advanced technologies and applications in operational weather radars

Advanced Technologies and Applications in Operational Weather RadarsV. Chandrasekar Professor and Dean for International Research Colorado State University Distinguished Visiting Professor, IITM Fellow American Meteorological Society

Fellow, NOAA/ CIRAAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Dedication to Mr Ragahvan

Advanced Technologies and applications of Operational Weather Radar

Seminar on Doppler Radar and Weather Surveillance

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Operational Weather Radar Network SystemRadar NodesSystem Operation & Control Center

Internet

Scan Command & Control

End-usersSignal Processor

User RequirementInternet

Real-time DataObtained over the Internet

Internet

Timeseries Storage Data Storage

Retrieval algorithm and Data Archive

Internet



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Topics Dual polarization technology Advanced Signal processing technologies Advanced products ( ex: rainfall retrievals ) Attenuation correction systems Dual Doppler System Nowcasting System ExamplesAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Dual-polarization Technology and ApplicationsThe radar reflectivity is an equivalent factor by assuming spherical particles. Not always true!



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Dual Polarization MeasurementsSolution: observe the target using two orthogonal polarizations

V

H



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Dual Polarization Measurements



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Polarimetric Capability Raindrops are nonspherical and the nonspherical shape is increased more pronounced with size. Therefore different reflectivities are seen at horizontal and vertical polarizations.vDirection of propagation

h

Plane containing the electric field

We can measure other parameters to characterize the raindrop in more details shape, size, orientation.



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Concept of Polarization Electric field is a vector. It has a magnitude indicating the strength as well as direction.

In a plane wave the electric field direction is on a plane which is orthogonal to the direction of propagation. In addition to being a vector, the components of the electric fields are complex phasors.Direction of propagation

v

h

Plane containing the electric field



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Concept of Polarization (Continued ) The electric field of a plane wave can lie in any direction on a plane orthogonal to the direction of propagation of a wave. The electric field vector can be in any direction, on that plane. It is usually written in terms of two orthogonal components in horizontal (h) and vertical direction (v). As the wave propagates through a point is space, the components E h and Ev vary sinusoidally with time so that E can change both magnitude and direction.Ev

Eh



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H-receiver H-Transmitter V-Transmitter Duplexer Duplexer V-receiver

Antenna

Transmit H-Pol. Receive H-Pol. => Measure reflectivity at horizontal polarization Zh Transmit V-Pol. Receive V-Pol. => Measure reflectivity at vertical polarization ZvAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Differential Reflectivity => Zdr = Zh (dB)-Zv (dB)Zdr is high in rain, low in hail. A good hail detector.Return: H

Transmit: H

Return: V

Transmit: V



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Differential propagation phase (dp)

Electromagnetic waves slow down in precipitation.

In rain, they slow down more in horizontal polarization with respect to vertical polarization. Therefore if waves go back and forth, there will be a phase difference.



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Propagation PhasePropagation phase is

e

jkr

or (kr )2

k is wave number

c in free space or f f

Two way propagation phase is

2kr

To make the distinction to polarization:

Wave number (k) in horizontally polarized waves is khWave number in vertically polarized waves is kv.dp

2( k h

kv )r

2 K dp rSeminar on Doppler Radar and Weather Surveillance


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Propagation Phase.. continued

Kdp has some very interesting properties 1) Kdp is proportional to the rainfall rate or the volume of water. 2) It can pick up rain only in rain/hail mixture. 3) It is not affected by radar calibration errors.



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Correlation Coefficient (between polarization)

Precipitation particles exhibit very high correlation between horizontal and vertical polarized return signals.

Measurement of the correlation is

hv.



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One can transmit horizontal polarization and receive vertical polarization or transmit horizontal and receive vertical.Return: V

Transmit: H



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LDRReflectivity Zhv or ZvhTransmit Receive

LDR is a measure of cross polarization power Very useful for identifying ice, bright bandLDR = Zhv (dBZ) Zhh (dBZ)

Typically negative in dB



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Implementation of Dual-polarization Mode Fundamentally the H/V polarization states are the eigen polarization states of precipitation media. In propagation, the cross-polarization term of H/V is fairly small (-30dB).



