# Presentation: 703902

## Comparison of airborne sunphotometer andOMI retrievals of aerosol optical depth during MILAGRO/INTEX-B 2006

- J. Livingston(1),** **O. Torres(2), P. Russell(3), J. Redemann(4), R. Bergstrom(4),
- R. Johnson(3), Qin Zhang(4), B. Veihelmann(5), R. Braak(5), A. Smirnov(2),
- B. Holben(6), L. Remer(6), K. S. Schmidt(7), O. Coddington(7), P. Pilewskie(7)
- (1) SRI International, Menlo Park, CA, USA
- (2) University of Maryland, Baltimore County (UMBC)/NASA Goddard, Greenbelt, MD, USA
- (3) NASA Ames Research Center, Moffett Field, CA, USA
- (4) Bay Area Environmental Research Institute (BAERI), Sonoma, CA, USA
- (5) Royal Netherlands Meteorological Institute (KNMI), De Bilt, The Netherlands
- (6) NASA Goddard Space Flight Center, Greenbelt, MD, USA
- (7) Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO, USA
- http://geo.arc.nasa.gov/sgg/INTEX-B/index.html
- email: _[jlivingston@mail.arc.nasa.gov](mailto:jlivingston@mail.arc.nasa.gov)_

## Outline

- Jetstream 31 (J31) instrument payload and flight overview for MILAGRO/INTEX-B 2006
- Airborne, satellite, and ground-based AOD comparisons
- AATS-14, OMI (UV and MW retrievals), & MODIS over water (3 cases)
- 		  -10 March (Aqua, Aura)
- 	  -03 March (Aqua, Aura)    *(no coincident MODIS retrieval due to sun glint)*
- 	  -17 March (Aqua, Aura)
- AATS-14, OMI, & AERONET over Mexico City (1 case)
- 	  -19 March (Aura)
- Summary/Conclusions

## Jetstream 31 in MILAGRO/INTEX-B: Instrument Locations

**Jetstream 31 in MILAGRO/INTEX-B: Instrument Locations**

| RSP | Total & linearly polarized reflectance | 412-2250 nm, 9  |
| --- | --- | --- |
| SSFR | Upwelling & downwelling spectral hemispheric irradiance | 300-2200 nm, many 
~8-12 nm resolution |
| CAR | Spectral & angular distribution of scattered light from clouds, aerosols, land and water surfaces; imagery of clouds & surface | 340-2130 nm |

## NASA Ames Airborne Tracking Sunphotometer: AATS-14

- 1.	Measures direct solar beam transmission:
- 	 353.5    380.0     449.0      499.4     525.0
-      605.7    675.1     778.4      864.5     939.7
-     1019.1   1241.3   1557.8    2139.0 nm
- Yields:
- 	aerosol optical depth & columnar water vapor (ozone under certain conditions)
- 	aerosol extinction & water vapor (ozone) concentration when aircraft flies profiles
- Size:
- 	Telescope dome 8" OD  (hemisphere) atop 5" H pedestal.  (Total H:  9" above A/C skin), Inside A/C: 12" D x 18" H cylinder.
- Weight:
- 	131.6 lbs

## J31 flight tracks: 13 flights out of Veracruz, Mexico

**J31 flight tracks: 13 flights out of Veracruz, Mexico**

**9 flights over water**

**4 flights over land**

## Four J31 flight tracks coincident with OMI overpasses

**3 Mar**

**19 Mar**

**10 Mar**

**17 Mar**

## J31 flight patterns:Coordinated satellite, in-situ and radiative missions 

**J31**

**B200**

**DC-8**

**C-130**

- MODIS/Aqua

- MISR, MODIS/Terra

- POLDER/Parasol

- OMI/Aura

- CALIPSO

- CloudSat

- GLORY

**J31 flight patterns:****Coordinated satellite, in-situ and radiative missions**

## AOD Comparisons, OMI - MODIS - AATS

- INTEX-B/MILAGRO, 2006

- MODIS

**19:40-20:01 UT**

## AOD Comparisons, OMI - MODIS - AATS

- INTEX-B/MILAGRO, 10 March 2006

- J31 low altitude transect 19:40-20:01 UT

- OMI MW

- MODIS

- OMI UV

- J31 low altitude transect 19:40-20:01 UT

## Slide 10

## 10 March 2006 (over water)

**J31/AATS measurements**

- OMI near-UV retrieval quality flags indicate poor retrievals and suggest possible cloud contamination.

**OMI UV c02**

- AOD extrema along transect

## 10 March 2006 (over water)

- OMI MW & UV AOD retrievals significantly exceed MODIS and AATS values.

**OMI MW c03**

**OMI UV c02**

**MODIS c005**

**AATS**

- AOD extrema along transect

## 10 March 2006 (over water)

**OMI MW c03**

**OMI UV c02**

**MODIS c005**

**AATS**

- AOD extrema along transect

- Likely cloud-contaminated AOD spectra have been removed.

