Abstract:Using the monthly NH 500hPa mean height field data from 1951 through 1988,the blocking patterns in the northern hemisphere areanalyzed statistically from the viewpoint of monthly means. Power and cross spectrum analyses show that the results from Scheme Care similarto those from Scheme D; periods of two and a half years (about 30months), one and a half years (18-20 months) and 2-5 months are all of considerable importance for the time series of area index in the regions;there is a good negative in-phase correlation between Region Ⅰ and Region Ⅱ: and periods with remarked coagulation exist in both the longand short time periods.

Abstract:A steady, shallow water atmospheric model is used to studythe influence of the ocean heating scale on the structure of Walker and Had1ey circulation in the tropical atmosphere. It is shown that whenthe heating scale is smaller than the critical scale, the results are similarto Gill’s (1980), that is,a hadley cell is located in the region of Rossby waves and an anti-Hadley cell in the area of Kelvin waves. When theheating scale is larger than the critical scale. a Hadley cell exists inthe entire heating region. In the latter case, a large scale Hadley cellcan transfer a great amount of heat and energy from the ocean to the extratropical region. This causes the atmospheric circulation there tobe anomalous. The results are consistent with statistical facts and sup-port the oretically the teleconnection which Bjerknes put forward inthe 1960s.

Abstract:Diagnostic analyses and numerical experiments show that the inverse seasonal variations and different land thermal effectsbetween Australia and Asia may produce intense meridional stationary pressure waves between the Northern and Southern Hemispheres, whilethe phase and amplitude of the stationary pressure waves decide the direction and intensity of the cross-equatorial flow and hence the latitudinal location of the tropical monsoon trough and the charac-teristics of its seasonal variations.It is suggested in this paper that the inverse seasonal variations between the two hemispheres may beanother cause of the form ation of the tropical monsoon besides the well-known thermal difference between sea and land.

Abstract:The low frequency variations are closely related to thestationary waves and, in a sense, they may even be viewed as the timevarying part of the stationary waves themselves. Therefore, an understanding of the maintenance of the stationary waves is a prerequisite for a thorough understanding of the low frequency transients.The Eliassen-Palm (EP) cross-section and the three-dimensional waveactivity flux, which was derived by Plumb (1985) for the linear quasi-geostrophic stationary waves in a zonal flow, are used as the diagnostics for the output of a three-dimensional spectral model of the linearand nonlinear steady-state baroclinic primitive equations. The resultsshow that the EP cross-section and the wave activity flux are usefulfor diagnosing the vertical and horizontal propagation of the waves andthe significance of the nonlinearity. However, full attention should bepaid to the effect of the nonlinear interaction when diagnostic analysisis made of the observational data.

Abstract:A quasi-analytic method is presented for the computation of microwave attenuation. And numerical calculations are made for the attenuation cross sections of the melting and sponge ice spheroidal particles. The results are compared with those based on laboratory experiments.

Abstract:Following Wu and Chen (1989), in terms of the mean meridional circulation function elliptical differential equation similarin form to that developed by Kuo (1956) and by use of time average statistics of the atmospheric circulation in the wave number domain atthe same time intervals, a study is made of the contribution of the in-ternal forcing of the atmosphere on two space scales to the mean meridi-onal circulation. Results show that the planetary waves have a con-siderable influence on the intensity of the upper center of the bi-Hadleycell and, in contrast, the synoptic-scale waves exert vital effects on the Ferrel cell. In the NH such internal forcings by the planetary andsynoptic-scale waves make much the same contributions to the mean meridional circulation whereas in the SH the latter contribute far morethan the former. Further more, in the northern winter (summer) the contribution of heat (angular momentum) transport of the planetary waves allows the descending (ascending) branch to occur as far as around 40°N, a very important contribution to the winter (summer) monsoon circulation in East Asia.

Abstract:A ρ-σ incorporated coordinate 12-layer primitive equation model is adopted to investigate the distribution characteristics of the East-Asian cyclogenesis frequency in relation to the activities in the panetary frontal zone and dynamic effects of the Qinghai-Xizang Plateau.Numerical experiments show that the development and motion of the East-Asian cyclone are significantly correlated to the climatological locationof the frontal zone, and the joint effects of the westerly jet stream and the forcing of the plateau’s orography result in the distribution characteristics of vortexes, small highs and shears over the huge topography and the difference in their tracks.

