-95.

E

"O

-50

-55

-60

-65

-70

-75

-80

-85

-90



-- Scan 1-clutter

o Scan 8-vortex plus clutter/_ • Scan 8-vortex plus clutter with smoke

. . . , ---- .

I I , , , _ I I 1 , , L ,

10 15 20 25 30

Azimuth, deg


I

35

33

Oe_

e¢

-50

-55

-60

-65

-70

-75

-80

-85

-905



8 _-- 20:26:19.6, Arl =-112.3 dBm -1

-- Scan l-clutter



10 15 20 25 30 35

Azimuth, deg


-75.42

-75.44

-75.46

-75.48

-75.50

-75.52

20:26:20.0

20:25:09.0

North

20:25:21.0

Airplane track


o R5 radar

-75.54 ........ ' ......... ' ......... _ ......... ' ......... ' ......... ' ......... '37.92 37.90 37.88 37.86 37.84 37.82 37.80 37.78

Lafitude, deg

Figure A40. Pass 107airplaneandRadar5ground _acks; head-on radar viewofairplanewake.

34

Figures A41, A42, and A43 contain two azimuth scans and the ground tracks for pass 108. In scan 7, a signal

increase is seen 4 ° clockwise or 78 m from the smoke trails. In scan 14, a signal increase is seen at the smoke trails with

a signal decrease on either side.

Figure A41.

01-10-95.

-50



-55

E _ F- 20:29:52.5, Aq = -112.4 dBm -1-60i

_._ -65 _ °__o_

-80-- Scan l-clutter


-90 L , J , i , , _ , i i , _ , _ i _ , , _ l i5 10 15 20 25 30 35

Azimuth, deg


E

..o

oe_

e-ex0"5

0)

--50

--55

--60

--65

--70

--75

-80

-85

--90 '5


Airplane crossing at time = 20:29:19.5, R = 1109 m, Az = 21.3 °, El -- 20.7 °, Alt = 407 m AGL

_ 20:30:37.0, Arl = -118.8 dBm -1

Scan l-clutter



10 15 20 25 30 35

Azimuth, deg


35

-75.44

-75.46

North

i Airplane track


o R5 radar


-75.48,; 20:30:37.0

2

-75.50,.d

// /20:30:12.0

-75.52 /4

20:29:44.0

-75.54 ........ i ......... t ......... _......... i ......... i ......... i ......... i

37.92 37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg


36

Figures A44, A45, and A46 contain two azimuth scans and the ground tracks for pass 109. During this pass, the

antenna was scanning slightly above the elevation of the aircraft track and the smoke trails could not be seen on the bore-

sight videotape. In scans 4 and 5, 21 sec and 54 sec after the aircraft crosses the radar track, a large signal increase is

seen at 43 ° azimuth, 155 m from the aircraft track.

Figure A44.

01-10-95.

-50



E

e_

e-

-55

-60

-65

-70

-75

-80

-85

--90

20

20:34:11.1, A'q = -113.3 dBm -1 --

,

-- Scan l-clutter

o Scan 4-vortex plus clutter; smoke not visible on video

J i _ I I _ , , L I I I I

25 30 35 40 45 50

Azimuth, deg


Ee_

e_

-50

-55

-60

-65

-70

-75

-80

-85

-9020


Airplane crossing at time = 20:33:50.4, R = 1167 m, Az = 34.7 °, El -- 18.2 °, Alt = 381 m AGL

20:34:44.5, Arl = -113.1 dBm -1

-1S Jo

_°°o%" _ _ _ca° _--.A

°°

-- Scan l-clutter

o Scan 5-vortex plus clutter; smoke not visible on video

I J k i L I I i I L

25 30 35 40 45

Azimuth, deg


50

37

-75.44

-75.46

_gj

._ -75.48

_0

_= -75.50,..1

_-- North

Airplane track

D R5 range cell track

o R5 radar


20:35:02.0

//

//

//

/

!-75.52 20:34:11.0

-75.54 ........ i ......... i ......... i ......... j ......... i ......... j .........

37.92 37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg


38

Figures A47, A48, A49, and A50 contain three azimuth scans and the ground tracks for pass 117. In scans 11, 18,

and 19, a signal increase is seen accompanied by a signal decrease on either side. The signal disturbance follows the

smoke trails as they drift from right to left.

Figure A47.

01-11-95.

-50



Ee_

e_

e-,

"5

ev

-55

-60

-65

-70

-75

-80

-85

-905

F 16:53:39'7, Aq =-1212 dBm-I

t

©

i J i

-- Scan l-clutter

Scan 1l-vortex plus clutter

Scan 1l-vortex plus clutter with smoke

10 15 20 25 30

Azimuth, deg

35


E

e.

"5

-5O

-55

-60

-65

-70

-75

-80

-85

-905



1654: :105. ,A'q=-1166dBm.

-- Scan 1-clutter



, , L _ I _ _ h _ L . _ _ _ I _ I I

10 15 20 25 30

Azimuth, deg


I

35

39

E"O

OIZk

_m

"3

Radar settings: R = 1 ! 11 m, Az = scanning, E1 = 20.0 °

Airplane crossing at time = 16:52:54.3, R = 1107 m, Az = 39.8 °, El = 19.6 °, Alt = 386 m AGL-50

_55__o_ _- 16:54:13.3, A'q = -107.1 dBm -1

F _

-70

-80-- Scan 1-clutter


--90 , , _ , I _ _ _ _ I , , , _ 1 _ J _ , I , , _ _ I , _ _ _ I

5 10 15 20 25 30 35

Azimuth, deg


-75.46

-75.44

-75.46

,i

._ -75.48

O

-75.50

_ North

mm Airplane track

t_ R5 range cell track

o R5 radar

16:54:13.016:54:11.0

-75.52 1

16:53:40.0

-75.54 ........ i ......... i ......... i ......... J ......... L ......... i ......... i37.94 37.92 37.90 37.88 37.86 37.84 37.82 37.80

Latitude, deg


40

Figures A51, A52, A53, A54, and A55 contain four azimuth scans and ground tracks for pass 122. In scan 4, signal

increases are seen on either side of the smoke trails. In scans 5, 10, and 11, a signal increase moves with the smoke trails

from right to left. The videotape showed that the smoke trails had been blown diagonal to the camera view by

17:21:48.0, which implies that the wake should occupy an increased angular span, compared to the wake in most of the

passes.

-50

Radar settings: R = 1366 m, Az = scanning, El = 20.0 °Airplane crossing at time = 17:21:31.7, R = 1367 m, Az = 27.2 °, El = 20.0 °, AIt = 481 m AGL

E

55-60 •

-65

-70

-75 ___ _ _ 17:21:53.3, A'q

-80 _C_e Z_

-90 , , , , I , , , , _ I , , , , I , _ , , I

10 15 20 25 30

Azimuth, deg

-- Scan l-clutter


= -122.8 dBm -1

ILkLI

35

Figure A51. Total signal level vs. antenna azimuth angle compared with clutter scan for pass 122, azimuth scan 4, on01-11-95.

E

O

'7,

cO

-50

-55

-60

--65

-70

-75

-80

-85

-90

Radar settings: R = 1366 m, Az = scanning, El = 20.0°Airplane crossing at time = 17:21:31.7, R = 1367 m, Az = 27.2 °, El = 20.0°, Alt = 481 m AGL

Scan l--clutter\ o Scan 5-vortex plus clutter


_ 17:21:56.8, At1 = -124.8 dBm -1

10 15 20 25 30 35

Azimuth, deg


41

E

t2

oIzL

.>,

-50

-55

-60

-65

-70

-75

-80

-85

-905



17:22:18.6, Ar I = -104.7 dBm -1

/__//_ J O_-O' .... Scan l-clutter

_6 _ o Scan 10-vortex plus clutter

10-vortex plus clutter with smoke

, , _ L I , , J _ 1 1 I I t

10 15 20 25 30 35

Azimuth, deg


Et_

¢xO

-50

-55

-60

-65

-70

-75

-80

-85

-90



cz_6:_gl_-- 17:22:22.3, Ar 1 = -106.2 dBm -1

x_r • ---- Scan l-clutter

\ /r_ _ o Scan I 1-vortex plus clutter

_5_Q_/ Scan I 1-vortex plus clutter with smoke

J , _ , I _ * _ , I , , _ _ I _ _ , _ I , _ , _ I , , _ L I

10 15 20 25 30 35

Azimuth, deg


42

-75.46

-75.48

._ -75.50

_o" -75.52O

,.d

-75.54

North

Airplane track

17:22:22.0 n R5 range cell track

_ 17"22"190 © R5radar_/ " " i7"21"570 Notrackin data

5_.0 .... g

........... I I I I I I I I J I I I I I 1 I I _ I I I I I ......... _ ......... _ ......... I-75.5637.94 37.92 37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg


43

Figures A56, A57, A58, and A59 contain three azimuth scans and the ground tracks for pass 123. In scan 4, a signal

increase is seen coincident with the smoke trails, immediately adjacent to a signal decrease. In scan 7, a signal increase

is seen between two signal decreases. In scan 123, a signal decrease is seen coincident with the smoke trails, adjacent to

a signal increase. Over a 48 sec period, the signal disturbance moves with the smoke from right to left.

Figure A56.01-11-95.

