Plateau Meteorology

Current Issue

28 December 2011, Volume 30 Issue 6   
  • Moist Helicity Analysis of a Heavy Rainstorm in Sichuan Basin Induced by Plateau Vortex Moving Eastward
  • HUANG Chu-Hui;LI Guo-Ping;NIU Jin-Long;LUO Ling;ZHANG Wei
  • 2011 Vol. 30 (6): 1427-1434. 
  • Abstract ( ) PDF (1102KB) ( )
  • Using NCEP 1°×1° reanalysis data and the different height data of conventional observation， a case of heavy rainstrom  in Sichuan basin caused by plateau vortex moving eastward  from 30 to 31 July 2009 was analyzed by both the synoptic and dynamic methods， including the moving of the plateau vortex， distribution of rainfall， transportations of water vapor and helicity. The results showed that distribution of 500 hPa moisture helicity can give good indicator to the distribution and center of rainfall， the moisture helicity increased in the period of severe precipitation. The moisture helicity can reflect the dynamic character of weather when the rainstorm occurs， and divergence of negative vorticity on upper level cooperated with convergence of positive vorticity and vapor rotate rising on lower leve1 is a dynamic mechanism to trigger rainstorm, which has a better positive correlation with precipitation area and distribution in the next 6 h. The severe precipitation center generally appears on the side of maximum gradient value of relative spiral. The results have a certain reference value to the forecast of precipitation area and intensity distribution.
  • Feature Analysis on Southwest Vortex of Triggering Rainstorm
  • KANG Lan;HAO Li-Ping;NIU Jun-Li
  • 2011 Vol. 30 (6): 1435-1443. 
  • Abstract ( ) PDF (1043KB) ( )
  • Using NCEP reanalysis data, conventional observation data, hourly satellite image and automatic station data, the characteristic of mesoscale system\|southwest vortex are analyzed， which is closely related to  four rainstorm processes. The results show that: (1) The southwest vortex that triggered heavy rainstorm is wet vortex relatived to the environmental field, the south boundary is the main direction of moisture transport. In the formation stage of southwest vortex, the whole levels are positive vorticity, and generally keep deep updraft, and have a deep warm\|cored structure. In the strong development stage of southwest vortex, the positive vorticity is rising, the lower\|level of the tropospher change to cold\|cored structure, and its upper\|level is warm\|cored structure mainly. (2) When the southwest vortex repeatedly generat and disappear in situ or last longer, vortex centers in the upper\| and lower\|level are tend to vertical and its speed is slow, the convective cells are usually independent of the upstream baroclinic system and develop into MCC or MCS closed to MCC. When  the southwest vortex center quickly move, the convective cells weakly develop and often incorporate into the upstream baroclinic cloud system eastward.
  • Contrast Analysis on Background Circulation of Plateau Shear Line Moving Out and not Moving Out of the Tibetan Plateau
  • SHI Rui;HE Guang-Bi
  • 2011 Vol. 30 (6): 1453-1461. 
  • Abstract ( ) PDF (1288KB) ( )
  • Using the NCEP reanalysis data, based on the contrast analysis of the background circulation  impacting on plateau shear line moving out and not moving out of the Tibetan Plateau  in summer from 2000 to 2004 are analyzed. The result indicates that, the situation of ‘two troughs  and one ridge’ is stable in middle and high latitudes on 500 hPa,  which helps the the genesis of plateau shear line. The meridional circulations with the East Asian Trough along 32°～49°N  are beneficial to plateau shear line moving out  the Plateau. And  East Asian Trough and the west westward extension of Pacific Subtropical High are significantly in the circulation background of plateau shear line moving out of Tibetan Plateau comparing with plateau shear line not moving out of the Tibetan Plateau. On 200 hPa troposphere layer, the existence of South Asian High is beneficial to the generation of plateau shear line, and South Asian High of plateau shear line moving out  the Tibetan Plateau is stronger than that not moving out of it. And stronger of the upper jet stream is beneficial to plateau shear line to move eastward. In the middle troposphere the warm advection is very important to generation of the plateau shear line.On the Tibetan Plateau, positive vorticity advection in the middle troposphere is very important to generation of the Plateau shear line. Positive vorticity advection of plateau shear line moving out of the plateau is stronger comparing with  plateau shear line not moving out of the Tibetan Plateau.
