Wednesday, 25 January 2012: 9:30 AM
Applications of Satellite Measurements for Studying Dust-Cloud-Precipitation Interactions Over Asian Arid and Semi-Arid Regions
Room 256 (New Orleans Convention Center )
Arid and semi-arid areas comprise about 30% of Earth's surface. Changes in climate and climate variability will likely have a significant impact on these regions. Due to the large spatial and temporal extent of desert dust in the atmosphere, the interactions of desert dust with clouds and land surfaces can have substantial climatic impacts over Asian arid and semi-arid regions. During the last few decades, warm winters and dry springs occurred more frequently in East Asia which, along with disturbances brought about by human activity, gave rise to anthropogenic dust emissions. This paper reviews new results from the application of satellite measurements to analyze dust-cloud- precipitation interactions over Asia arid/semi-arid region. Those results suggest that the dust reduces the ice cloud effective particle diameter and increase high cloud amount. Due to the effects of dust on the cloud properties, the instantaneous net radiative forcing at the top of the atmosphere for dusty clouds is reduced compared to that for dust-free clouds. The reduced cooling effects of dust may lead to a net warming. The water paths of dusty clouds are also considerably smaller than those of dust-free clouds. Dust aerosols could warm clouds, thereby increasing the evaporation of cloud droplets causing reduced cloud water path (semi-direct effect). The semi-direct effect may be dominated by the interaction between dust aerosols and clouds over arid and semi-arid areas and partly contribute to reduced precipitation.