MINI-DOAS

Jochen StutzMax Spolaor

University of California Los Angeles

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

Spectrometers

Telescopes

… on NASA’s Global Hawk

Quartz fibers

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