-50

Radar settings: R = 1366 m, Az = scanning, El = 20.0 °Airplane crossing at time = 17:27:31.7, R = 1364 m, Az = 30.0 °, El = 19.7°, Alt = 475 m AGL

E

e.

_J

t_

-55

--60

-65

-70

-75

-80

-85

-90

/___ • ii:_ i--CvvlU_t:texxrp:u: :llU:t_e_with smoke

rI =-124.6 dBm-l_

10 15 20 25 30 35

Azimuth, deg


E

@e_

-50

-55

450

455

-70

-75

-80

-85

-905

Radar settings: R = 1366 m, Az = scanning, E1 = 20.0 °Airplane crossing at time = 17:27:31.7, R = 1364 m, Az = 30.0 °, E1 = 19.7°, Alt = 475 m AGL

,--. _ Scan 1--clutter/ v _ o Scan 7-vortex plus clutter

/ V _can 7-vortex plus clutter with smoke

17:27:53.7, AT]= -124.8 dBm -1

i i i _ J i i i i I _ i i I I i i I L I i I i J I J _ _ _ r

10 15 20 25 30 35

Azimuth, deg


Oe_

-50

-55

-60

-65

-70

-75

-80

-85

-90


Airplane crossing at time = 17:27:31.7, R = 1364 m, Az = 30.0 °, El = 19.7 °, Alt= 475 m AGL

17:28:30.0, _J \

ArI = -102.2 dBm-l_

L i _ J I i J J _ I i i i I I

10 15 20

Scan l-clutter



25 30 35

Azimuth, deg


-75.46

O,.d

-75.48

-75.50

-75.52

-75.54

-75.56

-75.5837.94

_/ 17:28:30.0

17:27:54.0

_/ 17:27:42.0

_ North

Airplane track


o R5 radar


37.92 37.90 37.88 37.86 37.84 37.82 37.80

Latitude, deg


45

FiguresA60,A61,andA62containtwoazimuthscansandthegroundtracksforpass127.In scans8and9,signaldisturbancesareseeninvariouspartsof thescan.Thedisturbancesnotclosetothesmoketrailsareequalinmagnitudetothoseatthelocationof thesmoketrails.

FigureA60.01-11-95.

-50Radarsettings:R=1109m,Az=scanning,El=20.0°Airplanecrossingattime=17:51:25.7,R=1170m,Az=35.7°, El = 17.7 °, Alt = 370 m AGL

-55

Ea_ -60

_2*_ -65o

-70e-,

-75

-80

-85

_ 17:52:04.6, Arl = -115.2 dBm -1



, _ I , _ _ , I h _ J A I , , , j I I _ , , _ I

10 15 20 25 30 35

Azimuth, deg


E

e_

e-

0_.,>

_D

-50

-55

-60

-65

-70

-75

-80

-85

-905



Scan 1-clutter



52:10 -

J _ I L , , , I t , _ , L , _ , , I , _ , , I

10 15 20 25 30

Azimuth, deg


, I

35

46

-75.48

-75.50

-75.52

2

= -75.54O,-2

-75.56

-75.5837.94

17:52:11.0

_/ t7:52:05.0

North

1 Airplane track


o R5 radar


\\

\

\

37.92 37.90 37.88 37.86 37.84 37.82 37.80

Latitude, deg


47

Figures A63, A64, A65, A66, and A67 contain four elevation scans and the ground tracks for pass 132. In scans 7, 8,

9, and 11, a signal decrease is seen coincident with the smoke trails. During this span of 13 sec, the smoke trails have

moved slightly downward, then returned to their original position.

-50



-55

Em -60

0_ -65

-70or)

"_ -75

-80

-85

-- Scan 1-clutter



_-- 18:34:57.1, ATI = -122.5 dBm -1

--90 _ i L i I i _ i _ _ i i i i 1 i L , _ I _ L _ i I L i _ J I

10 15 20 25 30 35 40

Elevation, deg


01-11-95.

E

_0

e_

-50

-55

-60

-65

-70

-75

-80

-85

-90lO



-- Scan 1-clutter



_1 _ AT1= -126.8 dBm -1

i r i

15 20 25 30 35

Elevation, deg

i I

40


48

Eea"O

O

-50

-55

-60

-65

-70

-75

-80

-85

-9010

Radar settings: R = 1259 m, Az = 145.0% El = scanning


-- Scan 1-clutter



o%o 18:35:04.4, Arl = -121.5 dBm -1

O

i _ L I , J , , I J h i _ I I I

15 20 25 30 35

Elevation, deg


J

4O

E

8.

,v

-5O

-55

-60

-65

-70

-75

-80

-85

-9010



-- Scan l--clutter

o Scan 1 l-vortex plus clutter


ee'_---- 18:35:10.2, Arl = -121.7 dBm -1

, i I i I I I I

15 20 25 30 35

Elevation, deg


I

40

49

-75.5637.90

18:35:04.018:35:10.0 18:35:01.0

¢_/ 18:34:57.0

North

Airplane track


o R5 radar

37.88 37.86 37.84 37.82 37.80 37.78 37.76

Latitude, deg


5O

Figures A68, A69, and A70 contain two elevation scans and the ground tracks for pass 137. In scans 7 and 1 1, a

signal increase is seen at the elevation of the smoke trails.

-50



Ee_

@e_

e¢

-55

-60

-65

-70

-75

-80

-85

-9010

o

i i i

-- Scan l-clutter



, J _ J _ , L , , , , f _ J , L I L , ,

15 20 25 30

Elevation, deg

, 1 I

35 40


01-1 1-95.

Ee_

Oe_

e-,

e_

-50

-55

-60

-65

-70

-75

-80

-85

-9010


Airplane crossing at time = 19:10:40.6, R = 1031 m, Az = 151.0 °, El = 31.8 °, Air = 559 m AGL

-- Scan 1-clutter


• Scan 1 l-vortex plus clutter with smoke

i _ _ I i i i i I i i i L I i i i J ] I i i i J J d _ h

15 20 25 30 35

Elevation, deg


I

40

51

-75.48

-75.50

ot_

._ -75.52

_ -75.54

-75.56

-75.5837.92

North

19:10:59.0 1 Airplane a'ack

i 19:10:51.0 D R5 range cell tracko R5 radar

37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg


52

Figures A71, A72, A73, A74, and A75 contain four elevation scans and the ground tracks for pass 141. In scans 7, 8,

9, and 14, a signal level increase is seen at the elevation of the smoke trails.

-50


Airplane crossing at time = 19:37:47.3, R = 1095 m, Az = 151.0°, El = 25.6 °, Alt = 489 m AGL

E

rg

"7,

-55

-60

-65

-70

-75

-80

-85

-9010

©

i i i

_- 19:38:01.0, Arl = -115.8 dBm -1

0 ©

-- Scan l--clutter


15 20 25

Elevation, deg

_,1 I I

30 35 40

Figure A71. Total signal level vs. antenna elevation angle compared with clutter scan for pass 141, elevation scan 7, on01-1 1-95.

E

r;O

"3

-50

-55

-60

-65

-70

-75

-80

-85

-9010

Radar settings: R = 1089 m, Az = 151.0 °, E1 = scanningAirplane crossing at time = 19:37:47.3, R = 1095 m, Az = 151.0°, E1 = 25.6 °, Alt= 489 m AGL

_ 19:38:03.7, Ar I = -117.7 dBm -1

-- Scan l-clutter

o Scan 8-vortex plus clutter• Scan 8-vortex plus clutter with smoke

15 20 25 30 35

Elevation, deg


, 4

40

53

-50

-55

Em -60

-65

&-70

"_ -75.._

-80



19:38:16.8, Arl = -117.0 dBm -1

-- Scan l-clutter

-85 o Scan 14-vortex plus clutter


--90 L , _ , I , , , _ I _ _ _ , I _ _ _ _ I , _ _ _ I _ _ _ , I

10 15 20 25 30 35 40

Elevation, deg


-50



-55

Et_ -60

-65O

-70

"_ -75

-80

-- 19:38:24.8, AB = -117.4 dBm -1

O O

-- Scan l-clutter

-85 o Scan 18-vortex plus clutter


--90 , , , , I , , , , I , , i , I , _ , , 1 , , _ _ 1 , _ , , I

10 !5 20 25 30 35 40

Elevation, deg


54

"O

e*O

,.d

-75.46

-75.48

-75.50

-75.52

-75.54

-75.56

Figure A75.

North

Airplane track

R5 range cell track

19:38:17.0 o R5 radar19:38:25.0. : : .

i _ iii i i i I i i , I

37.92 37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg

Pass 141 airplane and Radar 5 ground tracks; lateral radar view of airplane wake.

55

Figures A76, A77, and A78 contain two elevation scans and the ground tracks for pass 143. In scan 12, a signal

increase is seen coincident with the smoke trails. By scan 27, the smoke had dissipated too much to locate precisely.

Examining scan 27 around 28 °, the elevation of the smoke trails in scan 12, one sees a signal decrease directly above

that point and a signal decrease directly below. This pass was flown using 50 percent flaps, which caused the smoke

trails to be visibly larger initially than the smoke trails with no flaps; the trails also dissipated faster.

