89th American Meteorological Society Annual Meeting

Tuesday, 13 January 2009: 11:00 AM
(Invited Speaker) The Impact of Asian Pollution on Pacific Storm Track
Room 131B (Phoenix Convention Center)
Renyi Zhang, Texas A&M University, College Station, TX; and G. Li, Y. Wang, and Y. Diao
Atmospheric aerosols indirectly impact climate by altering cloud development, lifetime, precipitation, and albedo. Current understanding of the aerosol indirect effect remains highly uncertain, constituting the greatest uncertainty in climate prediction. Anthropogenic aerosols may influence the cloud processes and precipitation by serving as cloud condensation nuclei (CCN), potentially forming smaller cloud droplets and higher concentrations. Increasing pollution levels in Asia and associated outflows have raised considerable concerns because of their potential impact on regional and global climate. In this presentation, results from long-term satellite measurements of clouds and precipitation will be presented to show a trend of increasing deep convective clouds and precipitation over the Pacific in winter (1984-2005). Simulations using the WRF model reveal that the enhanced deep convective clouds and precipitation are reproduced when accounting for the aerosol effect from the Asian pollution outflow, which leads to intensified storms. We suggest that the wintertime Pacific is highly vulnerable to the aerosol-cloud interaction because of favorable cloud dynamical and microphysical conditions from the coupling between the Pacific storm track and Asian pollution outflow. The intensified Pacific storm track is climatically significant and represents possibly the first detected climate signal of the aerosol-cloud interaction associated with anthropogenic pollution. In addition to radiative forcing on climate, intensification of the Pacific storm track likely impacts the global general circulation due to its fundamental role in meridional heat transport and forcing of stationary waves.

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