Current Issue

• COMPARATIVE ANALYSES OF DIFFERENCES BETWEEN CIRCULATION AND DYNAMICAL EFFECT OF QINGHAI-XIZANG PLATEAU OVER NWCHINA DROUGHT AREA IN DRY-AND WET-SUMMER
• WU Tongwen;QIAN Zhengan
• 1996 Vol. 15 (4): 387-396. 
• Abstract ( ) PDF (373KB) ( )
• To further analyze the forming cause of the drought over the northwest China and to also seek the relation among all the factors which may cause the drought,in this paper,the differences between the circulation and the dynamical influences of the Qinghai-Xizang Plateau on the north side of the Plateau(NSP) in dry-and wetsummer have comparatively been analyzed utilizing the gridded data of ECMWF for June to August of 1979-1986.The cont ribution of the differences to the dry-or wet-summer climate on NSP has also been discussed in the paper.The main results show that the combined effects of the Plateau thermal and dynamical influences,dominant circulation,as well as the geophysical environment far from the ocean result in the drought backg round over the northwest China.The year-to-year difference of each factor leads to the dry or wet year in northwest China drought area.The schematic diagram showing how to cause the dry and wet years on the NSP area has,finally,been drawn.

• THE INFLUENCE OF SNOWON THE SURFACE NET RADIATION OVER QINGHAI-XIZANG PLATEAU IN WINTER
• SHEN Zhibao
• 1996 Vol. 15 (4): 397-403. 
• Abstract ( ) PDF (250KB) ( )
• The results of the previous studies show that the geographic distribution of surface net radiation over the Qinghai-Xizang Plateau in winter consist of a basic pattern determined by the geographic conditions and a perturbation pattern caused by snow.In order to study quantitatively the perturbations of surface net radiation caused by snow,the daily totals of surface net radiation and their variations after snow with different snowfall were calculated by use of the relationship between the albedo after snow and the snowfall,and the empirical formulae for calculating surface net radiation in cases of snowcover.The results show that the duration of negative surface net radiation after snow is determined mainly by the snowfall,6 days of the duration of negative surface net radiation may occur when snowfall is 2.0mm,but 20 days when snowfall is 10.0mm.The sunshine duration affects strongly the magnitude of surface net radiation,the absolute value of the totals of net radiation in case of the clear day( S ₁=0.9) is greater than that in cloudy day( S ₁=0.2) after snow with the same snowfall.In winter,the surface net radiation is positive in Nagqu if none of snowcover,the monthly totals of surface net radiation in December is about 2.52-2.88MJ/m ².But the totals of the negative surface radiation budget after snow with the snowfall 10.0mm is -2.62MJ/m ²,the absolute value of which is nearly equal to the monthly totals of the positive surface radiation budget(3.19MJ/m ²) in Lhasa.

• THE SPATIAL AND TEMPORAL DISTRIBUTIONS OF THE TEMPERATURE AND PRECIPITATION ANOMALIES IN SOUTH QINGHAI PLATEAU DURING WINTER HALF YEAR AND THEIR CORRELATION WITH SNOW DISASTER IN PLATEAU
• JIN Liya;WU Yongsen;QIN Ningsheng
• 1996 Vol. 15 (4): 404-413. 
• Abstract ( ) PDF (319KB) ( )
• In this paper,by using the mean precipitation and air temperature anomalies data obtained from 15 observational stations in South Qinghai Plateau during the period of 1959-1993's winter half year,and with a joint-space and-time EOF method,a diagnostic study of the feature of spatial and temporal distribution of the precipitation and air temperature in South Qinghai Plateau is presented.Some typical patterns of precipitation and air temperature as well as the coefficients of their interannual variation are obtained.The results show that there is a good correspondence relationship between the severe snow disaster year in Sonth Qinghai Plateau and the extremum(maximum or minimum) year of the time coefficient.

• NUMERICAL EXPERIMENT OF UNSTABLE THEORY FOR MESOSCALE SYSTEM WITH HEAVY RAIN
• MA Yan;CHENG Linshen
• 1996 Vol. 15 (4): 414-424. 
• Abstract ( ) PDF (371KB) ( )
• Based on studies of the previous instable theories,a method that unstability problem is solved by initial value problem but not calculating eigenvalue problem is presented.Considering the perturbation pressure and moisture,we developed a twodimension linear nonhydrostatic model which describes comprehensively the characters of the unstable disturbance.The fact that the experimental results of symmetric instability and slantwise instability conform to previous theoretical results prove that the method is successful.Results of numerical experiment show conditional gravitational instability led to the occurence of the heavy rain during 12:00UTC 5-00:00UTC 6 July,1991.

