Abstract:Preliminary studies are made of the time and spatial distribution of the major climatic disasters, such as drought, flooding and cool injury, in China and their impact on agricultural production. And the causes of their formation are analyzed in brief.

Abstract:Based on observational data, the stability in the empirical orthogonal expansion of the drought and flood indexes is analyzed, Results show that there have been no significant long-term trend and periodic oscillation in the eigenvectors during the last 500 years. It is also found that the stability in the structure of the eigenvectors decreases with their orders, whereas that in the characteristic value of the eigenvectors increases with their orders. Considering the stability in the spatial structure and variance contribution of the eigenvectors, only the first 4-5 eigenvectors are of climatological significance

Abstract:The relationship formula for the vertical and horizontal resolution coordination in the centered finite difference scheme of the adveetion equation(the vertical and horizontal spatial deviatives in the adveetion equation being transformed into centered difference)is derived and fully discussed from the two-dimensional linear advection equation(the two dimensions are in x and y directions)and on the principle of equality in the truncation error caused by vertical resolution and that caused by horizontal resolution in the difference equation.This study is important for the determination of the vertical levels and horizontal grid spacings in the Mid-Range Numerical Weather Forecast Model of China.

Abstract:Much climatological-statistical information of practical significance has been obtained through the study of the statistical features of dry/wet month runs at a number of representative stations by using Markov chain and from the concepts of runs and turning points presented in Literature 1 In addition, the stability of the dry/wet month transition probability matrix and its limit distribution are discussed. The results in this study provide a climatic background for making long-term forecasts.

Abstract:Control testa are carried out for three categories of numerical schemes to treat the lateral bounday conditions of aone-way nested model, which was originaily an operational 5-layer primitive equation model developed by the National Meteorological Center. The horizontal distribution of forecasting errors and the possible computational effects at different levets are examined in some detail Finally, an improved scheme for the treatment of the lateral boundaries is proposed.

Abstract:In this paper, the abnormal large-scale atmospheric circulation in the Northern hemisphere and its energetic characteristics during the strong El Nino period of 1982-1983 have been analyzed by using the ECMWF/WMO data. It has been found that both. diabatie heating and conversion from potential to kinetic energy were so anomalous that the ultra-long wave kinetic energy greatly increased and the abnormal large-scale atmospheric circulation occurred in the Northern hemisphere. The results can be used for explaining the energetic mechanics of the effects of the strong tropical SST on the large-scale atmospheric Circulation in the Northern hemisphere.

Abstract:From the viewpoint of application, two catagories of stability problems in the EOF analysis method are advanced and described. And then the convergent velocity is compared between the EOF and Orthogonal polynomial analysis methods.The obtained conclusions are different from the reference [1].

Abstract:Diagnostic analyses are done for the equilibrium of enstrophy and its nonlinear cascade in the wavenumber domain for each season and different latitude zones by using the 500 hpa pentad average data for 1979. Results indicate that in winter and spring super-long waves (wavenumber 1-3) and Rossby long waves(wavenumber 5-6) are suppliers of enstrophy for the other waves and the zonal flows in middle and higher latitudes. In summer, Rossby waves are no longer the enstrophy "source", which shifts to shorter waves. Meanwhile, the wavenumber 4 component, which is the enstrophy "sink" in winter and spring, now becomes the "source" In autumn, the wavenumber 4-5 components are the "source", a transitional pattern from summer to winter superlong waves are the "source" in all seasons but their distribution differs with latitudes The width is only 20 latitudes, in about 37.5-57.5°N in winter and shifting northward about 10-15 latitudes in summer. In the subtropics south of 35°N, super-long waves are the enstrophy "sink" in almost all seasons.

Abstract:A 16-layer spectral model for the linear steadystate primitive equation of stationary waves in the atmosphere is used to investigate the responses of wintertime stratospheric atmosphere to large-scale thermal forcings in the troposphereNumerical experiments show that the thermal forcing in the troposphere makes a considerable contribution to the maintenance of the vertically propagating stationary planetary waves in the stratosphere in winter. The horizontal structure of the forced disturbances in the stratosphere and its difference compared with the tropospheric disturbances are closely related to the vertical distribution of the heating field. As a source similar in strength and spatial structure, the forcing in midlatitudes has a stronger effect on the stratospheric circulation than that in lower latitudes.