Abstract:The integral equation method applied to the electromagnetic scattering of heterogeneous dielectric objects is discussed and a set ofmatrix equation established by the moment approach. The equations are solved numerically for the tapered-spheric meteorological particles.

Abstract:A one-and-a-half-dimensional nonsteady cloud model is designed for predicting the heavy rain cloud containing mainly the warmrain process accompanied by sleet. A short-and very short-range forecasting method is proposed for the heavy rain cloud and its rainfall overthe middle reaches of the Changjiang River during the warm season byusing the satellite imagery and routine sounding data combined with themodel. Results show that the evolution processes of the two types ofthe model clouds and their features resemble in the main those of thetwo types of the natural heavy rain clouds, suggesting that the methodis feasible for the purpose.

Abstract:The maximum temperature field over Nanjing in winter andsummer has been simulated by using the energy balance model. Results arefound to coincide with observational facts, showing that the model canbe used to predict characteristics of the highest temperature field and urban heat island in Nanjing.Analysis of the energy field of the mode lsuggests that transfer of net surface radiation in urban areas is mainlythe sensible heat transfer while that in rural areas the latent heattransfer. Tests for the sensitivity of the model to the influencing factorsfor the city heat island indicate that the dominant influencing factorsfor the urban heat island in the afternoon over Nanjing are the roughness of the underlying surface and the relative humidity of air while artificial heat transfer in the city has only a minor effect.

Abstract:Mesoscale rainband activities and the distribution characteristics of the weather elements in the vicinity during the Meiyu periodare examined based on exhaustive data.It is noted that the activities of several rainbands running from east to west one after another and thelow-level SW jet play an important role in the formation and maintenance of the Meiyu front in the boundary layer.

Abstract:In early summer, the ground surface of the eastern Qinghai-Xizang Plateau and the air above are heated quickly while thewarming process of the air over the Sichuan Basin is much slower.As aresult, a remarkable east-west temperature difference at the same level isformed and a synoptic-scale zonal vortex develops between the easternplateau and the basin. Investigation is made of the thermal reason for thevortox formation, the synoptic conditions of its eastward movement andits imapct on the weather-climate in the surrounding areas, revealingthat the ortex has a direct influence on the weather system in theboundary layer over the eastern plateau, and its frequent occurrence maybe one of the important factors responsible for the early summer excessiverainfall in the eastern plateau and the summer drought in the Sichuanbasin.

Abstract:Examinations of the errors in radar measurement of precipitation on the ground surface indicate that the zero-layer bright bandinter cepted by radar beams is one of the main reasons for the error inthe measurements. By the statistical method based on the zero-layerbright band and sounding data of the temperature, pressure and humidityin the area of Wuhan,a prelimitary study is made on the possibility of lowering the radar elevation so as to avoid the interception of the bright band in the zero layer by radar beams.

Abstract:Based on the mechanism of crop growth and development,a dynamic model is established to simulate the development stages ofwinter wheat and the biomass of each organ. The model contains three environmental submodels for calculating temperature, radiation and water,and five biological submodles for simulating phenology, photosynthesis,respiration, assimilation product distribution and leaf area index. The validity and applicability of the model are given.

Abstract:Based on the three-year meteorological data (April 1983--March 1986) and extensive agroclimatic investigation on the south slopeof Shen Nong Jia, the spatial distribution models for the agroclimaticelements are proposed. In terms of these models the values of thecorresponding elements at different elevations are estimated. After cal-culating the indices by mathematic methods, such as the principal component analysis and Miani model, the division of the verticalagroclimate layers on the south slope of Shen Nong Jia is made by meansof A. I. D. cluster analysis. This provides scientific grounds for reasonable utilization and exploitation of the agroclimatic resources onthe south slope of Shen Nong Jia.

Abstract:Based on Wu’s NH long-wave spectrum model and by nu-merical simulation, a preliminary study is made of the role of the tran-sient eddy forcing in the structure responsible for the formation of the atmospheric circulation. Analyses suggest that the transient eddy forcing has a pronoinced effect on the intensity and position of thezonal mean flow and the temperature and pressures of the stationary waves.