• A SIMULATION STUDY OF NON-INDUCTIVE CHARGINGMECHANISM IN THUNDERSTORM Ⅰ.AFFECT OF CLOUD FACTOR
• YAN Muhong;LIU Xinsheng;AN Xuemin;ZHANG Yijun
• 1996 Vol. 15 (4): 425-437. 
• Abstract ( ) PDF (375KB) ( )
• In this paper,an axisymmetric,time-dependent numerical cloud model has been applied to study non-inductive charging,and to discuss affect of convection,rainfall and ice crystal size distribution on the charging The results show that there are intensive charging in the cloud when intensive updraft centre passes -20℃ temperature layer,and one appear during the updraft velocity just begins to decrease after acquiring maximal updraft velocity After,with as increasing of space charge concentration,with as droping of height of main negative charge center and that there is a stable height The ice crystal size distribution can change vertical structure of ice particles,and also can change charging rate and time-space charge distribution The simulated positive charge center in the lower part of the cloud has shorter duration The results also show that if just weaken updraft can maintain relatively intensive velocity,the duration of the lower positive charge center also can increase This perhaps is a reason of different characteristic in lower positive charge center for southern and northern thunderstorms.

• A SIMULATION STUDY OF NON-INDUCTIVE CHARGINGMECHANISM IN THUNDERSTORM Ⅱ.AFFECT OF ENVIRONMENTAL FACTOR
• YAN Muhong;LIU Xinsheng;AN Xuemin;ZHANG Yijun
• 1996 Vol. 15 (4): 438-447. 
• Abstract ( ) PDF (348KB) ( )
• In this paper,observational data and an axisymmetric,time-dependent,numerical cloud model has been applied to study relationship between electrical action and environmental factors in the thunderstorm.The results show that the condition of temperature and humidity at ground layer,stratification thermal instable factors,and convective available potential energy(CAPE),and so on can not singly represent intensiver or weaker of electricalaction in thunderstorm.Simulating calculations show that only when cloud-top height passes through the temperature layer of -20℃,there are intensive electric actions in the cloud.The thermal and kinetic forcing of the air around cloud base and temperature layers of -10℃,-20℃ can well exhibit intension of electric actions in the thunderstorm.Above three kinetic fo rcing have optimumth reshold value,0.8-0.9,60.0-80.0,20.0 J/kg,respectively.There are positive relationships between above three factors and electric charge concentration,and have upper limit threshold value.The simulated cloud has the tripolar charge structure for seven plateau stratification conditions.

• THE MESOSCALE ANALYSIS OF SEVERE DUST DEVIL FORMATION OVER THE NORTH-WEST OF CHINA
• XIANG Xukang;JIANG Jixi
• 1996 Vol. 15 (4): 448-455. 
• Abstract ( ) PDF (301KB) ( )
• Based on GMS satellite data,the formations of the six severe dust-devil events over the North-west of China are analysed The results indicate that the genesis of dust-devil is caused by mesoscale systems,which include the mesoscale-α squall line system,the mesoscale-Upàēě severe convective system and the mesoscale convective complex The characteristics,development process and large scale environment of these mesoscale systems are also analysed in the work.

• THE MESOSCALE STRUCTURE CHARACTERISTICS OF SOUTHWEST VORTEX OVER JIANG-HUAI RIVER AREAS
• WEI Tongjian;XUE Jianjun
• 1996 Vol. 15 (4): 456-463. 
• Abstract ( ) PDF (301KB) ( )
• By using composite method,the three cases of low vortex occurring along the Yangtze River valley are presented in this paper.Structures of airflow vertical motion,temperature,humidity fields are analysed.The analyses indicate that there is a series of wave along the shear line in the mesoscale wind field and the low vortex wavelength is 250-300km.The low vortex is a baroclinic system and the heavy rain usually occurring on its right side.

• NUMERICAL SIMULATION OF WIND AND TURBULENCE STRUCTURE IN NATURAL VENTILATION IN OPEN MINE
• WANG Weiguo;LIU Hongnian;JIANG Weimei;HU Yongtao
• 1996 Vol. 15 (4): 464-471. 
• Abstract ( ) PDF (288KB) ( )
• A three-dimensional,nonhydrostatic atmospheric boundary layer numerical model,in which simple energy closure scheme was used,has been developed.Under the condition of netural stability the special wind and turbulence fields in natural ventilation at a open iron mine in Hubei were simulated by using this numerical model.Their characteristics and impact factors were studied.The results indicated that,when the ratio of mine depth to mine width was small or the inflow shear was lower,a straight-pattern of the airflow was found in pit,this was favourable for the ventilation.On the contrary,the circulation area in pit appeared easily and high value of TKE was found in the circulation area.Under this condition,natural ventilation in pit was difficult and the high value of the pollutant concent ration may be found.Horizontal wind field was obvisouly affected by terrain near the bottom of pit or on the pit wall.Some results obtainted from this model were agreement with these from wind tunnel simulation or high-order closure model.

• CORRELATION ANALYSIS BETWEEN ANNUAL RUNOFF TYPES AND SOIL TEMPERATURE FIELD IN TANGNAIHAI
• CAI Ying;WANG Dongmei
• 1996 Vol. 15 (4): 472-477. 
• Abstract ( ) PDF (215KB) ( )
• In this paper,the annual runoff(1956-1994) of upper reaches of Yellow River are classified into five types:rich,normal,poor water years,first poor water then change into rich water(normal) and first rich water(normal) next poor water years.The seasonal mean soil temperature fields at 3.2m depths in spring and summer in the runoff source area are classified into warm vortex,warm vortex lies in the east or west,warm vortex decreasing and vanishing,zero deviation field and cold vortex six categories.We find that there is good correlation between soil temperature types and annual flow-off cycles,so,we may make qualitatively preliminary prediction of runoff of Tangnaihai reservoir.