- 10 March 2006 *(over water)*

## Comparison of OMI SSA retrievals for 10 March to AATS/SSFR results from other field campaigns 

**Comparison of OMI SSA retrievals for 10 March to AATS/SSFR results from other field campaigns**

**OMI UV 10 March**

**OMI MW (all) 10 March**

## Comparison of OMI SSA retrievals for 10 March to AATS/SSFR results from other field campaigns 

**Comparison of OMI SSA retrievals for 10 March to AATS/SSFR results from other field campaigns**

**ICARTT urban***

**ACE Asia dust/urban***

**SAFARI biomass***

**PRIDE Saharan dust***

- *Bergstrom et al., Spectral absorption properties of atmospheric aerosols, *Atmos. Chem. Phys. Discuss., 7, 10669-10686*, 2007.

**OMI UV 10 March**

**OMI MW (all) 10 March**

## Slide 16

## Aqua MODIS   03 March 2006   19:50-19:55 UT

**True Color Image**

**Cloud Mask**

**Aqua MODIS   03 March 2006   19:50-19:55 UT**

**J31 low altitude transect**

**18:50-19:02 UT**

**19:23-**

**19:29 UT**

## Aqua MODIS  17 March 2006   20:00-20:05 UT

**True Color Image**

**Fraction of Cloud**

**J31 low altitude transect**

**Aqua MODIS  17 March 2006   20:00-20:05 UT**

## 17 March 2006 (over water)

- 17 March 2006 *(over water)*

- 03 March 2006 *(over water)*

- OMI MW

- OMI UV

- MODIS c005

- AATS

- OMI MW

- OMI UV

- OMI UV

- OMI MW

- OMI MW

- OMI UV

- AATS

- AATS

- -1

- -1

- PRIDE   Saharan dust

- ACE-Asia dust/urban

- AATS

- Aura overpass: 20.12 UT

- Aqua overpass: 20.07 UT

- Aura overpass: 20.32 UT

- no MODIS AOD retrievals coincident with J31/AATS due to sun glint

- OMI retrievals likely cloud-contaminated

## Slide 20

## (rendezvous with C-130, B200, DC-8)

**(rendezvous with C-130, B200, DC-8)**

## 19 March 2006 (over land)

- Aura overpass: 20.11 UT

- 19 March 2006 *(over land)*

**OMI MW c03**

**OMI UV c02**

**AATS**

- less variability, slightly more  dependence than at T2,T1

- AATS AOD:

**AERONET at T0**

**J31 ~450 m above surface**

- Do AODs retrieved by OMI exceed sunphotometer AODs because of an incorrect assumption of surface reflectivity?

**“****Much clearer as we approach T0.”**

## SSFR T0 Surface Albedo Retrievals for 06 & 10 March;   OMI Retrieval Surface Albedo Assumptions for 19 March 

**T0 surface albedo* SSFR 15 March**

**T0 surface albedo* SSFR 06 March**

**OMI MW 19 March **

**OMI UV 19 March**

**SSFR T0 Surface Albedo Retrievals for 06 & 10 March;   OMI Retrieval Surface Albedo Assumptions for 19 March**

- *Coddington et al., Measurements of areal resolved surface spectral albedo, a sensitivity analysis, and validation of MODIS land albedo product during MILAGRO, submitted to *J. Geophys. Res.*, 2007.

## Aerosol Absorption Optical Depth for 19 March 2006

**OMI UV**

**AATS**

**OMI MW**

**AERONET T0**

## Aerosol Absorption Optical Depth for 19 March 2006

- -1

**OMI UV**

**AATS**

**OMI MW**

- -3

- -2

**AERONET T0**

## Aerosol Absorption Optical Depth for 19 March 2006

- -1

**OMI UV**

**AATS**

**OMI MW**

- -3

- -2

**AERONET T0**

## Summary/Conclusions

- During MILAGRO/INTEX-B 2006, AATS-14 acquired near-surface AOD measurements coincident with four Aura OMI overpasses: 3 over the Gulf of Mexico and 1 over Mexico City.
- Aqua-MODIS AOD retrievals are available for 2 of the 3 over-water AATS/OMI events, and these agree well with the corresponding AATS AOD spectra.  For the Mexico City event, AATS AOD spectra agree with coincident surface-based AERONET retrievals at the T0 site.
- For all AATS/OMI coincidences, OMI near-UV and MW AOD retrievals significantly exceed AATS AODs.  Differences may be due to enhanced absorption in the UV due to organic aerosol, OMI instrument calibration, incorrect aerosol height assumption, incorrect surface albedo assumption over land, or cloud contamination over water.
- When expressed in terms of Aerosol Absorption Optical Depth (AAOD), OMI near-UV retrievals and estimated AATS spectra agree better than do the OMI near-UV and AATS AOD spectra.  However, comparisons of OMI MW and estimated AATS AAOD spectra show little improvement in agreement over the OMI MW and AATS AOD comparisons.
- Inversions of AERONET direct sun and almucantar measurements acquired at the T0 site in Mexico City on 19 March near (~20 min before and 40 min after) the time of Aura overpass yield SSA values (0.733 and 0.758) at 441 nm that are significantly less than the OMI retrievals.  The corresponding AERONET AAOD value of 0.073 falls between corresponding OMI UV and MW retrievals of AAOD.** **