Plateau Meteorology

Current Issue

28 June 2008, Volume 27 Issue 3   
  • CLM3-Simulated Chinese Soil Moisture during 1979-2003 and Its Possible Response to Global Warming
  • DU Chuan-li;LIU Xiao-dong;WU Wanli
  • 2008 Vol. 27 (3): 463-473. 
  • Abstract ( ) PDF (2761KB) ( )
  • Hydrological process related to soil moisture plays an important role in determining regional and global climate. However, a wide range and long-term observation of soil moisture is extremely sparse. In order to investigate energy and hydrological cycles between soil, vegetation and atmosphere, land process models are often used to produce soil moisture data which have physical consistency and spatio-temporal continuity. In this study, using a state-of-art Community Land Model(CLM, version 3) developed by the National Center for Atmospheric Research(NCAR), we simulate Chinese soil moisture and its possible response to global warming through a long off-line experiment under 0.5°(longitude)×0.5°(latitude) resolution and real atmospheric forcing of the NCEP/DOE reanalysis during 1979—2003. The main conclusions can be summarized as follows:(1) The spin-up time of soil moisture varies with the depth of soil layers. The deeper a soil level is, the longer the soil moisture reaches its equilibrium state. The equilibration time needs over 20 years at soil levels below 1.5 m. This shows that the soil moisture is sensitive to its initial condition in the land process model that a long spin-up process is necessary in climate modeling studies related with land hydrological processes.(2) By comparing the CLM-simulated soil moisture with observed values at a few representative stations with different types of soil property and reanalysis-obtained grid-box soil moisture, we find that the CLM can reasonably reproduce the seasonal variation and interannual variability as well as the horizontal and vertical patterns of soil moisture in East Asia including China.(3) On the basis of the CLM-simulated soil moisture, an analysis of the linear trend during the 20 years shows that it is getting drier in most regions of East Asia including northern China north of 30°N but wetter in southern China and the Tibetan Plateau, especially in summer. The regionally-averaged soil moisture indicates a significant drying tendency in northeast Asia. However, no clear tendency in summer precipitation is observed during the same period. Therefore, we attribute the regional drying to increasing of the land-surface evaporation induced by global warming.
  • Design of Global(Z) Bicubic Numerical Model(BiNM) and Its Case Simulation(Ⅰ): Dynamic Framework of Model
  • GU Xu-zan;ZHANG Bing
  • 2008 Vol. 27 (3): 474-480. 
  • Abstract ( ) PDF (325KB) ( )
  • Introducing Bicubic Numerical Model(BiNM, shortly), that has all the advantages of mited difference model as well as the basic advantages of spectrum model, it is with the fitting of cubic curved spline/bicubic curved surface to the discrete mesh, physical fields of the model atmosphere, and getting their second-order derivatives, and doing time integration for the forecast governing equations. BiNM can use Navier-Stokes primitive equation set, but, we adopt an assumption of static equilibrium to "diagnostic atmosphere" but of non-static equilibrium to "motion atmosphere", to get perpendicular speed in the vertical equation;and do other assumption of incompressible air for "diagnostic atmosphere" but of compressible air for "motion atmosphere", so that acoustic wave should be eliminated in the model atmosphere. So, BiNM has a governing equation set in the spherical coordinate, that is, BiNM's dynamic framework of non-static, holo-compressible, and dry/wet adiabatic model atmosphere may be set up. Actually, the global BiNM in the Z coordinate with its simulation cases in this paper use the Navier-Stokes primitive equations of so called "shallow atmosphere", and adopt the explicit semi-Lagrangian time integration scheme in horizontal direction but Euler time integration scheme in vertical direction because of the gravitation. BiNM's discrete pressure and temperature predictive equations as well as its cases show that, for the condensation and precipitation in the model atmosphere, the synoptic reason not only is the wet air making vertical movement in the Z-coordinates, moreover is the wet air being reduced by pressure and temperature, that does the "vertical movement"in the P-coordinates, latter may be caused by the atmospheric advection motion(for example, the Rossby wave).
  • Design of Global(Z) Bicubic Numerical Model(BiNM) with Its Simulation Cases(Ⅱ): Analysis of the Simulated Case Result
  • GU Xu-zan;ZHANG Bing
  • 2008 Vol. 27 (3): 481-490. 
