Abstract:Based on the local eddy kinetic and available potential energy functions, detailed diagnosis of daily energy evolution is conducted to reveal the relative contribution of several inertial processes such as baroclinic, barotropic processes and eddy ageostrophic geopotential flux, etc., to the maintenance of storm track. It is shown that the "downstream development effect" caused by eddy ageostrophic geopotential fluxes serves as an important factor for the maintenance of track in a preferred region.

Abstract:The atmospheric flow is divided into barotropic and baroclinic flow fields in a dipole blocking case over the Ural mountains.Investigated are the evolution features of barotropic and baroclinic flow fields and the lifespan of the blocking case which is excited by the interchange between barotropic and baroclinic flow fields.

Abstract:It is found that there exist quasi-45 d,quasi-23 d and quasi-14 d low frequency precipitation over the plateau and that the lower of the frequency,the more likely of their propagation from south and east side of the plateau to the plateau itself,and v.v.The low-frequency rainfall propagation trends to follow the path of propagation of the overhead low frequency divergence at 150 hPa.The intensity of low-frequency rainfall,which is somewhat different from that of low frequency divergence,is far more strong over center and south of the plateau than over north of the plateau and is relatively independent of the plateau’s vicinities.

Abstract:Following the targets defined by the program “China Heavy Rainfall Experiment and Study”,research is undertaken of a typically exceptional torrential rainfall event in July 1998, revealing the features, evolution and interrelation with meso-scale rainmass activity of recurring structures of surface flow patterns of two kinds in Hubei of central China, whereupon is established a physical representation of the interrelation of the surface flow patterns with meso rainmass activity during an intense Meiyu frontal rainstorm typical of its occurring region.

Abstract:A method of vector composite analysis is developed to describe the character of northern land precipitation for high/low SO phases.The effect of SO on northern land precipitation with its periodicity is also discussed.Results show that such an effects is obviously of harmonic with a period of longer than 2 years.It explains the fact that the rainfall extrence anomaly happens usually in the years of around the high/low SO phases but seldom on the years of the high/low SO phases.It is also found that the 36 month harmonics is a reasonable description to the precipitation change. The method of the paper is based on harmonic analysis,so it has its limitation in identifying the periods.

Abstract:Defined are three indices about western Pacific subtropical high(WPSH),i.e.,the WPSH ridge index,area index and western extension index.On the basis of the indices,the interannual relations between equatorial eastern Pacific SSTA and WPSH are studied,and further discussion reveals the influence of equatorial eastern Pacific spring SSTA on the seasonal change of WPSH.Results show that the equatorial eastern Pacific spring SSTA is closely connected with the strength and position of summer WPSH on interannual and seasonal scales.Related to the warm(cold) spring SSTA in the equatorial eastern Pacific,the WPSH from spring to summer lies to the south(north) of its mean,the west(east) of its normal,and is slightly intensified(weakened) with insignificant(noticeable) northward shift in June and slow(fast) southward retreat in Autumn.

Abstract:Airborne measurements of atmospheric aerosols were made during 16 aircraft flights in 10 days conducted over Liaoning province,China in the early summer of 1996 and 1997.This paper deals with aerosol concentration and size distribution under 5 km and their spatial changes.Correlations of aerosol concentration with temperature and relative humidity are analyzed.Results demonstrate that there are different vertical distributions of aerosol concentrations between the mixed layer and free atmosphere.Due to different formative processes,aerosol distribution is of multi modal.Aerosol concentrations have considerable changes along horizontal flight legs.Inversion layer and relative humidity have significant influences on aerosol concentration and size distribution.

Abstract:Field experiments performed in Nanjing area show that enhanced UV-B radiation causes marked variations in canopy structure of wheat and in turn affects the canopy’s light reflectance and absorption. Investigation has been conducted in detail and quantitatively on the variations of the structure and with possible mechanism under discussion.

Abstract:Influences of SSTA over Kuroshio on SCS summer monsoon onset and the western Pacific subtropical high from April to June are investigated.The numerical simulation further shows that the SSTA in the area plays an important role in SCS summer monsoon onset and in the position and intensity of the western Pacific subtropical high(WPSH).When the SSTA is positive,the position of WPSH will be to the south of its mean and its intensity will be strong.Accordingly,SCS summer monsoon onset will be late and its intensity will be weak and flood will occur in Changjiang-Huanhei River valleys,and vice versa.

Abstract:Based on monthly COADS SSTA dataset,linear inverse modeling(LIM) is developed to predict SSTA over tropical Indian Pacific Oceans.Prediction results of independent and dependent samples show that the RMS errors of SSTA predicted in 10~12 months ahead are smaller than SSTA mean square deviation and that the relative errors in 5 months ahead are less than 50 %.The prediction accuracy is btter during El Nino and La Nina periods than during other periods,especially during La Nina periods.The prediction accuracy of LIM is better than that of auto regression model,SSA-MEM model,climate value prediction and persistence prediction.