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Dual-polarization ResponseThe Alternate H/V ModeSample Time Sample Time Pulse Train Sample Time Dwell Period Observation

Measurements:

Z hh Z vh

Z hv Z vv

Available when transmitting h-polarized wave Available when transmitting v-polarized wave

The full matrix can be directly determined.Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Dual-polarization ResponseThe Simultaneous H/V ModeSample Time Sample Time Pulse Train Sample Time

Measurements:

Z hh Z vv

Get only co-polar measurements. This is the mode planned for WSR-88D and all the broadcast industry radars.Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Dual-Polarization radar variables Single polarization radar: Reflectivity Doppler velocity

Dual polarization radar: Reflectivity at each polarization on Zh, Zv The difference - Zdr Specific differential propagation phase Kdp, Correlation between the measurements hv

Available in WSR-88D upgraded systemsAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Measurements with respect to precipitation particles: what do they measureReflectivi ty, Z h Average of S hh2

S hh

2

or hh

D62

Differential Reflectivity, Z dr

Average of Svv 10log10 2 Average of S hh180Re f h fv

10log10

Svv S hh

2

2

Specific propagati on phase, K dp

Linear depolarization ratio, LDR 10log10

Svh S hh

2

2

Colpolar correlation coefficient,

* Svv S hh

co

S hh

2

Svv

2



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Differential Reflectivity (Zdr) Differential reflectivity (Zdr) is the ratio of received power from a horizontally polarized transmit signal to the received power of a vertically polarized signal.z

Zdr (dB) 10 log

S HH S VV

2

2

y

x

ki

Zdr is the ratio of average radar cross section at horizontal polarization to average radar cross section at vertical polarization. Zdr gives information about particle shape and orientationAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Diagram and Model for Axis Ratio of Raindrops

Beard and Chuang modelEquilibrium drop shapes for drop shapes for drop diameters of 1-6 mm.



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Diagram and Model for Axis Ratio of Raindrops (Continue)

PB: Pruppacher and Beard (1970) BC: Beard and Chuang (1987) THBRS: Thurai et al. (2007)

Shape-size relation of oblate drops as a function of equivalent volume diameter



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Specific differential phase (Kdp) zero for isotropichydrometers and non-zero for anisotropic hydrometeors.

K dp

h K eff

v K eff

The effective propagation constant for vertically polarized waves

The effective propagation constant for horizontally polarized waves

K dp

2 n Re f h (r , D) k0

f v ( r , D)

fh,v = forward scatter amplitude at horizontal and vertical polarizationAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Model calculations of Kdp/W versus Dm for exponential DSD

Kdp

180o

W (1 rm )

180o

W

DmSeminar on Doppler Radar and Weather Surveillance


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Linear Depolarization Ratio in:Rain LDR < -27 dB Aggregates, small hail, graupel (all dry) LDR < -20 dB Aggregates, small hail, graupel (all wet) -20 < LDR < -10 dB Hail, Rain/Hail Mixture

LDR > -20 dBAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Cross-Correlation Coefficient Hail

co

< 0.95 in:

Hail/Rain Mixture Wet Aggregates



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High Zdr value/large liquid drops in strong inflow region responsible for overhanging echo.



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Very strong signature (-11.2 dB) indicative of large hail falling out of storm, maximum Zh = 70 dBZ.



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Hail damage to WSR-88D in Denver, Colorado

Due to the storm shown in the previous two slides.



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Positive Zdr column indicative of liquid drops in an updraftRaindrops being carried by updraft Zdr columnVertical section of radar data (from the NCAR CP-2 radar) in a vigorous growing cell in Florida. Grayscales depict Zdr values and arrows depict tripleDoppler derived wind vectors. Two aircraft penetration tracks are shown with solid dots spaced at 10-second increments

0o C

Liquid water above 00 C isotherm (~4.5 km) is supercooled.Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Dual Polarization Radar Observations and The Basis for Interpretation for Various Types of Storm Observations



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Polarimetric Techniques Polarization diversity observations bring some unique characteristics that are important for addressing data quality issues. Second, the precipitation back scatter at horizontal (H) and vertical (V) polarizations exhibits a high degree of coherency (>0.98 in rain) that can be used to detect and filter contamination from noise as well as from nonmeteorological echoes such as surface clutter, chaff, birds and insects. Third, the differential polarization parameters, such as differential reflectivity and specific differential propagation phase, are immune to absolute calibration errors. Furthermore, self-consistency constraints of the measurements in rain impose bounds on errors in absolute reflectivity measurement.



