Plateau Meteorology

Current Issue

28 October 2008, Volume 27 Issue 5   
  • Study on Evapotranspiration Retrieval Using MERIS and AATSR Data over the Loess Plateau Mesa Region
  • LIU RONG;WEN Jun;ZHANG Tang-tang;LIU Yuan-yong;LI Zheng-chao
  • 2008 Vol. 27 (5): 949-955. 
  • Abstract ( ) PDF (461KB) ( )
  • The evapotranspiration over the Loess Plateau mesa region where is heterogeneous landscape are critical and complicated, but the utilization of satellite remote sensing has unique advantage in wide observation and high temporal resolution over heterogeneous landscape. In this paper, the potential using the remote sensing data from Medium Resolution Imaging Spectrometer, one of the on board sensor of the Environmental Satellite, was established to explore estimates of the land surface albedo, plant coverage used in evapotranspiration estimate based on the Land Surface Energy Balance Theory on June 7, 11 and 27, 2005. The 'Splits Window' algorithm was used to retrieve the surface temperature from Advanced the Along-Track Scanning Radiometer, another onboard senor of the Environmental Satellite. Then the net radiation, sensible heat flux and soil heat flux were worked out over the Loess Plateau mesa in China. Considering of the vegetation canopy and land surface characteristics, daily evapotranspiration model was deriveded by combining the data of solar radiation, air temperature, sunshine integrator and wind speed from the weather station. The daily evapotranspiration model can also transform instantaneous evapotranspiration to daily value. Comparing with latent heates flux retrieved by remote sensing data and ground observation during Loess Plateau land surface process field experiment, the maximum and minimum errors of this approach is 10. 96% and 4. 80%, respectively. The case of the bias was also explored and discussed.
  • The Distinguishing Characteristics of Wave-Packet Propagation in Strong/Weak Qinghai-Xizang Plateau Summer Monsoon Year
  • XIAO Tian-gui;Li Jiang-lin;LI Xiang;PENG Jun
  • 2008 Vol. 27 (5): 956-966. 
  • Abstract ( ) PDF (2247KB) ( )
  • Using the daily NCEP/NCAR reanalysis of 600 hPa geopotential height field from 1996 to 2005 and the concept of Plateau monsoon index(PMI) and method of WPD investigate the different wave-packet characteristics in different stages of the strong/weak(1998/1997) year.(1) The Plateau summer monsoon characteristics calculated by PMI of 1997 and 1998 show that: Its strength is very different in the different phases, so this paper divide it to three phases(intensive and permanent and weakly days)and discussing it separately, the result also show the characteristic is distinct in strong/weak summer monsoon.(2) During the intensive days that before the Plateau summer monsoon break up, Plateau region has strongly wave-packet propagating eastward where come from Ural-Balkash Lake and propagating westward where come from Arabian Sea and Araby whatever in the strong or weak year, but wave-packet value in the strong monsoon year is higher than in the weak monsoon year. When Ural area wave-packet propagation become weak, and Plateau region wave-packet propagation mainly come from western Pacific Ocean, Plateau summer monsoon break up.(3) In the intensive days after Plateau summer monsoon onset, average wave-packets in Plateau region is strong and mainly propagating from west Pacific ocean in strong monsoon year, but weak in weak monsoon year. In the permanent days the average wave-packet in Plateau region is very strong and disperse to around in strong monsoon year, then average value become lower because of dispersion, but weak monsoon year shows the opposite characteristics, Plateau region has wave-packets propagation which come from Arabian Sea and Araby and west Pacific ocean, and the average wave-packet is weak.(4) In the weakly days while Plateau summer monsoon come to an end, the characteristics of Plateau summer monsoon begin translate to water monsoon and the average wave-packet is higher than before and the wave-packet in Ural region propagating northward in strong summer monsoon year(1998). In the end it indicate that the center of wave-packet is corresponding to the perturbation energy center for weather system, and the center of wave-packet propagation has relationship with the movement of trough and wedge.
