Current Issue

• ON THE CRITICAL HEIGHT OF THE EFFECT OF QINGHAI-XIZANG PLATEAU UPLIFT ON THE ATMOSPHERE
• Liu Xiaodong;Tang Maocang
• 1996 Vol. 15 (2): 131-140. 
• Abstract ( ) PDF (378KB) ( )
• Based on author's previous work and the atmospheric dynamics,thermodynamics and climatology theory,we further demonstrate the viewpoint that there is a critical height h _c~ 1.5-2km during the course of Qinghai-Xizang Plateau uplift.When the upheaval of the Plateau surpasses the critical height,strong orographic effect can produce a series of huge variations in the general circulation,atmospheric thermal structure,Asian regional and global climate,for example,the bifurcation #O of a westerly flow passing the Plateau,the formation of heat source in the upper-troposphere over the Plateau,the descent of the surface air temperature,the aridity in Asian interior continent but more condensation and precipitation in monsoon area of Asia.These conclusions need to be attested in the future with the geological evidence reflecting climatic change.

• THE SOLAR ULTRAVIOLET RADIATION OVER THE WUDAOLIANG REGION
• Jiang Hao;Ji Guoliang
• 1996 Vol. 15 (2): 141-146. 
• Abstract ( ) PDF (220KB) ( )
• In this paper,the climatological characteristics of solar ultraviolet radiation over the Wudaoliang region in Qinghai-Xizang Plateau are analysed based on the solar radiation data observed from September 1993 to August 1994.The results are as follows:the annual mean daily total of solar ultraviolet radiation is about 0.73MJ/m ²,less than that over Lhasa region and larger than that over HEIFE region.The instantaneous maximum of ultraviolet radiation is strong,its seasonal variation is influenced by relative atmospheric optical mass and ozone amount in atmosphere.The annual mean ratio of UV to Q is about 4.3%,larger than that over HEIFE and Lhasa region.The annual variation of UV over this region are the same as that over the rest region of the Plateau but opposite to the HEIFE region.

• EVALUATION ON CLOUD VARIABLES FROM ISCCP DATA OVER CHINESE CONTINENT
• Wei Li;Zhong Qiang;Hou Ping
• 1996 Vol. 15 (2): 147-156. 
• Abstract ( ) PDF (347KB) ( )
• In this paper,the ISCCP cloud amounts and cloud types for July 1983 and January 1984 are compared to the observations of cloud derived from Chinese weather stations and to the cloud climatology given by Hahn et al.The results show that the geographic distribution of the ISCCP monthly mean cloud amount is agreeable well to that from surface observation.The locations of more cloud and less cloud centres by two kinds of observation are close.However,differences in magnitude between the ISCCP data and the surface observations still exist.The ISCCP cloud amount is generally lower than the surface observations.The underestimates are more obvious in winter than in summer and at early morning than at noon.The disagreements are lareger over the northwest of the Qinghai-Xizang Plateau,the Yun-Gui Plateau and the area around Tian Shan mountains.Comparisons of the ISCCP cloud types with the cloud climatology given by Hahn et al.suggests that the ISCCP results are basically reasonable.But the high level clouds are underestimated and the low level clouds are overestimated over some desert regions.

• EVALUATION ON SURFACE ALBEDOS DERIVED FROM SATELLITE DATA OVER THE QINGHAI-XIZANG PLATEAU AREA
• Zhong Qiang;Wei Zhigang
• 1996 Vol. 15 (2): 157-164. 
• Abstract ( ) PDF (303KB) ( )
• The visib lesurface reflectance data from ISCCP data set and the surface albedo dataderived from ERBE broadband planetary albedo data set by Li Zhanqing,et al with a simple parameterization model were recommended in this paper.Choosing the Qinghai-Xizang Plateau and its surrounding areas as target region,comparison and evaluation weremade for them by combined with the observational data from the field experiments over the Qinghai-Xizang Plateau.We analysed the possible reasons of error and proposed the opinions for improving retrieval of the surface albedo over the Qinghai-Xizang Plateau.

• THE INFLUENCE OF SNOWFALL ON THE SURFACE ALBEDO IN THE NORTHERN XIZANG(TIBET) IN WINTER
• Shen Zhibao
• 1996 Vol. 15 (2): 165-171. 
• Abstract ( ) PDF (240KB) ( )
• Northern Xizang(Tibet) is one of the region in Qinghai-Xizang Plateau where the snowfall frequency and the intensity are higher,and the snow cover may continue for longer time after a heavy snow in winter.Each snowfall may cause the abnormality of surface albedo for a long time.Studies on the observed data of the surface heat source experiment over Qinghai-Xizang Plateau during the period from November 1982 to February 1983 found that there is a good relationship among the abnormality and its duration of surface albedo and snowfall under the condition of low air and surface temperature in winter.An empirical formula was obtained for expressing this relationship.

