Vol.4, NO.1, 1993

Display Method:
A Study of Vapour Transportation over Asian Monsoon Region in Mei–yu Season of 1983
Fei Jianfang Qiao Quanming Gao Taiping
1993, 4(1): 65-72.
The distribution of vertically integrated water vapour transportation and flux divergence in the Mei-yu season over the Changjiang River and the Huaihe River basins is studied. The water vapor budget over the Nanhai Sea and the eastern China area is calculated. The results indicate that water vapour associated with precipitation over south China before the Mei-yu period comes mainly from the two air currents which are the Indian southwestern monsoon and the eastern Asian southeastern monsoon, respectively; water vapour of precipitation in the Mei-yu period comes mainly from the Indian southwestern monsoon current; and after the Mei-yu period, the rainy season over North China is mainly affected by the convergence currents from the middle and the low latitude. The analysis shows the Mei-yu period is beginning when the Indian southwestern monsoon current strengthens and moves eastward then northward, and the western Pacific high shifts eastward; and the Mei-yu period is ending when the southwestern monsoon current weakens and declines westward, and the western Pacific high stretches westward and moves northward. In addition, the relationships between the water vapour flux convergence and cloudiness/precipitation over the eastern China are discussed
A Scheme of Spectral Horizontal Interpolation in T42 Post–processing Procedure
Zhang Jianchun Wang Shiwen Huangfu Xueguan
1993, 4(1): 16-21.
This paper describes the scheme of the horizontal interpolation from the Gaussian grid to regular latitude/longitude grid by using spectral method in the post—processing procedure of the T42 assimilation forecasting operational system in the National Meteorological Center (Beijing). The results show that the scheme has many advantages such as high interpolation precision and filtrating the short waves caused by the truncation error in the process of vertical interpolation. The scheme can provide more accurate forecasting values for users and first guess field for next assimilation
A Study on the Diagnosis System for Orientationally-introduced Rice Varieties and Its Ecoclimatic Pattern
Feng Daquan Peng Guozhao
1993, 4(1): 52-56.
Based upon the research of the Diagnosis System for Orientationally-Introduced Rice Varieties (DSIRV) in Sichuan, the principles of the DSIRV design and the methods for establishing a certain number of rice ecoclimate pattern and cultural technique are described in the paper. The results show that the DSIRV gains its success at a rate of more than 70%. And the DSIRV can cut short its whole procedure for introducing of a rice variety by 2 – 4 years less than the period the conventional way takes.
The Influence of Structure of Upper-tropospheric Cold Vortex on Typhoon Motion
Fei Liang Li Xiaofan
1993, 4(1): 1-7.
The role of upper-tropospheric cold vortex with different horizontal and vertical structures in the process of typhoon movement is studied. It is found that the structural variation of aloft cold vortex will affect the typhoon motion. The analysis shows that barotropic processes dominate in direction of motion, but under some circumstances, baroclinic processes dominate in its speed. Furthermore, it is also shown that contribution of horizontal vorticity advection to the positive center of TVT (total vorticity tendency) comes from the advection of asymmetric vorticity with steering current, and contribution of divergence field to TVT is mainly from the correlation field between the planetary vorticity and asymmetric divergence. Finally, it is concluded that within the ranging affected by the cold vortex, typhoon will move to the regions of convergence center in the upper-troposphere or divergence center in the mid-and-lower troposphere. This conclusion is useful to forecasters
Simulated Doppler Images of Mesoscale System
Tao Zuyu Zeng Lixin
1993, 4(1): 8-15.
The basic relationship between the Doppler velocity (radial velocity component) field and the horizontal wind field is analyzed mathematically. The major features of Doppler velocity image for various typical mesoscale systems, such as shear lines, vortex and low level jet, are discussed using the simulated Doppler images. The results can be used to interpret qualitively the observed Doppler pattern in nowcasting
The Influence of the Surface Heat Source over the Qinghai-Xizang Plateau of Summer on the Flow and Run-off in the Upper Reaches of Yellow River
Sun Guowu Liu Xiaodong Chen Baode
1993, 4(1): 22-29.