  • Characteristics of Temporal and Spatial Distributions of Annual Precipitation in Xinjiang
  • XIN Yu;CHENG Hong-wu;ZHANG Guang-xin;ZHANG Xin;LU Ge;BO Li-jian
  • 2008 Vol. 27 (5): 993-1003. 
  • Abstract ( ) PDF (1381KB) ( )
  • Based on the annual precipitation data at 88 representative meteorological stations in Xinjiang during 1961-2005, using the method of linear tendency coefficient, Kendall-τ test, REOF/RPCA, wavelet analysis of morlet and cross spectrum analysis, the change trend of annual precipitation was studied and annual precipitation fields can be divided into the six regions: The West of Northern Xinjiang along the Tianshan Mountains, the Middle Tianshan accompanying Tulufan Basin, the West of Southern Xinjiang, the North of Northern Xinjiang, the Tarim Basin and the Southeast of Southern Xinjiang. On the basis of this, the regional change features of annual precipitation were analyzed as well as the multiple periodic in decadal and interdecadal, and the annual precipitation correlations among different sub-regions. The results are revealed as fellows: It was the driest in the 1960's and 1970's in Xinjiang. From the 1980's, an increasing annual rainfall trend, more and less, appeared except desert basin. Neither the decadal nor interdecadal period of annual precipitation is always the same in the different sub-region. There exists a quasi-coupling oscillation of significant 6 years. There are outstanding coupling oscillations between the west of Northern Xinjiang and the middle Tianshan Mountains in many frequency ranges, and along with the north of northern Xinjiang including eastern Tianshan Mountains secondarily. The west of Northern Xinjiang processes striking five and six years reverse phase oscillations with the west of Southern Xinjiang, and six years adverse phase oscillation with the Tarim Basin. Except for the six year coupling oscillation, the abnormal change of annual precipitation in most sub-regions of Xinjiang appeared from north to south or from west to east in turn.
  • Analyses on Trends of Annual and Seasonal Four Kinds of Daily Precipitation in China
  • NING Liang;QIAN Yong-fu
  • 2008 Vol. 27 (5): 1010-1020. 
  • Abstract ( ) PDF (2689KB) ( )
  • Basing on a dataset of daily precipitation of 554 stations covering the landmass of China during 1961-2003, the linear trends in the annual precipitation, seasonal precipitation and four kinds of precipitation by the method of linear regression are analyzed, and the trends of extreme precipitation defined by two different definitions are compared. The results reveal that the annual precipitation has significantly increased over the northwest of China, the middle and lower reaches of the Yangtze River valley and the South China but significantly decreased over the northern China and the Sichuan Basin. Through the analyses of the trends of seasonal four kinds of precipitation, it is found that the precipitation of four seasons over northwest of China show increasing trends and the precipitation have increasing trends mostly in summer and winter over the middle and lower reaches of the Yangtze River valley, while the four kinds of precipitation over northern China have decreased in four seasons. It is notable that the extreme precipitation have increased significantly over northern China, the middle and lower reaches of the Yangtze River valley, part of southwest of China and the littoral of southern China, but North China, Sichuan Basin and parts of northeast of China show obvious decreasing trends.
  • Temperature Variations in Arid and Semi-Arid Areas in Middle Part of Asia during the Last 100 Years
  • WANG Jin-song;CHEN Fa-hu;ZHANG Qiang;JIN Li-ya;LI Jing;JIN Ming;CHEN Jian-hui
  • 2008 Vol. 27 (5): 1035-1045. 
