Plateau Meteorology

Current Issue

28 December 2006, Volume 25 Issue 6   
  • The Effects of Moist Potential Vorticity and Thermodynamic Parameter CD on Evolution of Vorticity and Divergence
  • CHEN Zhong-ming;GAO Wen-liang;MIN Wen-bin;HE Guang-bi
  • 2006 Vol. 25 (6): 983-989. 
  • Abstract ( ) PDF (320KB) ( )
  • Torrential rain and flood are the main disasters of meteorology in China in summer.So meteorology workers pay close attention to the causes of torrential rain and the forecast of it.Our level of understanding heavy rain process is low because of the complex nature of heavy rain formation.It is imperative to enhance research on occurrence mechanism of heavy rainfall.According to the occurrence and development of torrential rain relating closely to convergence increase in low and middle layer of troposphere,making further research on divergence equation and its application is conductive to reveal physical mechanics of the evolution of torrential rain process.In this paper,divergence equation explicitly including effects of thermodynamic parameter CD on divergence evolution is deduced from complete set of primitive equation system.Dynamic property of thermodynamic parameter CD and horizontal component of moist potential vorticity MPV2 is analyzed on basis of divergence equation and moist potential vorticity equation.Relationship between the evolution of divergence and vorticity and thermodynamic parameter CD is revealed.Coupling forces between dynamic and thermodynamic fields are able to excite the increase of convergence and positive vorticity in low and middle layer of troposphere while CD >0;conversely,they contribute the increase of divergence and negative vorticity.This paper provide theoretic basis for the thermodynamic parameter CD employed in diagnosis of generation and development of mesoscale heavy rain systems.
  • Preliminary Analysis on Near Surface Radiation Budget in the Region of Mt.Qomolangma in April and May 2005
  • LI Mao-shan;MA Yao-ming;ZHONG Lei;Lü Shi-hua
  • 2006 Vol. 25 (6): 1008-1013. 
  • Abstract ( ) PDF (263KB) ( )
  • Mt.Qomolangma(Everest) is the highest peak in the world.The mountains of Himalayas are the important channels for the mass exchange between surface layer of Northern Hemisphere and troposphere atmosphere.The mountains relate surface layer atmosphere over the Tibetan Plateau and the above free atmosphere through many atmospheric circulation systems including mountain-valley wind.The Mt.Qomolangma region is a representative case of mountains of Himalayas.During the Scientific Expedition to Mt.Qomolangma of Chinese Academy of Sciences in spring 2005,one radiation system[CNR1 radiation sensor] and one turbulent measurement system [sonic anemo-thermometer(CSAT3)] were set up on the base camp of Mt.Qomolangma(28.137°N,86.854°E,and 5149 m above m.s.l.).Another radiation system [CNR1 radiation sensor] and turbulent system [sonic anemo-thermometer(CSAT3)] was set up at Quzong site(28.310°N,86.896°E,and 4475 m above m.s.l.).Quzong site is about 43 km from Mt.Qomolangma site.With the radiation measurement data the radiation income and expenses in the near surface were analyzed over Mt.Qomolangma region.The results showed that:(1) The shortwave radiation flux was almost same in April and May 2005,but longwave radiation flux in May was larger than those in April.(2) The surface albedo changes with difference of elevation.
  • A Preliminary Study on Land-Surface Albedo in Northern Tibetan Plateau
  • LI Ying;HU Ze-yong
  • 2006 Vol. 25 (6): 1034-1041. 
  • Abstract ( ) PDF (1244KB) ( )
  • Based on the observed data at Automatic Weather Stations(AWS) including D105,Amdo,MS3478 and BJ in northern Tibetan Plateau during the experimental period of CEOP/CAMP-Tibet(Coordinated Enhanced Observing Period(CEOP) Asia-Australia Monsoon Project(CAMP) on the Tibetan Plateau),the temporal variation and spatial distribution characteristics of surface albedo in this area are analyzed.The results indicate that the surface albedo in this area has obvious diurnal,monthly and seasonal variation characteristics.The diurnal variation curves in winter and spring present marked saddle shapes,and the change of curves shape is not obvious in summer and autumn.The monthly average albedos from June to September are the lowest in the whole year,and the albedo fluctuation in May is obvious.As to the seasonal average values,those in winter are the hightest,the second in spring,the third in autumn,and the lowest in summer.The average value in the region is 0.2457.The spatial distribution of albedo is also not homogeneous.Both the values and the shapes of curves are dissimilar in different stations.It relates to the geographical position of observation station,but weather condition and underlying surface situation are also very important.
