# Presentation: 703903

## 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. Johnson(3),
- R. Bergstrom(4), 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: _[John.M.Livingston@nasa.gov](mailto:John.M.Livingston@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 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**

## Four J31 flight tracks coincident with OMI overpasses

**3 Mar**

**19 Mar**

**10 Mar**

**17 Mar**

## 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 9

## 10 March 2006 (over water)

**J31/AATS measurements**

- AOD extrema along transect

**AATS-14**

- 10 March 2006 *(over water)*

## 10 March 2006 (over water)

**MODIS c005**

**AATS-14**

- 10 March 2006 *(over water)*

- AOD extrema along transect

## 10 March 2006 (over water)

**OMI MW c002**

**OMI UV c002**

**MODIS c005**

**AATS-14**

- OMI MW & near-UV AOD c002 retrievals significantly exceed MODIS and AATS values.

- 10 March 2006 *(over water)*

- AOD extrema along transect

## 10 March 2006 (over water)

**OMI MW c003**

**OMI UV c003**

**MODIS c005**

**AATS-14**

- 10 March 2006 *(over water)*

- OMI near-UV AOD c003 retrievals are much lower than c002 retrievals and yield a non-absorbing aerosol.

- AOD extrema along transect

- Likely cloud contaminated

## 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**

## 03 March 2006 (over water)

- OMI MW c002

- OMI UV** **c002

- AATS-14

- OMI MW c003

- OMI UV c003

- 03 March 2006 *(over water)*

- 17 March 2006 *(over water)*

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

- AATS-14

- OMI MW c002

- OMI UV** **c002

- MODIS c005

- AATS-14

- OMI MW c003

- OMI UV** **c003

- MODIS c005

- AATS-14

- Aura overpass: 20.12 UT

- Aqua overpass: 20.07 UT

- Aura overpass: 20.32 UT

## Slide 17

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

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

## Slide 19

## 19 March 2006 (over land)

- Aura overpass: 20.11 UT

**OMI MW c003**

**OMI UV c003**

**AATS**

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

**AERONET at T0**

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

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

**J31 ~450 m above surface**

- AATS AOD:

- 19 March 2006 *(over land)*

## 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.

## Single Scattering Albedos for 19 March 2006 and from SSFR/AATS Measurements in Previous Field Campaigns

**OMI**** UV**

**PRIDE Saharan dust***

**OMI**** ****MW**

**ACE Asia dust/urban***

**AERONET**

**[Barnard-Volkamer]**

**MFRSR T2: 19 Mar 06**

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

**T0: 19 Mar 06**

**T0: 19 Mar 06**

**T0: 19 Mar 06**

## Aerosol Absorption Optical Depth for 19 March 2006

**PRIDE Saharan dust**

**AA****TS**

**AERONET T0**

**ACE Asia dust/urban**

**OMI MW**

**OMI**** UV**

## Summary/Conclusions

- _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 4 AATS/OMI coincidences during MILAGRO/INTEX-B, OMI near-UV and MW AOD retrievals using C002 radiance data significantly exceed AATS AODs.  When C003 radiance data are used for the 3 over-water cases, OMI MW retrievals change very little, but OMI near-UV retrievals decrease markedly and yield a non-absorbing aerosol model.  Retrievals for the Mexico City case show little difference between C002 and C003.
- AATS/OMI differences may be due to enhanced absorption in the UV due to organic aerosol, any remaining OMI instrument calibration issues, incorrect aerosol height assumption, incorrect surface albedo assumption over Mexico City, or cloud contamination over the Gulf of Mexico.
- For the 19 March Mexico City data set, OMI near-UV AOD retrievals near T2 agree well with AERONET AODs.  Near T0, OMI near-UV AAOD retrievals and estimated AATS AAOD 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.** **