Abstract:It has been noticed that there is big systematic error with the gravity acceleration formula quoted from the 《General Meteorological Tables》,which has been using for long time in China.The gravity acceleration formula in the Guide recommended by WMO was also discussed.It pointed out that the definite of H’ with the gravity formula in the Guide is incorrect.It has been verified by examples that the gravity used with Bouguer correction is enough accurate for atmospheric pressure measurement.At the end,some pieces of suggest have been given.

Abstract:The difference of the circulation feature between the continuous torrential rain events in June 1998 and the historical similar events in Jiangxi was described.The 500hPa pattern is unfavonrable to the formation of the continuous torrential rain.However,the prevailing southwest jet and stable shear in the mesosphere and the lower troposphere,and the convergence line existed usually on the ground provide a favourable condition for the precipitation events.Under this condition,the thermodynamic effect in precipitation is obvious.

Abstract:Based on the data of observations and weather charts,weather-climatic features of the first frost in the northeast part of China during the latest 31 years were analyzed,and the circulation characteristics and weather-developing process at the time of 24 hours before the first frost were discussed,and the geographic and space-time distribution features of the first frost and some useful criteria were presented,which play a reference role in real-time forecast operations.

Abstract:The reasons of the constant maintenance of the advection fog in Beijing area from December 17 to 19 in 1997,was synopolically analyzed.It is suggested that under the macroscale condition of the weak convergence which is formed by the relatively stable topographic trough in north China,saturated air is firm in a special terrainBeijing gulf which is below 239.4 m,due to the scarce inversion lid(r=5.84℃/100m);and that the surface mesoscale convergence line and the miniscale convergence line below 200m produced by the fluctuation of the wind on the timeheight section diagram result in the convergence lift.Thus helped the saturated air constantly being supplied and gathering in plains and valleys.

Abstract:Based on the meteorological observation and the winter wheat yield in 31 counties of Fujian province,the correlation between the climatic yield and the relevent meteorological elements was analysed.The results show that precipitaion in March and mean temperature in two dekads from last one of November to the first one of December were the key factors.Accroding to climatic changing,the climate is unadvantageous for winter wheat production in Fujian,it pointed out the new plant division for winter wheat in Fujian.

Abstract:A neural networks development system which is made by Neuralware company of America was introduced.Classification results of four cloud systems of cold front,stationary front,hail storm cloud and MCC are given here using the neural networks development system.

Abstract:Shandong province was divided into six forecast regions,based on the frost climate in the province representative stations were selected in each region,and the short-range forecast equation of daily minimum air and soil temperatures was established for each selected station by the use of sounding,surface observation and stepwise regression method.The forecast equation introduces HLAFS numerical forecast data instead of sounding and gives the forecast results of minimum air and soil temperature.According to the relationship between frost and air and soil temperature and the sectorized forecast indexes for frost,a determination whether it is frost or not in the forecast region was given.The operational system of the shortrange forecast for frost in Shandong province was developed.

Abstract:Through the climatic analysis of fog during 1980～1996，the weather situation was summed up as weak high pressure and cyclone inverted trough over Yancheng city in Jiangsu province.Base on the indexes,the local meteorological elements were analyzed.The diagnose for five indexes of fog occurrence was conducted by the use of probability addition principle.The fog forecasting system was built with the aid of the meteorological information comprehensive process system,and the better effects in operational practice were achieved.

Abstract:The position to catalyze a cloud can be determined by observing its physical quantities such as radar echo intensity,distribution of water content and temperature.In the triangle consisted of a radar station,a launching-site and an object cloud,the launching azimuth can be worked out.According the height of the seeding position observed by radar and the ballistic parameters of rockets or anti-aircraft guns,the launching elevation can be determined too.Thus,eye observation blindness can be properly reduced in weather modification actions.

Abstract:Based on precipitation data of 52 meteorological stations in Hunan province from April to September during 1958～1998,the flooding years are determined,the features and evolution trends of flooding in the last 40 years are analysed.The causes of increasingly serious of the damage in recent years are studied on the basis of above discussion.The climatic background, the unusual atmosphere general circulation,the influence of ElNino,the specific property of hydrology and area rapid reduction of Dongting Lake and elements of society are the influential factors.

Abstract:By analyzing of the meteorological conditions of heavy yield reduction of summer harvest crop in Jiangsu province in 1998,it is known that the crop was affected by a great variety of meteorological disasters,such as wet injury,waterlogging,freeze injury and insect pest throughout the whole growing season all over the province.The main reason is climatic anomaly in 1997～1998.

Abstract:The information system on monitoring drought in Henan province was established on the basis of the research achievements of monitoring drought by polar-orbit meteorological satellite data integration of GIS.The system software,hardware and main functions were introduced.Finally,some application examples were given.