  • Abstract ( ) PDF (2865KB) ( )
  • Introducing Bicubic Numerical Model(BiNM for short) with a new algorithmof"bicubic surface fitting-time step integration-bicubic surface fitting", and gives a designto global(holospheric) BiNMwith latitude-longitude grids. The globalBiNMholds the dynamic framework of non-static, holo-compressible, and dry/wetadiabaticmodel atmosphere in the Z coordinatesystem, and uses the explicit semi-Lagrangian time integration schemeinhorizontal directionbut Euler time integration schemein vertical direction, and adopts the reanalysis data of NCEPbeing adopted for getting an initial field, and somecases are firstly shown to have succeeded in simulating the atmospheric general circulation form tropical zone to polar region, as well as the typhoon disturbances, the troughand ridge propagations, the subtropical high and tropical low movements, and so on. Sinceatmospheric motion is essentially non-linear, it does not need any smoothwhendefinition model atmosphere maks "linearmovement" in the simulation course. However, when the definition model atmosphere does "cubic movement", it must havesuitably smoothes. So the future BiNM according to the bicubic surface curvature of one variablefield, judge the reasonable local area, or simple point to be smooth, which must conform to the physical interpretation. If the instability area of atmospheric non-linear motion is justthe origin place of some weather system, accordingly a globalmulti-nested/time-variation grid BiNM had tobe developed in the future.
  • Regional Characteristics of Summer Precipitation on Tibetan Plateau and It's Water Vapor Feature in Neighboring Areas
  • FENG Lei;WEI Feng-ying
  • 2008 Vol. 27 (3): 491-499. 
  • Abstract ( ) PDF (2232KB) ( )
  • Regional characteristics of summer precipitation of 97 weather stations in Tibetan Plateau are analyzed by using a rotated empirical orthogonal function, based on summer total precipitation(June~August) from 1961 to 2005. And then the relationships between the first four regional characteristics corresponding to other factors such as water vapor transport and the circulation feature in neighboring areas are explored by using NCEP/NCAR monthly mean reanalysis data in summer from 1961 to 2006. At last, the differences of water vapor transport and the circulation feature between flood and drought years are investigated. The results show that the summer precipitation in the southern part of Tibetan Plateau is opposite to the northern part, and there is a remarkable difference between them in water vapor transport and circulation feature. If the moisture from Indian Ocean and Bay of Bengal transporting to the north and the moisture from the West Pacific Ocean transporting to the east are strengthened, also the Ural blocking high is strong and the circulation pattern is "+-+" from low to high latitudes in East Asia, water vapor will converging in Tibetan Plateau, so the rain in summer will be more than normal. And, contrariwise, the precipitation will be less than normal.
  • Aerosol Distribution over the Qinghai-Xizang Plateau and Its Relationship with Ozone
  • ZHOU Ren-jun;CHEN Yue-juan;BI Yun;YI Ming-jian
  • 2008 Vol. 27 (3): 500-508. 
  • Abstract ( ) PDF (1284KB) ( )
  • Using the HALOE data(from October 1991 to November 2005), the distributions and variations of aerosol number density, volume density, surface area density over the Qinghai-Xizang Plateau(QXP) have been analyzed, and their relationships with ozone have been discussed, then the aerosol distribution and the relationship between aerosol and ozone over the QXP are compared with those over the eastern part of China and North Pacific. The followed conclusions are made: The influence of Pinatubo volcanic eruption on aerosol volume density, area density over the QXP appearedsignificantly in 1991 to 1995;however the effect on aerosol concentration was not as clear as the volume density and area density. Near the tropopause there is a higher value of aerosol concentration over the Plateau which locates beneath the tropopause(~120 hPa) in summer and above the tropopause(~100 hPa) in winter. The main differences in aerosol densities over QXP, the eastern part of China and North Pacific occur below 60 hPa. In summer the differences are the most notable: Aerosol concentration at 120 hPa over the QXP is 1.8 times as large as that over the Plain, and 5.5 times as large as that over the Ocean. Near the tropopause and in the low stratosphere, the aerosol concentration and ozone mixing ratio have a good negative correlation over the QXP, but they have a significant positive correlation above 20 hPa. Comparing the relationship between aerosol and ozone over the three regions, the results indicate: Near the tropopause and in the low stratosphere, aerosol concentration and ozone mixing ratio both have a good negative correlation over the QXP and over the Plain, but the correlation over the Ocean is not clear. Above 20 hPa aerosol concentration and ozone mixing ratio all appear a good positive correlation over the three regions.