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Applications of Dual Polarization System



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Basic Principles of Hydrometeor Identification Polarimetric radar measurements within radar resolution volume are sensitive to hydrometeor: (1) type, (2) shape, (3) size distribution, (4) density, and (5) fall behavior. Thus, microphysical properties of hydrometeors are retrievable from polarization diverse measurements. Hydrometeor classification is a way to invert all the knowledge base to go from the set of measurements to hydrometeor type.



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Fuzzy Logic Hydrometeor Classification MethodologyArchitecture of hydrometeor classification systemZh Zdr Kdp LDRhv

Fuzzification

Rule Based Inference Engine

Defuzzification

Output

Height

Zh, Zdr, Kdp LDR, hv Altitude

Rain Hail Ice Crystals Non meteorological echo DrizzleSeminar on Doppler Radar and Weather Surveillance


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Inputs: dual-polarization radar measurements (reflectivity, differential reflectivity, specific propagation phase, linear depolarization ratio, co-polar correlation coefficient) -- plus dominant environmental factor (height).

Output: precipitation type (drizzle, rain, hail, snow, graupel, rain+hail)Hydrometeor Ice

Rain

Radar measurements + Altitude

Reflectivity (Zh), Differential Reflectivity (Zdr), Specific Phase Shift (Kdp), Linear Depolarization Ratio (LDR), Correlation Coefficients ( co)Seminar on Doppler Radar and Weather Surveillance


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Architecture of the recently developed CSU model of fuzzy hydrometeor classification

Recent Advances: Apply melting layer detection algorithm for height membership function. Use hybrid method that combines additive and product methods. Use weight factors extensively to manipulate input variables more effectively.Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Data sources and instrumentation for evaluation Data collected by CSU-CHILL radar In-situ data taken by T-28 aircraft armored aircraft operated by South Dakota School of Mines and Technology

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Three sensors cover different portions of size range1. 2DC cloud probe: image cloud ice and small precipitation. 2. Hail spectrometer: Larger precipitation (0.9 mm to 12 cm) 3. HVPS: measure particles up to 4.5 cm.Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Examples from Severe Thunderstorm Electrification & Precipitation Study (STEPS): 17 May to 20 July 2000 -- Goodland, KansasReflectivity: Chill Radar(solid line: T-28 aircraft track)

June 11 TrackDifferential Reflectivity(dotted line: detected melting layer)

Hydrometeor Type: FL AlgDZ drizzle (DZ: Drizzle, R: Rain, WS: R rain WS wet DS: Wet Snow, snow Dry Snow, DS dry snow G/SH: Graupel/Small Hail, G/SH graupel/small hail SH small hail SH: Small Hail, LH: Large LH large hail Hail, SRH: Small+ Rain+Hail, SRH small rain hail LRH large rain + hail LRH: Large Rain+Hail)Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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June 11: STEPS

Hail Spectrometer

T-28 aircraft: 2DC



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June 22: STEPS

T-28 aircraft: HVPS



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June 29: STEPS



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22 June 1995[Chill Radar]

FL algorithm classification vs A/C observation

PPI Sect of Zh

T-28 aircraft: HVPS

4.5 cmPPI Sect of H-type

T-28 A/C Track



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HydroClass HydroClass is an advanced operational product in all dual-pol radars. A very important product for climate studies



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University of Helsinki weather radar: Bright band case



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University of Helsinki weather radar : Convective Storm



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University of Helsinki weather radar : Snow Storm



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Advanced Signal processing Technologies Clutter Overlay Echo suppression Velocity ambiguity mitigation



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Spectral Clutter Filtering Example ( GMAP )

Obtain spectral coefficients and power spectral density of received signal

Obtain adaptive noise floor by sorting spectral coefficients by power Design notch filter in spectral domain Estimate clutter model based on Gaussian model fit to zero Doppler region Estimate notch width based on clutter model and noise

Notch the clutter signal with a spectral clipper Interpolate the notch filtered region by iteratively fitting a Gaussian model to the weather signal

Replace the clutter region with model and subtract noise powerAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Ground Clutter Filtering

UNFILTERED

FILTERED

Ground clutter Reflectivity before and after ground clutter filtering. Data collected on May 09, 2007 at Lawton (EL=1 deg).Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Ground Clutter Filtering

