Abstract:A scheme for conversing uniform into nonuniform mesh in the MM4 model was designed. A inhomogeneous mesh version of the model fitting Hebei region was developed. Anumerical weather forecast system for operational use was established. Finally,with the simulation experiment of a heavy rain process,it is certified that the inhomogeneous mesh modelis better than the uniform mesh model.

Abstract:Following the example of the thought of the modelling technique for the propagationalprocess of the epidemic disease,a most preliminary mathematical model of the propagationalprocess for the public forecast has been obtained.

Abstract:Based on the cloud track winds and the upper sounding winds,the first three terms ofright hand side of the fractionless barotropic vorticity equation, e. g. the relative vorticity advection, the planetary vorticity advection and the divergent term were calculated. The sum ofthese three terms gave an estimate of the local vorticity variation rate. Computations werecarried out to some tropical cyclone cases for the year 1998 over the region of the South China Sea and the Western Pacific. Results show that the local vorticity variation rate?ξ/?t hasspecial significance in indicating tropical cyclone movement,and it can indicate obviously botha steady track of tropical cyclone motion and a sudden turning on tropical cyclone movement.Tropical cyclones move generally toward the direction of maximum local vorticity variationrate. If ?ξ/?t has several maxima in the vicinity of tropical cyclone center, vector compositionmethod may give a mostly probable direction of tropical cyclone motion. In addition, just asthe steering current, there is an effective radius of interaction in ?ξ/?t field,within the effectiveradius the changes in ?ξ/?t field may have a direct influence to tropical cyclone motion.

Abstract:A hail process in Bameng area on Sep. 4, 1983 under the stable atmospheric stratificationwas analysed. The analysis of the physical quantity before and after the hail,e. g. altitudetrough,energy condition,initiation mechanisms and environment wind vertical shear,revealsthat the atmosphere characters can be used in forecasting this type of hail. In some specificbackground of circumfluence,the stable atmosphere structure may turn to instable.

Abstract:By using GMS-5 infrared and water vapour brightness temperature data from Mar. toApr. in 1997 - 1998, the methods of extracting hail weather parameters were developed anddigital remote sensing pictures were obtained in spring in Yunnan. Based on the bivariate probability distribution of infrared and water vapour brightness temperature of hail and no- hail, a criterion distinguishing hail from no-hail was set up. The results show that a precisiondistinguishing hail and no-hail is 94%,the accuracy of hail distinguishing is 30. 8%.

Abstract:The microphysical characteristics in high supercooled water area (higher than 0.1g.m^-3) in autumn's strait form cloud over Shandong were analyzed by means of the datafrom measurements with the particle measuring system (PMS) during 11 flights. The maxi. mum water content is 0.369.m^-3, 84.0% of supercooled water contents is between 0.1 and0.2g.m^-3, 86.1% of continual distribution width of supercooled water is less than 3km.The shapes of snow crystals mainly is graupel and smaller snow crystals. The cloud dropletscale spectrum can be fitted best by two-order Гfunction, and content spectrum can be fittedby log-normal function.

Abstract:Depend on the map information visualized tool (Mapinfo) database and hypertext library,the application system on flood disaster prediction was established by the windowsOLE automatic technique. The information on meteorology, flood, hydrometeor and insurance, as well as the historical flood observation is organically combined by the visual andvivid electric map. Linking with historical flood events database and meteorology-flooddatabase, the flood disaster can be predicted so as to provide the basis for the relevant department on application inquiring and decision-making.

Abstract:A typical hail event combing with strong wind and severe short--range precipitationcaused by a supercell storm on 4th. 9.1998 was analysed,based on 714CD Doppler radar data, relative surface elements and radiosonde data. The typical characteeristics both in theradar echo intensisty field of severe convective weather and in the Doppler speed field weregiven. The results may serve as reference for monitoring and distinguishing and nowcastingto strong convective weather and artificial hail mitigation.

Abstract:The Tibetan plateau rainfall mainly occurs between May and Septemeber,and frequentsummer drought is a major disaster in the plateau agricultural region. The daily rainfall dataat 34 stations in Tibetan plateau was used to define the standard of beginning and interruption rainy season depending on precipitation relative coefficient C. The circulation features ofseveral typical individual cases in wet season using NCEP and ECMWF height fields datawere discussed.

Abstract:By means of the conventional meteorological data,digitized infrared satellite imagery andthe radar echoes, the developing characteristics of the mesoscale convective cloud clusterswhich caused the cloudburst over the northern Fujian in 18 - 19 June 1998 were analysed,andthe effect of the wet-baroclinic front zone and the southwest jet flow in low altitude on themesoscale convective cloud clusters were discussed. Some features of cloudburst during thedeveloping were given.

Abstract:Using ECMWF's numerical weather forecast products,weather charts and the real-timesurface observational data of nine stations along the southeast coast of China in Mar. from1993 to 1996,several factors of cloudy-rainy weather for several days,such as the distributionof physical parameter fields,the daily change of rainfall and the area of rainfall were analyzed. Results show that the land-sea high pressure is the most direct,visible and importantweather system in cloudy-rainy weather for several days,and its establishment and destruction are a unique weather pattern.