Abstract:The analysis of 40-year mean daily data shows that marked differences lie in vertical structure and movement of subtropical high ridge (STH) between 120～150°E and 160°E～180°, which are closly related to nonuniform heating.The ridge line slopes northward with hight while southward in 160°E～180°.The ridge movement has 10～20-day low-frequency oscillation during its northward over central and western Pacific,particularly in East-Asian monsoon area with quasi-40-day oscillation period.The analysis shows that solar radiation is the main factor of STH movement and that nonuniform heating plays a very important role in its moving speed and change of strength,especially for its abnormality.

Abstract:Characteristics of the surface heating fields over the Tibetan Plateau and its adjacent areas during the onset period of Asian summer monsoon are analyzed in this paper using the NCEP/NCAP reanalysis pentadly averaged climate fields data and dekadly sensible heat and latent heat data.Effects of the sensible heating over the Tibetan Plateau on the onset of the Asian summer monsoon are discussed.Mechanisms of the Asian summer monsoon progress caused by the Plateau sensible heating and its effect on the tropical low-level west wind are revealed in detail.Results show that the longitudinal and latitudinal thermal contrasts caused by the middle latitude Plateau sensible heating trigger the onset of the Asian summer monsoon.The regional and temporal differences of the Asian summer monsoon onset bear a relation with the Plateau sensible heating region.The Plateau sensible heating has different effects on the low-level west wind in the South China Sea(SCS) before and after the onset of the SCS summer monsoon.It strengthens the low-level west wind before the onset of the monsoon but weakens the west wind after the onset.After analyzing the sensible heat in earlier and later onset years of Asian summer monsoon,it is also found that the interannual variation of the onset date of the Asian summer monsoon are related to the interannual variation of the heat source.

Abstract:The measuring experiment and DDA calculations for the scattering of ice particles are briefly presented in this paper. Twenty sphere-cone-oblate ice particles are simulated for lab observations and DDA calculations.Theoretical results are compared with the experiment data obtained with a microwave measuring system.It is shown that the theoretical results are consistent with the experiment data in general.As a result,the reliability of theoretical model is proved.Theoretical and experimental analyses indicate that the backscattering ability of sphere-cone-oblate ice particles increases as the particle size parameter increases,and fluctuates in the so-called resonance region.The backscattering cross-sections of sphere-cone-oblate ice particles depend upon not only their sizes(equivolume spherical radii R_e)but also their shapes.There is a linear relationship between differential reflectivity Z_DR and the shape factor which is defined as the ratio of the horizontal scale to the vertical scale of a particle.

Abstract:Inter-decadal variability characters of ocean-atmosphere interconnection in the tropical areas are investigated by the use of the NCEP/NCAR reanalysis data,the SST data set of GISST2.3b and the south oscillation index (I_SO) of CRU(Climate Research Unit).Results indicate that there exist remarkable inter-decadal variances of the ocean-atmosphere system in the tropical Pacific areas. In recent fifty years,the relationship between I_WP(the west Pacific seasurface temperature index in 125～155°E,10°S～10°N) and I_SO shows more obvious inter-decadal changes. The analysis of the atmospheric general circulation shows that when the correlation between I_WP and I_SO is weak and the West Pacific SST warmer (colder), there exists an anticyclonic (cyclonic) circulation in the lower troposphere over the northern equatorial western Pacific. In contrast to the typical low SST-anticyclone pattern in the ENSO phase,the dynamical effect of such a system is not in favor of maintaining a close correlation between I_WP and I_SO.

Abstract:Based on the multiple scattered theory,using a moderate resolution radiative transfer model,a method is developed to calculate the ground-based ultraviolet solar radiation of Shijiazhuang with measured atmospheric parameters as inputs.The model includes two major bands of ozone absorption.For the clear sky, the model mainly considers the multiple scattering of molecules and aerosols;for the part cloudy sky,the model also includes the effect of cloud on ultraviolet solar radiation.The discrete coordinate method was used in the computation of multiple scattering.In addition,the errors caused by the lack of ozone data are corrected.The model results are compared with the real measurements,and results show that the both are in good agreement.This means that the corrected model results of ultraviolet solar radiation can be used for operational forecast.

Abstract:A simplified scheme is used to calculate the monthly mean meridional circulation (MMC) mass stream function in 1948—1999,with which the MMC climatic state(Ψ)and the anomalous climatic state(Ψ′) during the strongest El Nino events in 1980s and 1990s are analyzed.Results show that the calculated MMC mass stream function reasonably describes the those seasonal variation of Ψ and the physical relationship between Ψ′ and SSTA.The above results are basically in accordance with those calculated by the interation method.

