Abstract:Using a global spectral model of the quasi-geostrophic barotropic vorticity equation, numerical study is made of the quasi-resonance interaction of three planetary waves.With two quasi-resonance wavevectors selected as 1)K₁+K₂+K₃=0,ω₁+ω₂+ω₃=Δω; 2)k₁+k₂+k₃=0, l₁+l₂+l₃=Δl,ω₁+ω₂+ω₃=0,model integrations are run for 90 days,separately,leading to the results of interest as follows:1)stronger wave-wave interplay is found among the three waves of zonal wavenumber k=1,2,3; 2)due to the interactions,the study waves exhibit about 20-45-day low-frequency oscillations and it is of note that all of the waves display quasi-biweekly oscillations; 3)the mentioned low-frequency periods relate to the initial amplitude of the waves under investigation.

Abstract:By employing a numerical typhoon model with a threefold structure horizontally,experiments were conducted with terrain contained and without to investigate the impact of landing typhoon 9216 on the enhancement of its torrential rainfall.Results show that 1)the model involves in structure terrains at a range of scales with both the fine structure of the key sector and the effect of the large-scale ambient flow field considered so that the track and the distribution of strong wind and rainbelts can be better predicted; 2)orographic effect is responsible for the improvement on convective rainfall conditions,causing amplified rising at mid-to low-levels as com-pared to no-terrain run,with significantly intensified precipitation on the windward slope,in which convective rainfall accounts for a greater part.In contrast,no-terrain model results indicate that the typhoon is positioned northward,so are the easterly/westerly wind belts,and no expected substantial reduction occurs in vigor of the onland typhoon.It follows that the convergence due to orographic lifting contributes greatly to precipitation enhancement.

Abstract:Using the OSU GCM,simulations are conducted,one being the control run and the other the assumed saturated wet soil run in North China(30～46°N,90～120°E).Results show that the increase in soil humidity contributes to the enhancement and northward shift of the western Pacific subtropical high and low-level jet,thereby causing the reduced rainfall over the Changjiang-Huaihe basins and SE North China east of 105°E,and favoring the increase of precipitation over the non-monsoon region and northern North China to the west.

Abstract:Singular value decomposition(SVD)is addopted to investigate the relation of soil temperature anomaly in China to Northern 500hPa height anomaly in the same month of January and January temperature to last December hight,previous and subsequent months,deriving a canonical spatial pattern of pairings for both.Evidence suggests that such patterns are noticeable over Eurasia in the same and previous month.Also,possible physical processes are presented for their interaction on the basis of observational study.

Abstract:A dynamic system describing limited-area weather/climate evolution is established in EOFD-extended phase space through the least square method,under the condition of orthogonal basis,for coefficients of the state evolution equation containing quadratic nonlinear terms,along-side the comparison to the results from the phase space continued by time series drift.Evidence suggests that the presented dynamic system is likely to give more accurate and realistic description of weather/climate development.

Abstract:A new scheme of function fitting suitable for multi-dimensional problems of meteorological nature is proposed.It is in reality a problem of"window"transform and small-wave analysis"being coarse".Fine small-wave analysis remains inaccessible to numerical solutions of an equation in a meteorological context.Through the"being coarse"method it is possible to formally construct a piecewise Galerkin scenario so as to realize the parallel solution of atmospheric governing equations.

Abstract:Based on the simulations of a turbulence stress model,characteristics of turbulent energy balance are documented in and above a canopy.A numerical experiment is made to evaluate the response of a turbulent structure to change in the density and vertical structure of the canopy.

Abstract:On the basis of previous studies in connection with 1989～1992 measurements from an experimental rice field,simulation and calculation are performed,in terms of an optimization algorithm,of the photosynthesis matter distribution coefficient α_i and the transfer coefficient β_i, followed by analysis of their variation as a function of development with weather/climate impacts considered,whereupon models are established for the growth trends of the stand and its various parts.

Abstract:The conventional Logistic equation fails to accuratelt describe the variation in growth of soybean irradiated with UV-A/B（280～400 nm）radiation.Based on simulations,analysis and statistics are carried out,leading to mathematical models for better describing the growth exposed to a range of vigor(0.1,0.15,0.35 and 0.75 W·m^-2).Evidence suggests that Logistic equation is preferential for the growth of the crop under natural illumination while Gompertz formulation is appropriate for the development under stronger UV irradiation.

Abstract:Study is performed of 182 samples of fog water collected in Chongqing over 1984～1990,disclosing the space/time patterns of chemical constituents of the water.Evidence suggests that the fog water has become acidified and is categorized into the type of sulphurie acid, with high concentration of ions,in close relation to air pollution and microphysies of the fog genesis.

Abstract:A micro-computer 386 based Cloud-motion Wind Inferring System(CWIS)has been developed for the winds from geostationary meteorological satellite images.In this paper,the main structure of the system in connection with the processing method.Preliminary analyses of the experimental data collected randomly from Beijing Satellite Meteorological Center have shown that the system is quite encouraging and the results are in good agreement with the analyses from weather maps and further improvement is possible to the system.It is pointed out that the characteristics of cloud motion winds must be kept in mind when they are used together with conventional wind soundings.