  • Preliminary Analysis on Evaporation/Condensation Processes of Soil in Jinta Oasis
  • HAN Bo;吕Shi-Hua;AO Yin-Huan
  • 2011 Vol. 30 (6): 1462-1471. 
  • Abstract ( ) PDF (1039KB) ( )
  • Using the surface and 0.40 m depth soil temperature in Jinta oasis as boundary condition, the temperatures at 0.05, 0.10 and 0.20 m depthes were calculated by a one dimensional soil thermal diffusion equation. Comparing with the calculated and observed results on these three levels, it was found that the most significant difference between them appeared at 0.05 m level. Then, based on the characteristic of soil water content variability, evaporation and condensation (EC) processes were considered by improving the former thermal diffusion equation, and more realistic results were obtained, which means the EC processes might be important for hydrothermal variability of soil in Jinta oasis. The affection of EC on the surface energy balance were analyzed based on the observation of energy flux in the local surface. Two phenomena were found: Firstly, from 08:00 to 12:00, the shallow soil heat storage was not totally caused by the net radiation, but partly by the vapor condensation there; secondly, the latent heat flux was abnormally large from 12:00 to 16:00, made the surface energy flux unbalanced at that time, which can be explained as the vapor flux from deep soil being wrongly involved into the vapor flux of surface.
  • Analysis on Frontogenesis Function and Jet-Front Secondary Circulation in a Snowstorm Process
  • LI Zhao-Hui;WANG Dong-Hai;WANG Jian-Jie;LIU Ying
  • 2011 Vol. 30 (6): 1505-1515. 
  • Abstract ( ) PDF (1668KB) ( )
  • The weather situation, frontogenesis function and jet-front secondary circulation of Wuhan during the snowstorm process on 25～28 January 2008 are analyzed. The results show that the snowstorm  happened with a condition of favorable atmospheric circulation and physical quantity. The change of frontogenesis function is consistent with the occurrence and stop of snowstorm. The elongation deformation in horizontal deformation term is the main reason for frontogenesis, while elongation deformation and shear deformation are both important to frontolysis. The horizontal convergence term has obvious effect on frontogenesis. The strengthening and effective allocation of upper  and lower level jets make the jet-front secondary circulation occurring, which could balance frontogenesis and frontolysis. Meanwhile, the ascending branch of the  jet-front  secondary circulation transports the moisture upward and has a direct relation with the snowstorm in Wuhan. The upward motion in Wuhan is in the effective allocation of upper and low level jets, ascending branch of the jet-front  secondary circulation, the front elevation, the solenoid in baroclinic atmosphere and the symmetric unstable  and potential unstable stratification layer to maintain and develop.
  • Characteristic of a Snowstorm Process with Strong Cold Front and Inverted Trough and Its Formation Analysis
  • ZHAO Gui-Xiang;DU Li;FAN Wei-Dong;WANG Shu-Feng
  • 2011 Vol. 30 (6): 1516-1525. 
  • Abstract ( ) PDF (1366KB) ( )
  • The wind field structure for a snowstorm caused by strong cold front and inverted trough and its formation in Shanxi Province on 14 March 2010 was analyzed using the general observation data. The result showed that : (1)There were four stages in this process. Duration of strong cold front snow is long and there were 2 times increase of snow, while  duration of vortex snow is shorter and its intensity was more stronger. At surface wind field of automatic station, the snowstorm was directly caused by meso-β scale convergence and meso-β scale vortex. The intensity and area of severe snow were related with  wind field structure and configuration between height and low systems. (2) Deformation diagnosis revealed that the total deformation on 500 hPa obviously effects on the surface frontogenesis. The maximum center of expansion and deformation was coincided with surface vortex. It strengthened the surface vortex to cause snow storm. To severe front snow, the contribution of shear deformation was greater than that of expansion. The occurrence and maintain of maximum value of shear deformation was important factor of vortex and shear line on 700 hPa and strong cold front maintain on surface. (3) 12 h before severe snowfall, there was warm advection on upper level while cold advection on lower level, so there was ‘moisture cold pad’ on lower level which effected on vortex development. (4) Before the severe snowfall, upper westerly formed ‘jet core’ on 300 hPa, and with ‘jet core transfered’ downward, the vortex on lower level was development and shear line maintained stability. The snowfall area and intensity were related to position of  jet axis and its intensity.
  • Anomalous Thermodynamic Conditions for Freezing Rain in Southern China in January 2008 and Their Cause
  • GAO Yang;WU Tong-Wen;CHEN Bao-De
  • 2011 Vol. 30 (6): 1526-1533. 