  • Abstract ( ) PDF (922KB) ( )
  • The temperature change is analyzed by using the surface temperature data of 69 stations from 1961-2003, which are extended forward to 1901 with an EOF interpolation method in arid and semi-arid areas in Middle part of Asia(it is abbreviated to ARID-ca hereinafter, which includes central Asia, Mongolia, Northwest China and North China). The results show that the main characteristic of temperature change is consistent arid and semi-arid areas in Middle part of Asia, at the same time 4 temperature abnormal areas are obtained by using REOF method, namely Eastern Monsoon Area(areaⅠ), Central Asia(area Ⅱ), Mongolia Plateau(area Ⅲ) and Tarim Arid Area(area Ⅳ), and every area represents distinct warming trend. The linear rates of temperature increase during 1901-2003 over the above 4 abnormal areas are about 0.19, 0.16, 0.23 and 0.15℃/10a for the annual mean, respectively, and those of the total ARID-AREA are about 0.18℃/10a for the annual mean and 0.21℃/10a for the winter mean, which exceed those of the Northern Hemisphere, Global and China, but are close to those of Tibetan Plateau. In the last 100 years, the temperature arid and semi-arid areas in Middle part of Asia has come through relative slowly warming process before 1970's and obvious warming after 1970's, and the rate of temperature increase is higher and higher. Comparing with East China, the temperature change has notable difference arid and semi-arid areas in Middle part of Asia. There is no obvious warming from 1920's to 1940's, but there are 6 zigzagged increased-decreased cycles of temperature in the whole warming process arid and semi-arid areas in Middle part of Asia, namely 1920's, 1940's, 1960's, 1980's, 1990's and early this century. The duration of temperature increase is longer and the amplitude is bigger, whereas it is shorter and smaller in period of temperature decrease. No matter in the stages of temperature increase or decrease, the vary amplitude of temperature is bigger than those in East China and global average.
  • Applicability Analysis of VCI to Monitoring Northwest China Drought
  • GUAN Xiao-dan;GUO Ni;HUANG Jian-ping;GE Jin-ming;ZHENG Zhi-hai
  • 2008 Vol. 27 (5): 1046-1053. 
  • Abstract ( ) PDF (811KB) ( )
  • The capability of Vegetation Condition Index(VCI) monitoring drought in northwest China was analyzed using GIMMS NDVI data set from January 1982 to December 2003 and the monthly precipitation data at 138 meteorological stations during the same period. The NDVI data set was collected at spatial resolution of 8×8 km2 and one month interval. According to the characteristic of climate type and vegetation planting in the northwest region, several typical research regions including rain-fed areas, irrigated areas and the grassland at the Qinghai-Tibet Plateau were chose. The applicability of VCI monitoring drought in different areas was studied in northwest China. The results show that VCI can reflect the drought spatial distribution and the development commendably in most of the areas in northwest China. The effect in VCI monitoring drought were different in these research regions. The VCI could preferable monitor the drought in rain-fed areas, it is an effective index in monitoring meteorological drought. The VCI were not useful in monitoring the drought happened in irrigated districts and in the grassland in Qinghai-Xizang Plateau. The VCI appears abnormal high value in the desert regions.
  • Features of Precipitable Water Vapor by GPS in Different Cloudform Precipitation——Analyses on Some Typical Cases in North China
  • LI Guo-cui;LI Guo-ping;LIAN Zhi-luan;SUN Li-hua
  • 2008 Vol. 27 (5): 1066-1073. 
  • Abstract ( ) PDF (823KB) ( )
  • Based on the precipitable water vapor received from ground-based GPS and surface meteorological data in Shijiazhuang, Qinhuangdao and Zhangjiakou city in April~October 2005-2006, the relation between precipitable water vapor and real precipitation are studied. With the analysis of precipitable water vapor in convective precipitation produced in the cumuli form, steady precipitation in the stratiformis cloud, and the heavy rain in the laminose and mixed stratiformis cloud, some valuable conclusions are put forward in this paper, the results are as follows: It is a necessary condition that high precipitable water vapor exist in the air. Precipitable water vapor change according to wave shape and phases character, there is a good relationship between change extent, maximum level, duration and weather system, precipitation kinds and etc. The oppearing time of maximum value between rainfall intansity and precipitable water vapor is uncertain coincidence, but it is known that severe rainfall usually begin at the period of high value of precipitable water vapor, and high value of precipitable probability is parallelism with the latter. In addition, there is different characteristics in the above three different precipitable kinds, and these results provide a reference for the short range forecasting and now-casting.
