Research into Wave Energy Characteristic Signal of Transition Rainfall in Summer Drought Period in Sichuan and Chongqing

Based on NCEP/NCAR reanalysis materials and wave-packet propagation diagnosis (WPD) method, this paper focuses on research into wave energy distribution and propagation features during two transition rainfall process in summer drought period in Sichuan and Chongqing in 2006. The result shows that two transition rainfall processes witnessed basically consistent wave energy evolution in middle and low layer. Before rainfall, wave-packet developed a lot in Arabian Sea region and strong wave-packet center was propagated to south of the plateau and moved to west of Sichuan and the wave-packet center of West Pacific was propagated northwest. At the time of rainfall, wave-packet was slightly reduced in Arabian Sea region but was still in strong phase in south of the plateau region. East and middle of Sichuan and Chongqing suffering rainfall was large wave-packet value areas due to impact of wave-packet propagation from West Pacific. During the rainfall, the wave-packet was propagated from Arabian Sea and West Pacific to south of the plateau and east and middle of Sichuan and Chongqing respectively. East and middle of Sichuan and Chongqing are under control of large wave-packet value areas, with heavy rain. At the ending of rainfall, wave-packet in Arabian Sea and West Pacific was gradually reduced and wave-packet propagation in south of the plateau, Sichuan and Chongqing was weakened. At ending of rainfall, wave-packet in Sichuan and Chongqing was weakened into small value. According to analysis, during the first rainfall, the wave-packet value in middle layer was stronger than that in low layer in Sichuan and Chongqing. During the second rainfall, wave-packet was stronger than that in the first rainfall process in general, the wave-packet in low layer was slightly stronger than that in middle layer, but the second rainfall was far heavier than the first rainfall. In general, wave-packet strength and propagation is related with two transition rainfalls in summer drought pe- - riod in 2006. Obvious characteristic signal was shown in terms of its generation, lasting, ending and strength, which shows that wave energy signal is meaningful for prediction.