~200m AGL

~400m AGL

Ground clutter

Circulation signature

Velocity before and after ground clutter filtering. Data collected on May 09, 2007 at Lawton (EL=1 deg).Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Range-velocity Ambiguity Mitigation Methods The maximum unambiguous range and unambiguous velocity have a limitation based on wavelength and pulse repetition time

+ + +---+ + -+ + - -+ + +

rmax

cT 2

vmax

4T

Maximum unambiguous range and unambiguous velocity are related to each other as

rmax vmax

c 8Seminar on Doppler Radar and Weather Surveillance


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Range-velocity Ambiguity Mitigation Methods

SX

If v max is increased then rmax decreases correspondingly ( Rangevelocity ambiguity) Fundamental limitation of pulsed Doppler radar transmitting uniformly spaced pulsesAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Radial Velocity Folding in Severe WeatherVelocity measurements with uniform PRT and staggered PRT with CSU-CHILL 2006-Dec-20

Velocity folding from -27 m/s to 27 m/s

Unfolded velocity folding using staggered PRT waveform



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Range-velocity Ambiguity Mitigation Methods

Phase coding to mitigate range ambiguity Random phase coding Systematic phase coding

Staggered pulsing to mitigate Staggered PRT Staggered PRF Polarization diversity to mitigate range ambiguity



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Range-overlay due to shorter PRT In order to obtain reasonable unambiguous velocities the Doppler radars PRT is significantly shorter

The shorter PRTs results in range-overlaid echoes which gives erroneous measurements of the Doppler spectral moments



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The transmitted pulses are phase coded and the received signal is cohered for the first and second trip

Vk1

Vk2

The transmitted pulses are phase coded with switching phase k

N

VkVk

Ve

1 j k

k

V ek 1 k

2 k

j

N 1

k 11

Vk1 Vk2e j

0

Where

ej

k 1

k

ej

k

is the modulation code



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Random Phase Coding For RangeOverlay Suppression

~500m AGL Overlaid echo

~200m AGL Ground clutter

UNFILTERED

FILTERED

Before overlaid echo suppression and clutter filtering. Data collected on May 06, 2007 at Lawton (EL=1 deg).

After overlaid echo suppression and clutter filtering. Data collected on May 06, 2007 at Lawton (EL=1 deg).Seminar on Doppler Radar and Weather Surveillance


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Data Products with CSU-CHILLData collected with PRT =1 ms; N=64 on Dec 20, 2006 at 23:58:19 UTC

Severe clutter from Rocky mountains

Reflectivity after spectral clutter filtering

Velocities biased due to clutter Velocities after clutter filtering



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Rain microphysics/ Advanced retrievals Equilibrium shape and orientation of raindrops

b a

The equilibrium shape of a raindrop is determined by a balance of forces involving hydrostatic, surface tension and aerodynamic forces.Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Raindrop Size Distribution (DSD)

Most commonly used distribution model is exponential.N D N 0 exp D; 3.67 D0 D0 Drop median volume diameterSeminar on Doppler Radar and Weather Surveillance


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Once you describe N(D) all other quantities such as rainfall rate, reflectivity can be computed. ExampleZh D 6 N ( D)dDv( D) N ( D) D 3 dD;

6 v( D) raindrop fall velocity

Rainfall rate is



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Common model for

v( D) 3.78D0.67 ; m s 1

A common expression for RR (0.6 10 3 )(3.78) D 3.67 N ( D) D 3 dD; mmh1

Some times these are referred as moments of the drop size distribution. The term moments refer to statistical moments.

Zdr was closely related to D0 or Dm. Dm = Mass weighted mean diameterD 4 N ( D)dD Dm0

D 3 N ( D)dD0



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Principle of Rainfall EstimationIf we know N DN 0 exp D

then we know rainfall rate. To know N(D) we need to know N0, Z is only one parameter. Z C1 D07 N0 R C2 D04.67 N0 or N0 and D0; Reflectivity

Implies that Z is incomplete information to estimate R. (though we have been doing this for a long time).If Zdr gives D0, then using Z we can find N0, then we know rainfall rate. This is a simplistic explanation of a more complex problem.Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Drop Shape The shape of raindrops can be expressed as a function of drop size. b axis ratio r f ( D) a Pruppacher Beard Approximat ion : r 1.03 0.062D

Mean raindrop axis ratio versus D based on aircraft imaging probe data from Florida rain cells and from the high plains, USAAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Simple model : r=1- D

r 1.0048 5.7 10 4 ( D) 2.628 10 2 ( D2 ) 3.682 10 3 ( D3 ) 1.677 10 4 ( D4 )Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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In similar terms

