Satellite remote sensing reveals regional tropospheric aerosol trends.

The Global Aerosol Climatology Project data product based on analyses of channel 1 and 2 AVHRR radiances shows 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 tropospheric aerosol load.