Abstract:In this paper, characteristics of variation in different physical elements in the key area and affected areas of the cold activities in East Asia during winter are, studied. Significant one-week and quasi-40-day oscillations are observed, which have close relation to the cold air activities. It is found that the strong cold air activity is mainly under the control of the low frequency oscillation. The phase of the quasi-40-day oscillation of temperature in the key area is about 5 days earlier than that in the affected areas (central China) and its amplitude responds quite well to the strength of cold air.This provides a good reference for the forecasting of cold air. Besides, the cold air may show different characteristics at different stages of its southward propagation. In the end, the relation between the intensification and westward extension of the upper easterly jet in the lower latitudes in East Asia and the strong cold air activities is discussed.

Abstract:A comprehensive analysis is made of the off-shore right-turning and north-moving,violent growth and structure of typhoon 8211 (Cecil) during the International Typhoon Operational Experiment (TOPEX). It is noted that the right-turning and northward movement of the typhoon is closely related to the intensification and maintenance of the cross-equatorial flow which set out in the southern hemisphere and moved along the African coast, and its off-shore violent growth has much to do with the favorable environmental flow field. The divergence or convergence term and cumulative convection play an important role in the vortex equilibrium and the vertical vortex transport should not beoverlooked. The temperature structare is not in symmetry during the off-shore development.The vortex develops and intensifies from the lower to higher level, and the vortex and the vertical velocity distribution are roughly in symmetry.

Abstract:Optimum partition-Stepwise Regression (OPSR) is the first procedure studied. By means of optimum partition, the threshold of the most sensitive meteorological variable to the index indicating specific conditions in society, economy and living beings is determined. Human mortality in the city of Guangzhou serves as the index in the study. Stepwise regression is then used to produce a weather/mortality model, based on the sample which consists of days beyond the threshold. The second procedure is the Optimized Classification of Weather (OCOW).Seventeen meteorological variables are treated by principal component analysis. Daily scores of a few top principal components are then classified using cluster analysis.The number of weather types is determined from the greatest drop of the sum of squares among groups.There is good correpondency between death rates and weather types.F-tests prove that OPSR is better than common regression, and OCOW is better than OPSR in terms of climatic impact assessment.

Abstract:In this paper the σ-coordinates system was used for the analysis of the main physical factors in 31 samples of heavy-torrential rains happening in the area of the Three-Gorges of the Changjiang River in early summer. The mean value fields of each factor were calculated and then the main features of the physical fields at 08 hour on the day when heavy-torrential rain occurred were obtained.

Abstract:Based on the calculation of the components of slope net radiation (SNR) by the climatological methods proposed by Weng,analysis is done of the SNR distribution characteristics over China with the focus on changes in SNR as functions of orientation/slanting degree of slope, latitude and season from some representative stations. SNR on both the north and south sides is used to prepare for the first time the chart to illustrate its geographic pattern, indicating great difference in SNR between the two slopes over the mainland.It is of much interest to note that the winter SNR negative-value belt of 20° north slopes extends as far as the Yunnan-Guizhou Plateau and the middle and lower reaches of the Changjiang River.

Abstract:In the modelling experiments on the accumulative amount of tile annual rings of Cunninghamia Lanceolate of different ages and heights growing on the southeast slope of the Tianzhu Peak, Gompertz function shows satisfactory response as well as small mean square error and high accuracy in simulation as compared with nonlinear least square Logistic function, and thus has considerable advantages over general linearized models.For this reason,it is safe to say that Gompertz function is good for the simulation of the accumulative amount of the annual rings of Cunninghamia Lanceolate growing on the southeast slope of the Tianzhu Peak in the Dabieshan Mountains.It has been proved that there is similar tendency in the influence of tree ages on the width of the annual ring.

Abstract:In tkis paper a new stability index ZI is designed for convenience of calculation. Its thermodynamic implication, dynamic feature and indicative significance to the convective weather process are discussed. A method of Convective weather forecasting is thus given, which is proved to be of practical value in the four severe weather occurrences in East China in recent two years.

