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Mesoscale Structure of Rainstorm Retrieved from Dual-Doppler Radar Observations Using the 4DVAR Assimilation Technique
作者姓名:XU Xiaoyong  LIU Liping  ZHENG Guoguang
作者单位:State Key Lab of Severe Weather Chinese Academy of Meteorological Sciences,State Key Lab of Severe Weather Chinese Academy of Meteorological Sciences,China Meteorological Administration Beijing 100081,Beijing 100081,Beijing 100081
摘    要:The four-dimensional variational (4DVAR) data assimilation method was applied to dual-Doppler radar data about two Meiyu rainstorms observed during CHeRES (China Heavy Rain Experiment and Study). The purpose of this study is to examine the performance of the 4DVAR technique in retrieving rainstorm mesoscale structure and to reveal the feature of rainstorm mesoscale structure. Results demonstrated that the 4DVAR assimilation method was able to retrieve the detailed structure of wind, thermodynamics, and microphysics fields from dual-Doppler radar observations. The retrieved wind fields agreed with the dual-Doppler synthesized winds and were accurate. The distributions of the retrieved perturbation pressure, perturbation temperature, and microphysics fields were also reasonable through the examination of their physical consistency. Both of the two heavy rainfalls were caused by merging cloud processes. The wind shear and convergence lines at middle and lower levels were their primary dynamical characteristics. The convective system was often related to low-level convergence and upper-level divergence coupled with up-drafts. During its mature stage, the convective system was characterized by low pressure at lower level and high pressure at upper level, associated with warmer at middle level and colder at lower and upper levels than the environment. However, a region of cooling and high pressure occurred in the lower and middle levels compared to warming and low pressure in the upper level during its dissipating stage. The water vapor, cloud water, and rainwater corresponded to the convergence, the updraft and the intensive reflectivity, respectively.

关 键 词:多普勒雷达  同化作用  暴风雨  中尺度结构
收稿时间:2006/4/30 0:00:00

Mesoscale Structure of Rainstorm Retrieved from Dual-Doppler Radar Observations Using the 4DVAR Assimilation Technique
XU Xiaoyong,LIU Liping,ZHENG Guoguang.Mesoscale Structure of Rainstorm Retrieved from Dual-Doppler Radar Observations Using the 4DVAR Assimilation Technique[J].Acta Meteorologica Sinica,2006,20(3):334-351.
Authors:XU Xiaoyong  LIU Liping  ZHENG Guoguang
Institution:[1]State Key Lab of Severe Weather, Chinese Academy of Meteorological Sciences, Beijing 100081 [2]China Meteorological Administration, Beijing 100081
Abstract:The four-dimensional variational (4DVAR) data assimilation method was applied to dual-Doppler radar data about two Meiyu rainstorms observed during CHeRES (China Heavy Rain Experiment and Study). The purpose of this study is to examine the performance of the 4DVAR technique in retrieving rainstorm mesoscale structure and to reveal the feature of rainstorm mesoscale structure. Results demonstrated that the 4DVAR assimilation method was able to retrieve the detailed structure of wind, thermodynamics, and microphysics fields from dual-Doppler radar observations. The retrieved wind fields agreed with the dual-Doppler synthesized winds and were accurate. The distributions of the retrieved perturbation pressure, perturbation temperature, and microphysics fields were also reasonable through the examination of their physical consistency. Both of the two heavy rainfalls were caused by merging cloud processes. The wind shear and convergence lines at middle and lower levels were their primary dynamical characteristics. The convective system was often related to low-level convergence and upper-level divergence coupled with up-drafts. During its mature stage, the convective system was characterized by low pressure at lower level and high pressure at upper level, associated with warmer at middle level and colder at lower and upper levels than the environment. However, a region of cooling and high pressure occurred in the lower and middle levels compared to warming and low pressure in the upper level during its dissipating stage. The water vapor, cloud water, and rainwater corresponded to the convergence, the updraft and the intensive reflectivity, respectively.
Keywords:dual-Doppler radar  4DVAR assimilation  retrieval  rainstorm mesoscale structure
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