Abstract:Relation between pre-flood season precipitation anomalies in South China and water vapor transport is analyzed by using the daily precipitation data of 57 stations in South China and the NCEP/NCAR reanalysis daily data for water vapor transport from 1958 to 2000,and the differences between drought and flood years are studied.Results show that anomalous meridional water vapor transport in South China will cause anomalous droughts or floods in South China,but anomalous zonal water vapor transport only causes the local precipitation anomaly;the anomalous water vapor transport in drought and flood years is not a simple out-of-phase relation;and the water vapor coming from the Indian Ocean and the West Pacific do not obviously affect the pre-flood season precipitation anomaly in South China,in fact,the South China Sea(particularly its north)is the key area of water vapor source for the precipitation anomaly of the South China.

Abstract:The paper analyses the developing characteristic of a torrential rain in Wuhan,and theoretically discusses the dynamic mechanism of the torrential rain.The results show that the low-level jet(LLJ) occurred before the torrential rain,and when the torrential rain is the strongest,the LLJ is also the strongest.The existence of non-thermal wind gradients on the right side of the entrance region of the upper level jet(ULJ) and the left of the LLJ,leads to the unstable amplitude of mesoscale waves.The unstable amplitude increases towards the torrential rain area,which tallies with the maximum amplitude area of waves due to the overlapping of the two unstable waves.Under the circumstance of the coupling of the upper and low level jets,the non-thermal wind mesoscale convection-symmetric instability might be one of dynamic mechanisms resulting in torrential rain.

Abstract:Based on a series of WSR-98D(CINRAD/SA) volume scan data every 6min,the structure of 3 hailstorms is analysed.Each storm had a mesocyclone,wherein the flow converged cyclonically at the low level,rotated cyclonically at the middle-low level,diverged cyclonically at the middle-up level,and diverged at the up level.On the right back of the mesocyclone there was an accompanying anticyclone at the middle-up level.Cyclone and anticyclone forms a "8" pattern flow and a "S" shape intense refractivity area.The "S" area at the middle-up level helps form a "cave channel".In the two turnings of the "S",the horizontal velocity is weaker,the "cave channel" forms more frequent and is the large-hail spawn region.

Abstract:Precipitation on ordered grid point,which is obtained from the Radar Estimating Precipitation model(REP) of Huanghe River and Huaihe River,is compared with the in situ data of a raingauge network.Results show that if the value of ground raingauge is taken as real value,then the optimal interpolation and joint calibration methods have the least root mean square errors,while the results of variational method are not very well due to parameter choosing.The calculating precision of Kalman filter method and average method is lower than the joint calibration method and optimal interpolation method.The method of Z-I has the largest root mean square errors.

Abstract:The heavy rain occurred from 2000BST July 4 to 2000BST July 5,2003 in the Yangtze-Huaihe River Basin was simulated by the mesoscale numerical model MM5.The analysis suggests that the heavy rain event was close related to the generation and development of a mesoscale vortex in the mid-low troposphere.The vortex moved together with a mesoscale rain cluster,and its intensity was in agreement with the evolution of precipitation intesity at the center of the rain cluster.The disposition of the intensive ascending motion at the center of the vortex,the lower-level convergence and upper-level divergence,and the accumulation of unstable energy in the low level of the vortex were very favorable for the generation and development of the mesoscale vortex.It was found that the higher helicity in the mid-low troposphere might be one of the possible mechanisms for the generation and development of the mesoscale vortex.

Abstract:Adopting a high resolution nested grid scheme and proper physical parameters,a Mei-yu heavy rain process in the middle reach of the Yangtze River from 0800 BST July 22 to 0800 BST July 23,2002 is simulated by use of PSU/NCAR mesoscale nonstatic numerical forecast model MM5 in this paper.The simulation results successfully describe the spatial and temporal distributions of the rain process and the developing course of the concomitant meso-β-scale system.The result shows that a series of meso-β-scale systems developing along the Mei-yu shear line are the direct influencing systems of this heavy rain process.The existence and changing fashion of the mesoscale divergence systems at high levels affect greatly the development of the meso-β-scale systems.The outgrowth of the mesoscale vortexes at low and middle levels could lead to the appearance of smaller scale strong cold and warm advection,which excites the baroclinic development of the mesoscale systems themselves.What's more,the latent heat of precipitation in turn have an important feedback effect to the development and maintenance of the heavy rain process,too.

