4.5
Enhancement of the Effect of Large Droplets on Radiative Transfer Process
Alexander Marshak, JCET/Univ.of Maryland Balitmore County, Greenbelt, MD; and Y. Knyazikhin
Traditionally, scattering and absorption properties of an "ensemble" of cloud drops are characterized by a drop size density distribution function. However, the use of density function results in the loss of information on jumps in the cumulative drop size distribution; the magnitudes of these jumps are related to the frequencies of large drop occurrence. Based on the analysis of data collected from different field campaigns, we demonstrate that the loss of this information can cause an underestimation of the contribution of large drops to the cloud absorption. Our analysis is based on a decomposition of the cumulative drop size distribution function into continuous and discrete components. The first one can be well approximated by a traditional drop size density distribution function. The discrete component represented by a jump function accounts for drops occurring at specific location and with specific radii along the direction of photon travel. Such a piecewise continuous behavior results in increased droplet effective radius and single scattering co-albedo.
Session 4, Shortwave Absorption in Clouds: Measurements and Modeling
Wednesday, 5 June 2002, 10:30 AM-12:00 PM
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