  • Abstract ( ) PDF (992KB) ( )
  • The snow and freezing rain weather occurred in Southern China in January 2008 is analyzed  using the observation data from 604 stations in China and NCEP 2.5°×2.5° reanalysis data from a point of view of the surface and atmospheric thermodynamic structure and its climatic anomaly. The result shows that the core area hit by freezing rain is in the region of 108°~ 113°E and 25°~28°N   where the mean surface air temperature is below 0 °C in January 2008,  relatively to ordinary year, it is 4~6 ℃ lower which is favorable to form freezing rain.  The warm and moist air from Southern China between 850 hPa and 400 hPa continuously transport to make mean air temperature on 850~600 hPa   more than 0 ℃, which is favorable to produce precipitation. On the other hand, predominately norther wind on 1 000~850 hPa  carrys a great deal of cold air to keep the surface air temperature below 0 ℃, which makes rainfall become freezing while reaching the surface becoming the freezing rain. From the annual climate anomaly, upper southerly and lower northerly are much stronger than  the averages, and upper air is far warmer and lower air is far colder than normal.These anomalous conditions in January 2008 are very favorable to occurrence of  snow and freezing rain disaster that is historically rare in Southern China.
  • Analysis of Water Vapor Transportation and Its Influence on Rainfall Anomaly in Yunnan during Autumn and Winter of 2009
  • ZHANG Wan-Cheng;WAN Yun-Xia;REN Ju-Zhang;FU Rui
  • 2011 Vol. 30 (6): 1534-1542. 
  • Abstract ( ) PDF (1351KB) ( )
  • Using the monthly precipitation at 122 stations in Yunnnan from 1961 to 2009 and the monthly reanalysis data of NCEP/NCAR, the air column precipitalbe water (PW) and water vapor flux in autumn and winter are calculated. Based on those data, the features of water vapor transportation are studied. The relationships of Yunnan precipitation and PW and water vapor transportation are also studied. The results show that the air column PW over Yunnan has a feature of southeast-northwestern ‘U’ pattern. The air column PW over Yunnan is changed from 10 to 32.5 kg·m-2 in autumn but from 5 to 20 kg·m-2  in winter. The precipitation in Yunnan is correlated to the air column PW in autumn and winter. The resource of Yunnan autumn precipitation are from the Indian Ocean, the Bay of Bengal and the South China Sea. The resource of Yunnan winter precipitation is from westerly wind water vapor transportation in middle latitude. The correlation vector distribution of Yunnan autumn precipitation and water vapor transportation is the type of cyclonic-anticyclone. The autumn precipitation is related to the southerly water vapor transportation in the Bay of Bengal and the Indochina Peninsula and to the intensity and location of the westerly wind of low latitude too. The stronger  the monsoon depression in middle and upper troposphere over the Bay of Bengal is, the more  southerly water vapor transportation from the Bay of Bengal and the Indochina Peninsula to Yunnan are, the more  the autumn precipitation in Yunnan is too. The winter precipitation is correlation of the water vapor transportation from the Indochina Peninsula to Yunnan. The less of the air column PW and the less of the meridional water vapor transportation and stronger of the anti-cyclone in middle and upper troposphere over the Bay of Bengal and the Indochina Peninsula are the reasons that precipitation in Yunnan during the autumn and winter of 2009 is less comparing with the climatologically normals.
  • Analysis on Circluation Characteristic and Cause of Rarely Continuous Rainy Weather in Zhejiang Province during Early Spring of 2010
  • ZHANG Jian-Hai;CAO Yan-Yan
  • 2011 Vol. 30 (6): 1543-1553. 