• ANALYSIS AND FORECAST FOR INTERANNUAL VARIATION OF THE QINGHAI LAKE'S WATER LEVEL
• ZHOU Lusheng;WANG Qingchun
• 1996 Vol. 15 (4): 478-484. 
• Abstract ( ) PDF (241KB) ( )
• Based on Shatuosi hydrologic station's data from 1959 through 1992,the influence of antecedent climatic type,SST of the North Pacific Ocean,Arctic sea ice and El Nino event on the interannual variation of the Qinghai Lake's water level is analyzed.The valuable results can be used to forecast the three states for next year's water level variation by using Bayers successive discrimination method.

• FIELD TO FIELD PREDICTIVE MODEL AND ITS APPLICATIONS TO CLIMATIC PREDICTION
• ZHANG Wancheng;WANG Yu;HENG Jianmeng
• 1996 Vol. 15 (4): 485-489. 
• Abstract ( ) PDF (183KB) ( )
• In this paper,the predictand fields and predictor fields are analysed by using EOF methed,a model of field to field prediction using time coefficient as predictand and predictor is given.The time changing parameter is considered throughly in the model.It is applyed to forecasting rainfall in May in Yunnan province.The predictive results show the model has a certain virtue in the forecasting of regional rain.

• DEVELOPMENT OF ECMWF'S SPECTRAL MODEL WITH REFERENCE ATMOSPHERE ON CONVEX320
• CHEN Jiabin;SHU Jingjun;CHEN Xiongshan
• 1996 Vol. 15 (4): 490-495. 
• Abstract ( ) PDF (238KB) ( )
• ECMWF's spectral model has been transplanted to the computer Convex 320,with modified the configuration of I/O Reference atmosphere is introduced in the model,and 6 cases are computed CXS-scheme is also tested with the model Interest results have been obtained.

• THE RELATIONSHIP BETWEEN THE QINGHAIXIZANG PLATEAU TEMPERATURE FIELD AND DROUGHT IN GUIZHOU PROVINCE
• FANG Zhifang;LI Chao;LI Xianlang
• 1996 Vol. 15 (4): 496-502. 
• Abstract ( ) PDF (265KB) ( )
• The relationship between the Qinghai-Xizang Plateau temperature and the drought in Guizhou province during spring and summer are investigated using Singular Value Decomposition(SVD) of temporal covariance matrix.It is shown that the spring drought center is located in the west of Guizhou province,the summer center is located in the east and middle of the Guizhou province.When there is the large temperature anomalous area in the Qinghai-Xizang Plateau during March or September,it would forecast the spring drought area of Guizhou in next year.The large area for temperature anomalies of the Plateau in November could forecast the summer drought area for Guizhou province in next year.When the large temperature anomalies appear in Plateau during summer,the Plateau Warm High Pressure will cause the air divergence and sinking motion around the Plateau,this would be areason of summer drought in Guizhou province.

• A STEAM FOG GENERATOR OF USING ULTRASONIC VIBRATOR IN SMALL VERTICAL SUPERCOOLED CLOUD TUNNEL
• ZHANG Tong;GONG Naihu
• 1996 Vol. 15 (4): 503-507. 
• Abstract ( ) PDF (179KB) ( )
• In the paper,the YaDu industrial ultrasonic humidifier that is installed in a small vertical supercooled cloud tunnel has been rebuilt.It becomes a steam fog generating system for cloud tunnel experiment.In the experiment,the fog's dro plets-size distribution is measured,and the ice-snow crystal growth process is simulated.The results show that this system is very convenient,safe and reliable for the experiment,and simulation also is true.

• APPLICATION OF DUAL-POLARIZATION RADAR IN HYDROLOGICAL FORECAST——A DEVELOPMENT OF HYDROLOGICAL FORECASTING SYSTEM
• LIU Liping;QIAN Yongfu;WANG Zhijun
• 1996 Vol. 15 (4): 508-514. 
• Abstract ( ) PDF (250KB) ( )
• Based on the data of stream flow and rainfall from hydrological and raingauge stations in Bajiazui reservoir from 1980 to 1987,the model of automatic and real-time hydrological forecast was developed,which used the dual-polarization radar data observed in Pingliang Radar Station,Lanzhou Institute of Plateau Atmospheric Physics,Chinese Academy Sciences When the computer in office of flood control received the radar data sent by radio,the model could forecast the hydrological parameters,including total amount of rainfall,run-off,outflow rate,stream flow of the peak of flood,the time of peak,displaying and printing these parameters Comparison with conventional forecast method,this forecast model with radar was accuracy,real-time,especially for storms The model provided basic data for the anti-flood direction and flood controlling In this paper,a new and advanced science and technology in meteorology was used in hydrology The work developed the applied range of meteorological radar.