  • Large Eddy Simulation of Airflow inside a Large Space Buildings
  • JIANG De-hai;JIANG Wei-mei;HU Fei;XUAN Chun-yi;FANG Xiao-yi
  • 2006 Vol. 25 (6): 1042-1051. 
  • Abstract ( ) PDF (1934KB) ( )
  • The large eddy modle is used to simulate the indoor airflow inside a large space buildings,and some good effects are obtained.The simulation contents include:(1) the indoor temperature and flow fields when fire takes place in the warehouse under the condition of mechanical ventilation;(2) the indoor airflow in simple square building and gymnasium under the condition of natural ventilation.Through analyzing the above results,we find that: When the building catches fire,the indoor flow is dominated by the thermodynamic effect.The position of the air-vents,the thermodynamic property of the ventilated airflow,the position and the thermodynamic property of indoor goods would significantly affect the airflow and temperature fields;under the condition of natural ventilation,the outdoor weather condition and the position of the air-vents have large influence on the indoor airflow,the outdoor wind velocity and wind direction have important influence on the indoor wind velocity and the distribution of the indoor airflow field,but the position of the air-vent mainly affects the distribution of the indoor airflow field.Because there are lots of factors influencing the indoor airflow,it must be analyzed in details to evaluate and design indoor airflow for the building like gymnasium,in which the requests for indoor airflow and indoor air quality are very strict.
  • Research on Retrieval of the Amount of Atmospheric Water Vapor over Qinghai-Xizang Plateau
  • LIANG Hong;LIU Jing-miao;ZHANG Jian-cheng;BI Yan-meng;WAN Kai-cun
  • 2006 Vol. 25 (6): 1055-1063. 
  • Abstract ( ) PDF (1754KB) ( )
  • Based on the ground data of 89 weather stations in Qinghai-Xizang Plateau,NCEP grid reanalysis dataset,and the ground GPS remote sensing data at three stations in July from 2001 to 2003,the results of the amount of atmospheric GPS remote sensing and radiosonde data are compared,the effect of the amount of atmospherc water vapor change on rainfall formation and the relationship between the amount of atmospheric water vapor and the ground vapor pressure are studied,the spatial-temporal variation characteristics of the amount of atmospheric water vapor over Qinghai-Xizang Plateau and its formation cause are analyzed.The result shows that a coincidence with root-mean-square errors(RMSE) of 0.15 cm dose exist between the results based on GPS and those based on the radiosonde data on Qinghai-Xizang Plateau.Also,there is a good relationship between the amount of atmospheric water vapor and sorface vapor pressure.There are three centers of high amount of water vapor over Qinghai-Xizang Plateau in every season.These centers are located respectively over southeastern part,southwestern part and northeastern part of the Qinghai-Xizang Plateau.There is a good relationship between the seasonal change of precipitable water vapor distribution and the change of 500 hPa wind field and integrated vapor flux over Qinghai-Xizang Plateau.
  • Impact of Finner Model Horizontal Resolution on a Heavy Rainstorm Forecast
  • JIANG Yong-qiang;ZHANG Wei-huan;ZHOU Zu-gang
  • 2006 Vol. 25 (6): 1071-1082. 
  • Abstract ( ) PDF (2507KB) ( )
  • For rainstorm that causing special large flood of Yangtse Rive drainage area during 12 June to 29 July 1998,the numerical simulation is made using a mesoscale rainstorm model(MRM1) varying-distance layers 21 levels,high resolution PBL,Eta coordinate model with 36 km and 18 km horizontal resolution.The results show that the average threat score of precipitation from slight rain to rainstorm which using 18 km model is as much as that using 36 km,but the forecast impact of heavy rainstorm has notable progress using the 18 km model,and the centers of forecast rainstorm or heavy rainstorm clearly close observation centers.10 cases of numerical simulation on 12~21 June 1998 show a trend that the precipitation concentrating to some area,and the rate of sub-grid precipitation increase from 14.1% to 27.5%,with the rate of grid precipitation decrease from 14.1% to 27.5% after promoting the model horizontal resolution.The numerical comparative analyses for weather systems that caused great rainstorm in Fujian and Zhejiang Province on 19 June 1998 show that the meso-βscale character of weather system has been preferably simulated using 18 km model,the forecast rainstorm and heavy rainstorm fields have obvious localization,and it is more close to the observation.