K dp

180

10 3 CW (1 rm ); km

1

rm

is mass weighted shape (axis ratio) of drops



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Rainfall Algorithmsa b a R(Z , Z dr ) CZ h Zdr or CZ h 100.1bZdr ( dB)

R ( K dp ) 129

K dp f

b2

a3 b R( K dp , Z dr ) C3 K dp Zdr3

mm h -1



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The use of Kdp to estimate rainfall has a number of advantages over power measurements: independent of receiver and transmitter calibrations, unaffected by attenuation, relatively immune to beam blockage, unbiased by presence of hail or other 'spherical' ice particles in the resolution volume



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Fort Collins Flash FloodRWSR(Z) R(Kdp) Peak=215mm

Storm total rainfall in mm from 17:30 to 22:15 hours MDT. The lines on the picture indicate the street map of the city of Fort Collins. The dark line shows the Spring Creek, which flooded and caused the flash food.Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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R(Kdp, Zdr)

R(Zh, Zdr)

Peak=240mm

Gage peak values=260mm

Peak=265mm



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In the presence of hail contamination On the other hand, hail can cause overestimation. Hail stone returns more power upon reflection given the same water content

Five-hour Rainfall AccumulationAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Robust Rainfall Rainfall estimation can be further improved by using different rainfall estimators for specific rain types. Blend algorithm: classification + quantitative estimation.

June 19, 2004

A time-series of rainfall over the location of the Urban Drainage and Flood Control District (UDFCD) ALERT rain gauge, located near Denver International Airport. The symbols represents most probable hydrometeor type in the radar volume over the location of the UDFCD rain gage based on hydrometeor classification. R represents rain and WG represents wet graupel. Figure credit Rob CifelliAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Summary Different polarimetric measurement parameters respond to different types of hydrometeor features

These principles have been converted to hydrometeor classification Examples of easy installation of hydrometeor classification and verification

Rain physics Rainfall estimation. Limits of Z-R algorithm Drop shape and D0 Modern rainfall algorithms QPE Examples in flash flood Examples of rainfall estimation in the presence of hail/rain mixture

Rainfall productAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Attenuation correction Application Cause of attenuation in precipitating atmosphere



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Cause of attenuation in precipitating atmosphere? Absorption and Scattering due to water particles.

Absorption dominant at lower frequencies say up to 14 GHz.



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Impact of precipitation particles in between the radar and the scattering object The Propagating Electromagnetic waves are described by

E0 e2

jkr

The propagation constant in free space isk 2 f cAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Impact of precipitation particles in between the radar and the scattering object When we sparsely fill up the intervening path with precipitation particles, the propagation constant gets altered by an unknown amount that is proportional to the absorption due the particles present there.



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Real-time Dual-Pol Based Attenuation CorrectionZh m Zdrm Raw Data (vectors of radar observables) dp Radar Const. Noise Power hv Parameter Estimation (h and v) kh= hKdp kv=vKdp

Data Preprocessing (Segmentation based on data)

Self-consistent method with modified cost function

Zh

c

Optimized for real-time computing Attenuation correction for Zh and Zv separately

Zdrc



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Dual-Pol Based Attenuation CorrectionReflectivity maps at 07:37:31 May 8 2007 and Nexrad reflectivity map at 07:37:24 May 8 2007. (a) IP1 reflectivity before attenuation correction (b) IP1 reflectivity after attenuation correction (c) Nexrad reflectivity.

(a)

(b)

(c)



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Dual-Pol Based Attenuation CorrectionZdr-Zh and Kdp-Zh 2D histogram plots for a squall line case on May 8, 2006 before and after attenuation correction.

