Abstract:Based on the NCEP/NCAR daily reanalysis data,the circulation background of the flash-flood-producing rainstorm over South China in June 2005 and its possible cause are analyzed.The results show that the weak ElNino events during 2004-2005 was the climatic background of the rainstorm.Compared with summer in 2005,the apparent heating source <Q₁>and apparent moisture sink <Q₂>were exceptionally strong over South China during June 17-26,2005.And the center of high value bands of <Q₁>and <Q₂>were basically coincided with that of rainfall.The anomalous heating source over the east coast of Arabian Sea and the Bay of Bengal forced an anomalous anticyclonic circulation over its northwest at the upper level,leading to the strenthening and westward stretching of South Asian High(SAH).An anomalous cyclonic circulation controlled the Chinese mainland,which went against the northward movement of SAH,but favored the maintaining of SAH over the south of the Tibetan Plateau and South China,so South China areas just located in the updraft areas in the south side of the upper level westeries jet,which is frequently in favor of the formation and maintenance of heavy rain,and thus severe flood.

Abstract:Using the subsurface temperature and thermal capacity data in the North Pacific and the summer precipitation and air temperature data at 160 stations of China from 1951-2002,we analyze the characteristics of the upper-ocean thermal state of the North Pacific in winter,and study the relationship between the thermal capacity and the summer climate in China,then discuss the coupling relationship between the thermal capacity in the North Pacific in winter and the summer climate in the east of China by SVD expansion.The outcome shows that according to the EOF expansions of sea temperperatures at 11 levels within the subsurace layer,the temperature of the winter upper-ocean in the North Pacific can be classified into two types of 40m and 240m depth,and both have obvious decadal characteristic.The anomalies of the winter thermal capacity in the North Pacific are similar to those,and have fairly good coupling relationship with the following summer climate anomalies in the east of China.When winter thermal capacity is higher than normal in the north and the south-east of the North Pacific,the following summer precipitation will be more in South China and North China while the summer temperature will be lower in South China;when winter thermal capacity is higher in the Kuroshio extension and the east of the North Pacific and lower in the west coast of North America,the following summer precipitation will be less in the Yangtze River valley and Northeast China,and the summer temperature will be lower in Northeast China and North China.Both of the coupling relationships of the precipitation and air temperature with the preceding winter thermal capacity have obvious characteristic of decadal time scale.

Abstract:The atmospheric boundary layer structure over a water-land heterogeneous surface(Baiyangdian region)is simulated by the RAMS(the Regional Atmospheric Modeling System)model.The simulated results of potential temperature and specific humidity are compared with the data measured during the field experiment in the Baiyangdian region in November 2004.Simulated results show that the weak local circulation induced by the thermal difference of underlying surfaces occurred in the Baiyangdian region,i.e.a water-land heterogeneous region(about 360km²),and it impacted the spatial distributions of specific humidity and temperature within the boundary layer,and of turbulent kinetic energy below 500m.Finally,the simulated results are also compared with the observed data.

Abstract:The individual influence of "pure" ENSO or "pure" Indian Ocean Dipole(IOD)events,and the combined influence of the two types of events on both the summertime rainfall and temperature in China have been investigated using the NCEP-NCAR reanalysis data in 1958-1999.Results show that either the "pure" ENSO or "pure" IOD event has distinct effects on both the summertime precipitation and temperature in China.When a positive(negative)IOD event occurs during an El Nino(La Nina)year,summer moisture content and precipitation tend to increase(decrease)in the northern part of China,however,in the eastern part of China,the rainfall tends to be less(more)than normal while the temperature over China mainland tends to be higher(lower)than normal.The IOD has been proved henceforth to weaken the influences of ENSO events on the summertime rainfall and temperature in the eastern part of China.

Abstract:In this paper,using a global spectral model of quasigeostrophic barotropic vorticity equation including diabatic heating,we studied the probable mechanism for SSTA to affect summer atmosphere circulation.Results show that the SSTAs in the tropical Pacific have notable influence on summer circulation,and the response to the SSTA in eastern equatorial Pacific is more visible than that to the SSTA in western Pacific warm-pool.The negative SSTA in western Pacific warm-pool can effect waves rising and falling on circulation,however,the positive SSTA in eastern equatorial Pacific can not.Either positive SSTA in western Pacific warm-pool or negative SSTA in eastern equatorial Pacific can create an teleconnection in vorticity field and meridional wind field.As negative SSTA in western Pacific warm-pool and positive SSTA in eastern equatorial Pacific occur at the same time,the variation of meridional wind field are very complicated,responses spread all over the Northern Hemisphere,and perturbantions show a character of stationary waves.

