Examination of direct cumulus contamination on MISR-retrieved aerosol optical depth and angstrom coefficient over ocean

The effect of direct cumulus contamination on the aerosol optical depth (AOD) and angstrom exponent (AE) from the Multi-angle Imaging SpectroRadiometer (MISR) was examined using overlapped 15-m resolution data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) over the tropical western Atlantic Ocean (RICO), the Gulf of Mexico (GOMX), and Indian Ocean (INDI). Overall, 12%, 6% and 11% of MISR 1.1-km pixels for aerosol retrievals contain some clouds, but 97%, 100% and 89% of these MISR pixels have the clouds covering less than 5% of the MISR pixel area over RICO, GOMX and INDI, respectively. On average, cumulus-contaminated pixels increase AOD at 558 nm by 0.02, 0.02 and 0.00 and decrease AE by 0.03, 0.11 and 0.04 for RICO, GOMX and INDI, respectively. Based on these findings, a MISR-derived aerosol optical depth climatology over the tropical oceans is biased high by no more than 0.002 from direct cumulus contamination. Citation: Zhao, G., L. Di Girolamo, S. Dey, A. L. Jones, and M. Bull ( 2009), Examination of direct cumulus contamination on MISR-retrieved aerosol optical depth and angstrom coefficient over ocean, Geophys. Res. Lett., 36, L13811, doi: 10.1029/2009GL038549.