Abstract:By the numerical method,the tropical air-sea interaction waves are studied.The results show that when the Kelvin waves are filtered out and only the equatorialRossby waves are reserved both in the atmosphere and in the ocean,the disturbances canalso propagate eastward because of the air-sea interaction. The critical wavelength ofthe eastward propagating waves is related to the intensity of the air-sea interaction,thestronger the air-sea interaction, the larger the eastward propagating components of theair-sea interaction waves. The results of the numerical experiments are in good agree-ment with those by theoretical analysis.

Abstract:By using a two-layer baroclinic model,dozens of experiments whose intergation time is equal to seven model days are performed in order to analyse the influence of such parameters as the static stability,the intensity and size of the tropical cyclone and the environmental flow on its track. Results show that the track of the tropical cyclone is intimately connected with the model parameters and exhibits some nonlinear characteristic features.

Abstract:An empirical infiltration model,established on the theory of information and entropy,is used to describe rain water added to soil profile. The model shows excellent agreement with the experimental data from field experiments. Contained in the model are three factors,i. e.,precipitation,water capacity of soil and parameter K that reflects soil characteristics,of which the former two are measurable and the latter is defined by trial selection. This model can be used for prediction of soil water,research of soil pollution and evaluatioin of water utilization by crops on farmland.

Abstract:In this paper,from Lagrangian viewpoint a detailed investigation is made of the vortexes in the formation, maintenance and collapse of blocking by locus integration of the material contour with some useful conclusions.

Abstract:In this paper, a two-dimensional model is established for a numerical study on the low-level jet in the nocturnal PBL with topography involved. Results indicate that its supergeostrophic features are related not only to the atmospheric thermal stability and the nonlinear advection of the free atmospheric undulation but alao to such factors as atmospheric batoclinicity,radiation and topography. Thus the strong low-level jet is the product of the concurrent effects of the momentum horizonntal transport, the dy-namic and thermal actions of topography,and the momentum vertical transport inducedby the atmospheric thermal action.

Abstract:In order to study the planetary-scale monsoon circulation,a simple coupled model is developed,with which the seasonal variation characteristics of the planetary-scale ocean-atmosphere system is simulated and the impact of the asymmetric forced heating in the atmosphere on the ocean-atmosphere seasonal mean circulation exam-ined. Studies show that this coupled model is of great theoretical and practical signifi-cance in the study of monsoon circulation.

Abstract:In this paper,a coupled model for water end heat transfer in unsaturated cropped soil is presented and its numerical solution is given under the second boundary conditions. The fitting accuracy of the model for soil humidity is doubled as compared with that simulated by a single weter flow equation.

Abstract:This study is the subsequent work on the numerical simulation of radiation and heat balance over the hilly land.Based on the zero-dimensional surface heat balance model proposed in the previous article,into which are fed the data from investigation and the weather stations in the vicinity, calculation is done of the heat regime over the do-main 3.0×3.5km²at grids of 100×100 m in the hilly-area of Zhaogongling located in the southern Dabishan Mountains.And for the first time maps are prepared for the January and July mean temperature.Results suggest that the hilly-land temperature pattern de-pends heavily on the terrains in winter as compared to its much smaller effects in sum-mer.

Abstract:By using the June-September bandpass filtered grid data of 1984 from the ECMWF,the global distribution of 40-50 day oscillation of the 200 hPa wind field in summer and its fluctuation features are examined. Analysis indicates that the 40-50 day oscillation of the wind field has significant meridional-zonal phase propagation. It is found that the oscillation has a larger zonal scale and a greater phase propagation velocity in the tropics than in the extratropics; the zonal wind oscillation has a larger zonal scale but a smaller meridional scale than the meridional wind oscillation with their zonal propagation quicker than their meridional propagation; the zonal wind oscillation has a meridionally-arranged wavetrain structure while the meridional wind oscillation has a zonally-arranged wavetrain structure.

Abstract:Using the data of the 500 hPa pentad anomaly of 14 winters (1971-1984) in the Northern Hemisphere,the geographical distribution of the general circulation anoma-lies in the Northern winter is analysed. The effects of the 30-50 day low-frequency fluctuation and quasi-14 day fluctuation on the persistent anomalies in their evolution are studied. Results show that the time scale of the persistent anomalies is mainly associ-ated with the 30-50 day low-freqency fluctuation. It is found that Alaska is the key region of not only the persistent anomalies but also the 30-50 day low-frequency fluc-tuation. The persistent circulation anomalies and weather-climate anomalies are chiefly dominated by the 30-50 day low-frequency fluctuation.