Abstract:Relationships between global temperature anomalies and the summer rainfall of China are investigated by the use of the global air temperature data from 1930 to 1998. It is found that the summer large-scale precipitation of China has close simultaneous correlations with the maritime area seasonal temperatures over the tropical western Pacific and tropical mid-east Pacific as well as the continental area temperatures over East Europe,the northeast of North America and East Asia.The relationships between the temperature anomalies and the summer rainfall of the middle-lower reaches of the Yangtze River are aslo studied with Monte Carlo correlation method. Results indicate that when temperature over the Indian ocean region in spring, and temperature over the northern of North America and the southwest of northern Pacific in summer have positive anomalies, the middle-lower reaches of the Yangtze River are liable to waterlogging.And furthermore their correlations with the summer rainfall of the middle-lower reaches of the Yangtze River show a stage character,and become stronger with time.

Abstract:Using a semi-spectral barotropic quasigeostrophic vorticity equation in the cylindrical coordinates,four experiments whose integration time is seven model hours are performed in order to study the propagation characteristics of vortex Rossby waves in different initial distributions of perturbation vorticity. Results show that propagation of vortex Rossy waves in an initial perturbation vorticity field of azimuthal wave-number 2(i.e positive alternating with negative) is obviously different from that in an intial field of only positive perturbation vorticity.The inward propagation vorticity decays more rapidly in the former case than in the latter case.And the inward propagation of vorticity exhibits a single peak form,but it shows a double peak form in the latter case.

Abstract:The distribution of early day sub-surface sea temperature of 0 to 400 meters(especialy 120 to 300 meters) in abnormal onset years of SCSSM is discussed in terms of composite analysis and correlation method.Results show that the anterior sea temperature in the North Pacific basin(150°E～150°W,35～50°N) has a profound influence on the onset dates of SCSSM.When the sea temperature of previous winter in the basin is lower,the onset date of SCSSM is later,and vice versa.A thermal parameter(I_tp) is defined to represent the underlying surface effect over the basin,and it is inferred that the influence of sea temperature anomalies on the onset date of SCSSM can be realized through atmospheric teleconnection.

Abstract:In the context of the NCAR daily reanalysis data of 1998,this paper investigates the source or sink features of atmospheric LFO (low frequency oscillation) over the Tibetan Plateau in summer 1998.Results indicate that sometimes the Plateau is a source region of LFO and sometimes is a sink area for the LFO of zonal wind. With further analysis of LF vorticity flux-divergence,it is found that at different time and place over the Tibetan Plateau LF vortex source (sink) has different distribution and propagation features.LF vortex source (sink) at 100hPa over the Plateau is influenced significantly by South Asia High.

Abstract:The data of upper level circulation,sea surface temperature and surface meteorological elements are used in this paper to construct 5 forecasting models of long,medium and short ranges for the incidence date and insect quantity of planthopper in Shanghai.There are field beginning date forecasting model,lamp-trap beginning date forecasting model,peak quantity date forecasting model,peak inset quantity forecasting model,and natural observation garden inset density forecasting model.By comprehensively using those model,the incidence date and damage levels of planthopper in Shanghai can be predicted,thus providing a real time basis for prevention and elimination of planthopper.

Abstract:Based on the per unit area grain yield data throughout China at the level of province, three indexes,which reflect the risk level of grain yield of China from different angle are defined,namely:the annual decrease rate,the annual variation coefficient and the risk probability.The method of iterative self-organization dynamics assemble is adopted to divide China into several risk regions at different risk levels on the basis of the indexes.The result demonstrates the outlook and risk level of the grain yield in the past fifty years,which would provide a reference for policy makers to plan crop production and make risk decision.Furthermore,the reason of regional risk difference from the factors of disaster-inducing environment,disaster-inducing factors and productivity is also discussed.

