Abstract:With application of four designed simulation schemes,effects of the Taihang mountain terrain on heavy rain in August 1996 was explored by MM4 model,and the mechanism of the increasing precipitation in terms of some elements such as perpendicular motion,vaporflux etc.was discussed.The results show that the terrain affects obviously the intensity and location of precipitation cell,increases rainfall by 60%,and favors the upward current and vapor convergence.It is proved that the closer active terrain is,the better the model forecast will be and the higher terrain is,the more obvious precipitation enhancement effect will be.

Abstract:By means of MM4 model,the process of torrential rain over the southern Haihe River Basin during August 1996 was simulated.Through compared tests,the changes of precipitation and elements were studied after low-and high-level jets were weakened.The results demonstrate that the jets are favorable to the torrential rain occurrence and maintenance,the lowlevel jet has more important effects on the rain compared with that of the high-level jet.

Abstract:The vapor sources of the heavy rain during August 1996 in terms of real data was studied.The result points out that the vapor of the torrential rain comes from the South China Sea and the Bay of Bengal as well as typhoon-low itself carrying moisture.Finally,the heavy rain sensitivity to vapor by virtue of MM4 model was analysed.It is suggested that a little variety of vapors can bring large change of rainfall and latent heat releasing has positive feedback effects to heavy rain.

Abstract:The stream field and thermohyet field of heavy rain in August 1996 were analysed and the low-level weak cold air influence on the heavy rain by means of MM4 model was studied.The results indicate that the weak cold air has noticeable effects on the falling area and intensity of the torrential rain.It is favorable to low-level convergence and upward current as well as vapor and energy accumulation in Hebei province.

Abstract:The distribution characteristics of satellite picture,radar echo,surface wind field and θ_se field were analyzed in order to in vestigate the very heavy rain occurred in the southwest of Hebei province in August 3～5，1996.The results show that meso-β and mesoγ cloud clusters in meso-αare able to result in not only the precipitation enchancing but also the bursting of severe precipitation.In addition,the wet neutral structure is beneficial to the emerging and strengthening of very heavy rain.

Abstract:After diagnosing the operational meteorological data, the satellite cloud pictures, and the intensive surface observational data, it was found that there were six surface mesoscale rain clusters (1 hr rainfall≥10mm, life cycle≥3hr) formed in succession in the two meso-a cloud clusters causing the torrential rain in Hebei in August 1996. And, associated with the clusters, there were several surface mesoscale systems closely related to the surface moist baroclinic front and the surface convergency in their development.

Abstract:An operational routine flow of Ningxia short-time weather forecast was introduced, which is based on Project 9210 and guided by the Ningxia MOS guidance. Combined with the local meteorological operational situation, this automatic flow has set the forecastors free from the traditional paper-operation with computer-operation, and the automatic level of forecast is greatly improved.

Abstract:The status quo of water resource shortage and general climate situation were analysed.The necessity and technique feasibility of artificial precipitation enhancement were discussed.With different means of delivery,such as aircraft,balloon,artillery and rocket,an introduction to achievements in science research on seeding agent,selection of operating opportunity,operation method,effect test and numerical simulation were also given.

Abstract:First,from the viewpoint of atmospheric energetics,several factors and dynamical condition favourable to the hail genesis were described.Then,after conducting 84 case studies to the precipitation with hail occurred between 1980 and 1987,some forecasting indexes were obtained.These indexes were proved to be effective in the routine weather prediction.

Abstract:The routine meteorological fields were expanded by use Chebyshev Polynomials.The coefficients of them could represent the main characteristics of meteorological fields.Using them as factors,the forecast equations for dekad temperature abnormal of China in winter were established.The result indicated that this method was useful to the forecast of temperature abnormal.On the other hand,the relativity between each level data and temperature was discussed.

Abstract:The development of the mesocyclone squall storm in Beijing region on June 9,1998 was observed and analysed in detail by using the Chinamade 3824cband single Doppler weather radar,and the storm recognition and its formation process were also studied.

Abstract:The mechanism of a heavy fog which result serious problems in winter 1997 Henan province was analysed.It concludes that if the water vapor condition and weather tendency condition are satisfied,continuous heavy fog could be formed by radiation effect.The continuous reconstruction of the conversion and the sufficient water vapor from LBL are necessary for the heavy fog's formation and maintenance.