-50


Airplane crossing at time = 19:51:49.2 R = 1133 m, Az = 151.0 °, El = 25.7 °, Alt = 507 m AGL

E

t_

e-

"7,

"3

e¢

-55

-60

--65

-70

-75

-80

-85

-9010

O

F 19:52:16.5, All =-116.3 dBm -1

-- Scan l-clutter



15 20 25 30 35

Elevation, deg

I

40


01-11-95.

E

"-d

"3

r_

-50

-55

-60

-65

-70

-75

-80

-85

-9010


Airplane crossing at time = 19:51:49.2 R = 1133 m, Az = 151.0 °, El = 25.7 °, AIt = 507 m AGL

©

___ _-- 19:52:54.6, Ar I = -114.5 dBm -1

_ (smoke no longer distinct)

©

Scan 1-clutter


_ J _ I , _ J L I , , L _ I J i L _ I _ _ , _ I _ _ , _ I

15 20 25 30 35 40

Elevation, deg


56

-75.46

-75.48

tao

._ -75.50

g -75.52,.d

-75.54

North

Airplane track


© R5 radar19:52:55.0

: : .

-75.56 h ......... J I ......... i _ I ......... I37.92 37.90 37.88 37.86 37.84 37.82 37.80 37.78

Latitude, deg


$7

Figures A79 and A80 contain one elevation scan and the ground tracks for pass 149. In scan 5, a signal increase is

seen just above the smoke trails. The clutter scan does not quite reach to the position of the smoke trails.

Figure A79.

01-11-95.

-50

-55 1


Airplane crossing at time = 20:36:45.2, R = 1401 m, Az = 141.0 °, E1 = 14.5 °, Ait = 403 m AGL

ra -60

-65O

-70

"5"_ -75.,>0)

-80

-85

-9010

i L

<3

L

-- 20:36:54.6, Ar I = -113.1 dBm -1

Scan l-clutter \ /Scan 5-vortex plus clutter "-,---x.J


15 20 25 30 35

Elevation, deg

i , I

40

Total signal level vs. antenna elevation angle compared with clutter scan for pass 149, elevation scan 5, on

-75.46

-75.48

-75.50

.__ol)

_ -75.52

-75.54

-75.5637.90

North

_- Airplane u'ackD R5 range cell track

k o R5 radar

i lilllll _lll _nll_ll k_ll Lllll llL_a ILI II Ill] I Llal _

37.88 37.86 37.84 37.82 37.80 37.78 37.76

Latitude, deg


58

Appendix B

Meteorological Data

Wallops meteorological data were collected at 2-hr intervals. The following table contains those data recorded clos-

est in time to the wake vortex radar recordings shown in this report.

Table B 1. Meteorological Conditions at 400 m AGL

Condition

Temperature, °C

Pressure, mb

Water vapor mixing ratio, g/kg

Vertical gradient of water vapormixing ratio, mg/kg/m

Cross-aircraft beating windspeed, (1)m/s

1-5-95

20:00UTC

-7.1

977.8

0.8

-0.44

-15.0

1-9-95

20:00UTC

1.6

972.8

2.8

0.13

-1.6

1-10-95

20:00UTC

0.8

978.9

2.8

0.27

-1.5

1-11-95

16:00UTC

6.3

980.4

5.0

-0.05

5.2

1-11-95

18:00UTC

6.2

978.4

3.7

-8.24

5.0

1-11-95

20:00UTC

6.9

977.3

4.0

-2.83

2.4

(l JCrosswind may be estimated more closely for some passes by noting change in smoke position from azimuth scan to azimuth scan inappendix A.

59

Appendix C

Variability of Clutter Powerat Various Time Lags

Thisappendixpresentstheunsmoothedvaluesusedto createfigures5 and 6 in the text. Note that azimuth is the

interpolated antenna position in degrees, SD power is the standard deviation of the change in received power after thegiven time lag in dBm, time refers to the time lag given in seconds, and N denotes the number of samples.

