Current Issue

• THE RELATIONSHIP BETWEEN THE AREA AND THE DEPTH OF THE STORMS DERIVED FROM ENTROPY PRINCIPLE
• Zhang Xuewen;Yang Xiusong
• 1991 Vol. 10 (3): 225-232. 
• Abstract ( ) PDF (487KB) ( )
• The relationship between the area and the depth of the storm precipitation is a important subject with regard to the weather forecast, the flood control and the hydrology. In the past, there was only experience curve for precipitation area and depth but no theoretical relation. In this paper, the theoretical relationship between the area and the depth is deduced by the principle of the maximum entropy. The theoretical relationship has been verified by analyzing about 90 storms happening in China and the United States.The result shows that the above mentioned area-depth formula of the precipitation is in keeping with the truth.

• THE NONLINEAR ROSSBY WAVES FORCED BY TOPOGRAPHY
• Zhu Kaicheng;Wang Qin;Li Xiangru
• 1991 Vol. 10 (3): 233-240. 
• Abstract ( ) PDF (425KB) ( )
• Under semi-geostrophic approximation, the condition of topographic gradient and the initial perturbation in which the nonlinear equation describing Rossby waves possesses a wave solution were discussed by using the method introducing a phase angle function and analysizing the phase diagram determined by the ordinary differential equation.

• A METHOD OF ANOMALY SIGN FOR LONG-TERM FORECAST-A SIMILAR SIGN PROPAGATION MODEL OF PHASE SPACE
• Lin Zhenshan;Li Xiangru
• 1991 Vol. 10 (3): 241-247. 
• Abstract ( ) PDF (405KB) ( )
• A similar sign propagation model of d-dimensional phase space is set up by combining the theory about chaos with statistics theory in this paper. After debugging the model, its forecast accuracy will reach 60%-80%.

• THE PERSISTENCE DISTRIBUTION OF GENERAL CIRCULATION ANOMALY IN NORTHERN HEMISPHERE WITH KINEMATIC SCALE
• Zhang Banglin;Wang Yuxi;Liu Jie
• 1991 Vol. 10 (3): 248-257. 
• Abstract ( ) PDF (560KB) ( )
• In this paper the persistences of daily 500 hPa geopotential height anomaly on different scales during the period of from March of 1965 to December of 1977 are studied with harmonic and EOF analyses.The harmonic analysis shows that:the persistence on ultra-long wave scale is better than that on long wave scale;in the low latitude area, the persistence on all scales are worse than those in high latitudes when lag time is short. But the case is reversed when the lag time becomes longer because of the rapid decreasing of persistence in high latitudes. The results of EOFs show that the persistence of the first eigenvector and its contribution to total persistence are the largest, and with the decreasing of the eigenvalue, the persistence and its contribution to total persistence become small.

• THE LINEAR RESPONSE OF GLOBAL STATIONARY WAVES TO LARGE-SCALE TOPOGRAPHY
• Tian Yongxiang;Duncan;C. N.;Lei Zhaochong
• 1991 Vol. 10 (3): 258-267. 
• Abstract ( ) PDF (594KB) ( )
• In this paper, the structure of the global stationary waves on 200 hPa is simulated with a steady-state linear primitive equation model. The linear response of a model atmosphere to large-scale topography is also investigated.

• THE EFFECTS OF DUAL LINEAR POLARIZATION RADAR ANTENNA RADIATION CHARACTERISTICS ON THE MEASUREMENTS OF DIFFERENTIAL REFLECTIVITY
• Chu Rongzhong;Xu Baoxiang
• 1991 Vol. 10 (3): 268-276. 
• Abstract ( ) PDF (483KB) ( )
• Based on numerical simulations, it is found that the deviation(dB) of the reflectivity for the horizontal or the vertical polarization transmission calculated from main-lobe of the antenna gain pattern is at least one magnitude higher than the devia-tion(dB) as considering the effect of the side-lobe only. And it is also found that these deviations are correlated to a certain extent with the reflectivity gradient in cloud. The deviation of the differential reflectivity caused by the difference of the main-lobes at horizontal and vertical polarizations may be sometimes as high as 0.5 dB or so. This could provide some important evidences for the improvement of the radar antenna.

• THE ANALYSIS OF THE RELATION BETWEEN TOTAL OZONE AND THE STRATOSPHERE CIRCULATION OVER THE NORTHERN HEMISPHERE
• Zheng Guang;Wu Tongwen;He Huixia;Qu Zhang
• 1991 Vol. 10 (3): 277-286. 
• Abstract ( ) PDF (644KB) ( )
• This paper consists of two parts, i. e. the annual variations of the total ozone and the stratospheric sudden warming(SSW) in Feb. 1981. The results show:1. The total ozone and the stratosphere circulation are the same in seasonal variation. The polar vortex is corresponding with the high value of total ozone in winter;the polar high is corresponding with the low value in summer. 2. From winter to summer, the distribution of total ozone over the Northern Hemisphere and the lower stratospheric circulation are the same in transition time(May-June);from summer to winter, the former occurs in Oct.-Nov., it is one month later than the latter(Sept.-Oct.). 3. The total ozone increases with increasing of the amplitude of the extra-long wave of the stratosphere during the whole year. 4. The total ozone distribution of the pre-stage(before two months) of the SSW is quite different from the secular mean distribution in that month. 5. The strength of the centre of the total ozone continuously increases more than 20% each month in the SSW place from the before two months of the SSW to the warming-month. 6. The total ozone maintains more than 10% of minus anomaly from the pre-stage to the post-stage(after two months) in the SSW place, i.e the SSW occurs in the place where the total ozone maintains minus anomaly for a long time.