  • The Impact of Urbanization on City Climate of Beijing Region
  • LI Shu-yan;CHEN Hong-bin;LI Wei
  • 2008 Vol. 27 (5): 1102-1110. 
  • Abstract ( ) PDF (1132KB) ( )
  • The impact of urban growth on city climate variation is studied using the daily mean data of temperature/velocity and precipitation at 20 meteorological stations from 1970 to 2005. The results show that:(1)In the past 36 years the urban heat island(UHI) area is increasing, the UHI intensity is enhancing, and the UHI centers are evolving from single to several centers. In 2000's, the maximal UHI intensity is 2.11℃. In the past 36 years the mean temperature in winter increases 0.298℃/10a.(2)The urbanization has made the precipitation show a tendency of uneven distribution. In 1970's, the precipitation in the west of the city is much, while in the southeast of the city is little;in 1980's, all the urban zone's precipitation is little;in 1990's, the precipitation in both west and south of the city is much, while in the northeast of the city is little;in 2000's, the little precipitation zone extends from urban district to the southeast.(3)The urban wind speed has a decreasing tendency. The wind speed in 1970's is 2.49 m·s-1, in 1980's, is 2.32 m·s-1, in 1990's, is 2.16 m·s-1, and in 2000's, is 2.28 m·s-1. In the past 36 years the wind speed decreases 0.05 m·s-1·(10a)-1.(4)The temperature and the population density logarithm have a linear correlation, the correlative coefficient is 0.65;the temperature and the city land area have a linear correlation, the correlative coefficient is 0. 6387.
  • Observational Analysis on the 3-Dimensional Structure of a Hailstorm in the Eastern Part of Maowusu Desert
  • JING Xi;JING Yu;LI Ming-juan;TU Ni-ni;HE Wen-bin;DU Ji-wen;ZHANG Ren-he
  • 2008 Vol. 27 (5): 1119-1130. 
  • Abstract ( ) PDF (3236KB) ( )
  • A hail storm weather event occurred in northwestern Yulin on July 27, 2006, was continuously monitored and analyzed by using real time data provided by the new generation weather radar and MICAPS observed data including other physical quantity calculated upon them. The diagnostic analysis shows that the atmospheric stratification was stable at 08:00 that day, but a narrow strong convectively-instable tongue generated in the moist barotropic field at 925 hPa level extending from southeast to hail zone. In 2 hours before the hail storm near the up neighbor of the hail zone, there emerged a β mesoscale high energy ratio center and a β meso-scale low energy ratio tongue reflecting the weak cold air movement. The hailstorm also developed with the strengthening of moist atmospheric baroclinicity in lower troposphere and temperature leap in boundary layer. Dynamic situation for generating and maintaining hail storm derived from formation of the mesoscale secondary circulation along latitude. Radar reflectivity analysis indicates that strong hail and high wind were induced by the super cell storm which was a combination of the β mesoscale hook echo and a new γ mesoscale evere convective cell generated in the hook area by dry invasion. The super cell storm has unique dynamical features, except which accompanied by a long-lasting deep mesoscale vortex, in lower troposphere, the inflowing jet stream maintained full 50 minutes, the rare β mesoscale ring divergence emerged in hook area near surface level and represented features of outward expansion. In 0. 5°velocity field, stream in hailstorm zone experienced a evolution of longitudinal convergence, cyclonical convergence, cyclonical twist and longitudinal convergence till the end.
  • Application of VIL and VIL Density in Warning Criteria for Hailstorm
  • DIAO Xiu-guang;ZHU Jun-jian;HUANG Xiu-shao;YANG Chuan-feng;LIU Zhi-hong;GENG Li
  • 2008 Vol. 27 (5): 1131-1139. 