Abstract:This study is devoted to some aspects of mid-and high-latitude low-frequency pertur-bation(LFP)in the context of 1984～1986 ECMWF/WMO gridded data.Evidence suggests that the LFP’s equivalent barotropic structure can be described in terms of a"structure parameter"(the ratio of low-frequency barotropic kinetic energy to low-frequency kinetic energy total); the high-value areas of the energy are closely associated with the zonal asymmetry and meridional shear of westerly jet; the LFP’s propagation is marked by salient locality and confluence/difluence,and can be interpreted by the counterclockwise loops of the central-Pacific lowfrequency cyclone/anticyclone couplet(β-gyres); the Eastern-Asian longitudes at which westerly jet finds its entrance is the key region of interaction between NH mid-and low-latitude LFP’s, on one side,and between bihemispheric counterparts; low-frequency vortex activity of mid-and high-latitude bears an intimate relation to the change in blocking,on the other.

Abstract:Diagnosis is undertaken of the genesis and maintenance of interannual anomaly in summer monsoon with the aid of the departure vorticity equation in the context of 1980～1986 ECMWF 200hPa gridded u-and v-winds.Evidence suggests that the features of the interannual anomaly flowfield over the Asian monsoon region exhibit appreciable intraseasonal oscillation; the features,e.g.,vigor and phase,as uncovered by the terms of the vortieity equation may differ more or less for different years and areas; striking difference exists in sign and magnitude of monthly means of the terms in this equation over China mainland for the drought and flood years; the climatology of monsoon circulation plays a critical role in the maintenance of interannual anomaly disturbance.Great difference in terms of the equation used for the late spring-early summer Meiyu rainfall may serve as a precursor of anomalous rainfall forecasting.

Abstract:Obtained,following the ray theory of geometric optics,are the ray solution and generalized wave action conservation with the large-scale terrain and temporal mean flow considered, therewith the role is addressed in the Rossby wave propagation of the Tibetan Plateau under the control of the circulation pattern in winter and summer.Results show that the plateau serves as a barrier to the wave dispersion,with the effect varying versus wavelength and marked by seasonality.

Abstract:In the context of NWC 850hPa monthly mean wind data,estimation is made of the degree to which the El Niño exerts influence on circulation anomaly in the equatorial Pacific-the Indian Ocean,the transition between the Pacific and Indian Ocean and East Asia-western Pacific.Results show that great difference exists in the degree among the research areas,thereby discovering that the causes of some of regions are multiple.

Abstract:Study is made of Bayes estimation of the error rate proportionality parameter θ in the JM model for testing software reliability,leading to the a priori,a posteriori distribution of θ and the coresponding Bayes estimates on the Bayes assumption,Jeffrey’s principle and conjugate distribution,together with their comparison and discussion.

Abstract:Developed are the linear regression equation of measured maximum daily skin temperature in North China as dependent variable and the brightness temperature of channels 4,3 and 5 of AVHRR as independent variables and another regression equation of brightness temperature of channel 4 of the same radiometer as the independent variable.Analysis shows that the latter is an appropriate scheme for estimating winter maximum skin temperature in the conditions of clear skies and snowfree surface in North China.

Abstract:In the context of ERBE,ISCCP data,measured and calculated radiation absorptions at ground level,computation and investigation are performed of the spatial and temporal distribution features of atmospheric absorption of shortwave radiation over China,along with their relations to the affecting factors.Results show that such absorption changes greatly as a function of latitude and altitude and is in pronounced correlation with astronomical radiation and vapor pressure as well,with some influence of total cloudiness only in East China.Finally,calculation is carried out of atmospheric absorptivity of solar radiation in China,indicating preliminarily that the magnitude attains 0.30 in East China,with the maximum of 0.35,much greater than the mean evaluation presented in the literature.

Abstract:Using ERBE and ISCCP data and the climatological scheme for components of surface heat balance,computation is done of data from 215 stations in China for atmospheric heat source vigor(HS_a),with its correlativity to astronomical radiation,rainfall,air temperature and ground thermal source intensity investigated,whereby the atmospheric heat source parameteriza- tion scheme is formulated with its space/time patterns addressed.

Abstract:Using three-axis anemometrograph data from Tianjin suburbs measured in the summer of 1990,investigation is conducted of the features of near-surface turbulence spectrum obtained in normal weather and when a weather event occurred.Results show that in normal weather the spectral characteristics in the suburbs are in rough agreement with those over a flat terrain while with an emerging event(thunderstorm in the main)the spectrum exhibits some different features whose possible causes are explored.

Abstract:Study is made of abrupt typhoon-related rainstorm amplification during the onland storm moving into the north of East China by contrasting 10 amplification events to 7 nonamplifications for the difference.Focus is on diagnosis of physical conditions 24h previous to the amplification,which are considered in connection with the flowfield features and satellite imagery analysis,whereby an conceptual model for amplification is constructed for operational purposes.

Abstract:Analysis is undertaken of disastrous weather for post-rainfall forced maturity of wheat in late May to early June in relation to monthly mean 500hPa height,followed by compositing of the principal components of the preferred correlation sectors.The variables of the principal components are adopted for constructing a disaster-forecasting equation.The application shows good benefits.

Abstract:Close investigation is carried out of the 1991～1994 thermal conditions in the crop growth season,with focus on the no-frost duration,onset/terminal day of the disaster,and monthly mean temperature in May,August and September.Results show that the 1991～1994 climate advanced toward warming,and,in particular,abundance in heat was offered for the maturity with the delayed first frost day and prolonged frostfree period,which contributed to crop production.Also,it is noted that meteorology is of importance to bumper or poor harvests.