mini-doas jochen stutz max spolaor university of california los angeles
TRANSCRIPT
Identify and quantify trace gases using their narrow band absorptions.
Airborne remote sensing Slant Column Density (SCD)
What is Mini-DOAS ?
Rotating Telescopes
Alternating viewingdirections
+1˚ 0˚-1˚-1.5˚-2˚-2.5˚-3˚-4˚-5˚-15˚
How does Mini-DOAS work?
PCElectronicsTelescopes for UV, VIS, near-IR
Spectrometers
Optics
Scanner
Vacuum VesselIce-WaterInsulation
Spectrometer Assembly
QuartzFibers
Power consumption: 29VDC at 1.4A = 41W Size and Weight:11.8x9.84x8.0 inches; 75pounds including
9L ice-water
Identification and quantification of trace gases by their unique narrow band absorption in the open atmosphere
B
'
()
[cm
2 ]
[nm]
D'
I'0
I0
I()
250 300 350 400 450 600 650 700
0100200
detection limits
200 pptL=1km
1 pptL=16km
2 pptL=12km
20 pptL=12km
500 pptL=5km
5 pptL=5km
100 pptL=5km
200 pptL=5km
1 ppbL=5km
Phenol Wavelength [nm]
04080
20 pptL=1km
50 pptL=1km
250 pptL=1km
para-Cresol
05
10
Toluene
01020
Benzene
0100200
IO
050 BrO
020 ClO
0
1
HCHO
0100
NO3
04
HONO
0
2NO
2
048
SO2
0
4250 300 350 400 450 600 650
50 pptL=5km
'[1
0-1
9 c
m2 ]
O3
DOAS
Differential Optical Absorption Spectroscopy
BrO and O4 data analysis
BrO fit range: 345 – 360nm O4 fit range: 338-347nm 352-360nm
BrO
3x10-4
Inte
nsi
ty
9x10-3
Inte
nsi
ty
O4
0
0
Species to be measured & DL: NO2 50 ppt HONO 20 ppt BrO 0.75 pptHCHO 150 pptSO2 200 pptglyoxal: ?aerosol extinction (via
O4)
Alt
itu
de
[10
3m
]ATTREX Data Example
Rela
tive
Rad
ian
ce
[cou
nts
/m
s*s
can
s]
BrO
DS
CD
[10
14
mole
c./
cm
2]
Universal Time [5th November 2011]
+1˚ 0˚-1˚-1.5˚-2˚-2.5˚-3˚-4˚-5˚-15˚
Elevation
Angle
O4 D
SC
D[1
04
3
mole
c2./
cm
5]
From SCDs to trace gas concentration
BAMFs derived via radiative transfer calculations
Optimal Estimation Inversion to derive concentration profile c(h)
dhhcAngElBAMFAngElSCD )(.).(.).(
VCD
SCDScattered
sunlight
0 20 40 60 80 1000
2
4
6
8
10Detector at 4km
Box Airmass Factor (DBAMF)
Alti
tude
(km
)
-90.0°-45.0°-30.0° -4.0° -3.0° -2.5° -2.0° -1.5° -1.0° -0.5° 0.5° 1.0° 1.5° 2.0° 2.5° 3.0° 4.0° 5.0°
BrO vertical concentration profile retrieval
BrO at flight altitude:
~(1.8 ± 0.25) x107 molec/cm3= (5.0 ± 0.75) ppt
flight level
Modeled SCDs fit well
SZA=74°
SZA=56°
Science flight 2 on 11/05, 18:00 UTC
x1E14 Retrieved BrO profile
BrO vertical profiles
Consecutively retrieved BrO profiles
BrO at flight altitude
Science flight 2 on 11/05
34°N
30°N
Questions / Issues
Telescope fairing (pressure seal). Calibration of telescope geometry after installation
Meeting NSF specs for instrument Instrument has undergone environmental testing at NASA
Fast information on pitch, roll, acceleration ? Addition of sensor to instrument of from aircraft?
Data archive on C130 server (~5000 spectra each 10kbyte)?
Change of measurement strategy depending on flight status Profiling through elevation scanning vs limb during
ascent/decent