HR: 1340h
AN: A33C-0919    [Abstracts]
TI: Influences of aerosols and precipitation on low clouds from satellite remote sensing
AU: * Kawamoto, K
EM: kawamoto@chikyu.ac.jp
AF: Research Institute for Humanity and Nature, 335 Takashima-cho, Kamigyo-ku, Kyoto, 602-0878 Japan
AB: Clouds are dominant in deciding the earth radiation and energy budget. Since cloud radiative properties such as reflectivity and transmissivity are controlled by the optical properties, it is important to know the relationships between cloud optical properties and relevant meteorological parameters. Focusing on aerosols and precipitation as a relevant parameter in this work, following analyses were preformed. Comparisons between the precipitation amount, P, and monthly-averaged cloud properties (optical depths of low-level water clouds, tlow, and "total clouds", ttot, effective particle radius, re, and columnar-integrated droplet number of low-level water clouds, Nc) over the Amazon basin elucidated the effect of precipitation on low cloud properties and the relationship between precipitation and "total cloud" cover. P was constructed mainly from ground-based rain gauge data. Low cloud properties such as tlow, re and Nc are retrieved from Advanced Very High Resolution Radiometer (AVHRR) remote sensing. Total cloud optical depth ttot was taken from International Satellite Cloud Climatology Project (ISCCP) products. The relationship between re and P was positive, while the relationship between Nc and P was negative. Because low clouds in this region generally produce little precipitation, these relationships may reflect the scavenging of aerosols by precipitation and suggest the aerosol indirect effect of the first kind. Variation of aerosol amounts in this area taken from satellites supported the above explanation. The relationship between ttot and P was positive because the "total clouds" included actual precipitating clouds. The thicker clouds are optically, the more water they usually contain.
DE: 0305 Aerosols and particles (0345, 4801, 4906)
DE: 0319 Cloud optics
DE: 0321 Cloud/radiation interaction
SC: Atmospheric Sciences [A]
MN: Fall Meeting 2005