Current Issue

• A STUDY ON THE EFFECTS OF CLIMATIC FEATURE OF OLR OVER THE QINGHAI-XIZANG PLATEAU ON GENERAL CIRCULATION IN NORTHERN HEMISPHERE
• LI Dongliang;ZHANG Jijia;WU Hongbao
• 1996 Vol. 15 (3): 259-268. 
• Abstract ( ) PDF (359KB) ( )
• Based on the NOAA's monthly mean gridded OLR datd over the Qinghai-Xizang Plateau from 1974 to 1990,the first three characteristic vectores and their distribution feature of time and space anomaly have been analysed by EOF method.The climatic feature of OLR and the persistence in different climatic regiones and the relationship between OLR and general circulation over Northern Hemisphere were studied.It is shown that the anomaly of OLR can cause the anomaly of 500hPa monthly mean general circulation over Northern Hemisphere.A Rossby quasi-permanent wave train propagates along large circle route in the same time.There is a good persistence of OLR over the Qinghai-Xizang Plateau in winter and it can cause the anomaly of general circulation with one or two months lag.There are only northeast and northweest wave trains over the Qinghai-Xizang Plateau in summer.

• EFFECT OF CLOUD ON THE SURFACE NET RADIATION OVER THE QINGHAI-XIZANG PLATEAU
• WANG Keli
• 1996 Vol. 15 (3): 269-275. 
• Abstract ( ) PDF (240KB) ( )
• In this paper,utilizing the surface radiation and cloud data over the Qinghai-Xizang Plateau during the period from August 1982 to July 1983,the effects of cloud cover/type on surface net radiation flux were analysed and net cloud-radiative forcing and the other relative parameters were calculated.

• THE LOW-FREQUENCY OSCILLATION OVER THE QINGHAI-XIZANG PLATEAU AND THE ACTIVITIES OF THE SOUTH ASIA HIGH DURING THE SUMMER HALF YEAR IN 1981 AND 1982
• LI Yueqing
• 1996 Vol. 15 (3): 276-281. 
• Abstract ( ) PDF (210KB) ( )
• In this paper,the Low-Frequency Oscillation(LFO) in atmosphere over the Qinghai-Xizang Plateau(QXP) and its relationship with the activities of South Asia High(SAH) were analyzed during May September in 1981 with "the flood in west and the drought in east" and in 1982 with "the drought in west and the flood in east" in Sichuan basin.The result shows that the LFO in atmosphere over the QXP is significant,it is close associated with the activities of the SAH and the features of LFO with the activities of the SAH have obvious differences between in 1981 and 1982,which are basically opposite phase in west-east direction.Those features have definite significance for the understanding of flood or drought anomaly in summer in Sichuan basin.

• THE VARIABILITY PROCESS OF ATMOSPHERE OVER HETEROGENEOUS UNDERLYING SURFACE IN HEXI REGION
• ZHANG Qiang;HU Yinqiao;YANG Yufeng;ZHAO Hongyan
• 1996 Vol. 15 (3): 282-292. 
• Abstract ( ) PDF (375KB) ( )
• In this paper,the dynamic and thermodynamic characteristics of the underlying surface in Heihe River basin of Hexi regionin summer are analysed with the data observed in HEIFE(Heihe Earth-Atmosphere Interaction Field Experiment).Taking the data observed on a canonical clear day as an example,the process of the variability of atmosphere,which result from the sudden change of underlying surface from desert(or Gobi) to oasis or from oasis to desert(or Gobi) is given.From this,the mechanisms resulting in the inverse temperature gradient of surface layer over oasis and the inverse humidity gradient of surface layer over desert(or Gobi) have been explained primitively.Besides,the processes of water vapour transport over oasis and desert(or Gobi) is shown.

• THE PROPERTIES OF CLOUD AND CLUTTER ECHOESMEASURED BY DUAL LINEAR POLARIZATION RADAR AND DISCRIMINATION
• LIU Liping;WANG Zhijun
• 1996 Vol. 15 (3): 303-310. 
• Abstract ( ) PDF (297KB) ( )
• The clutter echo affects the measurement of rainfall rate and hydrologic forecast with dual linear polarization radar.In this paper,we have studied the range of reflectivity Z _H and differential reflectivity Z _DR and their spatial distributions in rainfall and clutter regions.The Z _DR of rainfall is positive and increases with increase of Z _H.This phenomena proved that there are more large particles in the region with great Z _H.But for the clutter,the values of Z _DR are positive or negative,and there is no obvious relationship between Z _H and Z _DR,the spatial variability of Z _H and Z _DR is greater than rainfall area.Based on these research,we have developed a model of discrimination between rainfall and clutter.The results of test is satisfied.This work is a new method reducing the effects of clutters on the dual linear polarization radar measurement,it can improved the results of measuring rainfall and hydrologic forecast.