Table C2. Unsmoothed Data for Figure 5, Azimuth Scans at 20 ° Elevation

SD

Azimuth power Time

10.750010.750010.7500

10.750010.7500

10.750011.0000

11.000011.0000

11.000011.000011.0000

11.2500I 1.2500

11.250011.250011.2500

11.250011.5000

11.500011.500011.5000

11.500011.5000

11.750011.7500

11.750011.7500

I 1.750011.750012.0000

12.000012.0000

12.000012.0000

12.000012.250012.2500

12.250012.2500

12.250012.2500

12.5000

1.865162.04956

1.992102.08377

2.191362.428652.09604

2.217902.01227

2.006222.251412.28617

2.338212.38351

2.430082.11737

2.350722.421062.29717

2.109022.15305

2.111392.093812.14627

2.11190

2.143091.938402.14580

1.962442.04499

2.498372.545772.53014

2.575672.50777

2.346072.68786

2.641232.567342.64848

2.735082.57608

2.61319

N

1.75279 49 12.5000

36.2105 98 12.500072.4204 96 12.5000108.645 94 12.5000

144.878 92 12.5000181.121 90 12.7500

1.96620 49 12.750036.2104 98 12.7500

72.4202 96 12.7500108.645 94 12.7500

144.878 92 12.7500181.121 90 13.00002.17793 49 13.000036.2104 98 13.0000

72.4202 96 13.0000

108.645 94 13.0000144.878 92 13.0000181.121 90 13.2500

2.39070 49 13.250036.2104 98 13.2500

72.4202 96 13.2500108.645 94 13.2500144.878 92 13.2500

181.121 90 13.50002.60196 49 13.5000

36.2105 98 13.500072.4203 96 13.5000108.645 94 13.5000

144.878 92 13.5000181.121 90 13.7500

2.81354 49 13.750036.2104 98 13.7500

72.4203 96 13.7500108.645 94 13.7500

144.878 92 13.7500181.121 90 14.00003.02431 49 14.0000

36.2104 98 14.000072.4202 96 14.0000

108.645 94 14.0000144.878 92 14.0000

181.121 90 14.25003.23453 49 14.2500

SD

Azimuth power Time

2.27141

2.294272.33967

2.401252.20463

2.227542.020641.95228

1.983842.07850

2.114701.972591.91869

2.100052.07644

2.191862.108901.92246

1.932792.05842

2.150232.26410

1.902991.90492

2.174992.040021.90837

2.281301.99290

2.144902.12263

2.091522.09159

2.112291.969202.24227

2.119062.06138

2.032372.078351.95188

2.27116

2.20321

N

36.2104 98 14.250072.4202 96 14.2500108.645 94 14.2500

144.878 92 14.2500181.121 90 14.5000

3.44523 49 14.500036.2104 98 14.5000

72.4202 96 14.5000108.645 94 14.5000144.878 92 14.5000

181.121 90 14.75003.65553 49 14.7500

36.2105 98 14.750072.4203 96 14.7500

108.645 94 14.7500144.878 92 14.7500181.121 90 15.0000

3.86567 49 15.000036.2105 98 15.0000

72.4204 96 15.0000108.645 94 15.0000144.878 92 15.0000

181.121 90 15.2500

4.07518 49 15.250036.2104 98 15.2500

72.4202 96 15.2500108.645 94 15.2500144.878 92 15.2500

181.121 90 15.50004.28508 49 15.500036.2103 98 15.5000

72.4202 96 15.5000108.645 94 15.5000

144.878 92 15.5000181.121 90 15.7500

4.49522 49 15.750036.2103 98 15.7500

72.4202 96 15.7500108.645 94 15.7500144.878 92 15.7500

181.121 90 16.00004.70416 49 16.0000

36.2105 98 16.0000

SD

Azimuth power Time

2.32172

2.166272.1 64662.13369

2.162392.02886

2.202611.91414

2.093062.083512.38763

2.339282.53594

2.359142.441 I0

2.575102.374662.18045

2.187222.250012.29479

2.309622.23267

1.95569

1.980442.268552.16308

2.231902.32088

2.046362.066392.42046

2.086692.09342

2.492862.21316

2.139512.42093

2.206312.264842.28421

2.196362.16279

N

72.4204 96

108.645 94144.878 92

181.121 904.91406 49

36.2104 9872.4202 96108.645 94

144.878 92181.121 90

5.12317 4936.2104 98

72.4202 96108.645 94

144.878 92181.121 905.33251 4936.2103 98

72.4202 96

108.645 94144.878 92181.121 90

5.54098 4936.2105 98

72.4204 96108.645 94

144.878 92181.121 905.75096 49

36.2104 9872.4202 96108.645 94

144.878 92

181.121 905.95982 49

36.2103 9872.4202 96108.645 94

144.878 92181.121 906.16773 49

36.2104 98

72.4202 96

60

Table C2. Continued

SD

Azimuth power Time

16.0000

16.000016.0000

16.250016.2500

16.250016.2500

16.250016.2500

16.500016.500016.5000

16.5000

16.500016.500016.7500

16.7500

16.750016.750016.7500

16.750017.0000

17.000017.000017.0000

17.000017.0000

17.2500

17.250017.250017.2500

17.250017.250017.5000

17.500017.500017.5000

17.5000

17.500017.750017.7500

17.750017.750017.7500

17.750018.0000

18.000018.0000

18.000018.0000

2.30214

2.226622.36057

2.469032.44565

2.321092.63281

2.479272.49600

2.411352.303612.26556

2.402832.34931

2.318232.34139

2.342472.13042

2.140142.32302

2.155342.19963

2.242032.140382.06668

2.221522.15245

2.317732.14314

2.260302.215342.48979

2.206662.273552.48322

2.483832.50840

2.767882.39943

2.190722.36958

2.449072.538762.76777

2.369612.13331

2.291632.21561

2.418252.28506

108.645144.878

181.t216.37739

36.210372.4202

108.645144.878

181.1216.58586

36.210472.4202

108.645144.878

181.1216.79520

36.210472.4203

108.645144.878181.121

7.00367

36.210372.4202108.645144.878

181.121

7.2126136.2103

72.4202108.645144.878

181.1217.4210036.2104

72.4203108.645

144.878181.121

7.6292336.210472.4203

108.645144.878181.121

7.83881

36.210572.4203108.645

144.878

N

9492

9049

9896

9492

9049

9896

9492

9049

989694

9290

4998

969492

90

499896

9492

90499896

94

929049

9896

949290

4998

9694

92

SD

Azimuth power Time

18.000018.2500

18.250018.2500

18.250018.2500

18.250018.5000

18.500018.5000

18.500018.5000

18.500018.750018.7500

18.750018.7500

18.750018.7500

19.000019.0000

19.000019.0000

19.000019.000019.2500

19.2500

19.250019.250019.2500

19.250019.500019.5000

19.500019.500019.5000

19.5000

19.750019.750019.7500

19.750019.750019.7500

20.000020.0000

20.000020.0000

20.000020.0000

20.2500

2.231191.95851

2.095882.06894

2.257121.98776

2.069192.11993

2.225022.21967

2.449962.077202.22686

2.475382.49033

2.492202.79249

2.245462.38295

2.231422.45348

2.369882.32219

2.216462.284272.22075

2.461622.58096

2.188902.45270

2.161792.016742.54149

2.561282.064262.53685

2.182252.28202

2.602092.60616

2.453212.591162.39600

2.306042.44864

2.330882.44010

2.301392.358842.27481

181.1218.04679

36.210372.4202

108.645144.878

181.1218.25502

36.210372.4202108.645

144.878181.121

8.4632536.2103

72.4202108.645

144.878181.121

8.6722736.2104

72.4203108.645

144.878181.1218.88074

36.210372.4202

108.645144.878181.121

9.0892936.2104

72.4203108.645144.878

181.1219.29696

36.210372.4202

108.645144.878181.121

9.5055836.210472.4203

108.645144.878

181.1219.71413

N

9049

9896

9492

9049

989694

9290

4998

9694

9290

4998

969492

9049

9896

9492

904998

969492

9049

9896

94929049

9896

9492

9049

SD

Azimuth power Time

20.250020.2500

20.250020.2500

20.250020.500020.5000

20.5000

20.500020.500020.5000

20.750020.7500

20.750020.7500

20.750020.7500

21.000021.0000

21.000021.000021.0000

21.000021.2500

21.250021.2500

21.250021.2500

21.250021.500021.5000

21.500021.500021.5000

21.500021.7500

21.750021.7500

21.750021.750021.7500

22.000022.000022.0000

22.000022.0000

22.000022.2500

22.250022.2500

2.356912.182342.36903

2.25634

2.234132.001951.96922

1.780081.87790

2.012582.04464

2.094342.32604

1.902412.01906

2.039522.11041

2.156352.306982.01225

2.078822.05137

2.253452.362242.51769

2.20970

2.3O9932.43410

2.521372.682352.691542.76200

2.449832.710002.67825

2.45259

2.627962.726812.32081

2.667032.39622

2.286582.453112.39949

2.197372.54563

2.195512.35840

2.439202.28541

36.2104

72.4203108.645

144.878

181.1219.9230736.2103

72.4202108.645

144.878181.12110.1309

36.210372.4202

108.645144.878

181.12110.3391

36.210372.4202

108.645144.878

181.12110.547336.2104

72.4203108.645

144.878181.121

10.755736.210472.4203

108.645144.878181.121

10.964636.2103

72.4203108.645

144.878181.12111.1728

36.210372.4202108.645

144.878

181.12111.379936.2103

72.4202

N

98

9694

9290

4998

9694

929049

9896

9492

9049

9896

9492

904998

9694

929049

9896

949290

4998

969492

9049

989694

92

904998

96

61

SDAzimuth power Time22.250022.250022.250022.500022.500022.500022.500022.500022.500022.750022.750022.750022.750022.750022.750023.000023.000023.000023.000023.000023.000023.250023.250023.250023.250023.250023.250023.500023.500023.500023.500023.500023.500023.750023.750023.750023.750023.750023.750024.000024.000024.000024.000024.000024.000024.250024.250024.250024.250024.2500

2.177202.459062.221492.368932.547822.420532.123472.544502.268302.193622.614832.434292.349622.539502.357492.329602.708572.685302.514632.565792.548882.356622.403872.443012.161762.327692.481182.443692.501412.617252.172502.415492.659272.245212.446392.612252.122132.332372.660002.096912.412412.515101.977762.249892.558882.149162.410142.460292.062582.22470

108.645144.878181.12111.589136.210372.4202108.645144.878181.12111.797436.210472.4204108.645144.878181.12112.006936.210372.4202108.645144.878181.12112.214436.210372.4202108.645144.878181.12112.421336.210372.4202108.645144.878181.12112.630736.210372.4203108.645144.878181.12112.839336.210572.4204108.645144.878181.12113.048736.210472.4203108.645144.878

TableC2.Continued

N94929O4998969492904998969492904998969492904998969492904998969492904998969492904998969492904998969492


2.427361.934332.507192.547122.089762.241052.292612.156632.712252.678432.344772.478392.486542.495032.923172.887672.679662.562982.688092.340832.673702.652732.775892.562912.677152.198182.588912.590032.764762.571362.504672.263142.816322.671672.764202.534612.721862.524533.080862.646132.794772.590572.741422.869043.091722.911523.333142.939552.773002.66045

181.12113.256136.210272.4202108.645144.878181.12113.464136.210372.4203108.645144.878181.12113.672836.210472.4202108.645144.878181.12113.881536.210372.4203108.645144.878181.12114.090536.210372.4203108.645144.878181.12114.298036.210372.4202108.645144.878181.12114.506636.210472.4203108.645144.878181.12114.715136.210472.4204108.645144.878181.12114.9235

N9049989694929049989694929049989694929049989694929049989694929049989694929049989694929049989694929049


2.815622.826353.006142.692452.932952.381222.688902.548342.886942.923622.706781.946582.243582.264692.540052.536612.199212.169992.166112.149912.492132.312402.008262.252782.120202.095792.391712.254192.344142.163812.253442.052262.331212.159822.180281.987262.218062.180752.430722.098192.438222.334702.552792.739862.738762.389702.923022.517652.728862.78159

36.210372.4202108.645144.878181.12115.131936.210372.4203108.645144.878181.12115.339836.210372.4202108.645144.878181.12115.548536.210372.4203108.645144.878181.12115.756836.210472.4204108.645144.878181.12115.966036.210472.4204108.645144.878181.12116.175136.210372.4204108.645144.878181.12116.382736.210372.4202108.645144.878181.12116.591736.210472.4204

N9896949290499896949290499896949290499896949290499896949290499896949290499896949290499896949290499896

62


2.781692.504212.707562.479782.918622.953102.829352.723822.692242.278942.409712.544492.297362.265352.400642.145882.178642.384942.085222.005562.292492.081912.093762.100861.977941.977842.249582.006791.978791.974601.894441.953331.964841.757391.787471.703701.675341.781211.815361.791791.879771.668011.698001.775371.742991.612221.698521.615191.578071.65555

108.645144.878181.12116.799536.210472.4204108.645144.878181.12117.009536.210472.4204108.645144.878181.12117.217136.210272.4201108.645144.878181.12117.424836.210572.4204108.645144.878181.12117.633436.210472.4204108.645144.878181.12117.841536.210372.4202108.645144.878181.12118.051636.210472.4204108.645144.878181.12117.954536.210372.4202108.645144.878

N9492904998969492904998969492904998969492904998969492904998969492904998969492904998969492905098969492

TableC2.Continued


1.574241.554351.538551.550231.517321.443041.459851.816751.778231.912001.798651.855711.923822.194092.197962.342492.230202.230432.296972.420482.265522.678272.687342.587532.423372.790012.514502.725602.928703.018682.585722.644322.756922.628992.921693.050372.563872.401552.458452.496622.730702.528502.546582.181882.128532.273072.270702.025302.035932.09751

181.12117.746036.210472.4204108.645144.878181.12117.536736.210472.4204108.645144.878181.12117.329036.210472.4203108.645144.878181.12117.119936.210472.4205108.645144.878181.12116.912336.210472.4203108.645144.878181.12116.703536.210372.4203108.645144.878181.12116.495436.210472.4203108.645144.878181.12116.286936.210472.4204108.645144.878181.12116.0776

N905098969492905O989694929050989694929050989694929050989694929050989694929050989694929050989694929050


2.120172.135351.894701.901791.967461.873081.927641.929101.714281.886821.847921.734881.636691.696461.598961.716171.724661.807991.591111.659141.782381.808531.844021.585711.604061.731411.741331.774131.682771.437081.712481.832631.679551.776261.854621.762841.868421.849601.867601.925262.034081.846412.042661.960332.051082.027022.212341.984762.169532.04150

