Current Issue

• CONTRAST ANALYSIS OF TWO DETECTIVE RESULTS ON HAILSTORM WITH 714CD WEATHER DOPPLER RADAR AND 711 RADAR
• WU Zhi-fang;ZHANG Pei-yuan;ZHANG Chun-liang
• 2000 Vol. 19 (1): 1-8. 
• Abstract ( 278 ) PDF (355KB) ( 448 )
• The structure and the evolution process of a stronger hailstorm over Weigan River Area,Xinjang is described.By means of observation and contrast,the differences between the two results taked by 714CD weather Doppler radar and 711 radar are analyzed.The result shows that the detective precision of 714CD is higher than that of 711 radar and the detective rang of 714CD is larger.The two radars are identical in detecting hailstorm structure.

• DISCUSSION ON THE RELATIONSHIP BETWEEN GLACIAL FLUCTUATION AND CLIMATE CHANGE
• GAO Xiao-qing;TANG Mao-cang;FENG Song
• 2000 Vol. 19 (1): 9-16. 
• Abstract ( 631 ) PDF (297KB) ( 679 )
• Glacial fluctuation is the result of climatic change,but the relationship between them is not stable.Theoretical analysis in this paper reveals that glacial fluctuation in time scale longer than century is controlled mainly by temperature,it is weak in the relation to precipitation.To glacial fluctuation in time scale shorter than 10¹ years,the general characteristics of glacial fluctuation in larger areas is also determined by temperature.The individual glacial fluctuation is complicated.But,the mass balance in the non-melting region of top part of glacial is basically dominated by precipitation.

• STUDY ON ROUGHNESS LENGTHS AND DRAG COEFFICIENTS OVER THE DIFFERENT UNDERLYING SURFACES
• GAO Zhi-qiu;WANG Jie-min;MA Yao-ming;SUN An-ping;SU Zhong-bo
• 2000 Vol. 19 (1): 17-24. 
• Abstract ( 244 ) PDF (311KB) ( 523 )
• In this paper,according to the extended Monin-Obukhov similarity theory for near surface atmospheric turbulence,the roughness(z₀),neutral drag coefficients(C_DN) and the exchange coefficients(C_HN,C_EN) of the sensible and latent heat over the different underlying surfaces,such as the Nansha sea region in South China Sea,the Gobi,desert and oasis over North China,and mid-and north-parts of Qinghai-Xizang Plateau,have been computed and analyzed by utilizing the observed data in the Nansha sea region in September 18~30,1994,HEIFE experiment on 1~24 August 1990 and the GAME/Tibet experiment in June,1998.Some meaningful results have been got.

• A PRELIMINARY ANALYSIS OF CHAOTIC FEATURES OF THE PRECIPITATION FLUCTUATIONS IN NORTHWEST CHINA
• WANG Bao-ling;XIE Jin-nan;YU Ya-xun
• 2000 Vol. 19 (1): 25-31. 
• Abstract ( 165 ) PDF (268KB) ( 378 )
• Based on the monthly normalized rainfall series in 30 meteorological stations in Northwest China,the attractor's dimension and predictable period are estimated.The results show that the fractal dimensions are between 3.7 to 6.2 in Northwest China.There are small fractal dimensions in extreme dry areas.The average predictability time scale is about 2~3 months according to Renyi entropy K.

• A SIMULATION STUDY OF THE EFFECT OF CHAFF FIBERS SEEDING ON STRUCTURE INSIDE THE THUNDERSTORM
• SUN An-ping;YAN Mu-hong;ZHANG Hong-fa;ZHANG Yi-jun
• 2000 Vol. 19 (1): 32-42. 
• Abstract ( 135 ) PDF (392KB) ( 420 )
• A two-dimensional,axisymmetric,time-dependent,dynamic-eletrification numerical cloud model has been applied to simulate chaff seeding effects on charge structure inside the thunderstorm.Transports of the chaff fibers in the wind field are calculated and ion production by chaff in the electric field is also parameterized.The results show the chaff ions reduce not only the charge on all kinds of hydrometers by conduction and diffusion but the inductive charging efficinecy.Finally,under this ideal condition,the best way to supress electric field is advanced.

• AN ANALYSIS OF THE 500 HPA CIRCULATION PATTERNS FOR DROUGHT AND RAINY YEARS OF EARLY SUMMER IN THE NORTHEASTERN PART OF QINGHAI-XIZANG PLATEAU
• YU Ya-xun;XIE Jin-nan;WANG Bao-ling
• 2000 Vol. 19 (1): 43-51. 
• Abstract ( 273 ) PDF (384KB) ( 450 )
• The NCEP/NCAR global monthly reanalysis data and the observed precipitation data at 17 stations in the northeastern part of Qinghai-Xizang Plateau about 40 years(1958~1997) are used in this paper.Based on the selected three severe drought years(1962,1995,1997) and three rainy years(1967,1984,1985) in early summer,the 500 hPa potential height fields,u,v vector fields,vorticity fields and the divergence fields over East Asia in early summer are analyzed respectively.The results show that the drought and rainy years in the northeastern part of Qinghai-Xizang Plateau in early summer are related to the circulation patterns at the middle and high latitudes,the differences of physical factors are obviously distinct.

