Abstract:Annual growth records from tress at Banma region in the southeastern Qinghai Plateau are correlated positivly with variations of summer precipitation and used to reconstruct the regional precipitation variation in the past.In a series of tests,it is shown that the relationship between the climate and tree ring variables is statisticlly significant and stable with time,confirming the power of dendroclimatic reconstruction in arid and semi arid region such as the south eastern Qinghai Plateau.

Abstract:The need of anti-flood and flood control can be satisfied with the forecast and application of area rainfall.The triangular algorithm calculating the area rainfall was given.The algorithm not only has certain strong points but also makes automatic operation more easily.The application of ares rainfall to forecast and service was discussed.The division and forecast of rainfall grade were analysed.

Abstract:The prediction of the catastropic flood and water-logging and extraordinary rainstorms in the Northeast and the Yangtze River valley in 1998 was summaried.The contributing factors causing the disasters were analysed.It was emphasized that the cross-equatorial flow and the geomagnetic anomaly were two important factors contributing for the catastropic floods.

Abstract:A numerical simulation on the effect of the Tibetan Plateau on weather systems in the neighborhood area was carried out by LASG η-coordinate limited area mesoscale model (LASG MM).Two cases of heavy rain storms on April 28 and August 19,1998 were investigated under the topography with different relative heights.Study is mainly concentrated on the geopotential height fields,the temperature fields and streamline fields of 500hPa and 200hPa.Among the three kinds of fields,the temperature field suggests a large variation.When the relative height of the plateau is reduced,the temperature over the plateau goes up,and the temperature over the Sichuan Basin goes down.The magnitude of variation is larger in spring than that in summer.With lower relative heights,the large scale weather system over the plateau is strengthened,but the weather systems with middle or small scale are weakened over the plateau.On the other hand,the geopotential heights is reduced and the weather systems with small scale are strengthened over Sichuan Basin.Effect of the plateau with different relative heights on the streamline fields is similar to that of the goepotential field.With the influence of the forced wave and the lee wave,the streamline fields suggest the largest variation over the intersection area of the plateau and basin,which is exactly where the relative height changes most greatly.

Abstract:The principle of the reduction method of Chebyshev polynomial in the common algorithm of integerizing chebyshev polynomial was interpreted.A calculating method was given to reduct the polynomial quickly.

Abstract:More and more observed data with higher resolution and higher precision are needed in the city weather research and city weather services.Meanwhile, there are a lot of conventional and non conventional observations are provided along with the development of the city weather observation system.In order to form the more perfect weather element fields with these data, objective analysis technique should be used firstly.The variational data analysis technique is tested based on the observations of meteorological posts, conventional weather stations and land use categories in Shanghai.

Abstract:Using the 713-type weather radar and its digitized extreme, by means of optimization method, the sequence of Z-I relation were obtained by calculating the precipitation processes caused by sheet cloud according to the different weather systems and the different precipitation processes.Then, rainfall estimated by radar data was derived from the sequence of Z-I relation and compared with the measuring of raingauge,the accurate problem of precipitation with radar measuring was analysed.

Abstract:The large-scale circulation characteristics in summer between 1998 and 1954 were comparied.Both years happened catastropic flood in the whole Yangtze River valley since the 20th century.The results of analysis show that the second seasonal jumping northward of subtropical high over the north-west Pacific had been obviously postponed in 1954, which appeared in early August.And subtropical high was unusually southward than normal from June to July.Nevertheless,its seasonal jumping northward was advanced in 1998, which appeared in early July, and the subtropical high was further south persistently than normal from the third dekad of July to the end of August.At the same time, ITCZ of summer was notably weaker in 1998 than in 1954.But the action of blocking high of the westerly belt in Asia was very frequently in summer of the both years, especially in 1998.

Abstract:The boundary layer temperature and humidity stratification were statistically analyzed using the upper-level data and the part of low-level data of 58 cold fogs (T≤0℃ when fog forms) in 1981-1996.The results are necessary basis for artificial dissipation of supercooled fog and improvement of forecast level.

Abstract:The temperature and precipitation data at four representative stations in Rikaze of Tibet from 1956 to 1997 was analysed.Rikaze region was divided into three climatic areas and the variation characters of temperature and precipitation in every area during forty years were studied.The results show that the climate gets warmer gradually in Rikaze in forty years,and it was obviously warm in the 1980′s.The rising temperature in the western Rikaze was more than that of the valley along the Yaluzangbu river and the southern border area.The anomalous warm may be occured in both winter and summer and the frequence is rising in the recently years,but the anomalous cold is seldom.The decreasing trend of precipitation appears in the west and in the valley and the increasing trend in the southern border area.

Abstract:According to the data of temperature and precipitation in Zedang from January,1960 to April,1999,the climate of Zedang was analysed.The results show that the precipitation of Zedang for 40 years appears to be descending (-8.97mm/10 years),the precipitation in winter appears to be ascending (2.16mm/10 years),and the temperature appears to be going up (0.230℃/10 years),especially in the middle-latter period of 1970′s to the middle period of 1980′s.The warming trend in winter is more than that in summer.For this reason,in terms of the limit of the middle stage of 1980′s the climate of Zedang for 40 years might be divided into 2 stages,the former is a cold period,and the latter is a warm period.

Abstract:By analysis of heavy rain,rainfall, hydrologic data and satellite cloud charts in the upper reaches of the Yangtze river in 1998, the basic characteristics of the heavy rain in the upper reaches of the Yangtze river in 1998 were summaried, and the direct impact of the heavy rain in the upper reaches of the Yangtze river, the activity of weather system over the plateau, the activity of cloud mass on the Yangtze river flood peak in 1998 was recognized.