36.210372.4204108.645144.878181.12115.870236.210472.4203108.645144.878181.12115.661636.210472.4203108.645144.878181.12115.453736.210472.4204108.645144.878181.12115.244536.210472.4204108.645144.878181.12115.035736.210472.4204108.645144.878181.12114.828136.210472.4204108.645144.878181.12114.618736.210472.4204108.645144.878181.12114.411236.210472.4203

N989694929O5O989694929O5O98969492905O9896949290509896949290509896949290509896949290509896949290509896

63

TableC2.Continued

SDAzimuth power Time34.750034.750034.750035.000035.000035.000035.000035.000035.000035.250035.250035.250035.250035.250035.250035.500035.500035.500035.500035.500035.500035.750035.750035.750035.750035.750035.750036.000036.0(036.000036.000036.000036.000036.250036.250036.250036.250036.250036.250036.500036.500036.500036.500036.500036.500036.750036.750036.750036.750036.7500

2.192652.156942.294982.128742.152652.131702.323602.210612.323092.229312.603002.548492.732082.363962.408642.514402.827652.636652.871082.625832.635342.544462.804662.634782.879032.858202.876282.296452.656312.734392.617693.084722.895012.634652.719542.836682.677472.881032.859752.749042.835852.766092.877732.945462.748402.426832.533082.560562.553882.43414

108.645144.878181.12114.202636.210372.4203108.645144.878181.12113.993636.210472.4204108.645144.878181.12113.786236.210472.4203108.645144.878181.12113.578036.210372.4203108.645144.878181.12113.369236.210372.4203108.645144.878181.12113.160536.210472.4204108.645144.878181.12112.953236.210372.4203108.645144.878181.12112.744636.210372.4202108.645144.878

N94929O5O98969492905O98969492905098969492905098969492905098969492905098969492905098969492905098969492


2.612362.154562.514552.518342.512002.520252.575162.509242.605352.445482.701102.827692.704132.524632.574342.392902.687492.817512.577922.275462.390842.360632.346742.665352.331862.202872.257172.339712.198042.524932.147452.322342.342472.403062.404142.424622.159642.016042.249612.204732.250272.100632.145712.243442.466062.318272.307002.290382.428372.70879

181.12112.535936.210472.4204108.645144.878181.12112.328436.210372.4203108.645144.878181.12112.118636.210472.4204108.645144.878181.12111.911436.210372.4203108.645144.878181.12111.702536.210472.4203108.645144.878181.12111.493936.210472.4203108.645144.878181.12111.285936.210472.4204108.645144.878181.12111.077336.210372.4204108.645144.878181.12110.8684

N905O989694929050989694929050989694929050989694929050989694929050989694929050989694929050989694929050


2.470232.738762.538802.693472.653282.498962.549142.494812.635712.595762.776322.680722.837512.719052.943212.765383.082592.485792.880772.854343.000772.869503.053002.596552.876812.707062.962282.788383.053213.419553.584353.058403.577923.336583.366943.302353.711733.178913.343043.228183.340053.441613.472642.997203.197963.044473.137843.256373.013012.87563

36.210472.4204108.645144.878181.12110.660936.210472.4203108.645144.878181.12125.761236.210372.4204108.645144.878181.12110.242936.210372.4204108.645144.878181.12110.035036.210372.4203108.645144.878181.1219.8262536.210472.4204108.645144.878181.1219.6181236.210372.4203108.645144.878181.1219.4087536.210372.4202108.645144.878181.1219.2003136.210472.4204

N

98

9694

9290

509896

9492

9049

9896

949290

5098

9694

9290

509896

9492

905098

96

949290

5098

969492

9050

98

969492

905098

96

64

SD

Azimuth power Time

41.0000

41.000041.0000

41.250041.2500

41.250041.2500

41.250041.2500

41.500041.500041.5000

41.5000

41.500041.500041.7500

41.750041.7500

41.750041.7500

41.750042.0000

42.000042.000042.0000

42.000042.0000

42.250042.2500

42.250042.2500

42.250042.250042.5000

42.500042.5000

42.500042.5000

42.500042.750042.7500

42.750042.750042.7500

42.750043.0000

43.000043.0000

43.000043.0000

2.77996

3.113273.11469

3.133193.38934

3.258122.93710

3.531313.31535

3.232393.257623.21970

3.12211

3.344783.334862.88262

3.076252.83180

3.033643.05406

3.021642.41600

2.761292.518102.61954

2.800112.79156

2.726612.42469

2.574782.62849

2.469902.660582.64288

2.636432.42356

2.508092.647682.71414

2.392522.82037

2.295882.560492.67069

2.574002.51329

2.810362.38392

2.666912.52507

108.645

144.878181.121

8.9916436.2104

72.4204108.645

144.878181.121

8.7829736.210472.4204

108.645

144.878181.1218.57477

36.210472.4204

108.645144.878

181.1218.36625

36.210372.4203108.645

144.877181.121

8.1565636.2104

72.4204108.645

144.878181.1217.94859

36.210472.4204108.645

144.878

181.1217.7403136.2104

72.4203108.645144.878

181.1217.53086

36.210372.4203

108.645144.878

Table C2. Continued

N

94

9290

5O98

9694

929O

509896

94

92905O

9896

9492

905O

989694

929O

5O

989694

92905O

989694

929O

5O98

969492

9O50

9896

9492

SD

Azimuth power Time

43.0000

43.250043.2500

43.250043.2500

43.250043.2500

43.500043.5000

43.500043.5000

43.500043.5000

43.750043.750043.7500

43.7500

43.750043.750044.0000

44.000044.0000

44.000044.000044.0000

44.250044.2500

44.2500

44.250044.250044.2500

44.500044.500044.5000

44.500044.5000

44.500044.7500

44.750044.750044.7500

44.750044.750045.0000

45.000045.0000

45.000045.0000

45.000045.2500

2.58887

2.412532.32940

2.522812.41275

2.116842.31436

2.390442.15895

2.362612.33989

2.331142.40060

2.115312.298092.41371

2.42139

2.552702.434652.41365

2.752522.78381

2.735433.078322.84249

2.538332.84194

2.79412

2.672673.065852.90050

2.635332.980382.83930

2.613392.867542.90864

2.65179

2.821542.789262.57978

3.018832.861832.30119

2.461142.41526

2.360132.81441

2.485662.00555

181.121

7.3220336.2103

72.4203108.645

144.878181.121

7.1144536.2104

72.4204108.645144.878

181.121

6.9053136.210472.4203

108.645144.878

181.1216.69688

36.210372.4203

108.645144.878181.121

6.4878136.2104

72.4204108.645

144.878181.1216.27906

36.210372.4203108.645

144.878181.121

6.0696936.2104

72.4204108.645144.878

181.1215.86078

36.210472.4204108.645

144.878

181.1215.65234

N

90

509896

94

9290

509896

9492

9050

9896

9492

9050

989694

9290

5098

9694

929050

989694

9290

5098

969492

905098

9694

9290

50

SD

Azimuth power Time

45.2500

45.250045.250045.2500

45.2500

45.500045.500045.5000

45.500045.5000

45.500045.7500

45.750045.7500

45.750045.7500

45.750046.0000

46.000046.000046.0000

46.000046.0000

46.250046.250046.2500

46.2500

46.250046.2500

46.500046.500046.500046.5000

46.500046.5000

46.750046.7500

46.750046.7500

46.750046.750047.0000

47.000047.000047.0000

47.000047.0000

47.250047.2500

47.2500

2.12263

2.268262.337122.48383

2.20208

1.884462.025192.21742

2.181952.30025

2.139591.78210

2.290272.28566

2.118672.37928

2.345251.78813

2.453752.27303

2.240052.684772.48650

1.967692.694172.46670

2.59593

2.695002.70540

1.859962.449412.152582.55554

2.308112.55700

2.311442.59643

2.597572.736742.42758

2.927442.47547

2.701412.633412.89840

2.581922.99951

2.508342.56408

2.44458

36.2103

72.4203108.645144.877

181.121

5.4430536.210472.4204

108.645144.878

181.1215.23336

36.210372.4203

108.645144.878

181.1215.02422

36.210372.4203108.645

144.878181.121

4.8149236.210472.4204

108.645

144.878181.1214.60609

36.210472.4203108.645

144.877181.1214.39531

36.2103

72.4204108.645144.878

181.1214.1861736.2103

72.4203108.645

144.878181.121

3.9756336.2104

72.4204

N

98

969492

90

509896

9492

9050

9896

9492

9050

989694

9290

509896

94

929050

989694

929050

98

969492

905098

9694

9290

5098

96

65

TableC2.Concluded

SDAzimuth power Time47.250047.250047.250047.500047.500047.500047.500047.500047.500047.750047.750047.750047.750047.750047.750048.000048.000048.000048.000048.000048.000048.250048.250048.250048.250048.250048.250048.500048.5000

2.620962.515152.506292.440292.486042.538932.749562.484772.614322.082932.102342.209932.491582.393932.480691.827112.030551.953402.329532.337982.433211.876921.889651.854872.071922.205062.278291.806332.18713