• THE ANALYSIS OF CAUSING THE SNOW DISASTER ON 1985 OVER CENTRAL QINGHAI-XIZANG PLATEAU
• LIU Yan-xiang;TANG Mao-cang;WEI Li;LIU Wei-ming
• 2000 Vol. 19 (1): 52-58. 
• Abstract ( 885 ) PDF (276KB) ( 472 )
• The surface variables and the characteristics of satellite radiation budget field about a serious snow disaster were analyzed in October 1985 over Central Qinghai-Xizang Plateau,and the causing snow disaster were preliminary researched.The results show that the range of precipitation(≥8 mm) and snow depth(≥5 cm) is almost equal.The lag-cooling effect of the snow cover is stronger,continuing time is about five months.The calculated results with satellite radiation data show that the albedo is important in the radiation budget field of earth-atmospheric system.In November,every variable in the central area of snow cover is getting to the largest:or so,albedo anomaly is high as 16%,OLR is low as 185.6 W/m² and the net radiation is-25.4 W/m².The preliminary result were discovered,which there will be serious snow disaster in the winter or/and the next spring over Plateau,if the earth-quake(Ms≥7) is appeared between the western Tianshan and Pamier(73°~75°E) or in the Central Plateau(32°~35°N,85°~100°E) when Ms≥5.9 in last half a year.

• NUMERICAL SIMULATION OF THE HAIL CLOUD OVER MOUNTAINOUS TERRAIN
• LIN Wen-shi;FAN Shao-jia;WANG Xue-mei;HUANG Mei-yuan;ZHOU Ling;GUO Xue-liang
• 2000 Vol. 19 (1): 59-65. 
• Abstract ( 329 ) PDF (257KB) ( 431 )
• A hail cloud model that is two dimensional elastic non-hydrostatic,uses a terrainfollowing coordinate system and includes double parameters for ice phase microphysics,has been developed.Numerical experiments were performed using the observed data under different domains of the initial potential temperature perturbation over symmetric mountainous terrain.The results show that the hail cloud which domain of the initial potential temperature perturbation is located inwindward slope and top of mountain is weak,but stronger in lee slope and plain.The hail fall of the hail cloud which domain of the initial potential temperature perturbation is located in lee slope is 6 times as large as in windward slope.The hail cloud over the mountainous terrain may be effected by the air-flow of middle layer over the mountainous terrain and the microphysical processes of the hail cloud.

• THE PRIMARY ANALYSIS OF CLIMATIC FEATURE OF 50 HPA MEAN CIRCULATION IN NH AND ITS RELATIONSHIP WITH SUMMER RAINFALL IN CHINA
• AI Yue-xiu;CHEN Xing-fang
• 2000 Vol. 19 (1): 66-74. 
• Abstract ( 257 ) PDF (403KB) ( 541 )
• According to the analysis of 50 hPa mean circulation in the Northern Hemisphere(NH),it can be concluded that seasonal variation of 50 hPa is the most significant.In the meantime,the correlation coefficient is analyzed between summer rainfall index in East China(including 5 areas:North China area,Huaihe River area,middle-low reaches of Yangzi River,areas south of Yangzi River and south China area) and 50 hPa mean circulation in previous winter,spring and in summer;and the relationship in previous spring is the most significant among the them.

• WINTER QINGHAI-XIZANG PLATEAU OLR INTERANNUAL VARIATIONAL FEATURES AND THEIR RELATION TO CHINA SUMMER RAINFALL
• ZHU Qian-gen;SHENG Chun-yan;CHEN Min
• 2000 Vol. 19 (1): 75-83. 
• Abstract ( 174 ) PDF (367KB) ( 456 )
• Based on 1979~1994 OLR data from NOAA satellite,interannual variation feature of Qinghai-Xizang Plateau winter OLR was analysed by EOFs,and then its relation to 500 hPa height field and summer rainfall.The results show that winter Plateau OLR anomaly has the close relation to the path,strengthen and region of winter 500 hPa cold surge.Also the winter Plateau OLR has a good relation to summer convection is well,that is,when the North Plateau is colder(warmer) in winter,heavier(lighter) rainfall will be in the regions f rom Yellow River to South China and Heilongjiang river,while lighter(heavier) rainfall in the North China in summer;when the SW Plateau is colder(warmer),in summer heavier(lighter) rainfall will be in the East China while lighter(heavier) in the NE and SW China;when the East Plateau is colder(warmer) and the West warmer(colder),In summer heavier(lighter) rainfall will be in Changjiang valley while lighter(heavier) in the North China and SE coast.

