Abstract:By dividing 850hPa u field into barotropic and baroclinic components,study is performed to the possible mechanism of the effects of SSTA in the preceding March over (42.5~52.5°N,170°E~170°W)on summer rainfall in east China.Results show that the SSTA in March has effects on 850hPa baroclinic wave train of the same season.The baroclinic wave train in March can effect the baroclinic wave train in summer,which at last can effect the summer rainfall in the east China.

Abstract:Study is undertaken of the climate base state of northern summer atmospheric action centers and sea level pressure (SLP)with its climate variability and temporal evolution in the past 100 years, indicating that the base state has its high value region of mean square deviation in the Pacific High and Indian Low. The climate base state of the summer SLP exhibits two modes for its variation.The first eigenvector of the base state displays Indian Low, the second Pacific High and Atlantic High.They have secular variation .The Indian Low and Pacific High is enhanced,with the Atlantic High being slightly enhanced in the past 100 years .The climate base state of the Indian Low displays oscillations at periods 80 years.Evidence suggests that the Pacific High and Atlantic High display a remarkably positive trend .They abruptly enhanced in the early 1900s,before that they are considerably weak and after that they become the strongest in 1910s～1930s.Further, the east Asian summer monsoon is closely positively related with the summer Pacific High intensity and with the second mode of northern SLP on the scale of more than 30 years.

Abstract:In terms of a developmental model, a super high yielding two line hybrid rice 65396 (AP64SE32)has been investigated both on steady sterile season and duration of its female parent AP64S and on sowing time difference between its female and male parents for seed production in a single rice cropping zone in the south of China. The agrometeorological technique for making hybrid rice seeds is applicable to zones of other rice cropping systems.

Abstract:Statistical analysis and image linear stretching have been performed for each AVHRR channel for rice planting area estimation. Besides two traditional crops monitoring channels 1 and 2, Channels 3 and 4 (thermal infrared)are employed in the study for the latter ones are also rich in information and their stretched images present lower brightness temperatures for rice than for rain fed fields. Results show that the additional channels are helpful to rice identification in combination of the traditional visible and near infrared channels.

Abstract:By utilizing the NMC of China objective analysis field at 12 GMT 1 April 1992 as its initial data and comparing the outputs of CCM1(R15L7)and CCM1(T21L7),numerical study is undertaken of the influence of horizontal resolution and its structure on the monthly weather prediction.Results show that CCM1(R15L7)has a better result in monthly prediction than CCM1(T21L7)because of its more realistic meridional structure in its horizontal resolution,which is rectangular with long axis in N-S(W-E)direction at high(low)latitudes and square at middle latitudes.

Abstract:Under the assumption that a geometric process at the start point follows a lognormal distribution, the statistical inference problem for the geometric process is studied. The distribution parameters have been estimated with either the maximum likelihood method or a modified moment method. Then some suggestions are made based on the theoretical results, the simulation experiments, and the real data analysis.

Abstract:The effects of global warming on the probability of extreme high temperature event (EHTE)in the Yangtze Delta are studied.It shows that the probability of EHTE will increase with global warming.When averaged daily extreme high temperature in summer increases 3.0℃,the probability will rise from 0.13 to 0.2～0.3, it means the days that daily extreme high temperature is equal or greater than 35 ℃ will rise from 12 now to 20～30 in the future.

Abstract:In terms of global SSTA,wind,OLR data and precipitation,temperature in China,five catalogues are defined of the phases in summer of ENSO cycle based on seasonal SSTA in equatorial central and eastern Pacific.It is found that the difference in Walker circulation is the most significant between Type A ang Type C.Further evidents show that the Walker circulation,the Hadely cell,subtropical high in western Pacific and the east Asian monsoon are week(strong)in summers of Type A(C),with lower(higher)temperature and more(less)rainfall in the reaches of the Yangtze River.

Abstract:Based on global SST and China rainfall datasets in 1951~1994,the SST in the preceding March over north Pacific region(42.5~52.5°N,170°E~170°W)is found to be essential to China summer rainfall and the region is defined as the SST key area.A possible teleconnection pattern is presented to explain the effects of SST in the preceding March over the key area on China summer rainfall.It is found that correlation between SST in key area and China summer rainfall is good and stable,which is not under the influence of interdecadal variation in SST.

Abstract:A numerical calculation method is presented for parameter estimation based on the technique of solving nonlinear model.The accuracy of parameter estimation in torrential rain intensity formula is improved.The method may be widely used to optimize other multivariate parameters in the model.

Abstract:Hour precipitation from AWS in urban and suburb of Beijing is analysed to study the effects of urbanization on short duration precipitation.Results show that hour precipitation can be fitted to logarithm Weibull distribution and that the enhancement of rainfall due to urbanization is remarkable in downwind under moderate/heavy short duration precipitation process,and that the increase of probability and intensity of torrential rain is significant in urban center.