108.645144.878181.1213.7663336.210372.4202108.645144.878181.1213.5562536.210372.4202108.645144.877181.1213.3450836.210372.4203108.645144.877181.1213.1353936.210472.4203108.645144.878181.1212.9239836.2104

N94 48.500092 48.500090 48.500050 48.500098 48.750096 48.750094 48.750092 48.750090 48.750050 48.750098 49.000096 49.000094 49.000092 49.000090 49.000050 49.000098 49.250096 49.250094 49.250092 49.250090 49.250050 49.250098 49.500096 49.500094 49.500092 49.500090 49.500050 49.500098

SDAzimuth power Time

1.99855

2.285182.26599

2.419841.94497

2.730092.389992.38837

2.533602.520541.86157

2.480012.20841

2.145102.40405

2.275232.00424

2.260841.937431.97363

2.036162.26058

2.280722.45436

2.094272.39108

2.169742.43425

72.4204

108.645144.878

181.1212.71344

36.210372.4203

108.645144.878181.121

2.5019536.2103

72.4202108.645

144.877181.1212.28930

36.210372.4202

108.645144.877181.121

2.0783636.2104

72.4204108.645

144.878181.121

N

96

9492

90

5O9896

949290

5O98

9694

9290

5O9896

9492

905098

96

949290

66

SDElevation power11.0000 2.3238111.0000 2.5828811.0000 2.7019511.0000 2.8081711.0000 2.8922811.0000 2.7297711.2500 2.2098911.2500 2.4267711.2500 2.6964211.2500 2.7795111.2500 2.8282211.2500 2.9349111.5000 2.7637011.5000 2.6681811.5000 2.9920611.5000 3.0283411.5000 3.0694611.5000 3.1761911.7500 2.3710111.7500 2.4033011.7500 2.8653411.7500 2.8777711.7500 3,0653911.7500 3.0564212.0000 2.2387712.0000 2.2741212.0000 2.5474312.0000 2.6466212.0000 2.5747412.0000 2.6387712.2500 2.2822612.2500 2.3883212.2500 2.6089912.2500 2.5160512.2500 2.7426812.2500 2.5612912.5000 1.8262112.5000 2.3322912.5000 2.4951712.5000 2.4201112.5000 2.6266112.5000 2.4760812.7500 1.5947312.7500 2.3318012.7500 2.6049812.7500 2.4408912.7500 2.5066312.7500 2.5938213.0000 1.7598913.0000 2.20894

TableC3.UnsmoothedDataforFigure6,ElevationScansat 141°Azimuth

Time N2.12925 46 13.000037.2756 92 13.000074.5643 90 13.0000111.867 88 13.0000149.177 86 13.2500186.478 84 13.25002.34868 46 13.250037.2756 92 13.250074.5642 90 13.2500111.867 88 13.2500149.177 86 13.5000186.478 84 13.50002.56726 46 13.500037.2756 92 13.500074.5644 90 13.5000111.867 88 13.5000149.177 86 13.7500186.478 84 13.75002.78550 46 13.750037.2757 92 t3.750074.5646 90 13.7500111.867 88 13.7500149.177 86 14.0000186.478 84 14.00003.00391 46 14.000037.2757 92 14.000074.5644 90 14.0000111.867 88 14.0000149.177 86 14.2500186.478 84 14.25003.22266 46 14.250037.2756 92 14.250074.5643 90 14.2500111.867 88 14.2500149.177 86 14.5000186.478 84 14.50003.44005 46 14.500037.2756 92 14.500074.5644 90 14.5000111.867 88 14.5000149.177 86 14.7500186.478 84 14.75003.65744 46 14.750037.2756 92 14.750074.5643 90 14.7500111.867 88 14.7500149.177 86 15.0000186.478 84 15.00003.87534 46 15.000037.2757 92 15.0000

SDElevation power Time

2.654552.372142.315252.595382.005812.226332.479872.193032.281092.651202.032022.070592.373922.171672.291922.442811.809452.054982.199192.235982.264232.543952.160682.051032.262102.110322.203552.549092.001042.154112.376682.167682.131292.467142.061802.177942.458192.295352.183852.388021.669342.298722.143762.249352.155512.239792.211962.643232.671032.59592

N74.5643 90 15.0000111.867 88 15.0000149.177 86 15.2500186.477 84 15.25004.09256 46 15.250037.2757 92 15.250074.5644 90 15.2500111.867 88 15.2500149.177 86 15.5000186.478 84 15.50004.30825 46 15.500037.2756 92 15.500074.5643 90 15.5000111.867 88 15.5000149.177 86 15.7500186.477 84 15.75004.52480 46 15.750037.2756 92 15.750074.5643 90 15.7500111.867 88 15.7500149.177 86 16.0000186.477 84 16.00004.74168 46 16.000037.2757 92 16.000074.5645 90 16.0000111.867 88 16.0000149.177 86 16.2500186.478 84 16.25004.95890 46 16.250037.2758 92 16.250074.5645 90 16.2500111.867 88 16.2500149.177 86 16.5000186.478 84 16.50005.17527 46 16.500037.2757 92 16.500074.5645 90 16.5000111.867 88 16.5000149.177 86 16.7500186.478 84 16.75005.39062 46 16.750037.2756 92 16.750074.5642 90 16.7500111.866 88 16.7500149.177 86 17.0000186.477 84 17.00005.60785 46 17.000037.2756 92 17.000074.5644 90 17.0000111.867 88 17.0000

SDElevation power Time

2.509562.707112.316992.536012.701042.808182.729922.833652.527492.789952.770342.768112.736092.857932.526682.601132.455472.514732.567822.712602.496082.217682.311842,369492.621412.449452.408011.997752.042342.099312.363272.359392.386832.270872.187532.277762.275392.464542.492912.504482.278162.361592.470692.261622.273412.349022.310002.207462.268972.17592

149.177186.4775.8220137.275874.5645111.867149.177186.4786.0399137.275774.5643111.867149.177186.4776.2559437.275674.5642111.866149.177186.4776.4707937.275774.5644111.867149.177186.4786.6866537.275874.5646111.867149.177186.4786.9023437.275774.5644111.867149.177186.4777.1190637.275774.5645111.867149.177186.4787.3340737.275674.5643111.867149.177186.477

N8684469290888684469290888684469290888684469290888684469290888684469290888684469290888684469290888684

67

TableC3.Continued

SDElevation power Time17.250017.250017.250017.250017.250017.250017.500017.500017.500017.500017.500017.500017.750017.750017.750017.750017.750017.750018.000018.000018.000018.000018.000018.000018.250018.250018.250018.250018.250018.250018.500018.500018.500018.500018.500018.500018.750018.750018.750018.750018.750018.750019.000019.000019.000019.000019.000019.000019.250019.2500

1.972062.116712.110252.052802.078662.144432.194082.229572.241292.375952.567292.416332.442682.384422.262072.465702.636952.539002.228172.377082.128432.622192.514952.606322.398142.588182.474472.846962.913582.960672.097722.277542.402422.437372.555012.543562.112082.231622.227472.408482.395792.455722.303362.388832.236742.576432.448452.503492.243732.19890

7.5490837.275674.5643111.867149.177186.4777.7661337.275774.5645111.867149.177186.4787.9806437.275874.5646111.867149.177186.4788.1961637.275774.5644111.867149.177186.4778.4116837.275674.5644111.867149.177186.4778.6289137.275874.5646111.867149.177186.4778.8427337.275974.5647111.867149.177186.4789.0591037.275874.5646111.867149.177186.4779.2744637.2756

N4692908886844692908886844692908886844692908886844692908886844692908886844692908886844692908886844692

SD!Elevation power Time

19.250019.250019.250019.250019.500019.500019.500019.500019.500019.500019.750019.750019.750019.750019.750019.750020.000020.000020.000020.000020.000020.000020.250020.250020.250020.250020.250020.250020.500020.500020.500020.500020.500020.500020.750020.750020.750020.750020.750020.750021.000021.000021.000021.000021.000021.000021.250021.250021.250021.2500

2.186722.466182.299482.252332.270732.106102.401552.674262.632082.537442.123862.178372.411772.432492.430892.286232.115972.151702.168602.246942.144102.208042.265852.104462.207282.297352.231042.453402.218012.076872.129002.169072.372352.162372.439802.349422.271382.264342.467872.120812.604252.597062.451552.530222.572982.421042.701472.619782.528622.61780

74.5643111.867149.177186.4779.4901537.275874.5646111.867149.177186.4789.7058437.275774.5645111.867149.177186.4789.9208637.275874.5645111.867149.177186.47710.137737.275774.5644111.867149.177186.47710.352437.275874.5646111.867149.177186.47810.567237.275774.5645111.867149.177186.47710.783537.275874.5645111.867149.177186.47710.999037.275974.5647111.867

N9088868446929088868446929088868446929088868446929088868446929088868446929088868446929088868446929088


2.599792.593572.834052.598142.558692.883202.955803.071402.748842.618332.670502.889852.986493.143942.925872.755113.195193.173713.224923.250943.095553.141543.486843.534913.489273.237473.235973.284723.568133.391463.636853.363582.716423.058333.186702.981983.071662.959192.172772.457922.808332.553872.400312.154342.083752.022862.242152.171852.144991.90407

