Analysis of terminal velocity and VHF backscatter of precipitation particles using Chung-Li VHF radar combined with ground-based disdrometer

作者：Su Ching Lun; Chu Yen Hsyang^*

来源：Terrestrial, Atmospheric and Oceanic Sciences, 2007, 18(1): 97-116.

• VHF radar
• precipitation
• terminal velovity
• reflectivity

The backscatter from precipitation particles observed by the vertically pointed antenna beam of the Chung-Li VHF radar and the drop size distributions measured by a ground-based disdrometer co-located at the radar site are analyzed and studied in this article. We rind that the disdrometer-measured drop size distribution can be well approximated to a Gamma distribution. On the basis of this property and a power law approximation to the fallspeed-diameter relation V-D = AD(B), we derive the theoretical re lation between terminal velocity VD and range-corrected VHF backscatter P of the precipitation particles. We find that the V-D - P relation follows a power law in the form of V-D = alpha P-beta, where alpha and beta are both the functions of the precipitation parameters. Chu et al. (1999) first found that the relation between alpha and beta can be empirically approximated to an exponential form of alpha = Ae(xi beta), where beta is a function of B and xi is a factor associated with precipitation. In this article, under the assumptions of the Gamma distribution of the drop size distribution and the power-law relation between V-D, and D, we theoretically show that the analytical relation between alpha and beta indeed follows an exponential form of alpha = Ae(xi beta), where is a function of the drop size distribution. The experimental results obtained by the Chung-Li VHF radar combined with the ground-based disdrometer measurements validate the exponential approximation to the alpha - beta relation. The uses of the alpha - beta relation for the investigations of the rainfall rate and properties of drop size distribution are presented and discussed.

• 出版日期2007-3
• 单位中央民族大学