# Presentation: 712357

## Jens Redemann1, B. Schmid1, J. M. Livingston2, P. B. Russell3, J. A. Eilers3, 
P. V. Hobbs4, R. Kahn5, W. L. Smith Jr.6, B. N. Holben7 , C.K. Rutledge8, M.C. Pitts6, M.I. Mishchenko9, B. Cairns10, J. Chowdhary10, J.V. Martins11, 		A. Plana-Fattori11, R.C. Levy7, T.P. Charlock6 

1Bay Area Environmental Research Institute, CA
2SRI International, CA, 3NASA Ames Research Center, CA  4University of Washington, WA, 5Jet Propulsion Lab, CA
6NASA LaRC, VA, 7NASA GSFC, MD, 8AS&M, Inc./NASA LaRC, VA,
9NASA GISS, NY, 10Columbia University, NY, 
11UMBC / NASA GSFC, MD; on leave from the University of Sao Paulo, Brazil

- P. V. Hobbs4, R. Kahn5, W. L. Smith Jr.6, B. N. Holben7 , C.K. Rutledge8, M.C. Pitts6, M.I. Mishchenko9, B. Cairns10, J. Chowdhary10, J.V. Martins11, 		A. Plana-Fattori11, R.C. Levy7, T.P. Charlock6
- 1Bay Area Environmental Research Institute, CA
- 2SRI International, CA, 3NASA Ames Research Center, CA  4University of Washington, WA, 5Jet Propulsion Lab, CA
- 6NASA LaRC, VA, 7NASA GSFC, MD, 8AS&M, Inc./NASA LaRC, VA,
- 9NASA GISS, NY, 10Columbia University, NY,
- 11UMBC / NASA GSFC, MD; on leave from the University of Sao Paulo, Brazil

**Airborne measurements of aerosol optical depth and columnar water vapor in support of the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) Experiment, 2001**

## Contents

- AATS-14 aboard the UW CV-580
- Comparability with other platforms and instruments
- Comparisons of AATS-14 to AERONET Cimel sunphotometer at COVE: implications for satellite validation
- Spatial statistics of AOD off the US East Coast
- MODIS validation over the ocean
- Summary

## AATS-14 aboard the UW CV-580

- 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   1059.4   1241.3   1557.8  nm
- Yields:
- 	aerosol optical depth + aerosol extinction when A/C flies profiles
- 	columnar water vapor + water vapor concentration when A/C 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

## Typical UW CV-580 flight track in CLAMS

- Typical UW CV-580 flight track in CLAMS

- Chesapeake Lighthouse

## Typical AATS-14 measurement day

## AERONET vs. AATS-14 at COVE, July 17, 2001

## Statistics of AERONET vs. AATS-14 at COVE, July 10 – Aug.2, 2001

- y=1.035x+0.016
- r2=0.995
- rmse=0.04

- y=1.041x+0.002
- r2=0.993
- rmse=0.021

- y=0.987x-0.004
- r2=0.959
- rmse=0.011

- y=0.957x-0.005
- r2=0.916
- rmse=0.012

## Suborbital measurements of AOD - spatial vs. temporal variability:

|  | Temporal:
Long-term | Temporal:
Short-term |  | Spatial resolution |
| --- | --- | --- | --- | --- |
| Ground-based (e.g., AERONET) | 
yes | 
yes (15 min.) | 
no | 
no |
| Ship-based sunphotometer | 
yes | 
yes | 
no | 
?? |
| Aircraft-based TDDR | 
no | 
possible | 
yes | 45 sec. ~ 3-4 km 
 |
| Aircraft-based
AATS | 
no | 
possible | 
yes | 2 sec. ~ 100-200 m
 |

## CV-580/AATS-14 location, CLAMS July 17, 2001, 16:00 - 16:15 UTC

## AOD variability on July 17th, 2001

- ΔAOD~30%

## AATS-14 vs. AERONET: spatial and temporal variability

## AATS-14: spatial variability

## Summary of AATS-14 derived AOD spatial variability by flight in CLAMS-2001

## Slide 14

## MODIS: 6 wavelengths validation over ocean

- Courtesy of R. Levy, MODIS team

## Vertical aerosol structure, July 17, 2001

## Vertical water vapor structure, July 17, 2001

## Summary

- Available as of Feb. 23, 2002: Version 1.0 of all full-column measurements of AATS-14 in CLAMS in 11 ASCII data files (one per CV-580 flight).
- In CLAMS, AATS-14 measured full column aerosol optical depth spectra and columnar water vapor at exact TERRA overpass time on at least 7 occasions. For five of these opportunities, AOD at 499nm was at or below 0.1.
- During TERRA overpass time on July 17, 2001, AATS-14 measured the highest AOD encountered during the entire experiment (~0.49 at 499nm), including a horizontal gradient in AOD of more than 30% over a horizontal distance of ~70 kilometers.
- Comparisons between airborne AATS-14 in the vicinity of and AERONET Cimel derived AOD’s directly at the Chesapeake Lighthouse show good agreement and complementary results in assessing both spatial and temporal AOD variability.
- AOD variability during low-level legs of 11 research flights was frequently as high as 50% over distances ≤ 50 km.