  • Primary Analyses on "Heat Island" Events in Beijing in Recent 40 Years
  • ZHANG Shang-yin;XU Xiang-de;LIU Chang-you;HU Bao-kun
  • 2006 Vol. 25 (6): 1147-1153. 
  • Abstract ( ) PDF (587KB) ( )
  • Based on the daily,mean surface air temperature data from 1961 to 2004 measured by the standard stations and Automatic Weather Stations in Beijing,a series of the strong heat island(SHIE) events in Beijing over the past 44 years are given.Moreover,the analyses were also made on the temporal and spatial distribution characteristics of these events.The results indicated that 79 strong heat island events took place in Beijing during 1961-2004,mainly occurred in winter,secondly in autumn and occasionally in summer.The heat island centers were often located in the vicinity of Gongzhufen,Tiananmen Square or Daguanyuan in Beijing,which differed from the Haidian or Tongzhou centers as revealed in other research findings.Furthermore,it was found that during 44 years,there was an evident tendency that the number of SHIE increased with the time.Meanwhile,the SHIE intensity has an evident interannual fluctuation,but not interdecadal variation.In general,SHIE intensity reach the maximum value at 02:00~08:00,and it becomes gradually weakened or even falls into a negative value at 12:00~17:00.
  • The Air Temperature Variation and Heat Island Effect in Urban Area of Shanghai City
  • ZHU Jia-qi;TANG Xu;JIANG Hao
  • 2006 Vol. 25 (6): 1154-1160. 
  • Abstract ( ) PDF (643KB) ( )
  • Based on the data set of automatic observation station,the variation characteristics of air temperature and heat island in urban area of Shanghai city are analyzed.The results show that,there are some high temperature centers in urban area of Shanghai city,located at Hongkou gymnasium,Jing'an district and Yan'anxilu road.Their air temperature are over 36℃ after noon and daily average temperatures are over 31.8℃ in summer.Temperature differences between the day and the night over these area are high over 8℃ in summer and still 2℃ in winter.It means a stable urban heating distribution.There are clear climate characteristics of daily and annual variation of air temperature in urban area and different to suburb,but small difference between each urban station.The urban heat island is affected by the temperature variation of urban area and suburb area,and made a special variation characteristic.Because the air temperature of urban area differs the suburb in variation,the urban heat island differs the air temperature in variation.Daily average urban heat island intensity over Shanghai is about 2.6℃ in summer,over 3.7℃ in spring,and under 1℃ in winter.Annual average heat island intensity is about 0.7℃.The urban heat island intensity over Shanghai is lower in the day and high in the night,and makes the highest peak in the midnight.Interannual variation of the urban heat island intensity over Shanghai is obvious,and with a rise trend over 0.05℃/a in July.
  • Research of Spatial-Temporal Evolvement Characters of Mean Air Temperature in China in Recent 50 Years Based on Spatialization Technique
  • CAI Fu;ZHANG Shu-jie;YU Gui-rui;ZHU Qing-lin;LIU Xin-an
  • 2006 Vol. 25 (6): 1168-1175. 
  • Abstract ( ) PDF (1079KB) ( )
  • Spatialization technique is used to quantificationally analyze the mean surface air temperature data in China in recent 50 years.Spatial-temporal evolvement rules of climatic factors are accurately found out.The spatializated climatic value integrating with the multi-annual deviation from normal interpolation methods is used to build annual and seasonal spatializated datum in China from 1951 to 2001 with a resolution of 10 km×10 km.By the analyzing,the conclusions are as follows: Firstly,the annual and seasonal mean air temperature indicate an increasing trends in China during 50 years,with a maximum rising of(0.313)℃/10a and a minimum rising of 0.152℃/10a in winter and summer,respectively,besides an annual rising of 0.208℃/10a.It is much more evident for increasing trends after middle of 1980's.Secondly,as far as space scale is concerned,the areas of decreasing temperature in every season include Southwest China,Southeast Tibet and the West of Tian mountain.On the contrary,the most area of North China and midwest of Tibet indicate a strong increasing trends.At the same time,in Southeast China,mean air temperature does not indicate evident change trends.Thirdly,the warm winter events happen frequently in North China and infrequently in partial area of Sichuan and Yunnan provinces.Besides,the area of happening warm winter is constantly expanding,with a rising range of country area of 8.6%/10a in the past 50 years.Additional,the south of Xinjiang province,the northwest and southeast of Tibet and the areas between Changjiang River and Huaihe River are the area where cold summer happen frequently.Furthermore,the south of Liaoning province,the desert area of Xinjiang province,the central Tibet,the most area of Sichuan province and the south of Changjiang River are the area where cold summer happen infrequently.The area happening cold summer is constantly decreasing,with a decreasing range of country area of 5.8%/10a in the past 50 years.
