Current Issue

• A RESULT OF NUMERICAL SIMULATING OF THE STRONG COLD ISLAND
• Hu Yinqiao
• 1987 Vol. 6 (1): 1-8. 
• Abstract ( ) PDF (585KB) ( )
• The structure of a strong cold island has been simulated by a two-dimensional and steady-state numerical model of the planetary boundary layer.This model has included the horizontal inhomogenei ties of the eddy exchange coefficient and horizontal turbulent exchange.

• ESTIMATION OF RADIATION AND TURBULENT FLUXES IN THE SURFACE LAYER
• Wang Jiemin
• 1987 Vol. 6 (1): 9-20. 
• Abstract ( ) PDF (753KB) ( )
• Based on several atmospheric boundary layer experiments, the methods of estimating the radiation and the turbulent fluxes in the surface layer by using the routine meteorological data are investigated, particularly the simplified calculation method for net radiation, the application of the profile method, and the assessing method for the parameters of the resistance formula. The model results are compared with observations.

• ON SOME VERTICAL INTERPOLATION SCHEMES AND NEW FORM OF HYDROSTATIC EQUATION
• Qian Yongfu
• 1987 Vol. 6 (1): 21-30. 
• Abstract ( ) PDF (658KB) ( )
• The accuracy of vertical interpolation of the initial data in numerical prediction is one of widely concerned problems.Some vertical interpolation schemes are checked in this paper by using given vertical profiles of both the temperature and the geopotential height fields.those schemes are the Lagrange method,the local linear interpolation method and the local spline method which is suggested in this paper by the author. Tests indicate that all of those three methods have quite good accuracy when the vertical resolution is high, for example, the number of vertical levels is ten or more, none of them can give satisfactory results when the vertical resolution is very low, for instance, the number of the levels is three or less. Generally speaking, the vertical resolution with 5 or more levels will obtain quite adequate interpolation accuracy. It is also suggested that a new form of the hydrostatic equation which is given in this paper should be used in order to keep the initial accuracy of the interpolated data. The new form keeps the balance between the temperature and the geopotential height fields in the vertical direction.

• THE CLIMATIC CHARACTERISTICS OF BOUNDARY LAYER WIND FIELD OF CHINA IN SUMMER AND WINTER
• Tang Maocang;Ma Zhuguo
• 1987 Vol. 6 (1): 31-44. 
• Abstract ( ) PDF (967KB) ( )
• Based on the upper wind data in January and July(1960-1969),the resultant wind field of three standard layers near surface layer was analysed, which shown that* A) boundary layer wind can be divided into three wind sys terns(Planet ary Western Wind, Plateau Monsoon and Ocean-Land Monsoon) j B) there are Low-Level Jets(LLJ) near the regions with strongest surface thermodynamics contrast in the boundary layer;C) the vertical profile of wind speed in LLJ region is like "S"; D) in summer, to the east of Tibet Plateau, there are two LLJ regions, they are matched with the two steps of topography respectively,while to the east of Rocky Mountain only one LLJ matched the topogrphic step.

• THE ENVIRONMENT ANALYSIS ON 500hPa VORTEXES MOVING EASTWARD OUT OF TIBET PLATEAU IN SUMMER
• Qiao Quanming
• 1987 Vol. 6 (1): 45-55. 
• Abstract ( ) PDF (715KB) ( )
• Using the composite analysis method, We analysed both basic meteorological element fields and the vorticity balance of two types of 500hPa plateau vortexes which moved eastward out of the plateau on 500hPa in summer. It is shown that the westerlies vortexes can be moved eastward out of the plateau only when there is a explosive cold trough in the west part of the plateau.Their moving directions and velocities are steered by the flow between 200 and 300hPa;The easterlies vortexes moved under control of the centre of heavy precipitation which was resulted from Indian monsoon stretched eastward East China.

• A STUDY ON THE MOVING SOUTHWARD OF SHEAR LINE WITH QUASI E-W ORIENTATION OVER QINGHAI-XIZANG PLATEAU
• Liu Fuming;Pan Pingshan
• 1987 Vol. 6 (1): 56-64. 
• Abstract ( ) PDF (611KB) ( )
• Based on the statistical analyses of the moving characters of the Plateau shear line with Quasi E-W orientation at 500 hPa during the period of May-September of 1977-1981, emphasis is placed on the reason for moving southward of the shear line. It is shown that the moving southward of the shear line is related to the intensification and moving south eastward of the anticyclone on its north side and to the weakening of subtropical high on its south side. As the shear line moves southward, there is moving southward of clockwise circulation cell associated with the moving southward of subtropical jet on the longitude cross-section of vertical circulation through the shear line.The maintenance and intensification of both the shear line and anticyclone on its north side are related to those of the vertical circulation cell.

• THE ELECTRIC FIELD PRODUCED BY THE LOWER POSITIVE CHARGE CENTER OF THUNDERCLOUD
• Wang Caiwei;Chen Qian;Liu Xinsheng;Guo Changming;Ge Zhengmo
• 1987 Vol. 6 (1): 65-74. 
• Abstract ( ) PDF (679KB) ( )
• Some characteristics of the ground electric field, precipitation, corona current and lightning flash are described when a thunder cloud was overhead in Dongxiang,Gansu Province in the summer of 1985. Observation and analysis show that the high and persistent positive electric field on the ground is due to the positive charge region in the lower portion of the clouds,while the fast transitions of the electric field from negative to positive and positive to negative are mainly the consequence of the positively charged raindrops falling from the cloud base. The heavy rain and the frequent lightning flashes during the positive electric field on the surface suggest that there is a powerful and precipitation-associated mechanism of electrification in thunderclouds, which makes raindrops charged positively and the lower positive charge center persist long. The life time, the dimensions and the formation cause of the lower positive charge center of the thundercloud we observed are quite different from that reported by Holden et al.(1980) and Marshall et al.(1982).

• A SUPERCELL HAILSTORM FORMED BY ECHO MERGENCE
• Ye Zongxiu;Xu Baoxiang;Gong Naihu;Chen Qian
• 1987 Vol. 6 (1): 75-85. 
• Abstract ( ) PDF (760KB) ( )
• In this paper we analyse the evolution and structure of a supercell hailstorm which was developed from a complete mergence of the intense echo cores of storms in Dongxiang area of Gansu province on July 13, 1985. The diagnostic analyses of the local enviroment conditions and mesoscale trigger mechanism for the storms have also been performed in conjunction with the rawinsonde data of Lanzhou and Xining, and densified surface data from east Qinghai and middle Gansu area.

• THE TRANSITION FROM HIGH SUMMER DROUGHT TO MUCH RAIN SPELL OVER NORTH-EAST SLOPE OF QINGHAI-XIZANG PLATEAU
• Huang Xiaoli
• 1987 Vol. 6 (1): 86-89. 
• Abstract ( ) PDF (299KB) ( )

• A PRELIMINARY ESTIMATION OF THE FARMLAND'S EVAPORATION IN THE HEXI AREA
• Wu Jingzhi;Li Dinghua
• 1987 Vol. 6 (1): 90-93. 
• Abstract ( ) PDF (290KB) ( )