Abstract:Results of measurement of supersaturation and temperature spectra of natural ice nuclei in a static vapour-diffnsion are presented and analysed along with descriptions of certain humidity characteristics of the chamber and the nucleation mechanism therein. The underrating of and the correction for measured values by the filter method are also discussed.

Abstract:Daily average flux-densities of possible direct solar radiation are determined by the Ukrainstev method. With the data thus obtained, problems concerning the theoretical approach based on the Kastrov expression and the variation of the Kastrov coefficient derived through iteration are investigated. In addition, the empirical relation of the coefficient to vapor pressure is explored and the sensitivity to the theoretical expression of the relation found is examined together with the retrieval errors. The results show that the daily average flux-density regime can be calculated quite accurately for various parts of the country by making use of the surface vapor pressure data. On this basis, the spatial and temporal characteristic features of the distribution of possible direct solar radiation are discussed in detail.

Abstract:The present work is the continuation of the experiment inaugurated in 1983. The model constructed in 1983 for the growth of various organs of the rice plant is solved by means of the trapezoidal method, resulting in a recurrence formula which described the processes of rice growth and yield formation. Preliminary investigation is also made on the assimilative ability, the assimilator distribution and the transition of the rice population. Optimal solutions of the model parameters are determined through optimization. Also simulated are the processes of rice growth and yield formation in 1984.

Abstract:A term for hailstorm development is added to the numerical cumulus model presented in an earlier paper [1]. Radiosonde and other data of 4 cases of rainstorms and hailstorms respectively, all of which occur over the ChangJiang(Yangtze)-Huaihe Valley in the warm months,are fed into the model,which is operated on a DJS-6 computer. The computed results approach what are observed in reality. The experiment shows that the model is fairly successful in identifying hails and the simulated macro-and micro-structure of the cumulus and its development process resembles those of the natural cloud.

Abstract:A nonlinear function of economic factors of clear agricultural meaning is established and the tendency of advancement in agricultural technology is simulated by means of optimization. In view of the instability of the time sequence of yields determined by climatic factors,the concept of yield at normal climatic conditions is introduced and expressed mathematically. With consideration of the contributions made respectively by the general circulation, sea-surface temperature and astronomical factors, three forecasting sub-models for yield at normal climatic conditions have been developed and dynamic synthesis of the three sub-models are also presented.

Abstract:Characteristic features of temporal and spatial variations of the flow fields at 850 hPa level over the areas dominated by the East Asian and Indian monsoons during the summer months from May to October, 1984 are analysed by means of synoptic-statistical method. By combining the results obtained in an earlier paper[1], preliminary knowledge of the discrepancy and relation of the lower atmospheric circulations between the two monsoon regions in the summer season is attained.

Abstract:Through a preliminary analysis of the observations of atmospheric Aitken nuclei on the Lushan and Shita mountains, the average concentration,its distribution with height and diurnal variation are determined. In addition, the interaction between the Aitken nuclei and cloud, fog and precipitation is discussed.

Abstract:Observational data of SO₂ in the effluent discharged from the chemical works at Dachangzhen in the outskirts of Nanjing are analysed and its annual mean concentration is computed by both the SD and CD models. The results by the two models are in good agreement with linear correlation coefficient as high as 0.94, average ratio being 0.91 and mean relative error 9%. Values computed by the American ATDL model for plane source are superimposed on the ones obtained by both of the above models and the outcome is found to be satisfactory by comparison with the observations from 26 monitoring cites. In a survey of the sensitivity of the model parameters, it is found that the most significant are the effective height of the source and vertical diffusion.

Abstract:According to radiosonde data from 100 weather stations, mean monthly atmospheric water content throughout the country is calculated by means of the formula W=1/g∫₀^pqdp. The spatial distributive features of water content and vapour pressure are analysed. As a result, a compact and convenient empirical formula involving only vapour pressure and station elevation is developed for computation of water content. Values computed by the empirical formula are in good agreement with those by the original formula aforementioned. On the basis of the newly computed values, the general distribution of atmospheric water vapour content over China for the significant months is graphically shown and qualitatively analysed.

Abstract:During the Qinghai-Tibet Plateau Meteorological Experiment (1979). the authors pointed out that there existed a synoptic-scale transient monsoon circulation system—the monsoon stream tube—over East Asia in early summer. Its ascending branch corresponds to an east-west orientated rain belt and it bears direct influence on the time of commencement, the precipitation amount and the length of duration of the South China rainy season and the Meiyu. Based on the analysis of the monsoon stream tube of 1983, an attempted is made to develop a short-range forecasting model concerning the rain belt over the Changjiang-Huaihe Valley.

Abstract:By making use of the radar echoes of July 14, 1983, Aug. 30 and Sept. 1, 1984, an attempt is made to probe into the possibility of using this type of radar to determine areal precipitation amount. The results show that the error is tolerable and a scheme of combined measurement by radar and station rain guages would considerably improve the accuracy. When an Apple Ⅱ microprocessor is connected to the radar, real-time data can be provided.

Abstract:Explicit integration schemes for the barotropic primitive equation model are tested for stability and accuracy. Influence of time and space smoothing on the stability and accuracy are also investigated. The results of the test will be beneficial to selecting suitable explicit integration schemes for medium-and short-range numerical weather prediction models.