149.177186.47811.214337.275774.5645111.867149.177186.47711.429237.275774.5643111.867149.177186.47711.645637.275874.5645111.867149.177186.47711.860937.275974.5647111.867149.177186.47812.076437.275874.5646111.867149.177186.47712.292637.275774.5643111.867149.177186.47712.507137.275874.5646111.867149.177186.47812.722737.275774.5645111.867149.177186.477

N8684469290888684469290888684469290888684469290888684469290888684469290888684469290888684469290888684

68

TableC3.Continued

SDElevation power Time23.500023.500023.500023.500023.500023.5O0023.750023.750023.750023.750023.750023.750024.000024.000024.000024.000024.000024.000024.250024.250024.250024.250024.250024.250024.500024.500024.500024.500024.500024.500024.750024.750024.750024.750024.750024.750025.000025.000025.000025.000025.000025.000025.250025.250025.250025.250025.250025.250025.500025.5000

1.830141.914211.858311.934111.894812.021111.898481.933952.068771.943461.983012.092482.090021.975222.039791.908332.060472.053092.328262.062682.306232.215402.192222.200142.167052.091522.383002.493892.268352.326392.397902.396002.890532.822262.788692.613762.689912.651872.950232.992803.231612.906552.501272.567462.709222.598373.171742.959312.561102.54068

12.937537.275974.5646111.867149.177186.47713.153537.275874.5645111.867149.177186.47813.368037.275774.5645111.867149.177186.47713.583937.275774.5645111.867149.177186.47713.799837.275874.5646111.867149.177186.47814.015137.275874.5646111.867149.177186.47814.229637.275774.5645111.867149.177186.47714.445737.275874.5645111.867149.177186.47714.661337.2757

N4692908886844692908886844692908886844692908886844692908886844692908886844692908886844692908886844692


2.562552.518513.000532.728232.273062.241652.146562.301552.522762.307432.449332.146322.236502.372502.412312.357292.422782.308412.735722.656162.682072.795532.617292.727582.761652.700092.694213.045772.425502.626832.684722.692672.571092.865962.477672.613252.973032.833252.911113.081732.713592.392992.884142.816023.014222.966092.701332.456282.816562.72799

74.5643111.867149.177186.47714.876237.275874.5646111.867149.177186.47815.091937.275874.5645111.867149.177186.47715.307237.275874.5644111.867149.177186.47715.522637.275774.5644111.867149.177186.47715.738337.275874.5645111.867149.177186.47715.953537.275974.5646111.867149.177186.47816.169037.275874.5645111.867149.177186.47716.384237.275874.5646111.867

N9088868446929088868446929088868446929088868446929088868446929088868446929088868446929088868446929088


2.764913.003882.489362.396982.520842.513752.588992.941952.637922.544712.764912.521192.448802.508192.801802.483722.737172.458172.474132.233222.689722.276422.317832.227752.269712.121762.494862.126382.095112.074272.119512.023792.333491.751091.715801.916071.746541.696571.994171.961521.880291.904671.738851.919391.836552.186352.195991.848931.852821.96238

149.177186.47816.599237.275874.5645111.867149.177186.47716.815637.2757149.17774.5645111.867149.177186.47717.030637.275874.5647111.867149.177186.47817.246837.275874.5646111.867149.177186.47717.462037.275874.5645111.867149.177186.47717.677337.275774.5643111.867149.177186.47717.893037.275874.5646111.867149.178186.47818.108037.275974.5646111.867149.177

N8684469290888684469286908886844692908886844692908886844692908886844692908886844692908886844692908886

69

TableC3.Continued


1.927292.320002.452762.177741.958412.334902.202361.998792.060692.136752.044092.153092.029192.128042.135652.324382.285312.195592.167362.348132.478052.416682.359142.370032.467612.412682.452382.595862.512282.623842.361662.389072.272262.561052.341902.686652.150181.929132.098222.175782.085712.401312.206372.043402.254072.081192.222702.380232.442712.28150

186.47718.323437.275874.5645111.867149.177186.47718.539437.275874.5645111.867149.177186.47818.522137.275874.5645111.867149.177186.47737.275874.5647111.867149.177186.47718.092437.275974.5646111.867149.177186.47717.876337.275874.5646111.867149.177186.47717.660937.275874.5646111.867149.177186.47717.444637.275774.5644111.867149.177186.47717.231137.2758

N8446929088868446929088868447929088868492908886844792908886844792908886844792908886844792908886844792


2.501722.471302.507372.703652.696182.331182.496592.706512.751992.730432.340062.095922.191392.216472.255562.195892.003491.863972.098182.165292.064931.931391.782512.099572.270292.102952.153352.144281.575852.066022.235952.091092.047921.958181.833802.149712.295412.169612.123292.138942.016012.440622.444052.361702.347992.440031.954722.391772.365402.22059

74.5647111.867149.177186.47717.014037.275974.5648111.867149.177186.47716.798737.275874.5645111.867149.177186.47716.583637.275874.5645111.867149.177186.47716.367537.275774.5645111.867149.177186.47716.153337.275974.5648111.867149.177186.47715.936837.275974.5646111.867149.177186.47715.721737.275874.5646111.867149.177186.47715.506237.275874.5646111.867

N9088868447929088868447929088868447929088868447929088868447929088868447929088868447929088868447929088


2.478392.401812.124902.392532.225792.116912.404072.222942.336712.248262.231582.253402.423042.285822.420732.370802.597042.508742.433572.691202.169642.390652.586752.454842.605092.584661.934902.063802.177732.271622.350682.239851.653981.912641.962752.095232.032742.083861.698522.147382.101542.312772.185292.298441.863872.172782.284302.403692.395802.29662

149.177186.47715.291137.275774.5645111.867149.177186.47715.075037.275974.5647111.867149.177186.47714.861237.275974.5646111.867149.177186.47714.645437.275874.5645111.867149.177186.47714.428537.275874.5645111.867149.177186.47714.214937.275974.5647111.867149.177186.47713.998537.276074.5648111.867149.177186.47713.782237.276074.5647111.867149.177186.477

N8684479290888684479290888684479290888684479290888684479290888684479290888684479290888684479290888684

7O

TableC3.Continued

SDElevation power36.000036.000036.000036.000036.000036.000036.250036.250036.250036.250036.250036.250036.500036.500036.500036.500036.500036.500036.750036.750036.750036.750036.750036.750037.000037.000037.000037.000037.O00037.000037.250037.250037.250037.250037.250037.250037.500037.500037.500037.500037.500037.500037.750037.750037.750037.750037.750037.750038.000038.0000

2.071222.197932.342152.452242.538732.227282.205681.959192.035852.122922.284582.063392.339312.229262.139482.182812.373822.315191.909932.121732.192812.194302.403662.362141.660871.836462.088041.987862.192142.094871.545831.726581.764551.750701.874821.984341.473221.666631.781921.627401.786681.909741.716272.018162.053871.788301.846802.058611.810792.01393

Time N Elevation13.5680 47 38.000037.2758 92 38.000074.5646 90 38.0000111.867 88 38.0000149.177 86 38.2500186.477 84 38.250013.3529 47 38.250037.2758 92 38.250074.5646 90 38.2500111.867 88 38.2500149.177 86 38.5000186.477 84 38.500013.1378 47 38.500037.2760 92 38.500074.5648 90 38.5000111.867 88 38.5000149.177 86 38.7500186.477 84 38.750012.9242 47 38.750037.2760 92 38.750074.5648 90 38.7500111.867 88 38.7500149.177 86 39.0000186.477 84 39.000012.7071 47 39.000037.2758 92 39.000074.5645 90 39.0000111.867 88 39.0000149.177 86 39.2500186.477 84 39.250012.4912 47 39.250037.2758 92 39.250074.5646 90 39.2500111.867 88 39.2500149.177 86 39.5000186.477 84 39.500012.2758 47 39.500037.2758 92 39.500074.5646 90 39.5000111.867 88 39.5000149.177 86 39.7500186.477 84 39.750012.0600 47 39.750037.2759 92 39.750074.5648 90 39.7500111.867 88 39.7500149.177 86 40.0000186.477 84 40.000011.8447 47 40.000037.2760 92 40.0000

SDpower1.867541.960271.936492.032081.859771.920381.939192.073292.098242.222401.754761.785822.043601.851932.038982.284282.005311.994102.188682.105352.197902.269321.852642.140222.166822.180892.318122.325951.993712.317692.301892.419322.519682.599532.013822.426152.343282.333422.526942.585421.919152.168912.103682.021912.089002.131541.741782.172151.872512.05009

Time N Elevation74.5648 90 40.0000111.867 88 40.0000149.177 86 40.2500186.477 84 40.250011.6288 47 40.250037.2759 92 40.250074.5646 90 40.2500111.867 88 40.2500149.177 86 40.5000186.477 84 40.500011.4132 47 40.500037.2758 92 40.500074.5646 90 40.5000111.867 88 40.5000149.177 86 40.7500186.477 84 40.750011.1990 47 40.750037.2759 92 40.750074.5648 90 40.7500111.867 88 40.7500149.177 86 41.0000186.477 84 41.000010.9832 47 41.000037.2760 92 41.000074.5647 90 41.0000111.867 88 41.0000149.177 86 41.2500186.477 84 41.250010.7676 47 41.250037.2760 92 41.250074.5647 90 41.2500111.867 88 41.2500149.177 86 41.5000186.477 84 41.500010.5505 47 41.500037.2759 92 41.500074.5647 90 41.5000111.867 88 41.5000149.177 86 41.7500186.477 84 41.750010.3371 47 41.750037.2760 92 41.750074.5647 90 41.7500111.867 88 41.7500149.177 86 42.0000186.477 84 42.000010.1201 47 42.000037.2760 92 42.000074.5648 90 42.0000111.867 88 42.0000