Based on statistical facts, the heat source variation of the Qinghai-Xizang Plateau is related with the flow of upper reaches of Yellow River. A numerical experiment of influence of the heat source variation over the Qinghai-Xizang Plateau on the flow of upper reaches of Yellow River in the summer is performed with a model of GCM. The results show that while the heat source of the Plateau is weaken, the runoff is decreased and flow is descended. As a result, the heat source vaiation of the Qinghai-Xizang Plateau is one of the important causes which led to flow variation of the upper reaches of Yellow River
A Numerical Study on Mesoscale Inhomogeneous Boundary—layer Climate: Part (Ⅱ) the Summer Numerical Experiment
1993, 4(1): 30-37.
The PBL climate characteristics over inhomogeneous underlying surface in North China for summer is studied by using the modified Nickerson’s model. The results indicate that the horizontal inhomogeneity of temperature and humidity over the underlying surface plays an important role in the boundary layer climate under conditions of clear and calm day without synoptic system disturbance. The PBL climatic features are closely related to the local circulation. A phenomenon called inversion of humidity in the PBL over a dry bare soil is ascribed to the joint of the heterogeneous humidity pattern and mesoscale advection over the inhomogeneous underlying surface
Influence of the Change in Solar Radiation on Summer Monsoon Rainfall in Mid—Eastern China and West Africa
Xu Qun Wang Bingmei
1993, 4(1): 38-44.
Since the late 1960s, especially during the 1980s, the global climate has warmed up significantly. However, this warming mainly occurs in winter, but the monsoon rain belt over the east Asia/west Africa during high summer shows a trend moving southward. Based on strict statistics with the support of numerical modelling, it is found that such a southwardly shift of the summer monsoon rain belt with less rainfall in North China and Sahel is caused by the decrement of direct solar radiation in the clear skies over the Northern Hemisphere/China. And the radiation decreasing is the result brought out by the increment of volcanic eruptions as well as air pollutants in recent years
Simulation for the Vertical Distribution of Ozone
Liu Yu Zhou Xiuji Li Weiliang
1993, 4(1): 45-51.
By using one-dimensional atmospheric chemistry model for stratosphere and troposphere, with including the vertical advection, diffusion and chemical processes, the vertical distribution of ozone is studied. It is found that the increase of ozone concentration in lower troposphere is due to increase of surface source of NOx, and its increase in the summer is larger than that in the winter. By comparison the sensitive experiments of diffusive coefficient with vertical wind, it is indicated that the effects of advective process in the ozone transfer from stratosphere toward troposphere may be more important
A Numerical Model for Diagnosing Boundary Layer Wind over Real Terrain
Zhao Ming Ma Jijun
1993, 4(1): 57-64.
Based on semi-geostrophic PBL model and large-scale model, a diagnostic model to calculate boundary layer wind is introduced. The horizontal inhomogeneities of terrain and the roughness of ground, the temporal and spatial variations of large-scale pressure field are included in this model. A terrain coordinate transformation is introduced to compute the horizontal gradient of the geostrophic winds. The tower layer wind model is used to diagnose the boundary layer wind instead of the semi-geostrophic model for the lower latitude. The comparison with the observational data shows that the diagnosis has attained a fairly high level accuracy for both wind direction and wind speed. Therefore, it can be used in practice to diagnose or forecast the PBL wind when largescale model is incorporated.
A Test of the Effect of Soil Moisture on Efficiency of Nitrogen Fertilizer
Li Xiangshan Zhang Tingzhu Wang Fangyun Zhang Yanhua
1993, 4(1): 73-78.
At present, it has been found that the reduction in production occurring in the high-yielded wheat plots is caused by the excessive utilization of nitrogen fertilizer and high frequency of irrigation. The effects of different nitrogens and water levels on wheat yield are discussed and a mathematical model is described in the paper. Based on the overall evaluation of input and output, the optimum requirements for the nitrogen amount and irrigation frequency are found out, thus bringing the great help to raise nitrogen and water efficiency to wheat.
The Relationship Between Celestial Tide-generating Forces and Activities of Blocking High over the Eastern Asia in Summer
Zhang Suqin Ren Zhenqiu
1993, 4(1): 79-85.
