Spatial And Temporal Distribution Characteristics And Dynamical Diagnose Of Severe Weather In China

The relationship between Global warming and the extreme weather and climate event cause the attention of academe and society. Society demand urgently the observation and the forecast about the severe convection and heavy rainfall. One of the important factors of the sever weather forecasting is the comprehensive understanding about the climate background and the space and time variation rule.This paper based on the dynamic-statistic analysis for the severe convective and heavy rainfall, using the high time resolution data in 50 years, showed the basic characteristics and the spatial distribution shape of the severe weather probility in different time scale. And then based on this result, applying many kinds of new data with the dynamic and numerical analysis, it showed the possible mechanism for the severe convective and heavy rainfall occurred in the Huaihe River in 2007. It gave the objective evaluation to the convective weather forecasting ability of Central Meteorological Station, and then analyzed the possible factors to improve it. The results of this paper are as follows:●The severe convective weather occurred frequently in five regions, South China area, the South of Yunnan , Sichuan, East Qinghai-Tibet Plateau and the west of Xinjiang province. Hail occurred frequently at the Qinghai-Tibet Plateau. The REOF analysis results showed that the above regions had the relative independence, with the whole tendency were drop besides slightly rise in Qinghai-Tibet Plateau. It also found that the severe convection has difference between the daytime and nightime. During the daytime(08-20) it occurred more frequently than at nitht(20-08).The Brier skill scores about Thunderstorm potential forecast of National Meteorological Center was between 5% to 20% in 12hours, 24hours and 36hours, compared to 20% to 80% when Bc=0.5.●The heavy rainfall occurred frequently in South China area, Changjiang and Huaihe area. The RMSE showed that the daytime variation of the 50mm rainstorm greatly changed from south Guangdong to east Haikou and South central Yangtze River, the same distribution of 100mm/d precipitation. The tendency analysis showed that rainstorm in South China area was reduced but raised in Huaihe area, the south area of Changjiang river and the eastern part of coast. The rainstorm days raised but the precipitation amount was reduced in Hunan and Jiangxi province. Abnormality of the precipitation in Huaihe River area became remarkable in 21st century.●The dynamic-statistic analysis results showed that a heavy rainfall occurring in the Huaihe River area between 8 and 9 July 2007 had more characteristics such as the southward retreat of the rige of the West Pacific subtropical high (WPSH),severe convection activitied and diabatic heating in rainfall area, the vertical transportation of the heating was the main factor and had the double peaks characteristic. Strong divergence and ascending motion at the rightside of Upper level westerly jet axis was arose by the second component of inertial advection meridian wind. Negative lightning flash occured in rainstorm area but the time of the lighting happened a little earlier than the rainfall. The radar echo characteristics were similar to the rainfall area. Those factors were very useful to the rainstorm forecasting.●By the adjoint assimilation of Doppler radar data of Hefei, Fuyang, and Nanjing into mesoscale model WRF found that the accuracy was improved with the high resolution data. The simulate result prove that the assimilation of radar data ameliorated the simulate of not only rainfall location but also rainfall intensity. The error of maximal rainfall intensity was reduced about 100mm.