  • Abstract ( ) PDF (1641KB) ( )
  • Rarely continuous rain happenes in Zhejiang Province in early spring of 2010, which has heavy precipitation intensity, duration long and the highest record of historical total process precipitation. Using the objective analysis data, the circulation characteristic, thermal and dynamic conditions in the continuous rainy weather process are studied, and these characteristic with those of the same period in history are compared. The results show: (1)The northerly flow in the front of Ural long-wave ridge provides the cold air condition for continuous rainy weather. The northward and westward location of the West Pacific Subtropic High is advantageous to establish enduring and steady water vapor channel on its northwest side. (2)The structure of  meridional temperature difference makes upper-level westerly jet branches. Zhejiang Province just lies in the upper-level divergent zone on the south side of  north jet axis, the formation and dispersion of north jet is ahead of the starting and endding time of the continuous rain. (3)Lower-level southward cross-equatorial flow is weaker than usual one during the rainy process. Southwesterly flow between the South Sea and Southeast China coast seems to be extraordinarily stronger than that in average year. The formation of  southwesterly flow is main northwesterly flow from Bay of Bengal rightward to passing through Indo-China Peninsula, then it swerves to form, which provides the abundant water vapor for the continuous rainy days. (4)Rain belt is on the north side of water vapor flux moist tongue area, which roughly concides with frontal zone of equivalent potential temperature energy. The cold air activity plays an important action in aggravation of rainfall intensity during the second stage of the continuous rainy process. (5)The dynamic structure of the continuous rainy weather is typical configuration of upper-level divergence and lower-level convergence. The height of divergent district gradually increase after the beginning of rainfall, and then stable on the upper troposphere.
  • Mesoscale Analysis on a Heavy Rainstorm in Jinan on 18 July 2007
  • SHENG Ri-Feng;WANG Jun;GONG Dian-Li;CHEN Xi-Li;ZHANG Hong-Sheng
  • 2011 Vol. 30 (6): 1554-1565. 
  • Abstract ( ) PDF (1826KB) ( )
  • A mesoscale heavy rainstorm in Jinan on 18 July 2007 is analyzed using the special observational data, including Doppler radar products, automatic meteorological station data, NCEP/NCAR reanalysis data and CloudSat satellite data. It is found that the heavy rainstorm process is generated by the interaction of westly trough, the southwest warm and wet airflow on the edge of  West Pacific Subtropical High and the cold air from the north. The result  shows that the mesoscale convergence center and line play important roles, which is the start  mechanism for the heavy  rainstorm. Furthermore, the  heavy rainstorm occurres near the center of mesoscale low pressure and accompanies with them. The mesoscale convergence center develops at intersection of the boundary layer convergence line, which increase the strong wind convergence and accumulation about moisture and energy. Radar products show that convection and precipitation enhance at the junction between two strong east-west echo bands. In the vertical direction, low level convergence and high level divergence are almost vertical. This configuration shows that mesoscale convective system has strong baroclinic characteristic. This case has the typical characteristic of convective storm, accompanying with vertical tilt of updraft and obvious sink flow compensation on both sides.
  • Change Feature of Net Primary Productivity of Natural Vegetation and Its Impact Factor in the Source Region of Yellow River in Recent 50 Years
  • YAO Yu-Bi;YANG Jin-Hu;XIAO Guo-Ju;WANG Run-Yuan;LU Deng-Rong
  • 2011 Vol. 30 (6): 1594-1603. 
  • Abstract ( ) PDF (999KB) ( )
  • Climatic observation data of monthly average temperature, maximum temperature, minimum temperature, relative humidity, precipitation, wind speed and sunshine duration in the source region of Yellow River during 1959-2008, the net primary productivity (NPP) was computed by revised Thornthwaite Memorial Model. The annual and interannual changes of NPP were analyzed and the impact climatic factors of NPP are discussed. The main results are as follows: In 1959-2008, the annual precipitation in this region has a increasing trend and the linear fitting ratio of annual precipitation change was 5.316~11.318 mm·(10 a)-1. The precipitation obviously increased during spring and summer in this areas. The annual temperature shows a ascending trend too. The linear fitting ratio of annual temperature change is 0\^273～0.322 ℃·(10 a)-1 and the ratio significantly increased in winter. The annual maximum evapotranspiration (ET0) displayed a ascending trend too, with a linear fitting ratio from 5.286 to 8.026 mm·(10 a)-1 and the rate of increasing obviously appeared in summer. The surface humid index displayed a ascending trend as well as precipitation, but the linear fitting ratio is 0.011~0.026 (10 a)-1 and the surface mositure index quickly increased in winter. There are five periods of dry and wet alternations in recent 50 years. Before 1990s, it was a light wet stage, but the light dry stages appeared about high frequency from 1998 to 2004. The annual NPP in this region had a increasing trend. The linear fitting ratio of annual NPP is 95.502～190.72 kg·hm-2·(10 a)-1. The major climatic impact factors of the NPP are the precipitation, maximum evapotranspiration and average minimum temperature in the regions.