  • Change of Large Scale Circulation and Its Impact on the Water Vapor over North China
  • MA Jing-jin;YU Bo;GAO Xiao-qing;LI Jie
  • 2008 Vol. 27 (3): 517-523. 
  • Abstract ( ) PDF (2107KB) ( )
  • Using the data of monthly precipitation at 25 stations form 1951to 2006 in North China and NCAR/NCEP monthly reanalysis datafrom 1948 to 2006, and the HYSPLIT_4 Model, the variation features of precipitation and the water vapor transportation in North China in summer(JJA) oninterdecadal and interannual time scales are investigated. The results show that the characteristic of water vapor transportation and it's path change are obvious. The interannual change of northern limit for south wind in summer(June~August) along 100°~125°E(East Asia) has very important influence on the water vapor transportation, the northern limit for south wind moved southward causing the decreasing of the water vapor. The D-value of wind field in more or less precipitation years shows that the southwest windstream of west Pacific subtropical high affects the water vapour transportation over North China in summer; its southwestern air flow from South China Sea carries abundant water vapor to the North China, which brings large quantity of rainfall, and it has obviously rised wind and meridional circulation in averaged along 100°~120° E in North China in typical wet years, which is different in typical dry years.
  • Research of Variety Rule of Soil Humidity in Loess Plateau of China
  • CHEN Shao-yong;GUO Kai-zhong;DONG An-xiang
  • 2008 Vol. 27 (3): 530-537. 
  • Abstract ( ) PDF (1764KB) ( )
  • The distributional characteristics of climate and variety regulation of soil humidity in Loess Plateau of China are analyzed using the monthly precipitation data of 59 weather stations from 1961-2002 and the data of water content at 29 agricultural meteorological observation stations in April to October from setting up of station to 2000. The result shows that:(1) The soil humidity of Loess Plateau from April to October is consistent well with the geographic distribution of precipitation; both the rainfall and soil humidity reduce from southeast to northwest, which is affected by Liupan Mountain and Taihang Mountain and Southeast monsoon, there is a narrow drought region extented southward in Gansu and Shanxi Provinces.(2) The soil humidity of Loess Plateau in China is divided into 5 climatic regions by annual precipitation and vibration parameter. They are the grassland desert sub-region which the soil severely loses moisture, the desert sub-region which soil loses moisture, the steppe region which soil loses moisture, the forest sub-region which soil periodically loses moisture and the Arden which soil periodically lacks moisture. The former three climatic sub-regions locates in the middle and north parts of Loess Plateau, the moisture among these regions can not be restored after rainy season and soil switches frequently in severe drought and light drought. The latter two climatic sub-regions are in the south of Loess Plateau, the soil moisture is recovered during and after rainy season, meanwhile, seasonal water deficit still exists in these regions.(3) The soil humidity has dynamic state variety regulation. Generally, the soil humidity has increased from July, but each area increase range there is difference in increasing range of each area.(4) Soil humidity is mainly influenced by precipitation.
  • Land Cover Classification in Western Loess Plateau of China with MODIS Imagery Data
  • LI Yao-hui;HAN Tao
  • 2008 Vol. 27 (3): 538-543. 
  • Abstract ( ) PDF (1194KB) ( )
  • Land cover and use are not only the important information for climate model of globe and region, but also the base character data of ecosystem. It has vital meaning for obtaining the spatial state and variety in formation of land surface, investigating the driving factor and analyzing and evaluating the regional ecosystem. Land cover classification using the multi-temporal and multi-spectral remote sensing observation data has been an effective technique. In addition to spectrum difference, the vegetation divergence is displayed by the variation of growing pattern. The plant growing period is one year and in this period the different plant types have different phenological successions and different growing patterns that go round and round regularly and this can be used as a point of departure to classify plant. Hence, the NDVI time sequence analysis became the basic means of land cover classification according to biometeorology characteristic. In this paper, based on MODIS data, we perform the discrete Fourier trans formation for NDVI of nine months in the plant growing season of 2003 and gets the mean value and the amplitude and phase of the former four harmonics. According to these data, the land cover classification in the West Loess Plateau of China and its surrounding area is finished by ISODATA method and the classification result merging and accuracy assessment are accomplished by using the current land cover maps. The calculated overall accuracy was 81. 3%, while Kappa was equal to 75.4%. It shows that these methods are valuable for practical use.