Abstract:The first principal component of the Southern Oscillation Index (SOI) is used as the intensity of annual SO. A composite analysis is made of typhoon activities over the Northwestern Pacific in the El Nino/anti-El Nino year and the year after. It is found that the characteristic of the correlation between ENSO and typhoon activities in June and before differs from that after June In the El Nino year the average number of typhoons developing over the Northwestern Pacific is greater than normal from January to June,smaller from June until next June and greater from then until next December.The date of the first typhoon in the year following El Nino will be postponed.The opposite is true for the anti-El Nino year. In most cases the first typhoon will appear in January. Moreover, the relations between ENSO and the number of severe typhoons landing on China’s coast are examined, which are of much use to the long-range forecasting of typhoon activities and to the early diagnosis of El Nino events.

Abstract:A numerical experiment is performed to retrieve the vertical profiles of the atmospheric temperature from the simulated brightness temperatures observed by a 6-channel 5 mm radiometer which operates in the same way as a part of the future satellite-based Advanced Microwave Sounding Unit (AMSU). The surface air temperature can modify the normal Empirical Othogonal Function (EOF) inversion method,resulting in statistically an improvement of about 1 K in retrievals below 500 hPa According to the error statistics in 120 profile retrievals in Nanjing, the vertical distribution of root mean square(RMS) differences between retrievals and radiosondes has a maximum of 3.0 K at about 150 hPa and a peak of 2.3 K at 850 hPa, and the unbiased RMS differences at these two levels are 2.4 and 2.2 K respectively. The average at 14 pressure Ievels below 30 hPa is 2.2 K for RMS and 1.8 K for unbiased RMS.

Abstract:The cross section of the Quonset-type plastic greenhouse is considered as a semi-circle. By means of the mathematical model,the incident angles of direct solar radiation at various elevations on the plastic surface of the greenhouse in north-south and east-west orientations are calculated and daily, seasonal and latitudinal changes of its reflectivityon the plastic surface are analyzed. On this basis, calculation is made for the mean daily ratio of the intensity of direct solar radiation normal to the surface of the greenhouse in the two orientations. A decision is thus made for the reasonable choice of orientation in the zone of 0-60°N from the seasonal and latitudinal changes of the ratio.

Abstract:By using a five-layer primitive equation model with topography, the process in which a vortex moves eastward out of the Qinghai-Xizang Plateau is simulated It is found that diabatic factors, such as radiation, cumulus convection, large-scale condensation latent heat, etc., only influence the intensity of the plateau vortex. Of all the factors, radiative heating is the most important, and the vortex is apt to move eastward when there is a cold trough in the west of the vortex or a high pressure ridge at 45-55°N in the north of the plateau.

Abstract:In this paper, the cloud features, source and path of 28 Mesoscale Convective Complexes (MCC) over the mainland of China are analysed. The interaction of weather systems of different scales and the conditions for MCC formation are discussed based on conventional observations. Features of the MCC structure are given from the quantitative calculations of physical parameters inside and outside the MCC cloud areas and a concept model of the MCC is presented.

Abstract:A new dynamic model describing the successive effects of the atmospheric temperature-humidity factors on the new growth of the tea tree is established by using meteorological data in the field of tea trees. Several critical temperatures for the growth of the tender stems are obtained from the regression formula--Q function of periodically fitted temperature T and humidity U.

Abstract:A numerical study is done of aone-dimensional model of the stationary atmospheric baundary layer with different extensively used K-models. Comparisons are made between the calculated results and the observational data at Zhengjiang and Nanjing, and applicability of the K formulas is discussed.

Abstract:This paper reviews the historical stages of the technological progress in weather guidology, pointing out the difficulties existing in field detection of cloud structures, laboratory experiments, construction of numerical weather guidological models and design of tests for statistical effects. Which are currently all under way for the purpose of improving the weather guidological effects. Approaches to tackling the difficulties are also proposed in this paper.

Abstract:Based on a brief review of the previous researcher, analyses are made of the recent meteorological data. Views are presented concerning the determination of the region and duration of Meiyu occurrence, and the relationship between the rainfalls in the ten-day periods before and after Meiyu episodes.