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