Wednesday, 25 January 2012: 9:15 AM
Use of A-Train Satellite and ARM Ground Measurements to Study the Impact of Aerosols on Cloud and Precipitation
Room 256 (New Orleans Convention Center )
Aerosol has complex effects on clouds and precipitation that may augment or offset each other contingent upon a variety of variables. As a result, its long-term impact on climate is largely unknown. Using 1-year global cloud and aerosol products from the A-Train satellite sensors (CloudSat and MODIS) and 10 years of the Atmospheric Radiation Measurement (ARM) measurements, strong aerosol effects of climatologically significance are detected. With increasing total aerosol loading measured by aerosol optical depth and index derived from MODIS, and number concentration (condensation nucleus, CN) measured near the ground, both cloud top height and precipitation change systematically for mix-phase clouds of warm-base (cloud base <1km) and cold-top (above the freezing level), but not for pure liquid and ice clouds. The response of precipitation to CN depends on cloud liquid water path (LWP). As aerosol increases, rain occurs more frequently for high LWP but less frequently for low LWP. Such strong signals of aerosol impact on cloud and precipitation have not been reported on large-scale data and long-term and thus have significant implications for climate change studies, especially concerning regional and global climate change induced by pollution.