Abstract:Using NCEP/NCAR reanalysis data,spatial structure and time variability of East Asian winter monsoon are discussed and relationship between East Asian winter monsoon and land-sea thermal contrast is investigated with the means of EOF,SVD and SSA.Results show that there is spatial distribution in East Asian when monsoon is anomalous.Three subsystems(WM1?WM2?WM3)are defined according to the situation and pattern of extremum centers of climate mean and the variance of meridional wind.Interannual and interdecadal variations of winter monsoon in WM1?WM2 are different from WM3.Winter monsoon in WM3 is becoming weaker in recent 40 years and the monsoons of WM1 and WM2 have a vague strengthening trend.Land-sea thermal contrast affects monsoon of different subsystems.Monsoon anomaly of subsystems WM1 and WM2 are well relative to temperature of tropical west Pacific.Monsoon anomaly of subsystem WM3 bears a close relation to the thermal contrast in high latitude.

Abstract:Proposed are a set of new regional flood/drought indices and standards of grading their severity whereby 1951-2000 summer wet/dry events are investigated for North China.It is indicated that the new indices in comparison with others are well indicative of the severity and extent of flood/drought events and of more objective classification of them,which is therefore quite applicable to an extended area.

Abstract:Through performing four experiments with integration time of 24 hours by means of a high resolution barotropic votictity equation model,the interaction between a mesoscal vortex at different initial radial location in typhoon circulation and a typhoon vortex is examined.The result shows that the different initial radial location of mesoscal vortex can cause changes in the characteristics of perturbation relative vorticity.

Abstract:L9R15 climate spectrum model is employed to investigate the effect of summer SSTA in the equatorial Indian Oecan and Pacific on Asian summer monsoon.It's found that the positive SSTA in summer in the tropical Indian Ocean or Pacific can,not only cause the response of atmospheric circulation and precipitation in the tropical region,but also lead to the weakening of east Asia and south Asia summer monsoons.However,the output with SSTA imposed in two waters together is not a linear sum of the output with SSTA imposed individually in two waters.As such, the schematic map is proposed to demonstrate the simultaneous relationship between the Asian summer monsoon and the atmosphere-ocean system in the tropical Indian Ocean and Pacific.

Abstract:Adaptive mesh technique is based on the variation method and it aims at improving the accuracy of prediction by arbitrarily densifying the grids in areas where the gradient of numerical solutions is large.By use of the multi-nested mesh method to speedup the simulation process,adaptive mesh technique is developed with MM4 model.A comparison between the adaptive mesh model and uniform mesh model is presented based on the simulation to the heave typhoon rainfall case which occurred in north of China during Aug. 4-5,1996.The results indicate that the simulation accuracy to the synoptic system and its rainfall is better in adaptive mesh model than that in the uniform mesh model.The prediction about the synoptic situation and the wind field has been improved too.

Abstract:A comprehensive research of glory formation mechanism is given to explain the glories appearing on clouds either containing water droplets or ice particles on the basis of negating Van de Hulst's backscatter glory promotion theory.

Abstract:By employing CCM3-RegCM2 nesting model which is developed on the base of NCAR CCM3 and RegCM2,the influences of surface conditions over the midwest Tibetan Plateau on summer precipitation in China are studied.The results show that the temperature gradient over the northern Plateau is strengthened as a result of surface albedo and temperature of the west-central Tibetan Plateau increasing if the vegetation over there are damaged,and the westerly jet should move to farther north and west to prevent the north cold air from reaching in the Yangtze River and the Huanghe River Basins so that the rainfall reduce in those areas,meanwhile,the anticyclonic circulation over the Tibetan Plateau which is enhanced by the increasing of air temperature would change the air stream direction from southwesterly into westerly in the Yangtze River.At the same time,subtropical high moves towards west and north and dominates the Yangtze River,leading to the summer precipitation decreasing in China.

Abstract:The temporal and spatial variations of the pentad mean surface air temperature have been analyzed in this paper based on the data of NCEP/NCAR from January of 1979 to December of 1995 in the South China Sea(SCS) monsoon region.It is found that there exist two maximum centers of the temperature standard deviation in the northwest Indochina and the Indian Peninsulas,and their location and strength change significantly during the period of SCS monsoon onset.The positive zonal deviation changes into negative deviation earlier in the southern Indochina Peninsula than in the Indian Peninsula,accompanied with a gradient from south to north in the longitudinal belt of the Indian Peninsula.In addition,the features of the temperture anomaly differences between the Indochina and SCS are different significantly.Therefore, the surface air temperature changes in the Indochina and the Indian Peninsula regions maybe have some connections with the SCS monsoon onset and the Indian monsoon onset,and the Indochina Peninsula becomes the sensitive or key region to the SCS monsoon onset probably.