  • New Anomaly Feature of Summer Air Temperature in Northeast China and Its Responding to Atmospheric General Circulation
  • ZHANG Qian;LI Dong-Liang
  • 2011 Vol. 30 (6): 1604-1614. 
  • Abstract ( ) PDF (1165KB) ( )
  • Based on the observational data at 123 stations in Northeast China and 500 hPa monthly average height of NCEP/NCAR reanalysis data,  through EOF and synthetic analyzing methods,  the variation of summer air temperature in Northeast China and its abnormal  atmospheric general circulation are studied. The results show that,  in the background of global warming,  there are two temperature changing patterns in the studied region. One is the consistent pattern in the whole region and the other is the spatially-oppsite pattern between the northeast and southwest. In the recent 60 years,  the summer air temperature in Northeast China performed ascendant trend overall,  especially after 1990s. The regional difference  main appears that the warming of the northeast is earlier than that of  the southwest. There are four mainly spatial anomolous patterns of the summer air temperature in Northeast China. The first pattern is consistent high temperature,  the second pattern is consistent low temperature,  the third pattern is low temperature of the southwest with normal or high temperature  of the northeast,  and the forth pattern is low temperature of the northeast with normal or high temperature  of the southwest. It is considered that the summer temperature in Northeast China has a significant correlation with atmospheric general circulation. The high and low temperaturesare corresponding to positive and negative anomaliesof 500 hPa potential height, respectively. While the total region is under the control of consistent positive or negative potential height,  the temperature inNortheast China is consistently high or low; while the northeast and southwest regionsare controlled by different phases of potential height anomaly,  the change trend of the summer air temperature in  two regionsis different.
  • Cross-Validation Error Analysis of Daily Gridded Precipitation Based on China Meteorological Observation
  • XIONG Qiu-Fen;HUANG Mei;XIONG Min-Quan;HU Jiang-Lin
  • 2011 Vol. 30 (6): 1615-1625. 
  • Abstract ( ) PDF (1227KB) ( )
  • Based on  daily precipitation of 2 403 gauge observations in China for the periods from 2006 to 2008, a gridded dataset with 0.1°×0.1° (about 10 km×10 km) is established using the methods by combining the Barnes interpolation and observation precipitation frequency. Then the precision of  gridded data is assessed by examining cross-validation statistics of the correlation coefficient(COR), the mean bias error(MBE)， the mean absolute error(MAE), the mean relative error(RMAE), the root mean square error(RMSE), compound relative error(CRE)， observation mean square deviation σ(O), interpolation estimated mean square deviation σ(I)， the relative variance ratio(RVAR) and the probability density function(PDF) distribution, the temporal and spatial characteristics of the statistics are investigated and the annual cycle of interpolation error for the gridded data is discussed. The results show that daily gridded precipitation has a higher precision with the correlation coefficient at 0.81, the mean bias error is -0.02 mm·d-1, the mean absolute error is 1.3 mm·d-1, the mean relative error is 58.67%, the root mean square error is 4.5 mm·d-1 and compound relative error is 41.17%, and the relative variance ratio is 93.12%. Moreover, the PDF distribution of interpolation precipitation is closer to observation as well as the interpolation error is the normal distribution. The mean absolute errors and the root mean square errors for gridded precipitation increase from northwest China to southeast China. The mean relative errors are small in the east of China, especially in the flatland but large in the west of China. In the meanwhile, the correlation coefficients show high in the east part of China and relatively low in the west part of China. In addition, the annual cycle of monthly mean absolute errors and the root mean square errors for gridded precipitation are increasing with the augment of monthly total precipitation, the maximum errors in July while the minimum in December in general. But the precipitation characteristics, such as convection activities, have a heavy impact on the distribution of error statistics. The correlation coefficient, reaching its peak in November and valley in August, associates with the precipitation characteristics that the high correlations are related to large-scale and systematic precipitation while the low correlations are related to local the convective precipitation.
  • Analysis on  Black Storm Cause in Hexi Corridor on 24 April 2010
  • QIAN Li;YANG Yong-Long;WANG Rong-Zhe
  • 2011 Vol. 30 (6): 1653-1660. 
