Abstract:By analysing the relationships between the five winter 500-hPa teleconnection patterns suggested by Wallace et al. and the winter surface temperatures in China,we find that there are significant simultaneous correlations between the Eurasian and West Pacific patterns,and the surface temperature anomalies in eastern China,and that there is a significant lag correlation between the West Pacific pattern in December and the surface temperature in eastern China in January. The results can be used as an important criterion for the prediction of China’s January surface temperature.

Abstract:In this study numerical experiments on the influences of the Qinghai-Xizang Plateau topography on the summer general circulation have been performed by using the OSU atmospheric general circulation model. Results show that without the influence of the massive topography the continental climate extends southward, and the summer monsoons over India and eastern China become greatly weakened and move southward. With the increase of the height of the plateau topography the Asian monsoon still exists, along with the enhancement of the monsoon circulation and the increase of the tropical monsoon rainfall. It is also found that the influences of the plateau topography on the general circulation are far beyond the Asian monsoon area, and are important both in the interaction between the southern and northern hemispheres and in the shifts of easterlies and westerlies.

Abstract:In this study,the monthly and seasonal telecorrelation intensity indices of the Pacific/North American (PNA), Western Atlantic (WA), Western Pacific (WP), Eastern Atlantic(EA)and Eurasian(EU) patterns for the period from1951 through 1990 are calculated. On this basis,their climatic variations and the relation between the five telecorrelation intensity indices and the El Nino events are examined. It is noted that when El Nino is at its mature stage(winter),the weak WP pattern is mainly characteristic of the circulation and the strong PNA pattern is the next. The mature stage of El Nino occurring in 1991 is found to be characterized by the weak PNA and WP patterns. Besides,the application of the telecorrelation intensity indices to weather prediction is discussed.

Abstract:A new distortionless method for compressing digital weather radar echo images is proposed. The digital images are first filtered by the improved partial difference method and then transformed by the first-order difference with the non-zero elements in the images encoded by means of chain codes. Finally, the codes are optimized aceordingto their probability distribution. By use of this method,the compressed data are only about 5 percent of the original in quantity.

Abstract:The hillside photosynthetically active radiation from 222 observational stations in China is calculated by using the hillside total radiation. On this basis the temporal and spatial distribution of the hillside photosynthetically active radiation in China is analyzed in much detail.

Abstract:The general law of natural herbage yield formation is illustrated by using the experimental data from the Meteorological Research Institute of Inner Mongolia in the Hulunbuil League meadow steppe between 1982 and 1985. The accumulated yield can be divided into two parts:the average economic yield and the meteorological yield. A natural herbage yield model is thus constructed which varies with its developing stage and heat-water index. Finally,the application of the model is discussed from the viewpoint of the optimum mowing time,which should be set in the period between July 10 and 20.

Abstract:A method of linear momentum approximation is proposed that deals with weak nonlinear problems in an approximate manner. A motion of nonlinear nature is obtained in the system by assuming the motion to be in the form of linear momentum flow in the corresponding introduced space,followed by the transformation from the specified into a physical space. Significant results have been thereby derived in examining the effects of baroclinic Ekman momentum flow on Early-type baroclinic waves and frontogenesis.

Abstract:The low frequency features of the atmospheric baroclinity in the northern hemisphere winter are analyzed numerically by using the ECMWF day-to-day grid point data for the years of 1981-1982. The factors governing the baroclinic state are discussed physically from the barocline equation given in this paper.

Abstract:The high and low pass filter analyses of the atmatmospheric motion in the process of a blocking for five days show that the genesis,maintenance and collapse of the atmospheric blocking depend chiefly upon the slow variable waves whose time scale is more than five days. At the stage of the genesis and maintenance of the blocking, the high-frequency waves which last less than 5 days show east-west contraction and north-south extension when they propagate eastward into the jet stream branch. Calculations of the energy transfer between different time-scale components indicate that the interaction between the slow variable waves and the high-frequency waves is the important mechanism of the genesis and collapse of the blocking pattern. And the time scale of the blocking is governed by the quasi-two-week oscillation of the atmosphere.

Abstract:Based on ECMWF/WMO data and using low pass and high pass filtering tech niques,the E-vector and its divergence of the low frequency and high frequency eddies in a blocking occurring in Europe-Ural during the winter of 1985-1986 are investigated in much detail. The vorticity flux divergence of the high frequency eddies in the maintenance of the blocking is also discussed. Some useful results are thus acquired.