SDpower

2.022012.055381.815102.175782.009562.183932.232662.105011.876432.277922.337602.516882.550632.221152.404582.643562.479622.716192.736822.265642.272622.407812.383652.544222.580412.169512.178592.100692.080582.109332.211391.905682.033191.854631.842421.925062.107801.873372.271221.997632.118192.033272.091412.043252.244312.015882.219762.054332.057592.37996

Time N149.177 86186.477 849.90459 4737.2761 9274.5648 90111.867 88149.177 86186.477 849.68833 4737.2760 9274.5647 90111.867 88149.177 86186.477 849.47141 4737.2759 9274.5646 90111.867 88149.177 86186.477 849.25698 4737.2760 9274.5647 90111.867 88149.177 86186.477 849.04338 4737.2761 9274.5649 90111.867 88149.177 86186.477 848.82497 4737.2761 9274.5647 90111.867 88149.177 86186.477 848.61004 4737.2761 9274.5647 90111.867 88149.177 86186.477 848.39528 4737.2760 9274.5648 90111.867 88149.177 86186.477 84

71

TableC3.Continued

SDElevation power42.250042.250042.250042.250042.250042.250042.500042.500042.500042.500042.500042.500042.750042.750042.750042.750042.750042.750043.000043.000043.000043.000043.000043.000043.250043.250043.250043.250043.250043.250043.500043.500043.500043.500043.500043.500043.750043.750043.750043.750043.750043.750044.000044.000044.000044.000044.000044.000044.250044.2500

2.238342.076152.311572.251512.184062.504562.403712.238992.480562.222062.070612.336752.102202.034562.188461.919431.976792.061981.646731.944352.170391.912682.009962.142812.016511.991072.227912.097822.216682.194192.069171.842651.947292.017722.103172.157511.841001.858262.044701.943061.856522.108241.741961.847501.968191.733281.693092.016491.776722.05313

Time N Elevation8.17869 47 44.250037.2761 92 44.250074.5648 90 44.2500111.867 88 44.2500149.177 86 44.5000186.478 84 44.50007.96443 47 44.500037.2762 92 44.500074.5648 90 44.5000111.867 88 44.5000149.177 86 44.7500186.477 84 44.75007.74701 47 44.750037.2761 92 44.750074.5648 90 44.7500111.867 88 44.7500149.177 86 45.0000186.477 84 45.00007.53208 47 45.000037.2759 92 45.000074.5645 90 45.0000111.867 88 45.0000149.177 86 45.2500186.477 84 45.25007.31732 47 45.250037.2760 92 45.250074.5646 90 45.2500111.867 88 45.2500149.177 86 45.5000186.477 84 45.50007.10040 47 45.500037.2760 92 45.500074.5648 90 45.5000111.867 88 45.5000149.177 86 45.7500186.478 84 45.75006.88514 47 45.750037.2762 92 45.750074.5649 90 45.7500111.867 88 45.7500149.178 86 46.0000186.478 84 46.00006.66872 47 46.000037.2760 92 46.000074.5647 90 46.0000111.867 88 46.0000149.177 86 46.2500186.477 84 46.25006.45329 47 46.250037.2759 92 46.2500

SDpower1.964972.188201.958012.228811.978232.290252.187912.517542.177722.263271.944132.149542.062062.312942.158042.255762.101272.233752.097562.151142.022512.289422.105402.090562.061041.981111.995902.127842.065542.051912.263381.980311.713052.178862.128632.202272.497592.090732.009522.261712.125342.451432.587292.332492.358132.353912.021022.052082.478682.26085

Time N Elev_ion74.5646 90 46.2500111.867 88 46.2500149.177 86 46.5000186.477 84 46.50006.23770 47 46.500037.2760 92 46.500074.5646 90 46.5000111.867 88 46.5000149.177 86 46.7500186.477 84 46.75006.02194 47 46.750037.2760 92 46.750074.5648 90 46.7500111.867 88 46.7500149.177 86 47.0000186.477 84 47.00005.80552 47 47.000037.2761 92 47.000074.5648 90 47.0000111.867 88 47.0000149.177 86 47.2500186.477 84 47.25005.58910 47 47.250037.2761 92 47.250074.5647 90 47.2500111.867 88 47.2500149.177 86 47.5000186.477 84 47.50005.37367 47 47.500037.2760 92 47.500074.5647 90 47.5000111.867 88 47.5000149.177 86 47.7500186.477 84 47.75005.15708 47 47.750037.2760 92 47.750074.5646 90 47.7500111.867 88 47.7500149.177 86 48.0000186.477 84 48.00004.93999 47 48.000037.2761 92 48.000074.5648 90 48.0000111.867 88 48.0000149.177 86 48.2500186.477 84 48.25004.72424 47 48.250037.2761 92 48.250074.5647 90 48.2500111.867 88 48.2500

SDpower

2.258602.343071.677661.769231.817271.889661.813332.093822.053851.976082.010302.108721.896862.146362.758512.385652.296722.555372.289662.692692.738142.492532.378792.608452.356232.570892.245052.266042.431102.529402.473092.298982.307922.375592.518752.571002.596022.464382.192212.551312.663692.588802.615262.455052.396082.518622.825992.486042.588292.55372

Time N149.177 86186.477 844.50681 4737.2760 9274.5648 90111.867 88149.177 86186.477 844.29023 4737.2760 9274.5646 90111.867 88149.177 86186.477 844.07447 4737.2760 9274.5648 90111.867 88149.177 86186.477 843.85688 4737.2761 9274.5648 90111.867 88149.177 86186.477 843.63863 4737.2760 9274.5647 90111.867 88149.177 86186.477 843.42221 4737.2760 9274.5647 90111.867 88149.177 86186.477 843.20296 4737.2760 9274.5646 90111.867 88149.177 86186.477 842.98637 4737.2760 9274.5647 90111.867 88149.177 86186.477 84

72

TableC3.Concluded

SDElevation power Time48.500048.500048.500048.500048.500048.500048.750048.750048.750048.750048.750048.750049.000049.000049.000049.000049.000049.000049.250049.250049.250049.250049.250049.2500

2.303792.411352.734182.467752.326842.723342.513152.430932.507992.498982.390042.855372.187392.182512.351002.293882.173712.470912.064272.286802.432492.189692.266812.53466

2.7676237.276174.5647111.867149.177186.4772.5482037.276074.5646111.867149.177186.4772.3296237.276174.5647111.867149.177186.4772.1097137.275974.5645111.867149.177186.477

N479290888684479290888684479290888684479290888684

73

References

1. Hardy, Kenneth R.; and Gage, Kenneth S.: The History

of Radar Studies of the Clear Atmosphere. Radar in

Meteorology--Battan Memorial and 40th Anniversary Radar

Meteorology Conference, David Atlas, ed., AMS, 1990,

pp. 130-142.

2. Tatarski, V. 1. (R. A. Silverman, transl.): Wave Propagation in

a Turbulent Medium. McGraw-Hill Book Co., Inc., 1961.

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74

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November 1997 Technical Paper4. TITLE AND SUBTITLE 5. FUNDING NUMBERS

Measured Changes in C-Band Radar Reflectivity of Clear Air Caused byAircraft Wake Vortices WU 548-10-4 I-01

6. AUTHOR(S)Anne I. Mackenzie

7. PERFORMINGORGANIZATION NAME(S) AND ADDRESS(ES)

NASA Langley Research Center

Hampton, VA 23681-2199

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National Aeronautics and Space AdministrationWashington, DC 20546-0001

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L-17618

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Subject Category 32Availability: NASA CASI (301) 621-0390

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Wake vortices from a C-130 airplane were observed at the NASA Wallops Flight Facility with a ground-basedmonostatic C-band radar and an antenna-mounted boresight video camera. The airplane wake was viewed from adistance of approximately I km, and radar scanning was adjusted to cross a pair of marker smoke trails generatedby the C-130. For each airplane pass, changes in radar reflectivity were calculated by subtracting the signal magni-tudes during an initial clutter scan from the signal magnitudes during vortex-plus-clutter scans. The results showedboth increases and decreases in reflectivity on and near the smoke trails in a characteristic sinusoidal pattern ofheightened refiectivity in the center and lessened reflectivity at the sides. Reflectivity changes in either directionvaried from -131 to -102 dBm-l; the vortex-plus-clutter to noise ratio varied from 20 to 41 dB. The radar record-

ings lasted 2.5 min each; evidence of wake vortices was found for up to 2 min after the passage of the airplane.Ground and aircraft clutter were eliminated as possible sources of the disturbance by noting the occurrence ofvortex signatures at different positions relative to the ground and the airplane. This work supports the feasibility ofvortex detection by radar, and it is recommended that future radar vortex detection be done with Doppler systems.

14. SUBJECT TERMSWake vortex detection; C-band radar; Bragg scattering; Clear-air reflectivity

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