• AN ESTIMATION METHOD OF DETECTING EFFICIENCY OF A LLS
• Chen Mingli;Guo Changming;Liu Xinsheng
• 1991 Vol. 10 (3): 287-292. 
• Abstract ( ) PDF (374KB) ( )
• By analyzing the characteristics of Magnetic Direction Finder(MDF) System, we suggest that there are two main factors which can affect seriously the detecting efficiency of Lightning Location Systems(LLS). One is the setting of wave shape criteria and amplitude threshold value.The another one is the environment of DF site and the limited processing speed of DFs and Position Analyzer(PA). Using a new estimation method of DF detecting efficiency developed in this paper, we have got some results on DF detecting efficiency for a LLS installed in Beijing region. The results indicate that:1) The maximum detecting efficiency of the DF in this system is about 70%;2) The interference signal can lower the DF detecting efficiency.

• A MODEL CALCULATION OF ATMOSPHERE ELECTRIC VORTICITY IN CONVECTIVE STORMS
• Zhang Yijun;Yan Muhong
• 1991 Vol. 10 (3): 293-304. 
• Abstract ( ) PDF (716KB) ( )
• Basing on electric parameters measured in actual storms and considering that charges distribute along a axial symmetry cylinder, in this paper the changing rate of vertical electric vorticity with time in shear and anvil storms are calculated respectively. The result indicates that the rate of vertical electric vorticity variation with time caused by electric field force is about the order of 10-7-10-8/s2, which can be matched with the changing rate of vertical dynamic vorticity. The magnitude is the largest at storm bottom and with increase of height decreases. The electric energy concentrates mainly in middle and low layer of storm. The result is same as in anvil storms, but the magnitude is a order smaller. Meanwhile, the result also indicates that the convective motion of charged hydrometer particals due to electric field force can form horizontal vortox of air current. The electric circulation is an important factor.

• INFLUENCE OF HEAT SOURCE ANORMAL OF UNDERLYING SURFACE OVER TIBETAN PLATEAU AND WESTERN TROPICAL PACIFIC ON SHORT-TERM CLIMATE IN CHINA
• Liu Xiaodong;Hui Xiaoying;Chen Baode
• 1991 Vol. 10 (3): 305-316. 
• Abstract ( ) PDF (797KB) ( )
• By using a two-level, grid point, global general circulation model, three numerical experiments including the control one, the one with the increase of the surface albedo in Tibetan Plateau as well as the one with the increase of the sea surface temperature(SST) in western tropical Pacific have been conducted in order to investigate the influence of underlying surface heat source abnormal in this paper. The results suggest that when the heat source intensity in the Plateau is reduced by increasing its surface albedo, the continental low at sea level over Asia weatens;the 500 hPa height over the Plateau and to its west side falls, but that in the north of Yellow River rises;the precipitation in the Plateau, the reaches of Yangtse River, Huai He and Hei Long Jiang decreases, but that in the areas from the north Xinjiang and Nei Mongol to the reach of Liao He as well as southwest and southeast part of China increases. When the SST over west tropical Pacific increases, the continental low trough at sea level extending toward east China deepens;the geopotential height from north European to Tajmyr Pennisula rises, but that in north Asia falls;the precipitation in most of west China, Da Hingg An Ling and Mid-and lower-reaches of Yangtse increase, but that of rest China decreases. In addition, the possible application of heat source abnormal of underlying surface to short-range climate in China is also discussed in the paper.

• A PRELIMINARY STUDY OF TRACKING AND WARNING SEVERE STORMS BY THE METHOD OF TRACKING ECHO CENTROIDS
• Liu Liping;Xu Baoxiang;Wang Zhijun
• 1991 Vol. 10 (3): 317-324. 
• Abstract ( ) PDF (487KB) ( )
• Using the method of tracking echo centroids, we have analysed the C-band digital weather radar data observed during the events of thirteen isolated severe storms and one squall line weather in 1987 and 1988, and presented the main results in forecast application, including forecast errors of cloud centroids under different weather conditions and for different intensity thresholds or different forecast time periods, and finally determined the suitable forecast parameters and corresponding forecast accuracy. On the knowledge, we will further introduce this program of tracking and warning storms into our digital radar analysing system for applications of the hail suppression and the flood forecast.

• THE INTERANNUAL VARIANCE OF SURFACE NET RADIATION OVER LHASA RAGION
• Jiang Hao;Qu Zhang
• 1991 Vol. 10 (3): 325-331. 
• Abstract ( ) PDF (425KB) ( )
• In this paper, the meteorological element and surface net radiation at Lhasa station is basic data, which observed during Qinghai-Xizang Plateau's field heat sources experiment from August 1982 to July 1983. Base on these two data series and there relationship, the monthly surface net radiation from January 1953 to December 1980 of Lhasa station are calculated by new method. The interannual variance's characteristic of surface net radiation and the relation between above characteristic and 500 hPa height field are analysed. The results are as follows:the main period of interannual variance of surface net radiation is about three years, and there is a late response for one month in the variance of 500 hPa height field to the surface net radiation.

• THE INFLUENCE OF "ABRUPT CLIMATIC CHANGE" UPON THE STATISTICAL CORRELATION OF CLIMATIC FACTORS
• Li Cunqiang
• 1991 Vol. 10 (3): 332-336. 
• Abstract ( ) PDF (324KB) ( )
• The statistical method is still one of the most important methods of long-range weather forecasting and climatic prediction. Although the statistical means and methods were unceasingly improved in recent years, the accuracy of statistical prediction have not marked progress. In this paper, the change of the correlative stability of climatic essential factors around several "abrupt climatic change" in recent 100 years were calculated and analysed. It is shown that the "abrupt climatic change" is one of the most important reason that it influenced the statistical correlation stability of climatic factors. So it is also one of the most important reason influencing the accuracy of statistical prediction.