Abstract:Based on monthly rainfall data from 160 stations in China from January 1951 to November 1987 and monthly average sea surface temperature data from January 1951 to September 1988, we analysed the effects of the zonal gradient quasi-biennial oscillations of sea surface temperature anomalies in the India and West Pacific Oceans. Some practical meaningful results were achieved. Furthermore,the possible relationship was discussed among El Nino events,zonal gradiant of sea surface temperature anomalies,and summer-summer half year rainfall in different areas over China.

Abstract:Using wind data from three-axis propeller anemometers in the meteorological tower of Tianjin for the period from July 22,1990 to August 11,1990,the turbuleat intensity, the friction velocity, the turbulent parameter, the Eulearian-time correlation coefficient and the integral time scale of turbulence in the surface layer over a suburban area of Tianjin are calculated. The results are very useful in understanding the turbulent characteristics inthe surface layer of Tianjin suburbs.

Abstract:A digital system for processing GMS-LR-Fax satellite imagery is described, which is designed by using the PC/AT microcomputer, with focus on the discussion of data sampling and a few operational problems.

Abstract:The relationships between DVS (taken as a biological stage variable) and the leaf area index,the rate of old leaves,the allotment and transformation coefficients of cumulative dry matter were studied in this paper. Three dynamic sub-models, i. e., DVS model, leaf area index model,and dry matter cumulation and yield formation model, were established. These models have been verified by the experiments made in the Agrometeorological Experimental Station,the Nanjing Institute of Meteorology in 1989 and 1990. The results are consistent with the fact and the models can be used in other stations.

Abstract:The evolution of two bolcking cyclones in the North Atlantic are investigated by using isentropic potential vorticity(IPV) maps. The results show significant dynamic forcing of aynoptic-scale vorticity on planetary-scale blocking highs. Broken Rossby waves are also observed in the surf-zone in the process of blocking.

Abstract:Numerical experiments show that on the northeastern edge of the Qinghai-Xizang Plateau the formation and movement of a vortex is closely related to topography and the activities of high-and low-level systems. After the removal of topography, the vortex would no longer exist. When the low-level subtropical high is powerful in intensity, the southerly wind prevails all through the eastern part of the plateau and its northeastern part is within the divergence field of the upper-air jet stream with vortex easily occurring. The factor of the non-adiabatic change can weaken the upper trough and make the vortex stagnant.

Abstract:Analysis is made of the 10min rainfall and air pressure by using automatic data from 76 stations, indicating that the heavy rain above the meiyu front lasts about half an hour and is concentrated in a narrow area. Rainfall of 5mm/10 min is mainly concentrated in the area of one station and occasionally spreads over three stations. Rainfall of>10 mm/10 min is observed in the area of one station and seldom covers two stations. Rainfall of>15mm/10min or 20 mm/10 min has very little probability for its occurrence. It is found that every heavy rain forms when several rain masses occur one after another and every rain mass is composed of 2-3 or more powerful rain nuclei. From the 10min variation of the greatest amplitude of air pressure at each station, the intensity and time of occurrence are well related with rainfall.

Abstract:The structure and working principle of a new type of lysimeter used in both paddy field and dry farmland are described and comparison is made between the type and the old dry farmland type. The functions of the new type are also discussed.

Abstract:In the process of developing "QD69" refrigerant compressor, the emulation of the working process of "QD67" refrigerant compressor, whose performances are similar to those of "QD69", is carried out, and the emulation model proves to be effective. With this emulation the design of "QD69" refrigerant compressor is accomplished, and the main indices of the prototype conform to the emulation results and meet the design requirements. Thus, the compressor design is done in practice gradually from the traditional empirical method to the optimum method on the basis of computer emulation.

Abstract:While compiling the "provincial meteorological affair record book" we should keep in mind four general and five specific principles. The four general principles have been expounded in a separate paper entitled "Four Genenal Principles for compilation of the ’Record Books of Regional meteorological Affairs’". In this paper the five specific principles are introduced:principle of relating factual events, principle of providing meteorological data, principle of preserving historicity, principle of composing personage biography,and principle of cataloging achievements.