Details

Autor(en) / Beteiligte

• Wetzel, Melanie A
• Stowe, Larry L

Titel

Satellite-observed patterns in stratus microphysics, aerosol optical thickness, and shortwave radiative forcing

Ist Teil von

• Journal of Geophysical Research, 1999-12, Vol.104 (D24), p.31

Erscheinungsjahr

1999

Quelle

Wiley-Blackwell Journals

Beschreibungen/Notizen

• A long-term global daily data set of satellite-derived radiances has been applied over oceans to investigate the effect of aerosol particles on marine stratus cloud physical parameters and cloud shortwave radiative forcing. Tropospheric aerosol can indirectly influence cloud reflectance and radiative forcing by acting as cloud condensation nuclei, thus modifying the droplet size distribution and cloud optical properties. The NOAA polar-orbiting satellite advanced very high resolution radiometer Pathfinder Atmosphere (PATMOS) data provide estimates of aerosol optical thickness (AOT) which were utilized to represent the amount of aerosol available to modify marine stratus. PATMOS multichannel radiances for cloudy pixels were combined with radiative transfer modeling to estimate cloud droplet effective radius and cloud optical thickness for several months and years in (110 km)-squared grid cells between 50 deg S and 50 deg N. The results indicate an inverse relationship between aerosol burden and cloud droplet size, including seasonal and regional variability that compares well with known aerosol sources. Analyses suggest an AOT value above which the stratus properties do not change; that is, the indirect effect reaches a 'microphysical saturation limit'. (Author)