  • Land Surface and Vegetation Variables Estimated from ASTER Data over Akesu Region of Xingjiang in April 2002
  • MA Wei-qiang;MA Yao-ming;Tsuneo Matsunaga;HU Ze-yong;ZHONG Lei;LI Mao-shan;ZHAO Yi-zhou;WANG Yong-jie;WANG Jie-min
  • 2008 Vol. 27 (3): 544-550. 
  • Abstract ( ) PDF (2042KB) ( )
  • Using ASTER data on 12 April 2002 from visible and near-infrared band and the short wave infrared band, the land surface variables(land surface temperature, albedo) and vegetation variables(NDVI, MSAVI, Pv and LAI) over the Akesu area are retrieved. The values of vegetation index are discovered in desert to be less than that in oasis. ASTER remote sensing data have higher resolution and can get the vegetation status reasonably. At the same time ASTER has higher ground resolution, so land surface and vegetation variables can show real land surface variables using its data. The derived surface variables(land surface albedo and surface temperature) over the study area are in good accordance with the land surface status. The experimental area includes variety of land surfaces such as a large area of grassy marshland, some desertification grassland areas, many small rivers and several lakes;therefore these derived parameters show a wide range due to the strong contrast of surface features. Surface albedo is from 0 to 0.287 in April. Surface temperature ranged from 12 to 38℃ in April. NDVI changed from 0 to 0.4. MSAVI changed from 0 to 0.25. Pv changed from 0 to 0.11. LAI changed from 0 to 0.25 in April in Akesu area. Further more it points out that ASTER remote sensing data can use in the desert and oasis in this paper.
  • Analyses of Recent Xinjiang Snow Cover Feature Utilizing Satellite Remote Sensing and Surface Observation Data
  • ZHANG Jia-hua;WU Yang;YAO Feng-mei;WEI Wen-shou
  • 2008 Vol. 27 (3): 551-557. 
  • Abstract ( ) PDF (1455KB) ( )
  • Based on two kinds of remote sensing data(snow depth data of SSM/Ⅰ from 2003 to 2005, snow cover data of NOAA/AVHRR from 1996 to 2004) and 11 weather observation station data in Northern Xinjiang from 1996 to 2002, the temporal and spatial distributions of snow cover and snow depth in Xinjiang region were analyzed. The result showed that the snow cover days fluctuated from year to year, the maximum snow cover days occurred in 2000—2001. Spatially, the northern part of Tianshan Mountains was the primary snow cover area, and the snow cover areas exceed 15 ten-days in every winter-half year. There was also a high value in the Kunlun Mountains region in Southwest part of Xinjiang, and snow cover areas exceed 15ten-days in some winter-half years. It was found that snow cover days in mountain region were obviously more than that in plain region in Xinjiang region, and Zhunge'r Basin was more than Tarim basin. The remarkable areas for the variation of the snow cover over the Xinjiang area was in the Tianshan Mountains, Kunlun Mountains and Altyn Tagh Mountains. All the areas covered by snow were past six ten-days. The maxium snow cover occurredin February in Xinjiang region, the distribution area of high snow depth values over 40 cm located in Altay, Tachen Basin, Northern part of Tianshan Mountains, the south edge of Zhunge'r Basin, and Tashigan river.
  • Numerical Simulation and Analysis of a Heavy Rain Process
  • LIAO Yi-shan;LI Jun;MIN Ai-rong;WANG Xiao-fang;CUI Chun-guang
  • 2008 Vol. 27 (3): 558-566. 
  • Abstract ( ) PDF (2395KB) ( )
  • A heavy rain event occurred in the area from western Hubei to southern Henan during 9~10 July 2005. According to the development process of the weather,two possible weather evolvement modes are deduced. Based on the simulated result by the mesoscale heavy rainfall prediction model(AREM),the mesoscale process and feature are analyzed. This process consists of convergence line inhancement and cyclone development. During the dry and cold air intrusion process, along with the dry air intruding towards south and the warm-wet air inclining upwards from north to south and developing, the ascending movement develops to the troposphere then diverges to the south and the north. Thus a meridional dipole circulation is formed in the middle of troposphere. The sinking movement compensates and joins to the rising movement, which enhances and maintains the low convergence. During the cyclone development, the wet air in the south of the shear line develops towards north obviously, then a new meso-β-scale cyclone forms on the shear line. The south wet air of the cyclone converges intensity and rises. The dry sinking airflow which lies in the north of ascending movement extends downwards near to the top of boundary layer,but it does not join to the rising airflow because of the action of low wet air developing towards north and through the wet front. In the end of this paper, the three-dimensional special frame schematic diagram is given.