Abstract:The main purpose of this paper is to improve the warm rain process in the LASG-REM(State Key Laboratory of Numerical Model for Atmospheric Sciences and Geophysical-Regional ETA Model),via adding the explicit prediction of water vapor,cloud water and rainwater for mesh resolvable systems and the parameterization scheme for subgrid cumulus convective systems.The sounding data of Eurasian as well as the surface data at 0000Z 21st July 1998 are used as the initial fields in the simulation.Results show that the improved LASG-REM model is able not only to forecast rainfall of Wuhan area,but also to predict the temporal and spatial distribution of cloud water and rainwater successfully.

Abstract:The forecasting models of momentum BP(MBP)and Elman neural networks are developed for Fujian rainy season drought/flood prediction,and the abilities and differences of the two types of models are compared.Results suggest that the forecasting model of MBP,especially the Elman neural network which has the character of local feedback,have better fitting precision and forecast accuracy.Additionally the forecasting abilities of the two kinds of models are worse for the drought/flood grades of 2 and 4,but best for the drought/flood grades of 3.

Abstract:The observed data of acid rain and pollution source are analyzed, and the analysis shows that the frequency of Nanning acid rain is high and the pH value is low.The computational results of the Lagrange plume model indicate that the Nanning acid rain is mainly affected by external pollution sources.The synoptic diagnoses for pollution sources suggest that the Nanning acid rain is mainly affected by the NE pollution source,especially in winter and spring,and it is influenced also by wind frequency and inversion.Based on above analyses,we conclude several types of circulations affecting acid rain,among those,the upper trough-cold front type is the major one.

Abstract:The circulation and meso-scale synoptic analysis was conducted on a severe sandstorm event on April 8,2001.The topographic effect on the cold front and the features of sandstorm movement are discussed.Using MM5 products,non-geostropic Q vector,frontogenesis and total temperature were calculated and analyzed,and results show that all the indices above had notable relation with the observations during this sandstorm event.

Abstract:Influences of the intensified Ultraviolet radiation(UV-B radiation,280-320nm)on wheat and spinach were compared and analyzed in this paper.Results indicate that the enhanced UV-B tends to suppress the plant height and dry matter accumulation of wheat and spinach,to reduce the chlorophyll content and leaf area,and to raise the flavonoid content.In addition,field experiments also show that impacts of enhanced UV-B on wheat are smaller than that on spinach.

Abstract:This paper introduces a plug-in system based on dynamic-link library technology in the software design of Second Product processing Doppler Weather Radars.Each product is designed as a plug-in separated from the main system,so researchers can concentrate on how to implement product algorithm.It also makes this software well organized and modularized.This project is easy to manage and further develop.This software also provides a platform for new product research and development.

Abstract:Based on field experiment,investigation and research,as well as analyses of the experimental data of eco-climatic adaptability for citron daylily,lily and beer barley,the integrated index system of eco-climatic zoning is determined.The results show that the primary indexes for citron daylily are ≥0℃accumulated temperature from April to the first ten days of August,rainfall accumulated sunshine-hour from June to July,and the supplementary index is the average yield;Lily's major indexes are ≥0℃annual accumulated temperature,frost-free season and rainfall from bloom to caudex becoming large(from the middle ten days of June to the first ten days of August),and similarly,the supplementary index is the average yield;for bee barley,the major indexes are ≥0℃annual accumulated temperature,the average temperature of spike polarization's phase(from the last ten-day of May to the first ten-day of June)and grouting phase(from the last ten-day of June to the middle ten-day of July),and the supplementary indexes are the average yield and quality.The planting zoning of climatic-ecological adaptability of the three characteristic crops is divided into 5 grades, best suitable,suitable, hypo-suitable,just suitable and unsuitable regions.At the same time,the way to raise the utilizing efficiency of eco-climatic resources is also presented,which offers a scientific basis for building planting base,developing production on a large scale and enhancing economic benefit.

