Abstract:The first snow in North China during 6—7 Nov. 2003 is simulated by the GRAPES global numerical model developed by the Chinese Academy of Meteorological Sciences. The analysis of the output data indicates that GRAPES model can simulate out circulation's evolution og high and low level and the main synoptic systems,beside the distribution of psecipitation areas and the precipitation cells. The effect of simulation inserted cloud data is better than not inserted. But precipitation areas above 25mm are boti too large. The model can provide correct and high resolution data of diagnostic analysis also.

Abstract:Through the study of six-hour raingauge data from about 120 stations in East China and the corresponding 4400 multi-channel cloud imagines of GMS-5 during the summer of 2001—2002,it is found that the temporal and spatial variation of the TBB and its gradient of the infrared channel,the TBB difference between the infrared and the vapor channel have certain function to eliminate error caused by cirrus,even to solve the absence of visible-channel data. Based on the study above,the rainfall estimate equations between six-hour rainfall and GMS-5 data are obtained by using double-judging & double-MOS regression method,which can be used to estimate six-hour rainfall. In order to further eliminate error caused by deep cirrus or special terrain,a day-by-day rainfall estimate equation by using real-time data is set up. The operational application in Shanghai Meteorological Center shows that its average estimate accuracy reaches about 70%.

Abstract:The evolution of cloud systems of severe tropical cyclone Koni and the effects on its path and precipitation in central part of South China Sea are studied in detail. The results show that the attraction of convective cloud cluster was responsible for turning southward after Koni's landing. The distribution of vertical motion has close relationship with the path changing of the tropical cyclone in a short period. The tropical cyclone tends to move towards ascending motion. The meso-scale heavy rain occurs in spiral cloud band of a small vortex in the severe convective cloud cluster or in the overlapping area of dense gradient of TBB and surface wind direction convergence.

Abstract:The scheme is designed to describe the composite assimilation analysis field of satellite retrieval data,conventional observations and T106 analysis field. Results show that the composite analysis field is more similar to the actual atmospheric condition and make up the lack of the observations based on the reasonable design of the objective function,in contrast to the conventional radiosonde observations. It is found that the error is smaller and the isoline is smooth.

Abstract:Based on remote sensing snow cover data in the Northern Hemisphere and surface observations for snow depth and days with snow cover in China,the monitoring and diagnosing methods for snow cover are studied. An operational system for snow cover in the Northern Hemisphere was set up. The operational products included spatial distribution for days with snow cover in the Northern Hemisphere,snow depth and days with snow cover in China,anomalies indices for snow area,and snow depth and days with snow cover in each region.

Abstract:The radar data,collected from the field experiment of the national fundamental program entitled‘Mechanism and predict theory of disastrous weather over China',in the middle and ower reaches of the Changjiang River in the summer of 2002,are analyzed by the inter-comparison of the PPI and CAPPI echo intensities nearly simultaneously detected by the different radars but covering the same region. Four cases for such inter-comparisons are given out. The first two cases were observed at 05:00 BJT on June 21st,and at 03:00 BJT on June 24,2002 respectively,using the S-band radar in Hefei,and C-band radars in Maanshan and Wuwei,Anhui Province,the lower reach of the Changjiang River. The last two cases were observed at 00:00 BJT on June 24,and 05:00 BJT on July 23,2002 respectively using the S-band radar in Yichang,and C-band radar in Jingzhou,the middle reach of the Changjiang River. Statistical distribution of the echo intensities in each inter-comparison has a good agreement between the radars in Yichang and Jingzhou,however,pronounced difference among the three radars deployed in the lower reach. This may indicate that problems may exist in their initial calibrations. The low correlation is evident from the scattergrams of echo intensities among different radar observations. It is concluded that the location scheme of these radar data needs to be improved. In addition,the research confirms that the precipitation attenuation correction is need for the precipitation intensity measurement if by C-band radar is used.

Abstract:By using Doppler Radar data,the characteristics of rainfall intensity and wind field in Xiamen caused by tropical cyclone “Beimian” are analyzed. The results show that the heavy rainfall is induced by the interaction of multi-synoptic systems,and by the convergence of southeast wind and southwest wind in low atmosphere as well as the cells' mergence. In addition,the cells' breakaway and mergence have a connection with the perturbation of the jet in low atmosphere.

Abstract:The reanalysis of NCEP data are used to analyze the average θ_e profile characteristics of downburst days in July. and Aug. from 1999 to 2003 in Beijing area. The results show that there is a θ_{e max} at the bottom of troposphere. In addition,there is a θ_{e min} in the middle of troposphere (500—660hPa).

Abstract:The Meiyu cases,including non-typical and typical Meiyu,occurred in the Changjiang-Huaihe River valley from May to July in last 34 years are reviewed. It shows that the lasting period of non-typical Meiyu is shorter than that of typical (normal) Meiyu,the intensity of precipitation of non-typical Meiyu in May is less than that of typical Meiyu,and the precipitation of non-typical Meiyu in June and July could be the same as that of typical Meiyu. It indicates that there is difference between the large circulation character of non-typical Meiyu and that of typical Meiyu. It is suitable to the occurrence of Meiyu in the valley that the ridge of subtropical high is steadily located in the region of 20—25°N,110—130°E,but it is not necessary. A more rational standard of Meiyu should be defined according to so many year operation and data analysis.

Abstract:The detailed analysis is carried out in terms of mean annual and seasonal maximum and minimum temperature series of Jinan (1919—2002) and Qingdao (1900—2002).The results indicate that the annual minimum and mean temperature have obviously increased,and the increasing rate of the former has exceeded that of the latter. Increasing trend of maximum temperature has occurred in Qingdao; while decreasing trend has happened in Jinan. There were two abrupt warming in Jinan and Qingdao,i.e.1930s and 1980s. 1930s warming occurred in daytime,1980s warming mainly happened in nighttime. Because of the asymmetric change of in maximum and minimum temperature,the diurnal temperature ranges become smaller in the second warming period than that of the first.

Abstract:Since the 1980’s,climate in Heilongjiang is obviously warming. And therefore extreme weather events occurred: such as ①increasing heavy rain events; ② days with extreme maximum temperature above 30℃ decreased; ③ below -30℃ extreme minimum temperature mean days obviously decreased; ④ the first frost date has prolonged for 2—5 days; ⑤ The last frost date in the north and middle comes 3—5 days earlier,while in the south it prolonged; ⑥ In summer,the low temperature days decreased obviously,the north decreased more than the south; ⑦ The heavy drought years increased,the flood number decreased in the north and increased in the south. The southwest regions was sensitive to the drought/flood.

Abstract:Analysis of spatial-temporal variation of precipitation in the upper reach of the Yellow River and its circulation characteristics are made. It shows that the bend region of the Yellow River is one of the area with richest precipitation in the upper reach of the Yellow River. The first ten days of July and the first ten days of September are the optimum periods of artificial precipitation enhancement over the bend region.

Abstract:The grasshopper infested again in Inner Mongolia grassland in 2004. The higher temperature in the winter and in the spring and the precipitation in the earlier 10 days in May,2004 are favorable to the incubation of the grasshoppers. The appearance date is 11 days ahead of time. Drought and desertification are the two main climatic factors that lead to the grasshopper infestation in succession since 2000.