HR: 1340h
AN: A33E-1655    [Abstracts]
TI: GACP climatology of aerosol properties: an update
AU: * Geogdzhayev, I
EM: igor@giss.nasa.gov
AF: 1NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, United States
AU: Mishchenko, M I
EM: crmim@giss.nasa.gov
AF: 1NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, United States
AB: The Global Aerosol Climatology Project (GACP) product is the longest uninterrupted satellite record of aerosol optical thickness (AOT) and size dating back to 1981. The GACP data based on analyses of channel 1 and 2 AVHRR radiances show significant regional changes in the retrieved optical thickness of tropospheric aerosols which had occurred between the volcano-free periods 1988-91 and 2002-05. These trends appear to be generally plausible, are consistent with extensive sets of long-term ground-based observations throughout the world, and may increase the trustworthiness of the recently identified downward trend in the global and hemispheric AOT averages. To the extent that radiance calibration remains to be a potentially significant source of uncertainty, our regional results cannot prove unequivocally the existence of the relatively weak global and hemispheric downward trend. However, their plausibility appears to increase the trustworthiness of the overall tendency. An additional, albeit indirect, confirmation of the overall decreasing tendency in AOT comes from the widespread contemporaneous reversal from global solar dimming to global solar brightening. We thus believe that the totality of our results demonstrates the potential of satellite remote sensing to identify long-term aerosol trends. Nevertheless, more work still needs to be done in terms of both verification and potential improvement of the AVHRR radiance calibration and comparisons of GACP aerosols retrievals with potentially more accurate retrievals afforded by the newer satellite instruments.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0360 Radiation: transmission and scattering
DE: 0365 Troposphere: composition and chemistry
DE: 1640 Remote sensing (1855)
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting