Abstract:By using the monthly data from 1951 through 1984, empirical orthogonal ex-pansion is performed for the 500 hPa geopotential height north of 65°N and the canonicalfields are clustered by fuzzy classification. It is noted that both the mean monthly polarvortex fields and the large-scale anomaly fields fall into three regimes, with those ofthe January mean field and the April anomaly field having characteristic features. In addition,the relationship between the time weighing coefficients of the canonical fields andEl Nino/SO is examined,showing significant anomalies in the large-scale polar anomaly fields during April and October of the year when E1 Nino occurs. These polar circulation anomalies havd considerably influenced the temperature fields in China during Apriland October. Thus, we may conclude that this is one of the most important reasons for arelatively cool April and a warm October in China during the El Nino year.

Abstract:Asia is a distinct monsoon region in the world. In China the characteristics ofrainfall distribution are not only closely related to the background of the East Asian planetary scale circulation, but also to the structure of large topography in this area. By using a primitive equation model in p-σ coordinates,this study focuses on the West Pacific subtropical high,the intensity of the continental warm low system and their combination, i. e., the characteristics of zonal stationary waves corresponding to the EastAsian summer monsoons of different intensities and the East Asian sealand thermalstate in order to reveal the relationship between the summer monsoon flow pattern andthe rainfall distribution in East China. Studies are made of the correlation between the confluent features of the East Asian monsoon flow and the sea-land zonal stationary wave patterns, and the relationof the pattern of warm wet regions in summer and the formation of the warm wettongues to the rainfall in East China. In addition. the dynamical structure of the upper-and lower-level flow fields and the features of the South Asian high during the formation of rain belt in East China.

Abstract:Emphasis is laid on the stability of the initial data and empirical coefficients for calculating the global solar radiation (GSR) in this paper. Using the GSR from clearskies as the initial data for calculating the GSR is an effective method if it can be computed in advance. The formula for computing the GSR under actual weather conditions isremade on the basis of the work completed by the authors and the results are comparedwith others. Meanwhile,both the stability of the empirical coefficients in different kindsof formulas and the sensitivity of these coefficients to the GSR are examined. Resultsshow that the formula used in this paper has high accuracy,stable coefficients and lowsensitivity compared with others. The geographical distribution of the coefficients is analyzed and the coefficients at the nonactinological stations are worked out via interpolation. As a result, the GSR over China is computed.

Abstract:The process of scavenging below-cloud pollutants (SO₂, H₂O₂, O₃, NH₃, CO₂)by raindrops is studied,based on a physico-chemical model. Besides the aqueous oxidatiom of S(Ⅳ) by H₂O₂ and O₃,the catalyic oxidations of S(Ⅳ) by Fe³⁺ and Mn²⁺ in thefalling drops are also considered. Results indicate: (1)the[SO₄^2-] and pH spectra can bede developed; (2)the scavenging process below clouds is influenced by a number of factors: initial concentration of pollutants in the raindrops,precipitation intensity and NH₃ concentration, and (3) this study can be uded for explaining some phenomena observedfrom field measurements.

Abstract:The seasonal variation of the cross-equatorial flow in the eastern hemisphereis analyzed by using the 6-level monthly mean wind data from January 1979 to December 1987. The results are shown as follows:The center of the cross-equatorial flow exists in the lower troposphere in winter and summer but in the upper troposphere inspring and fall. The flow propagates southward in winter and fall but northward in summer and spring. The flow turns south wind into north wind in March and November inthe lower troposphere but in June and January in the upper troposphere. Remarkableanomaly is observed in the crossequatorial flow during the the El Nino year,but assumesdifferent forms. During the El Nino year, the summer lower cross-equatorial flow becomes steadily set up 2-3 pentads later than during the normal year and has more intraseasonal variation and shorter steay maintenance.

Abstract:The distribution and evolution of rainfall during MONEX in May-July, 1979 has been analyzed. The effects of air flows and topography in low latitudes on the rainfallare discussed. The low frequency oscillation and the correlation between rainfalls in different places are also examined in the paper.