Abstract:Using the summer daily precipitation of 355 stations over eastern China,the spatial standard precipitation index is first computed in this paper.Interannual and interdecadal changes of summer rain band propagation over eastern China are then analyzed using the extended empirical orthogonal function(EEOF)method.The results show that the summer rain belt can be divided into two segments by 110°E,and their inconsistent propagation leads to the northward propagation of the two rain belts in a form of NE-SW orientation.During the strong(weak)propagation years,the rain belt could reach a position north(south)of normal and the summer precipitation always appeared as a rainfall pattern 1(2 or 3).The intensity of rain belt movement showed two obvious abrupt changes in 1966 and 1979,respectively,and it was overally strong in 1957-1966,but weak in 1979-1989.

Abstract:The four seasons'significant teleconnection on both interannual and interdecadal scales of sea surface temperature anomaly between North Atlantic and North Pacific are demonstrated using the diagnostic method of SVD(Singular Value Decomposition).The anomaly index I of sea surface temperature anomaly is constructed of the time coefficient of the principal SVD pattern.The correlation of index I with anomalies of contemporaneous Asian-Pacific summer monsoon and the summer precipitation of eastern China are analyzed.The results show that the teleconnection pattern between North Pacific and North Atlantic SST is correlated with the anomaly of summer Asian-Pacific monsoon on both interdecadal and interannual scales,and remarkably with the precipitation of the Yangtze River valley on interannual scale.

Abstract:In order to obtain the precipitation distribution of high resolution in the upper-middle reaches of Yangtze River,this paper analyses the annual precipitation on the basis of the precipitation data of 613 meteorological stations from 1992 to 2001 with an interpolation method which adapts to the Geographic Information System(GIS).The result shows that the effect of the SIA based on the DEM of 4km resolution is preferable.This method improves the computational accuracy,embodies the precipitation changes with topographty and the distributive incontinuity of precipitation,and solves the problem of the precision of the spatial interpolation of precipitation under complicated topographty condition.

Abstract:On the CCN(Cloud Condensation Nuclei)condition of mineral aerosols coated with(NH₄)₂SO₄ by heterogeneous-phase chemical processes,the rule of the condensation growth process of droplets is discussed first.Based on the aerosol and cloud droplet size distribution data measured in the aerial survey in Liaoning on May 14,1997,the cloud drop size distributions are calculated for mineral aerosols coated with(NH₄)₂SO₄ and pure(NH₄)₂SO₄ nuclei,respectively.Comparison shows that the cloud drop size distributions for mineral aerosol coated with(NH₄)₂SO₄ are wider than the ones for pure(NH₄)₂SO₄ nuclei,and the former is in agreement better well with the observation than the latter.

Abstract:The variational adjoint method in combination with Tikhonov regularization principle is applied to retrieve the initial gas concentrations and reaction rates in chemical reactions about ozone destroying in the stratosphere.The adjoint models and functional gradients are deduced for the complete and incomplete(terminal time)observations of the gases'concentrations,respectively.Finally,a series of ideal numerical experiments are preformed to show the validity of the variational adjoint method.Especially,Tikhonov regularization principle can be used to overcome the ill-posedness in the case of combinational retrieving for incomplete observations.

Abstract:Influences of the Indian Ocean Dipole(IOD)on the intensity of ISO(30-60d,hereafter)have been studied in the present article,by using the NECP/NCAR Reanalysis and monthly GISST SST data from 1979 to 1998.The results demonstrate that the IOD has significant influences on the intensity of ISO in Africa.The effects of IOD on the intensity of ISO in Asia are also significant.The variations of the zonal wind(U),geopotential height(H)and meridional wind(V)on intraseasonal timescale at 200hPa are modulated by the IOD.There are distinctly different or even opposite,in some areas,impacts of IOD and ENSO on ISO intensity.A further analysis on the anomalous distributions of the intensity of U,V ISO at 200 hPa in 1994 are also presented to display the propagation features of ISO phase and the Rossby wave energy.

Abstract:The characteristic of global zonal mean Hadley circulation has been investigated by using the NCEP/NCAR monthly wind reanalysis data from 1948 to 2004.The intensity index of Hadley circulation is defined and calculated by using the 3 levels wind data in 4 key regions for the southern/northern hemisphere and the global.Results indicate that the index calculated can represent the Hadley circulation intensity reasonably.The monthly Hadley circulation indices showed an increasing trend in the northern hemisphere except for the months from July to September,in the southern hemisphere except for May.The yearly averaged indexes were both increased obviously over the southern and northern hemisphere.Interannual correlation analysis shows a significant negative correlation between Hadley circulation index and SOI.The interannual variation of Hadley circulation intensity was close related with ENSO.

