Abstract:Based on the data of meteorology and crop yield in 7 regions of China from 1961 to 1990,the method of entropy analysis in information theory is applied to discussion of the temporal and spatial distribution patterns of the entropy change of 4 meteorological factors (mean temperature, maximal temperature, minimal temperature and rainfall) in recent 30 years. The unsteadiness of climate change in China is analyzed in detail. After that,the relationship between climate fluctuation and agrometeorological disasters and the impacts of climate fluctuation on crop yield are revealed qualitatively. The regression models of yield and entropy of meteorological factors in different regions are established.

Abstract:It is suggested that uncontinuous propagation of cold front is the direct cause of fast -southerly movement of cold fronts,i. e. ,as a result of frontogenesis in the southern part of the cold front and its evolution,the new frontogenetical front takes the place of the cold front in north China. The southwesterly low-level jet plays important roles in the frontogenesis process,these roles are: (l)northerly warm-wet transportations in the low-level jets;and (2) the jets can induce low-vortices in the north of jets,and northerly air current of west of the vortices is favourable to south ward movement of cold air mass. The result of interaction of the air currents which possess distinct property induces frontogenesis. The caues of the low-level jets formation in winter arc also preliminarily discussed. It shows that they are different from those in the summer.

Abstract:The characteristics of rainfall variation in water resource divisions in Shandong province are analysed using precipitation data of 41 weather stations in recent 40 years. Mean generation function is used as basic function,which is screened through principal component analysis. Mean-step predictive models are set up in water resource divisions in term of mean generation function. The forecasting results are rather good through testing and fitting calculation.

Abstract:Based on the researches and experiments in the past three years,a comparative perfect objective severe convection weather monitoring and nowcasting system suited to Hunan conditions was developed. It consists of subsystem for graph and picture display,regional rainfall measurement by weather radar and severe convection weather nowcasting.

Abstract:A hail process occurred over the Yellow River delta on 24,June, 1995 was analysed using echoes of 713 digital radar data in Dongying city and satellite cloud pictures. Their features are discribed and the reason is discussed.

Abstract:T_bb field features of torrential rain caused flood at the midsouth in Northeast China from 25 to 31 July, 1995 were analysed and compared with that in the lower and middle reaches of the Yangtze River during the Meiyu period. The results show that both are similar in the cloud band movement, the relation with tropical or subtropical cloud systems and the allocation of the various systems, except the location of the tropical and subtropical systems was northward and westward.

Abstract:Since Numerical Weather Prediction has been operated,the forecast accuracy of upper synoptic situations and weather elements have been improved. Recently,it is a common concerned question to explain and to apply NWP production for forecaster. Based on cluster analysis,the forecast of heavy rain area and it's character of circulation pattern have been studied by the use of NWP production 500hPa height fields and precipitation data. Results show that the method has reference value in the operational forecast. Simultaneously the features of circulation field corresponding to precipitation patterns in China are given.

Abstract:The function of numerical forecast products was assessed and the explanatory level to subtropical weather was calculated. The comparison with the B-model was made, its result shows that T42 products can serve and be apply to key tasks.

Abstract:In order to understand the performance of T63 NWP and the efficiency of its products,the assessments and synoptic verifications are made for main rain-producing systems and circulation in the summer of 1995. The results show that forecasts by T63 model have significant improvements compared with that by T42. The 96-hours、 120-hours、 144-hours and 168-hours predictions by T63 model are considerably reliable for the motion of atmospheric long wave and extra-long wave. The forecast on tendence of large-scale circulation's evolution becomes better. They are considered to be valuable for the medium-range forecast. The forecasts by T63 model are better than that by T42 for the westerly system and subtropical high. It provides useful information for the medium-range forecast.

Abstract:In the location of the GMS scanned images,a deviation appears at times for a variety of reasons. An adaptive calibration method eliminating the deviation is given.

Abstract:The system structure of dual-polarized Doppler weather radar and its working principle are introduced. Some examples of data processing based on CSU-CHILL S-band dual-polarized Doppler weather radar measurements are illustrated , and the application to meteorology is interpreted.