85th AMS Annual Meeting

Tuesday, 11 January 2005: 9:00 AM
Radiative Forcing of North Pacific Cloud Systems Under the Influence of Asian Aerosols
Eric M Wilcox, NOAA/GFDL, Princeton, NJ; and G. S. Mauger, O. Lariviere, G. Roberts, V. Ramanathan, and S. Haimov
The radiative forcing of Northeastern Pacific Ocean cloud systems during April 2004 is evaluated in order to determine the impact of aerosol indirect effects in air masses containing Asian aerosols. The analysis blends satellite observations with in-situ measurements during episodes of transport of Asian dust and pollution across the ocean basin to the California coast. Measurements of cloud radiative forcing are made from the CERES instrument aboard the Terra and Aqua satellites. The satellite observations are coincident with in-situ measurements of cloud and aerosol properties from 24 flights of the U. Wyoming King Air research aircraft during the Cloud Indirect Forcing Experiment (CIFEX). A range of clean and polluted conditions were observed by the aircraft during the period, in addition to two Asian dust storm events. The aircraft measurements of aerosols confirm the basin-scale aerosol distributions determined with chemical transport model forecasts. A variety of cloud systems were sampled as well, ranging from shallow stratus and stratocumulus clouds to mixed-phase precipitating cumulus. Under pristine conditions, many shallow clouds were observed to be drizzling, suggesting that the notably reflective clouds characteristic of the Northern Pacific Ocean may be highly susceptible to the influence of aerosols. Satellite retrievals of cloud drop effective radius are combined with aircraft observations of cloud drop concentrations and size distributions in order to constrain the influence of aerosols on cloud microphysics. Satellite observations of cloud top height are combined with aircraft observations of cloud thickness and vertical velocity from the Wyoming Cloud Radar aboard the aircraft in order to constrain the cloud dynamics.

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