Abstract:Analysis of the effects of soil, plant and atmospheric factors on the calculation of evapotranspiration is made on the basis of field experimental data. Models of potential evapotranspiration and crop coefficient are determined by the modification and simplification of the well-known Penman-Monteith Model. Tests agains field experimental data show that the models derived give satisfactory results.

Abstract:Two dynamical-statistical spectral models for forecasting the 500 hPa monthly mean height (MMH) in the Northern Hemisphere are described. One is based on the annual variation of MMH; the other on the monthly variation. First, the spectral equations with unknown coefficients are given by means of variation method.Then,making use of past data, the unknown coefficients are estimated by the least square method. Finally, solutions of the two models are obtained by simplex method. It is shown that the skill scores of the models are better than that of persistence forecasting.

Abstract:A way to improve the original recursive estimate method is found by applying it to the forecasting of rice yield. In the improved process only one parameter, which may be the best estimate among the parameters in the layer, is involved, evading the massive amount of work in estimating parameters layer by layer in the original method and thus reducing the errors of computation. Tests made with rice yield and meteorological data of Huaiyin City show that the improved method is satisfying.

Abstract:An indirect estimation model for Gamma distribution of monthly (or yearly) Precipitation of a station with a short series of historical observations by means of the longer record of an adjacent station is presented. It is demonstrated that the indirect estimation is more realistic than the directly estimated theoretic distribution of station precipitation based on the small sample of record of its own. Moreover, the indirect method has simplified the calculation for fitting the distribution.

Abstract:Based on the data over the period of late January and early February, 1984, during which heavy snow fell over East China,a preliminary study is made of the short term effect on the climate of the Nanjing area. The weather regime is quite stable over this two week period after the predominence of the cold air and the specific condition of the underly ing surface with a persisting snowcover results in a series of correspond ing climatic phenomena. With these findings, regularities are summa rized concerning the effect of short term snowcover on the climate at lower latitudes.

Abstract:Based on the simplified formula of precipitation rate and the divergence equation by the kinematic method, a set of formulas for discriminating intensification, weakening and movement of heavy precipitation area, which is associated with the center of relative divergence of large scale motion, is derived under the condition that theageostrophic departure is greater than the actual winds in both the upper and lower troposphere, i. e., and .By utilizing the derived formulas, nowcasting of heavy precipitation in the Bengby area 0—3 hours in advance has been made and the results are consistent with the observations.It is indicated in the discussion that, under the above-mentioned condition, the ageostrophic motion fluctuates about the equilibrium state of geostrophic vorticity and affects the heavy precipitation area by the variation of the positive center of relative divergence in both the upper and the lower troposphere.

Abstract:For a climatic field having p climatic elements in a region embedding n weather stations, the climate may be characterized by the first m major factors in the analysis with the climatic implication of each major factor discriminated by the factor loading amount. Examination of the major factors for 17 climatic elements at 100 weather stations of Shaanxi Province shows that the accumulative contribution rate of the first three major factors comes to 88.8 percent. Based on the distribution of these three major factors, the Province can be delineated into a 3-level climatic demarcation consisting of five climatic sub-zones, eleven climatic regions and twenty-six sub-regions.

Abstract:Characteristics of a multi purpose real time microcomputer processing system for satellite Cloud pictures are described. Emphases are placed on the enhancement of infrared cloud pictures, the pseudo-color screen dis play of images, the addition of geographic coordinate grid and the cartoon parade. Hard copy cloud pictures may also be obtained from facsim ile apparatus.Essential principles for hardware and software designs are presented. Necessary parameters are given for quantitative analysis of the cloud pictures.

Abstract:Air craft observations of cloud condensation nuclei (CCN) were carried out over Qingdao area along the Shandong coast in August, 1984. The main results are presented herewith. The CCN concentration near the ground level is found to be about 10³cm³, decreasing with height exponentially. The concentration tends to decrease gradually from inland to the sea coast across the peninsula and is higher in the morning than in the afternoon as a whole. The relationship between the distribution of CCN and related meteorological factors is roughly examined.

Abstract:Application of the wave spectrum parameter to three mathematical models, namely, stepwise regress on multiple regression and canonical correlation analysis, shows that they are of the same order of applicability as far as precipitation prediction is concerned However, for heavy rainstorms, canonical regression is found to be preferable to the other two.

Abstract:Meso-analysis is made for the three hailstorm processes occurring on 26—28 April, 1983 by means of the three-hourly infrared and visible GMS cloud pictures together with the conventional synoptic and upper air data. The synoptic situation, including the interaction between weather systems and their effects on development of strong convection as well as the physical processes of the hailstorms are discussed.