  • Abstract ( ) PDF (894KB) ( )
  • Using the conventional sounding and ground enhanced observation data, based on dynamical diagnosis and mesoscale method, the causes of a  regional strong sandstorm in Hexi corridor on 24 April 2010 is analyzed. The result shows that the main reason of strong sandstorm formation  is the  surface heat low with cold front. The large-scale system of forming strong sandstorm is that  the polar cold air ahead of Ural Mountains high pressure ridge erupts toward south. The strong barocliny on 700 hPa over Hexi corridor, Gansu Province is not only advantage to frontogenesis and low level convergence, but also momentum transport along downward. The large gradients of pressure and temperature before and after cold fronts are caused by development of thermal low pressure, which provide the thermal instability condition for convection development. Ascending motion before cold front and overlap of upper and lower jets provide the developing condition of deep vertical circulation for information of black storm. Using the sounding  data before and after black storm ocurring, the atmospheric dynamic characteristic as ‘windstorm horizontal helicity’ and thermal characteristic as ‘V-3θ’ are calculated and analyzed. The result reveals that reasonable atmospheric temperature-humidity structure is beneficial to forming and developing of sandstorm.
  • Change of Surface Pressure in Northeast China during 1961-2008
  • JIN Wei;REN Guo-Yu;QU Yan
  • 2011 Vol. 30 (6): 1661-1667. 
  • Abstract ( ) PDF (704KB) ( )
  • Monthly surface pressure data from 1961 to 2008 are used to study the temporal and spatial changes of surface  pressure in three provinces (Liaoning, Jilin and Heilongjiang) of Northeast China. The results show that: (1) The trend of average surface pressure in three provinces of Northeast China is not significant  during the whole analyzed period. However, there is an increasing trend in the period of 1961-1990 and a obvious decreasing trend in the period of 1991-2008 with the rate of -0.32 hPa·（10 a）-1, which has passed the significant level of 0.05. (2) The trend of  region  average surface pressure has seasonal variations, with decreasing trends in spring and autumn, and increasing trends in summer and winter,  but the trends in spring and summer have passed the significant level of 0.05. (3) The trend of annual mean surface pressure shows clearly regional differences. In most of Liaoning Province,Jilin Province and the west of Heilongjiang Province surface pressure have appeared a decreasing trend while  the rest of the study region has experienced an increasing trend. The  change of surface  pressure  in three provinces of Northeast China   might have been related to the weakening of the Siberian High and the increaseing of  surface air temperature in the study region.
  • Analyses on Aerosol Optical and Microphysical Properties over Taihu Lake Region
  • XU Ji-Liang;ZHANG Lei;LV Da-Ren
  • 2011 Vol. 30 (6): 1668-1675. 
  • Abstract ( ) PDF (944KB) ( )
  • Using Level 2.0 data of AERONET Taihu station, change of the Aerosol Optical Depth (AOD) with wavelength is analyzed.  The  results indicate that the curve is not linear at the double logarithm coordinate, but it can be fitted well with quadratic polynomial.  Aerosol particles consistent with lognormal size distribution.  the single-scattering albedo (SSA) is investigated also. SSA is relatively small in winter.  When the wavelength get longer, SSA increases in spring but decreases in August and September. Additionally, the particle spectra and volume concentration from September 2005 to November 2006 are analyzed. In  spring, the volumetric concentration of coarse particles are 2.0~2.5 times that of fine particles; and total particle concentration, affected by the coarse one, appears a peak. In the late summer and early autumn, however, the situation is in reverse. Increasing amount of smaller coarse particles(<3 μm) is larger than that of bigger particles(>3 μm) during  spring, which induces the diminishment of coarse particles effective radius. Finally, a dust weather process influence on the aerosol micro-physical parameters during 16～18 April 2006 are analyzed.
  • Analysis on Radar Echo Characteristic of a Supercell Storm Disaster Hail
  • ZHAO Jun-Rong;GUO Jin-Qiang;YANG Jing-Hui;YANG Jian-Cheng
  • 2011 Vol. 30 (6): 1681-1689. 
  • Abstract ( ) PDF (1289KB) ( )
  • Using C-band Doppler weather radar data in Shihezi, radar echo evolution characteristic of severhail storm supercell  in the southern edge of Junggar basin, the northern edge of the desert area Shihezi on 28 June 2010 is analyzed. The results showed that the rightside ofsupercell storm forward appeared bow echo, and its rear left and right side respectively appeared  ‘V’notch; thevertical profile of reflectivity along the inflow direction of the strongest echoes through the location showed the typical bounded weak echo area, the strong echo wall on the left of echo overhang and bounded weak echo area, the maximum echo intensity appeared in the narrow area along the lower part of  echo wall, and its value is70 dBz; the radial velocity  presented mesocyclone, the development and maintenance of mesocyclone madethe supercell bow echo development and maintenance; severehail occurredin weak wave zone, large value of the vertically integrated liquid water content and the overlap region in the cyclone area; mesocyclone can warn the hail ahead 30 min, the bounded weak echo of vertical profile for reflectivity and its echo hanging and strong echo center intensity (70 dBz) under echo wall takeas an early warning indicator.
