Current Issue

• MEASUREMENTS OF INTERNAL STORM MOTIONS BY CONVENTIONAL WEATHER RADAR AND COMPARISON WITH DOPPLER RADAR RESULTS
• Tang Dazhang;Fu Desheng;Li Li
• 1991 Vol. 10 (2): 113-122. 
• Abstract ( ) PDF (599KB) ( )
• After the paper describes briefly the principle and processing technique for measuring the wind field in echo area by use of moment invariant method, the wind vectors of every module in actual PPI echo data observed by digitized conventional weather radar are estimated. In order to value quantitatively the accuracy, the estimated vectors are projected onto radar azimuth to obtain radial speed estimations. And the estimations are then compared with the radial speed field observed simultaneously by single Doppler radar. The results of comparison for four cases in two precipitation processes show that average accuracy is near 80%, and above 90% if the edge effect is eliminited.

• THE DIFFERENCE BETWEEN ATMOSPHERIC HEATING FIELDS OVER THE WEST PACIFIC AND ITS SURROUNDING SEA AREA DURING TWICE El Nino EVENTS IN THE 1980S
• Yao Lanchang;Cai Ying
• 1991 Vol. 10 (2): 123-133. 
• Abstract ( ) PDF (720KB) ( )
• In this paper, the difference between atmospheric heating fields over the West Pacific and its surrounding sea area during twice El Nino processes in 1986-1987 and 1982-1983 is analysed.The results show that:(l)Atmospheric heating fields over the West Pacific and its surrounding sea area are very strong heat source during twice El Nino processes. But atmospheric heating intensity is stronger in the last El Nino time than in the first time.(2)There is evident difference for the location of strongest heating regions during twice El Nino.The distribution region of atmospheric heating field is unusual inclined toward north in tne last El Nino time and it is unusual inclined toward south in the first time. It is in agreement with variation of equatorial low belt in same period.(3)The difference of atmospheric heating intensities is mainly caused by the different of increasing latent heat of precipitation.

• CORRELATIONS BETWEEN THE PROFILE CHARACTERISTICS OF THE EASTERLIES AND WESTERLIES AND STATIONARY WAVES IN EQUILIBRIUM STATE
• Xu Xiangde;Zhu Fucheng;Lu Manyun
• 1991 Vol. 10 (2): 134-146. 
• Abstract ( ) PDF (729KB) ( )
• The correlations between profile characteristics of easterlies and westerlies and the structure of stationary waves of the general circulation equilibrium state, forced by external forcing, are investigated with a simplified two-level model. The connection between profile characteristics of the westerlies and seasonal characters of atmospheric circulation pattern are studied used observation data. The results indicate that the climatic features of westerly trough in the middle and high latitudes are correlated with the differences of westerly profiles in winter and summer, and the intense shear of easterlies in lower latitudes may be a cause for the periodic oscillations of easterly flow in the tropical region. The seasonal differences of westerly profiles in winter and summer can lead to different effects of orography and sea-land thermal forcings on the atmosphere. The research in this paper reveals the effects of basic flow characters on transformation of dominate wave patterns in the general circulation. Additionally, a characteristic function of westerly profiles and critical curves are also derived from the condition of resonant state between stream field and zonal thermal forcing.

• EFFECTS OF THE GROUND SURFACE ON THE DETECTION BY A DUAL LINEAR POLARIZATION RADAR
• Zhang Jianyun;Cai Qiming
• 1991 Vol. 10 (2): 147-155. 
• Abstract ( ) PDF (565KB) ( )
• When radar transmission wave is horizontally or vertically polarized, equations for calculating the returned power and the electric field distribution within radar beam have been derived, based on Ma Zhenhua work, especially, considering the effects of the ground surface on the measurement of ZHand ZDR. The results based on the equations show that effect of surface reflection on the echo power increses with detection range within a certain distance, and does not change with detection range out of the certain distance. The effect on vertical polarization radar is smaller than that on horizontal polarization radar. The longer the wave-length is, the greater the effect is. The results also show the effect of surface reflection on the measurements by a dual linear polarization radar which causes a error of ZDR about +0.6dB. The longer the wave-length is, the smaller the effect on ZDR is, when the elevation is higher than the radar beam width, the effects of the surface reflection on returned power or ZDR seem to be neglected.

• COMPOSITE DIAGNOSES OF THE SW CHINA VORTEXES
• Ding Zhiying;Lu Junning
• 1991 Vol. 10 (2): 156-165. 
• Abstract ( ) PDF (629KB) ( )
• In this paper, 16 cases of the SW China vortexes have been chosen, including 8 cases each both remaining in the origins(RV) and moving east-and northeast-wards out of their origins(MV). Their composite diagnoses of physical variables and kinetic energy were also done. The diagnoses show:(1) For the MV, the rising motion occurs in the east of the vortex;for the RV, in the west of the vortex.(2) The conversion between barotropic and baroclinic energy is stronger for the MV than for the RV, and their thermal structures are opposite as well.(3) For the MV, the gain of kinetic energy is larger than its lose;for the RV, vice versa.