Abstract:To a forced Liénard equation discussed in this paper,the estimates of the periodic solution are given by using the norm estimate in the Sobolev space,then by virtue of the variation principle and Schauder's fixed point theorem,the existence of the periodic solution is proved.

Abstract:This paper proposes a figure character recognition method based on features aiming at the complexity of character image,a large quantitity of input data and the slow convergence speed in recognizing and researching character image.Thirteen construction features designed and extracted in this paper compose a thirteen-dimension hyperplane space,wherein a character recognition system model is developed using the neural network cluster method(10 cluster number),the MATLAB with powerful matrix operating ability and the efficient code of C Language.Experiment results indicate that the recognition time and rate are still satisfactory under the indistinctive feature differences.

Abstract:By using the theory of moist potential vorticity(MPV,ξ(MPV)),a rainstorm happened in Shandong Province in April 2003 is analyzed.Results show that the rainstorm occurred in the neighbourhood of the stiff and dense section of the moist isentropes,where the convective stability was so small that it is beneficial to the development of moist baroclinic vorticity.The evolution of ξ(MPV1)<0 and ξ(MPV2)>0 at 700hPa level at the early stage of the rainstorm reflected convective instability and the intensification of baroclinic instability in the rainstorm area.The downward spread of high ξ(MPV)from the upper troposphere availed the release and storage of potential instability energy,resulting in the strengthening of precipitation.It is also an important mechanism through which the low vortex moved eastward and developed into a cyclone.

Abstract:Based on the NCEP/NCAR reanalysis monthly data,by means of correlation analysis and the Mexico Hat Wavelet analysis,the variation features of rainfall in Vietnam and its relation to Pacific SSTs are studied.It is found that the precipitation mainly happens in summer and autumn;the summer and autumn precipitation has interannual and interdecadal variabilities.Further study shows that the summer rainfall in North Vietnam has a close relation with Pacific SSTs.When the summer rainfall is more(less),the SST is higher(lower)in the west Pacific Ocean and lower(higher) in the east-central Pacific.

Abstract:Based on the daily SARS(Sever Acute Respiratory Syndrome)patients and local meteorological factors in Beijing and Hongkong,we conclude that air temperature and pressure had a high correlation with the incidence of SARS;high relative humidity,cloudy weather and the lack of sunlight were the common meteorological characteristics,and the cold air activities promoted the prevalence of SARS.In this paper we also formed an integrated index based on the corresponding relation of the number of SARS patients and meteorological factor changes,then calculated the high danger index(Zj)of air temperature in Beijing and Hongkong,and results show that daily average temperature and daily minimal temperature indices have a 3℃and 7℃differences,respectively,while the maximum temperature index are both 24-27℃in the two regions.

Abstract:After the analysis of the observed data of pollen in the suburban and urban areas of Kunming city from January 2000 to December 2001,it is found that the periodical and seasonal characteristics of pollen concentration variation in a year are clear.Based on the relation of meteorological elements and pollen concentration in air,a prediction equation of pollen-allergy disease was statistically developed.Then the equation is verified and improved by using the actual incidence of pollen-allergy from hospitals,and humidity,wind speed and temperature.The accuracy of the forecast equation is quiet satisfactory.

Abstract:Agricultural production is a process uniting natural and economic reproductions,and the agro-system is a complex system coupling natural ecological system,and social economic system,which is nonlinear and dissipative.The system behavior reflecting the nonlinear interaction of factors of the complex agro-system forms the whole evolutional locus of the system.Viewing from long term evolution ,the agro-system manifests chaotic characters due to interior self-organization and synergetic effects and exterior stochastic perturbation effects,therefore the complex system is unpredictable for a long term.According the prection standard of complex agro-system,on the basis of reconstructing the phase space of the complex agro-system,a nonlinear chaotic dynamic prediction model based on chaotic attractor is developed in this paper,and the model is analyzed and verified with the relevant data of Chendu agro-system.