  • Characteristic of Heavy Precipitation and Gale Analysis of Supercell Storm on 23 July 2009
  • WANG Fu-Xia;PEI Yu-Jie;YANG Xiao-Liang;LI Zong-Tao;YU Xiao-Ding
  • 2011 Vol. 30 (6): 1690-1700. 
  • Abstract ( ) PDF (1560KB) ( )
  • Based on the Doppler weather radar data of Shijiazhuang and Puyang, upper air data and automatic surface observation data, a detailed analyses of environmental condition, strcture and evolution of a heavy precipitation supercell are made. The analysis indicates that the heavy precipitation supercell storm occurs in the moderate convective available potential energy(CAPE value is 1 701 J·kg-1) and significant vertical wind shear (surface～500 hPa, 19.97 m·s-1) environment. The isolated convective cell rapidly develop after entering the thermal energy boundary. The increased lower vertical wind shear and cold cool along thermal boundary apper to promote the supercell development. The evolution of heavy precipitation supercell storm can be summarized as ‘common cell, heavy precipitation supercell and bow echo’ three stages. it is belong to the typical right shift storm. In the early stage, two strong reflectivity center of supercell storm have multi-cell storm features. Strong reflectivity of each center has its own V-front inflow notch and bounded weak echo regions. At the beginning, heavy precipitation supercell storm have the lower (about 2.5 km height) significant hook echo, echo overhang and bounded weak echo regions, which are the typical characteristics of the classic supercell. The cyclone is surrounded by heavy rainfall areas, the cyclone (Rankin model structure) firstly observed near 2.4 km, and then development up and down with very strong rotation. The cyclone extended to 5 km with the maximum rotation speed of 27 m·s-1, reached the strong cyclone standards.
  • Monitoring of Two Radar Echoes for a Tornado in Mountain
  • LI Yan-Jiang;SUN Li-Hua;YANG Mei
  • 2011 Vol. 30 (6): 1701-1708. 
  • Abstract ( ) PDF (1172KB) ( )
  • Using the radar data of CINRAD/SA in Qinhuangdao and CINRAD/CC in Chengde,   NCEP reanalysis data,  mesoscale physical diagnosis and disaster report, a tornado  in Pingquan county of  Chengde  on 20 July 2009 is analyzed. the preliminary conclusions indicate that the tornado take place in valley which is higher terrain in the west and lower terrain in the east, cold air move southtoward, the momentum of upper-level NW jet stream  go down, which make the component V of low-level wind field in mesoscale system to increase along the western valley, product an asymmetric secondary circulation of small-scale valley breeze, enhance cyclonic vortices and occur much more mesocyclone in outbreak zone of tornado. At Beijing station, the vertical wind shear is 19.44 m·s-1  at the heights of 0～6 km,  the index K is 24 ℃, SI is 4 ℃ at 08:00, K is 28 ℃, SI is 0 ℃ at 14:00. Because the rainfall quickly is evaporated under the action of strong radiation in the afternoon, so it supply the short-time vapor conditions for keeping tornado. C wave rang radar displays that there are five mesocyclones and two general storm cells in the east of valley from 13:06 to 14:36, and three times on TVS data are at 13:30, 14:06, 14:36, respectively. The maximum vorticity in the lower level is 29 m·s-1, height is 0.8 km, the moving direction of storm is from NNW to SSE, horizontal moving speed is 60～70 km· h-1, maximum echo intensity is 69 dBZ, tornado strength limit within F0～F1. Comparing with the special profile of the Doppler radial velocity and mesocyclone, it is found the duration time   until tornado touching the ground below 1 km is 10 min and the duration time of rotation above  4 km height is 45 min.

NewsDownloadMore+More+

DynamicsVideo InformationMore+More+

Links E-journal More+ More+

Official Wechat

QQ Group Chat

The system is designed and developed by Beijing magtec Technology Development Co., Ltd. with technical support: support@magtech.com.cn