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Mini-DOAS. University of California Los Angeles. Jochen Stutz Max Spolaor. What is Mini-DOAS ? . Identify and quantify trace gases using their narrow band absorptions. Airborne remote sensing Slant Column Density (SCD). +1˚ 0˚ -1˚ -1.5˚ -2˚ -2.5˚ -3˚ -4˚ -5˚ -15˚. Rotating

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Presentation Transcript
mini doas

Mini-DOAS

University of California Los Angeles

Jochen Stutz

Max Spolaor

slide2
What is Mini-DOAS ?

Identify and quantify trace gases using their narrow band absorptions.

Airborne remote sensing

Slant Column Density (SCD)

+1˚

-1˚

-1.5˚

-2˚

-2.5˚

-3˚

-4˚

-5˚

-15˚

Rotating

Telescopes

Alternating viewing

directions

how does mini doas work
How does Mini-DOAS work?

Telescopes for UV, VIS, near-IR

PC

Electronics

Power consumption: 29VDC at 1.4A = 41W

Size and Weight:11.8x9.84x8.0 inches; 75pounds including 9L ice-water

Scanner

Quartz

Fibers

Optics

Vacuum Vessel

Ice-Water

Spectrometers

Insulation

SpectrometerAssembly

slide4
… on NASA’s Global Hawk

Telescopes

Spectrometers

Quartz fibers

slide5
DOAS

Identification and quantification of trace gases by their unique narrow band absorption in the open atmosphere

Differential Optical

Absorption Spectroscopy

bro and o4 data analysis
BrO and O4 data analysis

O4

BrO

0

0

Intensity

Intensity

3x10-4

9x10-3

Species to be measured & DL: NO2 50 ppt

HONO 20 ppt

BrO 0.75 ppt

HCHO 150 ppt

SO2 200 ppt

glyoxal: ?

aerosol extinction (via O4)

  • O4 fit range: 338-347nm 352-360nm
  • BrO fit range: 345 – 360nm
attrex data example
ATTREX Data Example

+1˚

-1˚

-1.5˚

-2˚

-2.5˚

-3˚

-4˚

-5˚

-15˚

Elevation Angle

Relative Radiance

[counts/ms*scans]

Altitude

[103m]

BrO DSCD

[1014molec./cm2]

O4 DSCD

[1043 molec2./cm5]

Universal Time [5th November 2011]

from scds to trace gas concentration
From SCDs to trace gas concentration

BAMFs derived via radiative transfer calculations

Optimal Estimation Inversion to derive concentration profile c(h)

VCD

Scattered

sunlight

SCD

bro vertical concentration profile retrieval
BrO vertical concentration profile retrieval

Science flight 2 on 11/05, 18:00 UTC

Retrieved BrO profile

x1E14

SZA=74°

flight level

SZA=56°

BrO at flight altitude:

~(1.8 ± 0.25) x107 molec/cm3

= (5.0 ± 0.75) ppt

Modeled SCDs fit well

bro vertical profiles
BrO vertical profiles

Science flight 2 on 11/05

Consecutively retrieved BrO profiles

BrO at flight altitude

34°N

30°N

questions issues
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
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