Abstract:In this paper,investigation is conducted of the problem of existence and uniqueness of the maximum likelihood estimates in logistic discriminant analysis, which is a very difficult problem and can occur in practice. Proofs of the assertions in the completed sepatate and overlapped data situation are given.

Abstract:In this study, calculation is made for the physical quantity fields of the developing and eastward moving Caidamu vortex and the Caidamu vortex generating and dissipating in situ, and such terms as disturbance kinetic energy, disturbance available potential energy,total kinetic energy and total available potential energy in the balance equation within the limited areas around the vortexes. And the energy budget at each stage of the developing and eastward moving Caidamu vortex is analysed. Causes of the Caidamu vortex genesis and development are thus revealed.

Abstract:A WWSDES is developed with the aim of diagnosing winter wheat seedling on the Huanghe-Huaihe plains. The system has synthessized experts knowledge and experience in winter wheat seedling diagnosis and management. By adopting predicate logic expression,its knowledge base used a downward generation scheme. Based on Turbo Prolog language in both Chinese and English,the knowledge base consists of three parts:the domain scheme and facts, meta-rule and meta-fact, and suggested mea-surcs. The system adopts forward and backward inferences. By the effects of the inference device on the knowledge base,it has experts’solution and planning and can semiau-tomatically acquire knowledge and interpretation. With good user interfaces and complete functions,the system is suitable for IBM PC/XT and its compatible computer and can be widely used for agricultural and meteorological purposes.

Abstract:By adopting the EOF iterative formulae for recovering the meteorological factor fields,the recent 600 year temperature sequence in western China is rebuild after suitable sampling and accurate determination of the year of tree annual ring sequence from seven tables, namely,a data table of average annual ring of three junipers in the Qilian Mountains, a table of annual ring width of a Taibai epinette (A) in Shanxi province and 5 annual ring tables in Hami,the Xinjiang Uygur Autonomous Region and by use of the annual mean temperature data from 28 stations (1951-1975) in western China,The rebuild temperature sequence reveals three cold periods (1432-1526, 1622-1680 and 1834-1865) and two warm periods (1541-1567 and 1897-1923),which coincide very well with the tendency of the climatic variations in the past 600 years.

Abstract:The Hunshandake sand region is an area very sensitive to the climatic changes related to human activities. The tendency of climatic variations revealed in this study exhibits that the cold/warm and dry/wet periods occurred alternatively during the 1960s, warm and humid periods in the 1970s, and warm and arid periods during the 1980s. There exists a significant periodical oscillation in the meteorological factors related to desertification, with its duration varying from 2-4 to 6-8 years. A statistical model is established for various factors including aridity, and annual rainfall amount.The climatic tendency in the sand region predicted for 1990 and 1991 in terms of Chebyshev polynomials,ie,warm,humid 1990 and warm,arid 1991,is consistent with what actually happened.

Abstract:Three sets of 24 and 48 hr forecasts for two synoptic cases have been made with a shallow-water equation limited-area spectral model and two different-grid-point finite-difference models respectively, together with their statistical verification.Results reveal that the forecasts made with the spectral model are superior to thos emade with the other two models, especially in the case of the genesis of the closed low in Northeast China. The success of the experiments opens good prospects for further application of the limited-area spectral model and improvement of short-range forecasting.

Abstract:The process of a moviug SW China vortex is simulated in terms of a finemesh model over complicated terrain. It is found that the cumulus convection affects the motion of the SW China vortex. When the cold and warm advection is weak, the powerful cumulus convection causes the south wind in the vicinity of the vortex and the negative vorticity east of the vortex to increase, thus inhibiting the eastward motion of the vortex.

Abstract:Based on the agroflood-waterlogging indices that have been used in different areas in China and the thorough analysis of the causes of flooding damages, a distinctive agroflood-waterlogging index, which can be used to analyse flood in different areas of China,is established in this study. In terms of the index the characteristics of the temporal and spatial distribution of flood-waterlogging is discussed. The results are found to be consistent with the actual conditions in China.