• THE RELATIONSHIP AMONG SOIL TEMPERATURE ANOMALY AND EARTH DEFORQMATION AND PRECIPITATION ANOMALY
• MA Zhuguo
• 1996 Vol. 15 (3): 311-317. 
• Abstract ( ) PDF (283KB) ( )
• By using seasonal departure data of soil temperature at 3.2m depth( T' _3.2) from 1954 to 1993 in China,the spatial characteristics of terrestrial heat vortex have been analysed.The results indicate that the high frequency areas of soil temperature anomaly are similar to the areas of larger absolute value of earth deformation rate,and are similar to the high frequency areas of precipitation anomaly,but there is about 200km deviation between their centrical locations and that the lower frequency areas of soil temperature anomaly are alike to the areas of small absolute value of earth deformation rate,and are similar to the lower frequency areas of precipitation anomaly.The results also indicate that there is a difference between prohabilities of negative and positive anomaly created at the same place.The asymmetry geographic distribution of soil temperature anomaly is similar to the asymmetry geographic distribution of precipitation anomaly in China.

• SOME CONTRAST NUMERICAL EXPERIMENTS OF A LLJ AND HEAVY RAIN PROCESS IN SOUTH CHINA
• WANG Chunhong;JIANG Quanrong
• 1996 Vol. 15 (3): 318-325. 
• Abstract ( ) PDF (295KB) ( )
• This work is a continuation of article[1].Based on the successful modeling of a LLJ and heavy rain process on April-June flood period in South China,four contrast numerical experiments are analysed and discussed in this paper.The results show condensation latent heat and the Qinghai-Xizang Plateau relief are very important factors for forming heavy rain and maintaining LLJ in South China.Different boundary layer process and South China terrain play only arole in precipitation and its distribution.

• A NONLINEAR STATISTICAL-DYNAMIC CLIMATE MODEL AND ITS FEASIBILITY EXPERIMENT OF PRECIPITATION PREDICTION
• ZHENG Jianmeng;CAO Jie;LI Min;WANG Yu
• 1996 Vol. 15 (3): 326-333. 
• Abstract ( ) PDF (263KB) ( )
• In this paper,basing on a statistical-dynamic climate model with the linear feedback,we proposed one kind of nonlinear statistical-dynamic climate model and make use of the nonlinear statistical-dynamic model,rainfall prediction is tested in Mengzi during the rainy season.The phase linear method in the kind of nonlinear statistical-dynamic model is considered to describe the nonlinear character of climate.The forecast experiment results show that the kind of nonlinear statistical-dynamic model can accurately predict climate change.

• RESEARCH ON THE SOIL MOISTURE VARIATION RULE IN THE DRY LAND IN THE EAST GANSU
• QIU Huamin;DENG Zhenyong;FANG Debiao
• 1996 Vol. 15 (3): 334-341. 
• Abstract ( ) PDF (273KB) ( )
• The difference between the climate condition and the precipitation supply function with the crop growing state causes that the soil moisture have a special spatial and temporal distribution rule in the dry land in the East Gansu.The annual variation of moisture in 2m soil layer for the wheat field shows one peak and one valley pattern and is divided into the moisture consuming period in drougnt season and the moisture storing period in rain season.Its vertical change appears "S" pattern,and it is divided into the changeable layer,the transitional layer and the stable layer.

• INVESTIGATION OF LIGHTNING STROKE IN SHANGHAI REGION AND DISCUSSING OF PREVENTION MECHANISM
• YAN Muhong;HUA Guiyi;GUO Changming
• 1996 Vol. 15 (3): 342-349. 
• Abstract ( ) PDF (312KB) ( )
• In this paper,the case of lightning stroke has been investigated in Shanghai region,and its cause,characteristics,discharging way and destroied degree has been analysed for a lightning stroke event.Based on above mentioned and the stroke protection standard of the building,we also analyse working principle of some "lightning eliminator" and make to research and deliberate.