Zdr-Zh Kdp-Zh

Before attenuation correctionAdvanced Technologies and applications of Operational Weather Radar

After attenuation correctionSeminar on Doppler Radar and Weather Surveillance

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C-band example of attenuation correction using CPOL radar located in Darwin, AU



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MP-X radar data operated by NIED, Japan



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Summary Attenuation correction is an advanced product, available in operational radars Attenuation in C and X band are due to absorption Attenuation correction can be done using differential propagation phase Real time attenuation correction products are available Makes C band radar competitive with S band



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Dual Doppler Technology



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Dual-Doppler Scan and Retrieval Real-time Dual-Doppler wind velocity retrieval system has been developed and installed in IP1, based on proven algorithms and computation tools. 3-D observations from the IP1 radars are gridded and merged, fused into a common analysis grid Both horizontal wind field and vertical wind component are computed Automate Fast / Agile Scansu v sin 1 cos 1 sin 2 cos 2 sin 1 cos 1 sin 2 cos 2 cos 1 cos 1 cos 2 cos 2 cos 1 cos 1 cos 2 cos 21

v1 r v2 r

low level approximationwt)

1

sin 1 (w sin 2



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LDMIngestCyril Chickasha Rush Springs

WindSynchronization and Gridding Multi-Doppler Synthesis

Lawton

Closed-loop ControlScan Steering and Scheduling

Cell Detection

OptimizationDual-Doppler Rules



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Anadarko Tornado and Damaging Winds Event May 13, 2009EF2 Tornado ~9:22 9:40PM Prolonged Damaging Winds 100mph+ 3 injuries $43 million+ in property damage CASA Tornado Warning 9:21

NWS Tornado Warning 9:24Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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IP1 Radar Network Dual-Doppler Tornado Observation: 2009-May-14 Drop in co-polar correlation due to debris

The ability to observe tornadoes is excellent.



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Nowcasting



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Nowcasting System The Dynamic and Adaptive Radar Tracking of Storms (DARTS) based nowcasting system has been developed and installed in the operational IP1 environment DARTS has high computational efficiency Comparable nowcasting performance to the start-of-the-art (GDST) Ingest Merge and GridInput Data Processing Module Merged, corrected reflectivity image (NetCDF)NetCDF conversion Data restructuring and buffering

DARTS Module

Output Data Processing ModuleData restructuring NetCDF conversion

Predicted reflectivity image set (NetCDF)



MC&C

Display

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Nowcasting System The performance was evaluated for all weather events in 2009, using the standard nowcasting metrics:CSI Critical Success Index = FAR False Alarm Rate = Hits / (Hits + Misses + False) False / (Hits + False)

POD Probability of Detection = Hits / (Hits + Misses)

Nowcast Performance for 2009 Spring StormsAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Examples from Current Dual Polarization Station Installations



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CSU-CHILL National Science Foundation Radar Facility

Placeholder for optional product photo (Delete box if not used) Placeholder for optional product photo (Delete box if not used)



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University of Helsinki weather radar (Vaisala)Placeholder for optional product photo (Delete box if not used)



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Weather radar frequencies

S-band (10 cm, 3 GHz) CSU-CHILL

X-band (3 cm, 9.4 GHz) CASA radars C-band (5 cm, 5.6 GHz) University of Helsinki Radar



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The melting level, indicated by the enhanced LDR (top panel) and reflectivity (bottom panel) layers, descends as the surface precipitation changes from rain to wet snow



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Bright band pattern: The correlation between the horizontally and vertically polarized return signals has a distinct minimum in the vicinity of the melting level.



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Insect echoes typically have larger positive Zdr valuesAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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High time resolution RHI scans through a developing thunderstorm: 30 May 2009



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Reflectivity observations



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Stratiform precipitation



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Stratiform precipitation (contd.)



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Rain showers plus insectsTemperature at Jrvenp about 11 degrees C at 12 UTC, the site is at 32 km distance in the vertical cross section (RHI) direction. The rain shower is moving southwards, towards the radar. In front of the shower large insects are observed, at the surface moving away from the radar, maybe caused by the inflow to the convective cell or sea-breeze.



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Rain showers plus insects



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Insects

Flow from NW, strong echo lines along the flow including large insects.



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Birds migration (2009-04-22)



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Snowfall, March 4 2008

Wide spread ice precipitation consisting of ice crystalsAdvanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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Snowfall, March 3 2008Widespread snow precipitation. Temperature at the ground -5C



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Snowfall, October 13 2009Snow but melting, sticking sleet



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Thanks to IMD Thanks to Mr Raghavan who is the main source of inspiration for my travel to this. Thanks to Dr Tyagi and the convener . Thanks to IITM for the Distinguished Visiting professor appointment. Thanks to NARL for many years of collaboration.Advanced Technologies and applications of Operational Weather Radar Seminar on Doppler Radar and Weather Surveillance

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advanced technologies and applications in operational weather radars

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