Abstract:WT5BZ]The tracks of tropical cyclone 9611 and 9904 were predicted by nonhydrostatic model(MM5).The techniques of the nudging of four dimensional data assimilation and bogus TC were employed. The first bogus TC was forced to approach the second bogus TC gradually from t-12 to t0 during the 12 hours pre integration, which the observation nudging in MM5 was used. When the 6 hr.interval data of T106L19 were obtained in 1999, we created three bogus TCs separately at t-12, t-6 and t0.The former bogus TC approached later bogus TC during forecast integration. The influence of nudging was considered during integration from t0 to t12,and 48 hours forecast was completed. The results show that the forecast skill of track prediction with nudging is better than that without nudging, especially for unusual TC track.

Abstract:Climatically analyzed are the frequencies of tropical cyclone generated in the Northwestern Pacific and South China Sea, the times of tropical cyclone of different intensities landing on China and the spatial distribution of tropical cyclone activities based on the data from 1949 to 1995.Some relationships are found between the tropical cyclone activities in the Western Pacific and the ENSO phenomenon.

Abstract:The application of Q_VIL (Vertical Integration of Liquid Water)to estimating precipitation is discussed. It is the first time that the detailed comparison is made between the estimated precipitation from Q_VIL,from the conventionally used PPI and CAPPI,and the in situ measurement of raingauges.It shows that Q_VIL can make use of the three dimensional characteristics of radar observations,and better than Z from either PPI or CAPPI as far as for estimating precipitation.

Abstract:Based on 1995~1998 datasets at 4 AWS over the Tibetan plateau during the experiment of Sino-Japan cooperation on Asian Monsoon and 1995~1996 daily NCEP/NCAR reanalysis data,study is performed of the features of LFO phase structure with its relation to summer regional rainfall.Results show that the 30~50 d LFO of sensible/latent heat flux has the same phase,with the exhanced phase corresponding to less plateau rainfall and v.v..The propagation of 200 hPa LFO zonal wind reveals that the Plateau is a sink region for LFO in winter of 1995~1996.Further evidences show that 200 hPa LFO zonal wind,which is regatively correlated with LFO station pressure and lags about one week to LFO surface sensible heat flux with a phase difference of 3π/8,is positively (negatively)correlated to summer rainfall in Lhasa (north China).

Abstract:Based on the experimental data from wheat fields, the evapotranspiration has been estimated using Bowen ratio energy balance(BREB)method,profile gradient(PG)method and energy balance aerodynamic resistance(EBAR)method respectively.Estimations and their errors are compared among the different methods with the error causes under discussion.Results show that the latent heat flux calculated by the BREB method is systematically about 20% lower than by the PG method and slightly less than by the EBAR method.

Abstract:Based on the observational temperature over 695 stations in China from 1951 to 1997,winter temperature series over 8 regions and China are constructed in terms of a method which the average is weighted by the cosine of the latitude,to investigate their variation features.Results show that:1)winter temperature displays a discontinuous warming trend on the whole,with the linear trend of about 0.155℃·(10a)^-1 and the increment of about 0.61℃ from 1950s to 1990s,which is remarkable especially after 1985;2)such a warming trend is contributed not only to the minimum temperature,but also to the maximum temperature variation;3)winter temperature over Tibetan plateau is getting colder with the warmest period in 1950s.

Abstract:The velocity data for a single Doppler radar have been used in this paper to compute the feature values such as one dimensional radial shear,one dimensional elevation shear and two dimensional radial and elevation shear,and the effect of airflow on airplanes has also been analised.The study is to recognize the areas of wind shear,verify the observations of microburst,mesocyclone and gust front,and define the potentially dangerous areas for airplane during landing and taking off.The system can be regarded as an efficient tool to guarantee a safe flying.

Abstract:Path integrated attenuation factor for a mountain return is determined by a comparison of the radar reflectivities of the mountain during precipitating between the radar and the mountain and the reflectivities from the same mountain when it is clear.Then,the PIA factor is applied for the attenuation correction of radar echoes of the percipitation so that the real reflectivities of the precipitation are obtained.

Abstract:In terms of data provided by ERBE and ISCCP, effects of total cloudiness on earth-atmosphere system absorbed shortwave cloud radiation forcing (SWCRF)are investigated over Qinghai-Tibet Plateau on an annual and a monthly basis separately. It turns out that there is a good power-law correlation between them,and both have obvious seasonal variations. The SWCRF’s geographical distribution accords well with that of the total cloudiness over the region and its value is lower over the main and north parts, and higher over the south east part and the windward side of the west edge.

Abstract:For Hermitian matrices A and B,the following inequalities are proved: (1)tr(AB)^m ≤tr(A^mB^m);(2)tr(A B)m≤tr(A^m B^m),where m is a positive,even number.

Abstract:The absolute maximums of daily physical quantities during continuous torrential rain event in July 1998 are calculated and analysed,with the distribution of physical quantities in July 23 shown.It is found that the thermal,water vapor and stability parameters in the event are obviously stronger than those in general rainy season (April to the early of July),and that the helicity and divergence of Q-vector are correlation with precipitation inensity.

Abstract:Described mainly are technical fundamentals of future climate data processing system,including techiques of system integration,visualization,data warehouse,data mining,world wide web and intelligent agent.And the structure and function of the system are also discussed.