• A STUDY OF TURBULENT TRANSFER CHARACTERISTICS IN WUDAOLIANG AREA OF QINGHAI-XIZANG PLATEAU
• Qi Yongqiang;Wang Jiemin;Jia Li;Liu Wei;Ma Yaoming;Ren Yanxia
• 1996 Vol. 15 (2): 172-177. 
• Abstract ( ) PDF (218KB) ( )
• The paper analyses the turbulent data,which collected from the Wudaoliang area of Qinghai-Xizang Plateau in June July 1994.The results show:in the area,the energy fluxes of surface layer can approximately balance.The diurnal variations of net radiation,sensible heat,latent heat and ground heat flux are normal.The sensible heat flux is dominant,the latent heat flux is second in energy balance.Spectra of wind component analysis show,in near neutral stability,the vertical velocity spectral peak is about f=0.3,it is good when compared with others,but the longitudinal velocity(u spectrum) peak is about f=0.1,the cross velocity(v spectrum) is about f=0.2,which are higher than other results.There are same results in vertical velocity spectrum compared with other results.

• DEVELOPMENT OF THE STRONG DUST STORM AND DRY SQUALL LINE A MECHANISM ANALYSIS ON GENERATING BLACK STORM
• Hu Yinqiao;Yasushi Mitsuta
• 1996 Vol. 15 (2): 178-185. 
• Abstract ( ) PDF (295KB) ( )
• Development process of the black storm on May 5,1993 and the relation of development of squall line to the black storm are analysed.The results show that there exists a dry squall line in front of the cold front cloud system on May 5,1993,and the dry squall line develops further into explosive the black storm as it moves in desert area,in which the ground surface is strongly heated by solar radiation and the atmosphere is unstable stratification.Air flow ahead of the gust front rolls up dry sand on ground surface to generate sand wall of black storm.

• THE CHARACTERISTICS OF RADIATION OVER THE WEST PACIFIC DURING THE IOP OF TOGA-COARE
• Ma Zhuguo;Yao Lanchang;Hou Xuhong
• 1996 Vol. 15 (2): 186-194. 
• Abstract ( ) PDF (321KB) ( )
• By means of the observed radiation data during the IOP of TOGA-COARE(from Nov.10,1992 to Feb.18,1993) at observation station(2°15'S,158°00'E) of "R/V Shiyan 3",the global radiation,direct solar radiation,diffuse radiation,the ocean surface long-wave radiation,the atmospheric counter radiation,the ocean surface reflective radiation and the albedo,effective radiation and the net radiation have been analysed.Compared with the observed results over the Qinghai-Xizang Plateau,it is found that the global radiation and the direct radiation are larger;the reflective radiation and the albedo are smaller,the albedo is 0.04-0.05 in the clear sky,and 0.6-0.8 in the overcast sky;the upward long-wave radiation of ocean surface is larger,but its diurnal variation is smaller;the atmospheric counter radiation and its diurnal variation are larger;the effective radiation is smaller,but the net radiation is larger.

• THE IMPROVEMENT AND EXPERIMENTS OF PRIMITIVE EQUATION MODEL WITH MIXED p-σ COORDINATES
• Zhao Ming;Fang Juan
• 1996 Vol. 15 (2): 195-203. 
• Abstract ( ) PDF (340KB) ( )
• The five-layer primitive equation model with mixed p-σ coordinates is improved as a nine-layer model.The model has 17×39 grids with resolution of 5°×5°.Its physical processes are identical with the five-layer model.The model runs stably.We utilize this model to simulate a cold wave process during the beginning of the winter in 1994.The simulated pressure and temperature field characteristics are in agreement with the observations.The simulated results are better than that of five-layer model due to the higher vertical resolution.The experiments show that the model can be applied to operational prediction.

• NUMERICAL EXPERIMENTS OF EFFECT OF MODEL HORIZONTAL RESOLUTION ON CUMULUS PARAMETERIZATION
• Zhou Tianjun;Qian Yongfu
• 1996 Vol. 15 (2): 204-211. 
• Abstract ( ) PDF (281KB) ( )
• In this paper,an one-way nested limited area primitive equation model is used to study effects of horizontal resolution on cumulus parameterization.It is found that the change of horizontal resolution has notable effect on cumulus paramerization,and leads to the variation in the forecasted rain field and the synoptic situation.The role of cumulus parameterization in numerical model is also discussed.The results show that,when model horizontal grid length decreased to less than 1.0°,including the cumulus parameterization can increase remarkably correlation coefficient between the forecasted and the observed height field in the lower atmosphere layer,but it decrease evidently in the upper layer.