  • Rainstorm in the East Airflow of Typhoon Periphery and Its Isentropic Potential Vorticity Character
  • WU Zhen;FAN Xue-feng;ZHENG Shi-lin;XI Shi-ping
  • 2008 Vol. 27 (3): 584-595. 
  • Abstract ( ) PDF (4730KB) ( )
  • After the No.0414 typhoon named as "Yunna" makes landfall on Zhejiang Province it rapidly weakened into typhoon depression. The rainstorm appeared in the east airflow area of the north of the typhoon depression 48 h later. The 850, 700 and 500 hPa heights of middle and lower levels in the rainstorm area had no convergence system then and the stronger cool air had affected on the area before rainstorm occurring the potential instability. So both the dynamical lifting and potential instability conditions didn't make are unfavourable to the rainstorm occurring. In order to prove up the formative reason of rainstorm under this case, using the routine message and the 1°×1° reanalysis data of NCEP, the rainstorm occurring condition and the development and its is entropic potential vorticity character are analyzed. The results show that a declining westward updraft from bottom to top forms in the rainstorm area because the inverted trough in the middle level of the typhoon depression moves more rapidly than low level. And there were symmetric instability in the upper air of the rainstorm area. Inclined updraft causes symmetric instability energy to release and make the declining convection development. These content the dynamical and unstable conditions of rainstorm occurring. The water vapor transporting in the typhoon periphery provided abundant water vapor conditions for heavy rain birth. The analysis of is entropic potential vorticity shows that high value potential vorticity's band has better corresponding relationship to the precipitation area. The emergence of positive potential vorticity anomaly center has an indicative meaning for rainstorm's occurring and developing.
  • Diagnostic Analysis on Torrential Rain Caused by the Tropical Storm Billis(0604)
  • KANG Zhi-ming;CHEN Tao;QIAN Chuan-hai;YANG Ke-ming
  • 2008 Vol. 27 (3): 596-607. 
  • Abstract ( ) PDF (2400KB) ( )
  • Based on the intensive observations, precipitation data of automatic observations and NCEP(1°×1°) 6 h reanalysis data, the study on the torrential rain caused by the Tropical Storm Billis(0604) was made through the analyses on energy, thermodynamics, vapor flux, synoptic circulation, cold air and terrain effect. The results show that the combination of west Pacific subtropical high and mainland high, extremely strong southwestern monsoon, intensive divergent stream filed in upper level and weak vertical shear jointly contributed to the persistence of Bills over land, and the southwest monsoon was strengthened by cross equatorial flow and transported the moisture in the Bay of Bengal and South China Sea into the rainfall area. Also the study arrived at some conclusions as follows:(1) The apparent heat energy was the main component part of the energy of Billis, the latent heat energy was second only to the apparent one at the low level of troposphere, but the potential energy takes the place of latent heat energy above the middle level of the troposphere. The maintenance of the total energy of the storm mainly depended on the advection of latent heat energy, which also contributed to the persistence of warm structure and the advent of torrential rain. The kinetic energy that caused the blustering weather of the storm was generated by the Ageostrophic wind, which crossed the isobar and intensified the baroclinicity of the air.(2) The local variation term was reverse to the advection term for both the apparent heat source(Q1) and moisture sink(Q2). When warm and moist air at low level was lifted to higher level, the condensation of the moisture and the release of latent heat resultedin the anomaly of Q1 and Q2 through vertical transportation term. The feedback from the latent heat associated with cumulus convection playeda significant role in the torrential rain of typhoon.(3) The cold air invaded the lower level part of the storm from east and west sides, and triggered off the convection. The deformation term of the vorticity and divergence at atmospheric and surface level made the mountain area a vorticity source, where the mesoscale convective systems were constantly triggered off and the rainfall was increased.
  • The Quantitative Comparisons among Ageostrophic Q Vectors
  • YUE Cai-jun;SHOU Yi-xuan;SHOU Shao-wen;ZENG Gang;WANG Yong-qing
  • 2008 Vol. 27 (3): 608-618. 
