arctas bro measurements from the omi and gome-2 satellite instruments
DESCRIPTION
ARCTAS BrO Measurements from the OMI and GOME-2 Satellite Instruments. ARC-IONS Data Workshop 7-8 January 2009 University of Toronto. Kelly Chance, Thomas Kurosu, Trevor Beck, Andreas Richter, Michel van Roozendael, William Simpson, Ross Salawitch, Tim Canty, Yuhang Wang. Introduction - PowerPoint PPT PresentationTRANSCRIPT
ARCTAS BrO Measurements from the OMI and GOME-2 Satellite
Instruments
ARC-IONS Data Workshop 7-8 January 2009
University of Toronto
Kelly Chance, Thomas Kurosu, Trevor Beck, Andreas Richter,
Michel van Roozendael, William Simpson, Ross Salawitch, Tim
Canty, Yuhang Wang
• Enhanced tropospheric BrO has long been observed over the Arctic and Antarctic ice pack in the polar spring.
Introduction
BrO has been measured robustly and globally from space since the first GOME measurements in 1998
(Chance, GRL 1998), +, +
OMI BrOOMI BrO Tropospheric Tropospheric Shelf IceShelf 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
OMI BrOOMI BrO Tropospheric Tropospheric Salt LakesSalt Lakes 11stst Observation from Satellite Observation from Satellite
OMI BrOOMI BrO VolcanoesVolcanoes … … 11stst Observation from Satellite Observation from Satellite
Ambrym: First satellite-based BrO observation in volcanic plumes!
GOME/SCIAMACHY/OMI/GOME-2GOME/SCIAMACHY/OMI/GOME-2
Instrument DetectorSpectral Coverage
[nm]
Spectral Resolution
[nm]
Ground Pixel Size [km2]
Global Coverage
GOME(1995)
Lineararray
240-790 0.2-0.440320
(4080 zoom)3 days
SCIAMACHY(2002)
Lineararray
240-2380 0.2-1.5
3030 3060 3090 30120
30240 (depending on
product)
6 days
OMI(2004)
2-DCCD
270-500 0.42-0.63
1530 – 42162
(depending on swath
position)
daily
GOME-2(2006)
Lineararray
240-790 0.24-0.53
4040 (4080 wide-swath, 4010
zoom)
1.5 to 3 days
BestFitting
• 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
Fitting satellite BrO
GOME BrO fitting for the FIRS-2 overflight on April 30, 1997. The integration time is 1.5s. The fitting precision is 4.2% and the RMS is 2.710-4 in optical depth. Fitting and inversion give a vertical BrO column of 9.31013 cm-2.
• 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.
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 320.5 356.5 nm region for BrO, O3, HCHO, SO2, OClO
Publicly available retrieval: fits 340.5 358.5 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
SAO NRT algorithm
SAO new and improved algorithm
NOAA/SAO collaboration
The End!
• Nadir-viewing UV/vis/NIR
• 240-400 nm @ 0.2 nm
• 400-790 nm @ 0.4 nm
• Launched April 1995
• Footprint 320 x 40 km2
• 10:30 am cross-equator time,
descending node
• Global coverage in 3 days
ESA Global Ozone Monitoring Experiment
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
2%
High resolution solar reference spectrum
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).
Ambrym Eruption: 4th February 2005, OMI Granule 02968
SO2 courtesy of Simon Carn, UMBC BrO
BrO BrO Tropospheric Tropospheric Volcanoes … Volcanoes … 11stst Observation from Satellite Observation from Satellite
BrO: The FutureBrO: The Future•Polar spring BrO/tropospheric Polar spring BrO/tropospheric O O33
– Higher spatial resolutionHigher spatial resolution
– Better correlation; chemistry Better correlation; chemistry (high latitude Hg deposition)(high latitude Hg deposition)
•Volcanoes!Volcanoes!
•Salt lakes!Salt lakes!
Flight 4: 080404 (Fairbanks to Thule)
Thule
Thule
× OMI Overpass
× OMI OverpassOMI Column (1013 mol/cm2)
↑ DC8 O3
DC8 Alt →
DC8 Br2
T. Kurosu, K. Chance, T. Beck, G. Huey, A. Weinheimer