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Jens Redemann 1 , B. Schmid 1 , J. M. Livingston 2 , P. B. Russell 3 , J. E. Eilers 3 ,

Airborne Sunphotometry in Support of the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) Experiment, 2001. Jens Redemann 1 , B. Schmid 1 , J. M. Livingston 2 , P. B. Russell 3 , J. E. Eilers 3 , P. V. Hobbs 4 , R. Kahn 5 , W. L. Smith Jr. 6 , B. Holben 7 , K. Rutledge 8

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Jens Redemann 1 , B. Schmid 1 , J. M. Livingston 2 , P. B. Russell 3 , J. E. Eilers 3 ,

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  1. Airborne Sunphotometry in Support of the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) Experiment, 2001 Jens Redemann1, B. Schmid1, J. M. Livingston2, P. B. Russell3, J. E. Eilers3, P. V. Hobbs4, R. Kahn5, W. L. Smith Jr.6,B. Holben7 , K. Rutledge8 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

  2. Contents • Purpose of CLAMS • Sunphotometer measurements aboard the UW CV-580 – comparability with other platforms and instruments • Comparisons of AATS-14 to AERONET Cimel sunphotometer at COVE • First validation attempts of the MISR standard algorithm • Spatial statistics of AOD off the US East Coast • Conclusions

  3. Chesapeake Lighthouse: Centerpiece of CLAMS observations • CLAMS: clear sky, shortwave (SW) closure campaign • CERES, MISR, MODIS-Atmospheres, and the NASA/GEWEX/GACP • Measurements from: • Chesapeake Lighthouse research platform (36.9N,75.7W), • 6 research aircraft, • TERRA satellite • CLAMS research goals: • validation of satellite-based retrievals of aerosol properties, • vertical profiles of radiative fluxes, • temperature and water vapor

  4. 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 (ozone) + water vapor (ozone) 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

  5. Typical UW CV-580 flight track in CLAMS Chesapeake Lighthouse

  6. Typical AATS-14 measurement day

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

  8. 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

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

  10. AOD variability on July 17th, 2001 ΔAOD~25%

  11. Comparison between AATS-14, AERONET and MISR (unvalidated standard algorithm), CLAMS, July 17, 2001

  12. Vertical aerosol structure, July 17, 2001

  13. Conclusions • 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 (~0.48 at 499nm), including a horizontal gradient in AOD of more than 0.1 over a horizontal distance of ~80 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 strongest correlation coefficients at 380 and 500 nm). • Initial validation studies of the standard MISR AOD algorithm seem to indicate the lack of small particles in the mixture models.

  14. Acknowledgment • We gratefully acknowledge funding for AATS-14 participation in CLAMS through the EOS Validation Program (M. King).

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