• DISCUSSION ON THE FORCING OF SNOW COVER ON THE QINGHAI-XIZANG PLATEAU IN SIMULATION OF ASIAN MONSOON CLIMATE
• LI Peiji
• 1996 Vol. 15 (3): 350-355. 
• Abstract ( ) PDF (240KB) ( )
• The effect of snow cover over the Qinghai-Xizang Plateau on Asian summer monsoon has been the focus of climatologists interest for more than century.However,up to now it is still a tough question as how gives reasonably snow forcing in the model.The results in recent numerical simulations of Asian summer monsoon climate have notable difference due to the difference of the spatial scales and snow depth anomalies given in each model.In this paper,the author suggests a realistic snow forcing on the Qinghai-Xizang Plateau based on ground truth of the Qinghai-Xizang Plateau snow cover estimated by 10-year SMMR snow data.It consists of average snow depth distribution on the Qinghai-Xizang Plateau during the winter snow maximum period,annual cycles of the Qinghai-Xizang snow water equivalent for normal,heavy,and light snow years,and snow depth anomaly distribution in 1985 1986 heavy snow year as well as in 1984 1985 light snow year on the Qinghai-Xizang Plateau.

• A STUDY AND EXPERIMENT ON SHORT-RANGE PREDICTION OF SEVERE CONVECTIVE WEATHER
• HU Fuquan
• 1996 Vol. 15 (3): 356-362. 
• Abstract ( ) PDF (237KB) ( )
• A method for making short-range prediction of severe convective weather is developed by analysing the physical mechanism for the creation and development of the severe convective weather which occurred in Shanghai area from 1976 to 1990.That's θ _se characteristic method.Warning index pattern show convective instability characteristic and high energy.Trigger mechanism and removal mechanism are introduced to extend the range of the prediction and decrease the wrong prediction rate.This method was tested and has already got good results in Shanghai area.

• THE APPLICATION OF RELATION GENERALIZED TEMPERATURE ADVECTION TO ANALYSIS AND FORECAST OF SEVERE CONVECTIVE WEATHER
• LI Houying;SUN Chengxun
• 1996 Vol. 15 (3): 363-369. 
• Abstract ( ) PDF (251KB) ( )
• The temperature advection and generalized temperature advection of the yesterday data for the severe storm processes in boundary region of Hubei,Jiangxi and Anhui provinces in April of 1994 and 8 other cases in history,are calculated and analysed.The results show that around the negative center of the difference between the upper and lower layers of generalized temperature advection will occure the severe convection weather.

• DESIGN PROBLEMS ON DUAL-LINEAR POLARIZATION RADAR
• WANG Zhijun
• 1996 Vol. 15 (3): 370-380. 
• Abstract ( ) PDF (375KB) ( )
• Dual-linear polarization radar as a special weather radar is followed with interest by people day by day.In this paper,the design problems and design indexes of antenna,transmitter-receiver and data processing system of dual-linear polarization radar have been discussed.The result is usefull for design and making of dual-linear polarization radar.

• PRELIMINARY RESEARCH ABOUT CALIBRATION METHOD OF DIGITIZED WEATHER RADAR AND DUAL-LINEAR POLARIZATION RADAR
• WANG Zhijun
• 1996 Vol. 15 (3): 381-386. 
• Abstract ( ) PDF (219KB) ( )
• It is very important to the calibration method of digitized weather radar and dual-linear polarization radar,because the precision of radar data is related with calibration error of radar,especially for dual-linear polarization radar,the normal value of Z _DR is only -3 0+5 0dB and the difference of Z _DR is less than 1dB for different kind of precipitation.In this paper,a calibration method of above-mentioned radar is introduced.It is useful for weather radar practical research.

• ELECTROSTATIC CHARACTERISTICSNEAR GROUND UNDER THUNDERSTORM AND ITS EFFECT ON ARTIFICIAL TRIGGERING LIGHTNING
• QIE Xiushu;YAN Muhong
• 1996 Vol. 15 (3): 393-302. 
• Abstract ( ) PDF (342KB) ( )
• Electro static characteri stics near ground under thunderstorm have been studied by using a one-dimension model.Maximum corona current density produced due to ground irregularities is about 2.0nA/m ².Space charge density below 100m is about 1.1nC/m ³,the conduction current density,at same level,can is about 3.5nA/m ².Coronaions can reach up to 1 000m above ground level with a space charge density of 0.1nC/m ³ and conduction current density of 1.0nA/m ².During dissipating stage of storm,coronaions can produce an electric field of about 3-4kV/m that is similar in magnitude and opposite in polarity to that when storm is active.Effect of the space charge layer should be considered in artificially triggering lightning experiment.Electric field at several hundred metre level above ground would be a better criterion for triggering lightning.Triggering lightning experiment by using present small rocket would be successful when the electric field in low altitude reaches about 70kV/m in Lanzhou region where thunderclo uds have a typical charge structure with a large amount of positive charge.