Abstract:A one-dimensional and time-dependent numerical model for nocturnal atmospheric boundary layer is established,with which simulation is made of the characteristics of cloudless and cloudy nocturnal inversions. By comparison of the two cases,the influence of clouds on inversion development is discussed. Finally,the cloudless nocturnalinversion model is verified in terms of Wangara data with quite satisfactory results

Abstract:In this paper,a group of dynamic models, which can be used to describe quantitatively the extent suitable tovegetative growth and yield formation of corn crop,are set up by applying the viewpoint of syste motology and themethod of fuzzy mathematics. And various corn-climate indices are calculated, based on the data for 1951-1980 from 24 meteorological observing stations in Hebei,China and Missouri, America. It is shown that the corn-climate resource index(I_r),the efficiency index (I_α) and the utilization coefficient (C_α) of Hebei province are a little higher than Missouri’s. Finally, the reliability of the results,and the applicability of the suitability-degree theory and the dynamic models in the assessment of agroclimatic resources are demonstrated by analysing the results and comparing them with the facts.

Abstract:A model for water uptake by winter wheat is developed in terms of the zero-flux plane for the determination of the maximum depth of water uptake of root. Using asoil water flowing epuation governed by the temperature and moisture gradients, a nu-merical simulation is made of the time-spatial change of soil water content during theperiod from the late stage of stem elongation to the ripening stage of wheat milk in theexperimental fields of the Jingyang Weather Station in1988. Results of the simulation arecompared with the data obtained from the winter farmland and agree fairly well with ac-tual observations for a simulated period of 31 days.

Abstract:In this study a new rice growth/development rate model is developed from theanalysis of nonlinear effect of daylength and temperature on the rice growth and devel-opment process. Thereupon,the concept and estimating method of the physiological development day(PDD)is introduced. Several agrometeorological models,including linear/nonlinear models, logistic models with weak and/or strong time-lag effects, demon-strating leaf age,stem-tiller and leaf area index dynamics varying with accumulated PDD values, are constructed,based on the investigation of the changing agronomical features. Finally,the models mentioned above are all tested with the field data.

Abstract:A brief introduction is given to the present-day situation of corn observationdata systems in China. The service effects of historical corn observation data are analysed and some suggestions are put forward for improving the current observation methods.

Abstract:In this study a strong ageostrophic wind is observed in the 200 hPa upper tro-pospheric jet, which causes a large-scale gravity-inertia internal wave to propagateabout. In the right rear of the upper-level jet the wave energy is more easily developedand strengthened. The formation, maintenance and propogation of the wave determinethose of the heavy rain.

Abstract:The precipitation data from 30 stations over the Zhujiang River Delta duringthe period of 1965-1984 are used in this study. The statistical relationship between relative interpolation standard errors and correlation functions is concluded by computingthe correlation functions of the precipitation for June’s in this area. On the principle thatthe standard error of inter polation should not exceed the standard error of observation,the appropriate average distance between raingauge stations in this area is estimated tobe 36 kms. Finally, the rational distribution of raingauge networks in this area is laid down by calculating the optimum interpolation standard errors for all these stations.

Abstract:In this paper the seasonal and diurnal (in winter and autumn) variations ofboth ground-level and low-level inversion in the urban districts of Changzhou is analysed by using the data obtained from January 1984 to the spring of 1985 in Changzhou.The spatial distribution of air pollutant concentration in winter is examined, based onthe SO₂ and aerosol concentration data from airplane and low-level sounding on January 8, 1987. Photographs which display the "bulb-shape" and "vertical passage" areconstructed by using ground multi-band photography and image processing techniques.

Abstract:The effects of nonlinear advection in the PBL on the dissipation of the atmo-spheric kinetic energy (DAKE) are studied. The DAKE formula involving large-scaleparameters are thus determined. Results show that the effects of nonlinear advection willchange the magnitude of the DAKE, depending on the characteristic features of thepressure pattern. Hence, our knowledge of the DAKE will be further improved. comparison is also made of the above results with those obtained under the assumption ofthe geostrophic momentum approximation herein.

Abstract:With the rapid development of computer graphics and of computer networkand communication techniques in recent years, UHF or VHF channels have come intooperation in meteorological services for the transmission of meteorological data, weathercharts and radar echo images. In this paper the principles of a portable UHF band transceiver for transmitting the velocity echo images of Doppler weather radar to the Jiangsu Provincial Weather Bureau are described in detail.

Abstract:Two thousand and four or five hundred years ago,in a Chinese classical book,The Etiquettes of the Zhou Dynasty,optical phenomena were first classified into tengroups according to their nature,presenting the world’s earliest detailed optical classification system. The meanings defined. however,have been ambinguous and vague in the last two thousand years or so. This paper compares the definitions given by five famous authorities in history,proposes three principles for distinguishing true definitions from wrong ones,and hence reconstructs the original definitions of the pre-Qin’s ten natural optical phenomena in the earliest optical system. Finally,evaluation is made of the observation method and the original definitions in the optical classification system.