uv aerosol product status and outlook omar torres and changwoo ahn omi science team meeting outline...
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UV Aerosol Product Status and Outlook
Omar Torres and Changwoo Ahn
OMI Science Team Meeting
Outline-Status
-Product AssessmentOMI-MODIS ComparisonOMI-Aeronet ComparisonOMI-AATS Comparison
-Summary and Conclusions
Baltimore, June 6, 2007
Status
Products: - Aerosol Extinction and Absorption Optical Depth 388 nm-Also reports values at 354 and 500 nm (converted)
Validation Analysis-Comparisons to other satellite products (MODIS, MISR) (Ahn, et al, 2007)-Comparison to AERONET observations (Torres et al, 2007)-Comparison to Airborne observations (Livingston et al, 2007)
Data availability-Publicly released (L2, L2G)
(A) Jan 2, 2007, biomass burning (B)May 14, 2006, Pollution Aerosols
(C) March 10, 2006, Asian dust (D) August 15, 2006, Saharan dust
OMI Aqua-MODIS comparison of retrieved AOD
Aeronet Sites used in the Analysis
Site Location Aerosol typeAlta_FlorestaAgoufouBanizombouIER-CinzanaOugadougouMonguForth CreteBlidaSaadaDakarKanpurDhadnadHamimMukdahanXiangHeGSFCHalifaxBratts_LakeBondvilleCARTELCoveHJAndrewsMD Science CenterMVCOSERCSioux_FallsUCSBWallops
9S 56W15N 1W13N 2E13N 5W12N 1W15S 23E35N 25E36N 2E31N 8W
14N 16W26N 80E25N 56E22N 54E
16N 104E39N 116E38N 76W44N 63W
50N 104W40N 88W45N 71W36N 75W
44N 122W39N 76W41N 70W38N 76W43N 96W
34N 119W37N 75W
smokesmoke, dustsmoke,dustdustdust, smokesmokedust, pollutiondustdustdust,smokedust,smoke,pollutiondustdustsmoke,pollutiondust,smoke,pollut.weakly absorbingweakly absorbingweakly absorbingweakly absorbingweakly absorbingweakly absorbingweakly absorbingweakly absorbingweakly absorbingweakly absorbingweakly absorbingweakly absorbingweakly absorbing
13 sites2 years (2005-6)374 points
OMI-UV Aeronet Comparison Weakly-absorbing aerosols
0.03~0.05 BiasReasonable agreement for clear conditions
Poor statistics!
OMI-Aeronet ComparisonDesert Dust Aerosols
4 sites2years 2005-6256 pointsGood Statistics
High Noise Level, Aerosol layer height?0.3 bias
OMI-Aeronet ComparisonPollution Aerosols
2 sites101 points
Reasonable agreementBias of ~0.2 at low AOD’s
AOD Comparisons, OMI - MODIS - AATSINTEX-B/MILAGRO, 2006
MODIS
Aura/OMI overpass ~15 minutes after Aqua at 20:13 UT
J31 low altitude transect
J31 flight track color coded by
altitude
MODIS10x10 km2
OMI 13x24km2
True Color Image (Aqua), 10 March, 19:55-20:00 UTTrue Color Image (Aqua), 10 March, 19:55-20:00 UT
(Phil Russell, NASA, AMES)
AOD Comparisons, OMI - MODIS - AATSINTEX-B/MILAGRO, 10 March 2006
J31 low altitude transect 19:40-20:01 UT
OMI MWOMI MW
MODISMODIS
OMI UVOMI UV
84
4317
5
1
J31 low altitude transect 19:40-20:01
UT
OMI % cloud
MODIS % cloud22
22
Geo-collocation difference in OMI-UV and MW retrievals
10 March 2006 10 March 2006 (over water)(over water)
Case 1Case 1
OMI MW & UV AOD retrievals exceed MODIS and AATS values.
(Prelim)(Prelim)
Milagro Airborne AOD measurements vs OMI & MODIS
OMI near-UV retrieval quality flags indicate poor retrievals and suggest possible cloud
contamination; retrievals yield enhanced AODs
Photo from DC-8 over Mexico City, 19 Mar 2006Courtesy of Cam McNaughton (Univ. of Hawaii)
MWUVT2
T1
J31 track
OMI overpass: 20.11 UT
19 March 2006 (over land)
J31 ~450-750 m above surface
“Visibility poor; eyes burning in cockpit…”
Larger OMI MW AOD retrievals over land likely due to incorrect
surface albedo assumption.
highest quality
AATS AOD: high variability, flat depend.
(Prelim)(Prelim)
Phil Russell
Assessment of OMI-UV Absorption Retrievals during MILAGRO campaign
OMI-UV Aerosol Absorption Optical Depth agrees well withAATS Inferred Absorption Optical Depth Spectral on March 19, 2006
(Phil Russell)
Comparison of OMI and AERONET Retrievals ofSingle Scattering Albedo
Smoke and Pollution AerosolsRMS: 0.03
Dust AerosolsRMS: 0.02
OMI-Aeronet Comparison of Absorption Optical DepthDust Aerosols
RMS: 0.02
-Severe sub-pixel cloud contamination affects retrieval of extinction optical depth for weakly absorbing aerosols
-Reasonable agreement for absorbing aerosols
-In the presence dust-smoke mixtures, OMI AOD’s are over-estimated
-In general a bias of about 0.2 ~0.3 is observed with respect toAERONET observations
-Reasonable agreement in aerosol absorption parameters (AAOD and SSA)
-Reprocessing of Collection 3 data will start in summer-07
-Preliminary analysis indicate that in Collection 3 data the AOD bias will decrease
Summary and Conclusions