• PRELIMINARY ANALYSIS OF THE CHARACTERISTICS OF ATMOSPHERIC RADIATIVE HEATING FIELDS DURING THE AUTUMN IN THE MID LATITUDE ARID AREAS OF CHINA
• Ji Guoliang;K. N. Liou;;S. C. Ou
• 1991 Vol. 10 (2): 174-186. 
• Abstract ( ) PDF (790KB) ( )
• A parameterized radiation and cloud model developed at the University of Utah U.S.A. is used to compute the atmospheric radiative properties in Zhangye area during the pilot experement of HEIFE in September 1988. Some characteristics of atmospheric radiative heating fields during the Autumn in Zhangye area has been analysed. Some questions that merits attention in future observation are also discussed in this paper.

• A COMPOSITE ANALYSIS OF THE VORTEX OVER NORTHEAST SICHUAN BASIN
• Luo Hong;Yu Shuhua
• 1991 Vol. 10 (2): 187-193. 
• Abstract ( ) PDF (437KB) ( )
• A composite analysis of five cases of 700 hPa vortex with heavy rain, located at Lang-Zhong in northeast of Sichuan, is studied. The results show the vortex is a deeper system and it's horizontal scale is about 300-400 km. A very strong ascending motion mainly located in eastern of the vortex. The well-developed vortex has baroclinic feature.

• APPLICATIONS OF DECISION MATRIX TO DETERMINING THE WEIGHTS AND PRIORITIES AMONG MULTI-FORECAST FACTORS
• Long Congbin
• 1991 Vol. 10 (2): 194-201. 
• Abstract ( ) PDF (412KB) ( )
• In this paper, a new method for determining the weights and priorities among multi-forecast factors by using decision matrix was proposed and an accurate proof of it according to theory of matrix was given as well. It makes the determining of the weights and priorities among multi-forecast factors more reasonably, instead of artificially. The paper describes the steps of selecting multi-forecast factor in building the Microcomputer Expert System for Forecasting Spring Cold Wave Weather over Yaan District, Sichuan Province, utilizing the new method.

• THE DIAGNOSTIC ANALYSIS OF THE SUDDEN WARMING PROCESS IN NORTHERN HEMISPHERE AT 10 hPa IN WINTER
• Wang Yupei;Li Weijing
• 1991 Vol. 10 (2): 202-208. 
• Abstract ( ) PDF (441KB) ( )
• The study shows that the sudden warming at 10 hPa is a result of the horizontal transfer of the warm air from the lower latitude in Asia and Africa to the higher latitude and northern polar region. The special divergence field under the double polar circulation at 10 hPa is the thermodynamical processes of the strengthening of the warm advection transfer and sudden warming. The geostrophic wind convergence is the dynamic processes of the increase of warm air and the development of the anticyclonic circulation. They are the source of the forced oscillation of the circulation anomaly occurred in stratosphere in winter and the establishment of east wind circulation in Polar Highs.

• PRELIMINARY STUDY OF CHEMICAL COMPOSITION OF PRECIPITATION AT WUDAOLIANG, QINGHAI PROVINCE
• Yang Longyuan;Ren Yanxia;Jia Li
• 1991 Vol. 10 (2): 209-216. 
• Abstract ( ) PDF (539KB) ( )
• It has been determined that the chemical composition of precipitation at Wudaoliang, Qinghai Province. The data of 6 samples of precipitation in August of 1989 show 6.88-7.50 of pH value;7.7-35.0/μΩ/cm of electric conductivity.The chemical composition of precipitation have equal level to data which has been determined in Alaska area. The results show that the air over Wudaoliang area is very clean, and anthropogenic effect is little. The Wudaoliang station is suited to set up a globle baseline station of background air pollution monitoring.

• THE NUMERICAL EXPERIMENTS ABOUT THE EFFECTS OF SEVERAL FACTORS ON THE FORMATION OF SUPERCELL AIRFLOW PATTERN
• Wang Siwei;Xu Huanbin
• 1991 Vol. 10 (2): 217-224. 
• Abstract ( ) PDF (512KB) ( )
• The factors controling the evolution of convective air flow can be classified into two kinds. The ones are environmental factors such as buoyancy and wind shear;The others are derivative factors associated with convective development such as the interruption of horizontal velocity of air motion beneath the cloud base and the propagation of convective air flow field relative to hydrometeor. In order to explore the effects of these factors on the formation of supercell storm the numerical experiments have been done with two-dimensional model(TDHM).The results indicate that the environmetal factors are basic ones which determine the embryonic form of convective air flow pattern, the derivative factors affect the evolutional direction of air flow pattern. The proper coordination of both factors favour the formation of supercell.