The relationship between the celestial tide-generating forces and activities of the blocking high over the eastern Asia in the mid summer is described. It is indicated that the formation, persistence and collapse of the blocking high over the eastern Asia is related to the resonance of tide-generating forces concerning with the astronomical singularities. The blocking high in the Baikal Lake and Sea of Ochotsk forms when the resonance pressure-increasing of three or/and more astronomical singularities occurs in two or three days. And then, the high will persist if the resonance pressure-increasing occurs successively. Finally, the collapse is brought out by the resonance pressure-decreasing. Some cases found in other regions, which lead to severe weather processes, are similar to those over the eastern Asia.
Dimensional Analysis and Its Predictability of East Asian Precipitation Systems
Miao Jinhai Zhang Jingde Liu Zhiyuan Li Chaoxing
1993, 4(1): 86-91.
East Asian precipitation systems are chaotic systems with strange attractors and complexity. In which, the precipitation system along the Changjiang Valley is of global uniformity and more complexity. The average predictable time in Changjiang valley is 4.31 months, but 6.25 months in Beijing
The Study of the Cycle of Nitrogen Oxides in the Troposphere
Luo Chao Zhou Xiuji
1993, 4(1): 92-99.
The budget and cycle of the nitrogen oxides in the troposphere and their source/sink process are reviewed and discussed. The chemical behavior, anthropogenic and natural emissions and dry and wet depositions of nitrogen oxides in the troposphere are studied. In addition, the NOx from the combustion of fossil fuel, lightning and microbial activities in soils and dry and wet depositions in our country are estimated.
The Influence of Wind and Relief on the Speed of the Forest Fire Spreading
Mao Xianmin
1993, 4(1): 100-104.
The quantitative relations between the stretching speed of the forest fire and the wind and relief are given. An equation set for predicting the speed of the forest fire spreading is developed. Through the actual tests, it is found that this method is favourable for the operational use.
A Method of Calculating the Extreme Wind Speed with the Short-term Observations of Maximum Wind
Zhang Xiuzhi Chen Qianjin
1993, 4(1): 105-111.
According to the theory of complex extreme distribution, the extreme wind speed which recurs once every several years over the sea is estimated. The calculation is supported with the method of binomial log-normal distributioin based on the short-term observations of maximum wind. The estimated value is considered as the basic value and calculations with the empirical for mula incorparating the long-term observations of the maximum coastal wind is taken as the corrected value. The recurrent wind speed for engineering design over the sea is derived by summing up the basic value and corrected one. The result of estimation is approximately equal to those with the Person Ⅲ distribution and Poisson-Gumbel distribution and shows the greater stability than that derived from the binomial log-normal distribution. This method is more significant in estimating the extreme wind speed when the long-term observations are deficient
A Compositive Criterion for Forecasting Explosive Cyclogenesis in the Western North Pacific
Lin Mingzhi Li Xufang Yu Heshu
1993, 4(1): 112-116.
The contribution of meteorological factors (such as deepening rate, cloud patterns, aloft trough and jet) for explosive cyclogenesis in the western North Pacific is analysed by using the numerical prediction productions from ECMWF. A compositive index FZ which depends upon the factors is given. The compositive criterion for forecasting explosive cyclogenesis is determined. According to the technological process presented, experiments of 24-hour forecast were conducted during January through June of 1991 over the western North Pacific. The results show that the method has an accuracy of better than about 25%
Design of Parallel Comfuting Schemes for Numerical Prediction and Their Feasibility
Jin Zhiyan Yan Hong Ding Xiaoliang
1993, 4(1): 117-121.
This document is a report of a study into the feasibility of parallel computing for numerical weather prediction programs carried into excution on a Transputer network. Three different parallel schemes are presented using the diffusion equations with two and four orders. The results provide the basis for implementation of the numerical weather prediction model on Transputer parallel computer.
The Relationship Between Climatic Warming and the Production of Grain in Tianjin
Liang Pingde Wu Fengzhen
1993, 4(1): 122-126.
The climatic change in Tianjin and its influence on grain production are studied by using the temperature and rainfall data during 1932—1989. The results show that the warming in Tianjin coincides with that in the Northern Hemisphere, and the warming in winter is more obvious. The rainfall in Tianjin was increased in spring and early summer, while decreased in mid summer during the global warming period of 1980s. The warming climate in 1980s was very favourable to the yeild of winter wheat and maize, but unfavourable to the soybean in Tianjin. The drought climate in 1980s was unfavourable to the growth of rice, either in sown area or in yield per unit area.