Abstract:By performing eight experiments with a high resolution barotropic model,which is integrated for 36 hours,the interaction between a mesoscale vortex and a typhoon vortex is investigated with its effect on the variation of typhoon intensity.The relationship between the spatial scale dimensions of the initial mesoscale vortex and the variation of typhoon intensity is also discussed.The results show that the interaction can intensify the maximum tangential velocity of typhoon under the condition of certain parameter ranges.

Abstract:Based on the risk theory,this paper analyses the character of the grain yield sequence in a certain area.And making use of digital emulators,we combine the signal of probability existed in the grain yield sequence with a normal grain yield forecast model,which could give the confidence and probability of a certain expected grain yield in a future year.The result could serve as the criterion for government decision in disaster relief as well as in planning for agricultural development.

Abstract:Based on the definition of vulnerability by IPCC reports and the related literature on methods of vulnerability assessments,this paper explores the definition,methodological framework,indicator system,and computing method for agricultural vulnerability to climate change.It also discusses the relevant principles which should be taken into account while formulating adaptive strategies for the regional agriculture system to climate change.

Abstract:Based on experimental and meteorological data,charactrristics of cotton water consumption in different soil water contents(W 1-W 7) are analysed.Then the reference crop evapotranspiration is calcuclated using Penman-formula,the crop coefficient is estimated,and the models of cottonwater consumption in droughts and floods are constructed.

Abstract:The spatial characteristics and yearly,seasonally and daily variation properties of total cloud cover is analyzed in this paper based on every-three-hour mean monthly data of ISCCP from July,1983 to December,1993 over the Tibetan Plateau which is divided into 39 grids.Some scientific explanation are also made for the moisture condition,topographic dynamics and circulation patterns over the Plateau.Comparing the distribution of total cloud cover from ISCCP with that observed from surface stations,the rationality of ISCCP-D2 data is validated.It is concluded that there is a good(poor) correlation in summer(winter) by analyzing the correlation between the total cloud cover and OLR.

Abstract:This paper mainly discusses how to develop a modern weather analysis and prediction learning system based on the internet and how to produce a multimedia teaching resource.It introduces the methods of web-page design,meteorological database,and building a test database,and the technique of animated streaming.The paper also introduces the content of modern weather analysis and prediction learning system and its frame,structure and characteristics.

Abstract:By processing and analyzing the images taken by a digital camera with "fish-eye",we obtain the cloud-cover.The fundamental and method to obtain the cloud-cover are introduced,and the results are given.Compared with the observation,the results have an average error less than 15%.The accuracy is mainly affected by the visibility and the best result will be obtained when the visibility is larger than 15km.

Abstract:Combined with database managing technique and other computer languages,and on the basis of a vast amount of spatial and non-spatial data such as basic geographical,meteorological and hydrologic information,the GIS application system for storing,querying,analyzing,and displaying information makes it possible to monitor flood and to supply reference for government.

Abstract:To make predictions of ultraviolet radiation index on groud surface is one of the main tasks for domestic weather services.Proceeding from the necessity to establish a system for prediction and countermeasure of ultraviolet radiation on ground surface,it explains the principle,structure and function of the system.

Abstract:The ageostrophic wet Q^*method is applied to investigate apersistent rain storm process,which occurred in Yunnan from May 31 to June 2,2001.The results show that rain storm is most likely happen in a Q^* conver gent area and it locates near the ascending branch of a secondary circulation,whose intensity and direction can be indicated by vertical distribution of Q^*.

Abstract:Based on "3S" integrated application techniques,a GIS platform has been developed in terms of GISOCX active controller of Citystar 3.0,and it has many functions such as the project scheme establishment,real-time monitoring,information inquiry,the effect evaluating of weather modification by planes,antiaircraft guns and rockets etc.The platform can be flexibly run without the Citystar GIS tools environment,and much meteorological and geographic information can be inputted and outputted momentarily.

Abstract:The "7·9" torrential rain,which occurred under the weather situation of a shrinking subtropical high,jet developed from the peripheral southwest current and shear line passing at 850hPa level is analyzed by taking into consideration the main influential system,various physical features,satellite images as well as topography.It is shown that the torrential rain is triggered combinedly by the cold front,the middle-scale turbulence and the topography,mainly caused by the stagnant rain storm cloud cluster,and initiated in an ascending motion area with convective instability at the middle level,high energy tongue,warm advection convergence in the low level and cold advection divergence at the high level.

Abstract:Recent advances in land-atmosphere interaction and developing status of land surface models are reviewed comprehensively.By summarizing the relevant international observational projects and the most representive LSM,the problems deserved further exploration are proposed and the developing directions in this field are discussed.