Abstract:The persistence of amplitude anomaly of five low order spherical functions of total wave numbers n=0～4 with larger interannual anomaly variance contributions in Northern and Southern Hemisphere in January and July and its relations to tropical Pacific ocean surface temperature year-to-year anomaly(SSTA) are examined on the basis of spherical function coefficients of NCEP/NCAR 500hPa mean monthly geopotential height fields. The result shows that: 1)persistence of amplitude anomaly decreases quickly with the increase of the function n,and apparent persistence exists only in a few extra-long wave components with small n values; 2)amplitude anomaly of even spherical function(n=0) components is of noticeable persistence with seasonal and hemispheric differences;3)the amplitude anomalies of even spherical function components(n=0) of Northern and Southern Hemisphere are quasi-synchronism and so are they with tropical Pacific SSTA in ENSO scales; 4)amplitude anomaly of Southern band spherical function components (nn=2) is also of appreciable persistence, and is quasi-synchronism with tropical Pacific SSTA in interdecadal scales.

Abstract:The analysis of wavelet of wind field and rainfall in the Middle and Low reaches of the Yangtze River in summer 1991 shows that these elements exhibit a significant low frequency character and periodic change:quasi-two week oscillation before mid-June 30～60d oscillation after mid-June,and the time of peak value of low frequency u wind being 2～4d prior to the that of rainfall peak. Based on the study on divergence and wind fields, it is found that after July the low frequency vortex in low-latitude moves northward while the vortex in mid-latitude moves southward.As a result,the two meet between 30～35°N,which is the major cause of two heavy rainfall in the Middle and Low reaches of the Yangtze River.

Abstract:It is indicated according to the analysis of four cases that a great optic ring accompanied by glory is not always a primary rainbow.The great ring emerging with glory caused by ice cloud and fog is in fact an anti-solar(moon)halo,which is leading to a conclusion that the dominant Van de Hulst’s backward scattering theory on the formation of glory in recent years can not be used to illustrate all phenomenon concerning glory and gives a denial to the formulation that ice cloud and fog cannot produce any glories.It is also pointed out that there is an error in the explanations of Bouguer’s halo in the International Meteorological Vocabulary.

Abstract:Solar eclipse results in a shadow on satellite image,thus influencing the analysis and application of the satellite image. This paper describes the influence of eclipse on solar radiation and presents a method to eliminate the eclipse impact. An example is given to show the effect of shadow elimination.

Abstract:A rainstorm that caused a severe flood along the Yangtze River Valley in summer 1998 is investigated on the basis of weather maps and other data.The result shows that the occurrence and development of the flood-causing rainstorm is triggered by frequent activitives of mesoscale systems in the middle- and low- atmosphere under certain circulation pattern.Two circulation patterns which cause the rainstorm and lead to the flood peak in the valley are put forward,namely:pattern of strengthening subtropical high and eastward-moving trough;pattern of stable subtropical high and frequent southwest eddy activitives on shear line.It is concluded that the more(less) frequent of the appearance of the two patterns and rainstorm, the more likely the formation of flood(draught) in the valley.

Abstract:Based on the ground-level meteorological data and low-level sonde data from July to August,2000 in Nanjing,the characteristics of thickness and intensity of low-level inversion (LLINV) are discussed,especially on their relations to urban surface temperature and relative humidity variation as well as their influence on body discomfort status.The result shows that there exists a distinct influence of LLINV on urban surface temperature,relative humidity,and their scope.The early LLINV reinforces the gain in temperature and the abatement in relative humidity from 08:00 to 14:00.On the contrary,the late LLINV cripples the abatement in temperature and the gain in relative humidity from 20:00 to 23:00.In addition,the index of body discomfort will be enhanced when LLINV appears.Finally,the regression equation on the intensity of LLINV and the body discomfort index is established,which provides a new way for quantificational prediction of the body discomfort index in operational weather service.

Abstract:The differences between wet Q vector divergence field(WQVDF) and ω field from the modified MM4 model are examined in details by the use of data concerning a typical Meiyu front heavy rainfall in Jiang-Huai Basins during 5—6 July 1991. The results show that WQVDF convergence is more closely associated with the precipitation than ω field throughout the rainstorm; the 700hPa convergence field has indication to the surface rainfall on a synchronous basis, especially in the developing and developed stages, which serves as a better indicator to the fallout area and intensity of precipitation;the calculating scheme of vertical velocity involved in the MMM4 model needs to be further improved.

Abstract:The noninferior solution of mutiobjective decision problem is discussed based on a proposed simple mathematical model of city bus planning.

Abstract:The lastest version of the software for automatically plotting and drafting weather chart has developed by using Fortran based on the Windows98 platform.As a result of introducing window,icon and menu techniques,it is characteristic of friendly graph and character operation interfaces,flexible and changeable man-machine interactions,faster processing of data,good quality of plotting and drafting,and high stability.Practice confirmed that the software satisfactorily meets the demand of meteorological observatories and stations.