7th Conf. on Atmospheric Chemistry


The Indirect Effect of Aerosols on Cold Clouds in the East Asian APEX region

Rodrigo Munoz-Alpizar, University of Quebec at Montreal, Montreal, QC, Canada; and J. P. Blanchet and E. Girard

Cirrus clouds can significantly modify the radiation budget by changing the visible and infrared radiation fluxes. Although the role of ice particles in climate is well recognized, the mechanisms of cloud formation are still unknown, and thus it is difficult to identify how anthropogenic activities will change cloud abundances and cloud properties. In order to understand the aerosol-cloud-radiation phenomenon, known as the aerosol indirect effect on climate, the Northern Aerosol Regional Climate Model (NARCM) was used. NARCM uses an explicit mixed phase cloud resolving scheme that have 4 components with double moments (aerosols, water droplets, small ice (<100µm) and larger crystals with significant sedimentation rates). To assess the indirect effect of aerosols on cold clouds, cloud simulation at moderate resolution (1-7km range) were performed during the 2003 APEX-E3 experiment. The APEX-E3 experiment was conducted from March to April 2003 on East Asia. This region is of particular interest due to China’s large emissions of anthropogenic aerosols and gaseous precursors and the expected strong aerosol-clouds interactions. Detailed cold clouds (and mixed phase clouds) simulations were generated and verified against in situ measurements. At this stage of the research, one important objective is to test each level of the GCM/RCM current radiation-aerosol parameterizations in a systematic fashion, against measured data to define their strengths and weaknesses. APEX-E3 is an excellent opportunity to test the ability of the model to reproduce adequate meteorological and aerosol fields.

Session 3, Aerosol Measurements and Radiative Forcing Effects
Tuesday, 11 January 2005, 8:45 AM-12:00 PM

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