Abstract:A 3-dimensional non hydrostatic PBL model with a new non local counter gradient closure(CG) is developed and used to simulate the boundary layer on complex terrain near Hangzhou gulf.A comparison between the observed data and the simulated results is made.It is shown that this model can more reasonably simulate PBL wind,temperature and turbulent fields than the hydrostatic model in coastal areas.

Abstract:A simplified transmission model is used to estimate surface ultraviolet(UV) radiation over Nanjing area. Taking account of possible ozone variation in the future time, the value of UV radiation ampification factor(RAF) is obtained. Additionally, annual variations of UV, its relations to total solar radiation and weather conditions are investigated by virtue of one-year UV observations.

Abstract:In accordance with its occurrence and development laws,a nowcasting system of the severe convective weather in Shanghai is developed based on the output from mesoscale model,Doppler radar,GMS,MICAPS and AWS precipitation and on the atmospheric dynamic,moisture and stability conditions and the trigger mechanism,together with the forecasters experiences.The products of the system include the situation analysis of the severe convective weather,0~12 h forecast and 0~3 h alert.

Abstract:In the context of wavelet transformation,revealed is the multiple time scale structure of the monthly precipitation anomaly in Henan Province.Results show that there are periodic variations of 6~9 months,quasi biennial,4~8 years and 20 years or so for Henan drought and waterlogging changes.The distribution of small time scale period variations has been disordered in the discussed time region.

Abstract:The working princeple and characteristics of CUK converter in discontinuous-capacitor-voltage mode are studied.Theoretical analysis shows that the CUK circuit has inherently the features of power-factor correction and soft turn-off switching.Results from simulation and experiment are reported to support the theoretical analysis.

Abstract:The project,EuroMET,is an excellent achievement in meteorological education and training with web and internet.Briefly introduced in this paper are the EuroMET and the principal contents included in two available coursewares, NWP for Numerical Weather Prediction and SATMET for Satellite Meteorology.It is also mentioned that the modules will be translated into Chinese and used in the China Education and Research Network.

Abstract:In terms of data on radiation and cloudiness from ERBE and ISCCP, outgoing longwave cloud-radiative forcing(LWCRF) and cloud greenhouse effect(CGE) are investigated on seasonal and annual bases over the Tibetan Plateau.Results show that a good power-law correlation exists between LWCRF and either total or high cloudiness. The LWCRF changes seasonally and has a geographical distribution similar to that of total cloudiness, its value being higher in spring and lower in winter or autumn.

Abstract:Rainfall estimation from satellite data have many applications in climatology and meteorology but calculation associated requires a rapid processing to large amounts of data in order to achieve significant result.The neural networks(NN) method is one of the several techniques employed to extract meteorologically-useful information from remotely sensed data.However this method is hardly used independently to yield quasi-real time rainfall estimates since a large amount of satellite data are needed to generate the input/output data for the NN training.In order to overcome this shortage,multiresolution wavelet transform(WT) technique is proposed to decompose the images to obtain the key information for further analysis.As a result,the NN training becomes easier and faster.In the paper a case study to estimate rainfall over the central part of the Sá Paulo state,Brazil using both the NN and WT techniques is given.The analyses were performed using GOES-8 brightness temperature data and meteorological radar data from Bauru,SP.It is concluded that NN can be successfully used to estimate rainfall from remotely sensed imagery.

Abstract:The BP model method for nowcasting is discussed in this paper.The results are compared with that from Fourier descriptor method,and it is shows that the artificial neural network method is feasible for nowcasting.

Abstract:Investigated are the anomaly features of atmosphere circulation and meteorological elements prior to early spring drought in Guangxi.It is found that the drought is closely related with the geopotential height at 500 hPa,precipitation,temperature,SST,polor vortex intensity and Eurasian zonal circulation in the proceeding winter.A regression model is developed to predict the drought in 1998.

Abstract:The concentration of atmospheric ice nuclei was observed in 1994 in Yinchuan and in Bainhaote of Inner Mongolia respectively.The concentration of atmospheric ice nuclei under different sky conditions is studied and the relation is discussed between the concentration of atmospheric ice nuclei on one hand and wind,precipitation and the sky conditions,on the other hand.The observation results of ice nuclei from aeroplane are also given.

Abstract:Yunnan Province has plenty of light resource in its southern subtropical zone where both hybrid rice and winter sown maize yield high.Besides,thermal condition is also very good with 6000 to 7500℃·d of ≥10℃ accumulative temperature for a whole year,smaller annual and greater diurnal temperature difference.Such climate as warm winter and cool summer can make maize be planted any time in a year,being typical of the southern subtropical climate zone for the crop.Not so high temperature in summer when sunshine is weak in some degree causes lower yield of the hybrid rice.Rainfall is distributed unevenly either in season or in space,though its annual total amount is proper,and within dry spring and winter seasons it is only 10% to 15% of the total,accordingly restricting growth of the winter sown maize and pre jointing rice.To develop water conservancy and irrigation therefore is the most important for achieving high and stable yields of rice and maize in this zone.