  • Abstract ( ) PDF (1714KB) ( )
  • There is an obvious precipitation event associated with the typhoon Haitang landfalling Fujian Province during 19~20 July 2005, which is simulated successfully by WRF model. By means of output data of the WRF model simulation, the volume averaged(900~600 hPa) field of Q vector divergence and precipitation caused by the forcing of Q vector divergence are calculated, whereby the differences of diagnostic ability among ageostrophic-dry-, ageostrophic-wet-and revised-wet-Q vectors are quantitatively examined. The results are as follows:(1) The convergence fields of ageostrophic-dry-, ageostrophic-wet-and revised-wet-Q vector divergences all have reflecting ability to synchronous simulated rainfall area on some degree, meanwhile, the convergence intensities of ageostrophic-wet-and revised-wet-Q vector divergences are both stronger than the counterpart of ageostrophic-dry-Q vector divergence, in particular, which is more obvious in primary rain area. Relatively, the reflecting ability of the convergence field of the revised-wet-Q vector divergences to precipitation area is the best.(2) The ranges of rainfall forced by ageostrophic-wet-and revised-wet-Q vector divergence respectively are almost the same, which both are evidently larger than the counterpart forced by ageostrophic-dry-Q vector divergence, relatively speaking, the two formers are more close to synchronous simulated rainfall range. Based on the intensities of the rain forced by the three types of Q vector divergence respectively, the revised-wet-Q vector is the strongest, the ageostrophic-wet-Q vector is the secondary, and the ageostrophic-dry-Q vector is the weakest, however, they are all significantly weaker as against to the counterpart of the synchronous simulated precipitation, and the intensity of the rainfall caused by the revised-wet-Q vector divergence is more close relatively to the counterpart of simulated precipitation.(3) The differences among the three forced precipitation fields as well as among the three kinds of Q vector divergence fields sufficiently suggest that there are a lot of synoptic scale stable vapor condensational potential heating and convective vapor condensational potential heating release, what's more, the ageostrophic-wet-and revised-wet-Q vectors considering vapor condensational potential are advanced in comparison to the ageostrophic-dry-Q vector in the context of the reflecting ability to precipitation, especially, the counterpart of the revised-wet-Q vector is more marked.
  • Numerical Simulations for the Thermal Impact of the Long-Rang Transport of Mineral Aerosols
  • CHEN Li;YIN Yan
  • 2008 Vol. 27 (3): 628-636. 
  • Abstract ( ) PDF (2090KB) ( )
  • Using two-dimensional cloud model of a spectral micro physics, the numerical simulations are conducted to investigate the impact of absorbing and heating, the introduce of cloud condensation nuclei(CCN) and ice nuclei(IN) during long-rang transport of the dust aerosols. The results show that when the dust layer located at the cloud base and the heights of 3 km, where the temperature is warmer than-5℃, the increase in CCN and giant CCN(GCCN) leads to a higher activation of water vapor and more effective collision coalescence between water drops, resulting in larger amount of precipitation. Under this condition, the more efficient precipitation and evaporation due to the presence of a absorbing aerosol layer lead to reduced concentration of cloud hydrometers and lower cloud optical depth and albedo. Only when the transported dust layer located at the height colder than -5℃, the mineral aerosols can act as effective IN, and can inhibit precipitation formation and increase cloud optical depth and albedo. It is also found that the effect due to the presence of a dust layer becomes more pronounced when the concentration of the absorbing aerosols becomes higher, and when the dust layer is thicker and located at lower altitudes.
  • Solution of the Space Potential in a Three-Dimensional Dynamic-Electrification Coupled Model
  • GUO Feng-xia;ZHANG Yi-jun;YAN Mu-hong
  • 2008 Vol. 27 (3): 648-656. 
  • Abstract ( ) PDF (1007KB) ( )
  • The electronic circuit analysis is used in a three-dimensional dynamic-electrification coupled model, and the effect of hydrometeors with charge to conductivity and current density are included in this paper. The electric potentials and fields before the first discharge presenting are resolved by Poisson equation and electronic circuit analysis, respectively. The results indicate that the conductivity in thundercloud is greater than in fair weather, and peaks correspond with the centers of charge regions. The positive and negative maxima of current density that associated with charged particles circulating correspond with the centers of positive and negative charge regions, respectively. When the charge density is less then 0.7nC·m-3, the magnitude of the maxima of current density that associated with charged particles circulating is 10-9A·m-2, and conduction current density and displacement current density are 10-8A·m-2. The relationship between the vertical profile of electric potential and charge structure is obvious by the electronic circuit analysis. The positive and negative maxima of vertical electric field are located in the upper and lower edge of main negative charge region, respectively. This is close to the observational results.

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