1. ARCTAS BrO Measurements from the OMI and GOME-2 Satellite Instruments
Kelly Chance, Thomas Kurosu, Trevor Beck, Andreas Richter, Michel van Roozendael, William Simpson, Ross Salawitch, Tim Canty, Yuhang Wang
ARC-IONS Data Workshop
7-8 January 2009
University of Toronto

2. Introduction
BrO has been measured robustly and globally from space since the first GOME measurements in 1998 (Chance, GRL 1998), +, +
Enhanced tropospheric BrO has long been observed over the Arctic and Antarctic ice pack in the polar spring.

3. OMI BrO Tropospheric Shelf Ice
11 March 2005
BrO is a strong source of O3 destruction in the stratosphere and troposphere.
BrO is measured globally now by SCIAMACHY, GOME-2, and OMI

4. OMI BrO Tropospheric Salt Lakes 1st Observation from Satellite

5. OMI BrO Volcanoes … 1st Observation from Satellite
Ambrym: First satellite-based BrO observation in volcanic plumes!

6. GOME/SCIAMACHY/OMI/GOME-2
Instrument
Detector
Spectral Coverage [nm]
Spectral Resolution [nm]
Ground Pixel Size [km2]
Global Coverage
GOME
(1995)
Linear
array
40320
(4080 zoom)
3 days
SCIAMACHY
(2002)
3030 3060 3090 30120 30240 (depending on product)
6 days
OMI
(2004)
2-D
CCD
1530 – 42162
(depending on swath position)
daily
GOME-2
(2006)
4040
(4080 wide-swath, 4010 zoom)
1.5 to 3 days

7. Best
Fitting

8. Fitting satellite BrO
Requires precise (dynamic) wavelength and slit function calibration, Ring effect correction, undersampling correction, and proper choices of reference spectra (HITRAN!)
Best trace gas column fitting results come from direct fitting of satellite radiances

9. GOME BrO fitting for the FIRS-2 overflight on April 30, The integration time is 1.5s. The fitting precision is 4.2% and the RMS is 2.710-4 in optical depth. Fitting and inversion give a vertical BrO column of 9.31013 cm-2.

10. Differences among satellites and algorithms are a 30% or less issue (NB GOME-1).
Over high albedos, tropospheric and stratospheric AMFs differ by about a factor of two.

11. Salawitch et al., AGU Fall 2008:
ARCTAS & ARCPAC Inorganic Bromine Measurements
 April 2008 deployment from Fairbanks, Alaska
 Scientific Focus: quantification of the relationship between OMI BrO
and the nearly complete removal of ozone in Arctic boundary layer
“Ozone Depletion Events”
 OMI BrO: New “off line” retrieval that fits  nm region
for BrO, O3, HCHO, SO2, OClO
Publicly available retrieval: fits  nm region
for BrO, O3, HCHO, SO2, OClO, and O2-O2
New retrieval: low residuals, much higher signal to noise,
but slight correlation with surface albedo
OMI retrievals by Thomas Kurosu
GOME-2 retrievals by Trevor Beck

12. SAO NRT algorithm

13. SAO new and improved algorithm

14. NOAA/SAO collaboration

17. The End!

18. ESA Global Ozone Monitoring Experiment
Nadir-viewing UV/vis/NIR nm nm
Launched April 1995
Footprint 320 x 40 km2
10:30 am cross-equator time,
descending node
Global coverage in 3 days

19. SCIAMACHY German/Dutch/Belgian Atmospheric Spectrometer
2002 launch on ESA Envisat
Adds (to GOME) continuous coverage to 1700 nm, plus IR bands at 2.0 m (CO2) and 2.4 m (CO, N2O)
Higher spatial resolution footprint than GOME (as good as 30  60 km2)
Adds limb scattering and limited solar occultation measurements
Nadir-limb subtraction improves tropospheric measurements
Data and validation are still in a preliminary stage

20.  2%

21. High resolution solar reference spectrum

22. GOME BrO fitting: Relative contributions absorption by atmospheric BrO (top) and the Ring effect - the inelastic, mostly rotational Raman, part of the Rayleigh scattering – (bottom).

23. BrO Tropospheric Volcanoes … 1st Observation from Satellite
Ambrym Eruption: 4th February 2005, OMI Granule 02968
SO2 courtesy of Simon Carn, UMBC
BrO

24. BrO: The Future Polar spring BrO/tropospheric O3 Volcanoes!
Higher spatial resolution
Better correlation; chemistry (high latitude Hg deposition)
Volcanoes!
Salt lakes!

25. Flight 4: 080404 (Fairbanks to Thule)×
OMI Overpass
T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer
↑ DC8 O3
DC8 Alt →
OMI Column (1013 mol/cm2) ×
OMI Overpass
DC8 Br2