• THE DROUGHT AND FLOOD FEATURE IN YUNNAN
• DUAN Xu;YOU Wei-hong;ZHENG Jian-meng
• 2000 Vol. 19 (1): 84-90. 
• Abstract ( 247 ) PDF (258KB) ( 491 )
• Based on Yunnan's precipitation data from 1901~1997,the spatial and temporal distributions of drought and flood in Yunnan are studied.The result shows that the drought is mainly climatic disaster and it takes place the most regions of Yunnan.In winter and spring,eight years out of ten years will be drought years.The climatic changes of Yunnan during the last 100 years are drought,but this tendency of dry climate was descending after 1995.The variations of drought and flood are the significantest on larger time scales.There is the most drought period from 1930 to 1958 and the precipitation is more than its climatic average value from 1959 to 1986 in Yunnan.

• NUMERICAL EXPERIMENTS OF EFFECT FACTORS ON PBL OF CONCAVE TERRAIN ON MICROSCALE
• SHI Yong;JIANG Wei-mei
• 2000 Vol. 19 (1): 91-99. 
• Abstract ( 209 ) PDF (343KB) ( 441 )
• Some numerical experiments were done by using a high-resolution,nonhydrostatic,three-dimensional model for microscale concave terrain to study the effect factors on the structure of the boundary layer of concave terrain on micro-scale in this paper.Experiment results showed that structures of the boundary layer were related closely to some factors,such as the depth H of the terrain,αangle,u₀ and P,the initial ground velocity and the vertical shear of initial velocity et al.The stablity of the model was also tested.

• A STUDY ON SPRING RAINFALL ANOMALY IN NORTHWEST CHINA AND PACIFIC SSTA FEATURES IN AUTUMN AND THEIR CORRELATIONS
• LI Yao-hui;LI Dong-liang;ZHAO Qing-yun
• 2000 Vol. 19 (1): 100-110. 
• Abstract ( 199 ) PDF (422KB) ( 487 )
• With EOF,REOF and SVD,the spatial anomaly features of both the North Pacific SSTA and the spring rainfall in West China and the correlations are studied by using the pricipitation data in spring for the period 1960~1994 from 89 observational stations and the North Pacific sea surface temperature of 286 grid points in the area of 10°S~50°N,120°E~80°W in autumn.The results show that the first six rotated loading vector fields represent six principal SSTA areas,among which the east equatorial Pacific is the most sensitive signal area.There are five principal spring rainfall anomerly areas in Northwest China:the Eastern Plateau,the eastern part of Northweat China,the Northern Xinjiang,the Qinghai Plateau,the Southern Xinjiang-Hexi Corridor.Clear teleconnections really exist between the SSTA in east equatorial Pacific in autumn and the next spring rainfall in Northweat China.When the SSTA is high(low),that is to say,when El Niño(La Niña) appears in autumn,Northwest China is wet(dry) in the next spring.The cases are same in the next March and May.But the wet(dry) center in March is near Xining,Qinghai province;while in May,Pingliang,Gansu province,is the center.In April,the case is contrary with March and May.

• THE DIAGNOSIS ANALYSIS OF POTENTIAL VORTICITY FOR A SEVERE TYPHOON RAINSTORM IN NORTH CHINA
• YU Yu-bin;YAO Xiu-ping
• 2000 Vol. 19 (1): 111-120. 
• Abstract ( 321 ) PDF (382KB) ( 660 )
• Based on the analysis of potential vorticity(PV) and elements on isentropic surface about the typhoon 9608 and its heavy rain outside,the study is to show the PV structure and the interaction with midlatitude weather systems.It shows the feature of severe rainstorm dynamic and thermodynamic process.A picture about the process of heavy rain amplification is given.It is also shown that one of the most important reasons of the heavy rain amplification is the cold air(high PV region) which spreads to south from midlatitude in the lower troposphere and transports into the typhoon low pressure.The study of PV on isentropic surface shows the active state of the midlatitude cold air.The tropopause folding,which means that high PV spreads downward from the upper troposphere or stratosphere,helps the releasing of potential instability energy and the development of rainstorm.It also indicated that the rainstorm region lies in the northeast part of high PV center on the lower isentropic surface,corresponding to the maximum negative region of the PV baroclinic part,and supplies an important reference for forecasting the intensity and the region of the typhoon heavy rain.

• HAIL FORECAST BY USING OF TWO-DIMENSIONAL HAIL CLOUD MODEL
• WU Zhi-fang;ZHANG Chun-liang;XU Huan-bing
• 2000 Vol. 19 (1): 121-128. 
• Abstract ( 344 ) PDF (291KB) ( 601 )
• This paper stimulated and analysed the distribution and their evolution of macroscale and microphysical measurements such as structure and water content of hailstrom,which occurred in Weigan River Irregation Area,by using of two-dimentional hail cloud model.Hail forecast experiments were carried on with sounding data during July and August in 1995.The results show that this model could really stimulate the distribution and evolution of the streamline field,temperature and humidity field,suited to hail cloud growth.It could also stimulate the occurance and development of muti-cell hail cloud.According to the atmospheric layer stability,different heat disturbance indensity was selected,the hail forecast correct rate increase to 69.3%.