Abstract:A cold air invasion process into the Qinling Mountains during January 20-22,1997 is simulated by using the regional climate model RegCM3 with a higher resolution(10km),and the Qingling Mountain's barrier and blocking effects on cold air are examined as well.The results show that the simulated temperature and pressure changes are basically in good agreement with the observations,and the Qingling Mountain's barrier and blocking effects can lead to more than 4 ℃temperature difference between the south and north sides of the mountains and retard the cold air for more than 12 hours.The analyses of the temperature and surface pressure evolutions in this cold air invasion process show that RegCM3 has good performance in simulating the features of the temperature and surface pressure changes over the complex terrain areas.

Abstract:The Kriging method is used to conduct the spatial interpolation of surface air temperature dataset over China for each month from January 1951 to December 2004,and comparisons were made between interpolated and observed series.The results show that high correlations were detected between interpolated and original series,which proves that the interpolation of large scale historic climatic data is acceptable to some extent;and in interpolation,departure values in stead of origional values were recommended and 10 as the radius of the spherical model,which will improve the resultant series greatly,especially in station-sparse areas.While in some regions with particular local climate changes,it deserves more careful downscaling analysis and denser stations distribution.

Abstract:In the context of the non-hydrostatic MM5,the mixed ice phase,graupel(gsfc),graupel(reisner2)and schultz schemes are used to explore the impact of explicit schemes of cloud precipitation on the uncertainties in the numerically simulated idealized convective storm with full explicit approach.The numerical results show that there are signicicant uncertainties in the evolution of horizontal structure,rain,cloud prognostic variables and thermal and dyinamical fields.Therefore,explicit forecasts of precipitation,especially ensemble prediction of precpitation,should be performed together with the estimation of different uncertainties of different explicit schemes.

Abstract:Using the NCEP/NCAR daily and monthly reanalysis data from 1948 to 2002,the climatic distribution of heat source over the Tibetan Plateau in spring,the interdecadal variation of the heat source over the eastern Tibetan Plateau,and the relationship of its anomaly to the East Asian summer monsoon are analyzed.The results show that there was an abrupt change in the spring atmospheric appearent heat source over the eastern Tibetan Plateau in 1965,and especially,the increasing trend of the heat source was remarkable after 1970.Furthermore there was an interdecadal relationship between the spring heat source over the eastern Tibetan Plateau and the East Asian summer monsoon.That is to say,there exited a negative correlation between them before 1978,but the relationship has become blurred after 1977.

Abstract:In the years 2002 and 2003,the frequency of the sandstorm in the middle and west region of Gansu decreased and the intensity weakened.In order to find the Climatological reason for the change,the arctic vortex,temperature and the moisture of surface layer soil were analyzed.According to the source of sanddust,the transfer paths of sanddust can be devided into two type:the northwest and west path.The composite analysis is used to find their mean circulation,and in order to find the relation between severe sanddust storm and physical quantities,such as Q-vector,CSI(Conditional Symmetric Instability)and frontal secondary circulation,a severe sandstorm "20010408" was diagnosed based on the NECP data.And the result show that conditional symmetric instability layer was very thick before the happening of the sand storm and the frontal secondary circulation had a close relation with the sand storm.

Abstract:In order to analyze the training mechanism of Modular Fuzzy Neural Network(MFNN),partial training samples were adopted in the rough training model for lowering complexity and enhancing generalization.Statistical experiments of stepwise prediction errors were performed under various parameter conditions on mean rainfall in May of Guangxi province for continuous 47 years(1957-2003).The results show that the testing errors for employing partial training samples are generally lower than that for employing the whole training set.The feasibility of this method is thus confirmed and the further study on this question is worth performing.

Abstract:By using matrix-blocking,this paper gives the necessary and sufficient condition for the equatity sign in the Sylvester inequality,and the sufficient condition for the equatity sign in the Frobenius inequality,and the corresponding algorithm and example are also given.

Abstract:Homeomorphism theory can be used to prove that the Liénard type equation has only one periodic solution in some restricted condition.Based on this premise,this paper discusses the feability of using the homotopy method to solve the periodic solution of the boundary value problem of the lienard type equation.At last the concrete calculation methodology is given to solve the periodic solution.The given example shows that the calculation is feasible.