• RAINDROP GROWTH UNDER THE CONDITION OF LIGHTNING DISCHARGE IN THUNDERSTORM
• Ge Zhengmo;Dong Wansheng
• 1996 Vol. 15 (2): 212-220. 
• Abstract ( ) PDF (307KB) ( )
• The experimental relationship between coefficient of spherical drag and the Reynolds number was used in equations of raindrop motion with considering electric field force in thunderstorm.The instantaneous velocity of raindrop effected by external and law of raindrop growth were calculated under the periodic variation of environmental electrical field.The results indicated that the effect of lightning discharge on the growth of smaller drop was large and the effect degree was close related to charge carried by drop.If some droplets can carry a large number of charge by some artificial ways,this may be a new method of artificial precipitation stimulation in thunderstorm.

• CURRENT DENSITY MEASUREMENT BENEATH THUNDERSTORM AND ITS QUASI-STEADY FEATURES
• Qie Xiushu;Zhang Guangshu
• 1996 Vol. 15 (2): 221-228. 
• Abstract ( ) PDF (286KB) ( )
• The surface electric field E and Maxwell current density J _m have been measured simultaneously under small and active thunderclouds to verify the quasi-steady characteristics of Maxwell current density.The records show that under active thunderclouds surface Maxwell current density reflects the change of cloud charge sources,and is quasi-steady between lightning discharges.Observation and model calculation show that displacement current density dominates J _m when electric field near zero between lightning discharges.When electric field recovers to the value near that before the flashes and keep static value,the conduction and corona current densities increase while displacement current density decreases.Under small storms,the conduction current that flows in the atmosphere produce time variations in the Maxwell current density at the ground even if the cloud current sources is quasi-steady.

• TWO CONSIDERABLE PROBLEMS ON THE DIMENSION OF ATTRACTOR FROM ONE-DIMENSION TIME SERIES OF THE EXPERIMENTAL DATA
• Li Jianping
• 1996 Vol. 15 (2): 229-233. 
• Abstract ( ) PDF (190KB) ( )
• In this paper,the difference between strict self-similar and statistical self-similar has been given.Based on the difference,two considerable problems on the dimension of attractor from one-dimension time series of the experimental data,namely,the range of scale and the coefficient of proportion in the formula of fractal dimension,and the relationship between the doublelogarithmic figure and the D-m figure are discussed.

• REVIEW OF RESEARCH ON ATMOSPHERIC ELECTRIC PROCESSES AND CLIMATE CHANGE
• Yan Muhong;Zhang Yijun
• 1996 Vol. 15 (2): 234-242. 
• Abstract ( ) PDF (328KB) ( )
• This paper reviews research progress on the atmospheric electricity relative to the weather and climate phenomena.By contrast with measuring data,the correlation and probable coupling mechanism among fair weather electric processes,thunderstorm,lightning and the weather,climate are discussed.The results indicate that global and regional thunderstorms are a critical factor in the coupling mechanism,the lightning is an immediate parameter which can establish coupling relationship between parameters above mention and can introduce in the global circulation model(GCM) in the form of parameterization and quantitatively discuss coupling mechanism.A developing global circuit concept can establish a phsical relationship among solar,atmosphere and earth.A global and regional precipitation forecast and regional tornado storm,hail forecast at the ground are studied by using lightning data.

• EXPLORING FOR SOME PROBLEMS OF ATMOSPHERIC TURBULENCE IN BOUNDARY LAYER
• Zhang Qiang;Hu Yinqiao
• 1996 Vol. 15 (2): 243-249. 
• Abstract ( ) PDF (240KB) ( )
• In this paper,some problems of turbulent basic theory are discussed.According to the turbulent kinetic energy equation,mechanism about production and development of atmospheric turbulence of boundary layer is analysed.From this,the extent of turbulent motion scale,and turbulent mixing length expression which has a clear physical meaning are derived.

• LABORATORY STUDIES OF MICROPHYSICS PROCESSES OF ICE(SNOW) CRYSTAL
• Gong Naihu;An Junling;Wang Wanzhong;Zhou Yunjun
• 1996 Vol. 15 (2): 250-256. 
• Abstract ( ) PDF (307KB) ( )
• In this paper,the three respects as follows have been outlinedly introduced:(1) History and advancing condition of the microphysic laboratory studies of ice(snow) crystals growth.(2) Designing and making a new vertical supercooled cloud tunnel and its measuring system.(3) Main results including the influence of liquid water content and moving mode on the growth of ice crystals in cloud tunnel as well as the character of initial stageice crystals.