  • Correlation Analyses between Interannual Changes of Cloud Cover and Surface Air Temperature in Ningxia in Recent 40 years
  • CHEN Nan;ZHAO Guang-ping;CHEN Xiao-guang
  • 2006 Vol. 25 (6): 1176-1183. 
  • Abstract ( ) PDF (692KB) ( )
  • The interannual and interdcadal changes and their correlation relations of air temperature,total-and low-cloud covers have been analysed,utilizing the observed data of the surface air tempernture and 24 stations over Ningxia in recent 40 years.The results show that the mean temperature increase in wavy way in Ningxia in recent 40 years,especially after 1990's on wards.The interannual changes of air temperature in arid region of middle Ningxia is larger;in Guyuan region,lesser.Since 1951,the annual mean tatal cloud cover in Ningxia gradully decrease.the decreasing tendency of low cloud cover is more obvious than that of the total cloud cover,but the cloud cover in Ningxia has increased after 2000.The correlation analysis indicates that there is a negative relation between annual mean air temperature and total and low cloud covers in Ningxia and they have passed the test of the significant level at 0.01 and the low cloud cover has a more significant relation with the temperature.There is a obvious positive relation between precipitation and total and low cloud cover.Meanwhile,the relation coefficents between the total and low cloud cover in different regions and seasons of Ningxia and the air temperature and precipitation have obvious differences.
  • Research on Fineness Method of Numerical Forecast Precipitation Products Based on GIS
  • WANG Xi-wen;LIU Zhi-guo;BI Xiao-dong;ZHANG Xu-dong;ZHANG Tie-jun
  • 2006 Vol. 25 (6): 1190-1195. 
  • Abstract ( ) PDF (679KB) ( )
  • Based on the mesoscale numerical model(MM5),the precipitation forecast products were imported to ArcInfo's flat-top of geographic information system(GIS) on which precipitation forecast of meteorological station exported by MM5 modle was transformed to layers of data-point.Then grid layers produced by spline interpolation overlapped the basis-data layer with the boundaries of the province,city and county levels in Gansu,and with the different colors show different rainfall.As a result,precipitation forecast's precise products of Gansu was exported respectively according to region,county and falling area.It is proved that these fineness products are not only close to facts on spatial distribution,precipitation,and tendency of precipitation,but also useful for forecast of storm precipitation,local severe convective weather and precipitation at stations.It makes numerical,material and video precipitation products of Gansu true through binding forecast production in GIS.The method is of high resolution and great effects,makes precipitation forecast of Gansu accurate to town-level.So it is valuable and credible to plough into daily operation.
  • Changes of Wind Speed and Wind Energy over Gansu Corridor
  • WANG Yi-rong;ZHANG Cun-jie
  • 2006 Vol. 25 (6): 1196-1202. 
  • Abstract ( ) PDF (1485KB) ( )
  • Using the climatic data of wind speed at 19 stations in Hexi corridor during 1970-2002 and the intensive data of 10 min interval from 7 wind-towers in Gobi in 2004-2005,the wind speed of surface layer and evolution and distribution of wind energy in this region are studied.The result shows that the descendenting about wind speed in oasios of Hexi corridor is obvious,but it is stable in other areas in where its descenting trend is no obvious.The wind speed change exists periodic oscillation characteristic,and the vertical wind speed difference is to decrease from high to low near surface layer.The maximum or minimum wind speed values in high layer lag behind low layer.In while year,the maximum wind speed occurred from February to April,and the minimum one,in January and May.The wind speed with height according to the rules of natural logarithm increase,The wind energy rapidly change with height near the(8 m) levels of surface.The most of wind speed in Hexi corridor area is 4~12 m/s,which is main wind energy contributor.The resource of wind is very plenty in Hexi corridor that amount to 2200 khW/m2 and over in 10~70 m layers near surface.

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