  • Abstract ( ) PDF (472KB) ( )
  • Using the Jinan-CINRAD/SA data in 2002-2005, the distributive characteristics of Grid Vertically Integrated Liquid(VIL), the VIL Density(VILD) and the VIL above the 0℃ layer(VILH) in the cases of convective cloud are analyzed. It is pointed out that the difference of VIL, VILD and VILH are obvious, the hail shooting had significantly higher grid VIL, VILD and VILH values on the average, through the entire time series when compared to the non-hailstorms. The maximum average values of Grid VIL, VILD and VILH of hailstorms is higher than the non-hail shooting, they are 20 kg·m-2, 1.7 g·m-3 and 16 kg·m-2 respectively. Grid VIL values for hail shooting have obvious phenomenon of increasing abruptly in the late stage of storm developing, such as the increasing magnitude was 15.4 kg·m-2 for severe hail shooting. The hail shooting almost began after the VIL peak, so VIL peak used as a severe weather predictor has limited lead time. The average lead time was decided by the amount of time from the VIL increasing abruptly VCP end to the VIL peak VCP end. The average lead time in May, June and July was 4.8, 11.4 and 12.3 minutes, respectively. TS, PO and FAR were calculated for some parameters to determine the best possible points for which a warning or no warning decision can be based. The VIL, VILD and VILH thresholds in different months were examined for usable signals as warning hails. The VILH thresholds in May, the VILD thresholds in June, and the VIL thresholds in July have the best effect on warning hails.
  • Analysis and Numerical Simulation of a Severe Heavy Rainfall in Shandong Peninsula
  • ZHOU Shu-ling;WU Zeng-mao;YAN Li-feng
  • 2008 Vol. 27 (5): 1149-1160. 
  • Abstract ( ) PDF (2777KB) ( )
  • A diagnosis and simulation study have been conducted to reveal the feature of the heavy rainstorm in the east of Shandong Peninsula on 5 August 2004 by using T213 data and routine observation data. The evolutionary process and development mechanism of the heavy rainstorm process are analyzed with emphasis on the orogrphic effect of Shandong Peninsula on the development of the upper and low-level jets as well as the development of vortex in the boundary layer. The simulated results indicated that the moving echo of radar from south to north along with the rainstorm showed the structure and development of the mesocal systems. The low-level jet(LLJ) and upper-level jet(ULJ) intensified with the development of convective system while they reached the Shandong Peninsula. The center of LLJ which lay to the south of the mesocal systems was caused by the southwest ward warm air current on the western side of the western Pacific ocean subtropical high. The upper-level mesoscal jet formed by the upper level outflow of convection occurred during the evolution of convection. The interaction of LLJ and mesoscale ULJ could maintain and accelerate the development of convective system. It is also shown that the meso-β-scale vortex was produced in the boundary on the western side of the western Pacific ocean subtropical high. After its formation, this meso-β-scale vortex moved northwest ward accompanied with heavy rainstorm and the moving route of this meso-β-scale vortex is related to the distribution of the topography in Shandong Peninsula. The southwest warm air current was blocked by Shandong Peninsula and forced to move around it, which was one of the reasons the heavy rainstorm occurring in Weihai, Shandong Province.
  • Mesoscale Characteristic and Mechanism Analysis of a Heavy Flooding Rainstorm Process in Xijiang River Basin,Guangxi
  • LIAO Sheng-shi;LUO Jian-ying;YAO Xiu-ping;WANG Qing-guo;LIN Kai-ping
  • 2008 Vol. 27 (5): 1161-1171. 
  • Abstract ( ) PDF (2317KB) ( )
  • Based on the Black-Body Temperature(TBB)data of FY-2C Stationary Meteorological Satellite from China Meteorological Agency(CMA) and the reanalysis dataset from the NCEP/NCAR reanalysis project, combining the data of hourly precipitation at 90 stations in Guangxi, the mesoscale characteristic and the mechanism of a heavy flooding rainstorm process happened in Xijiang River basin is analyzed by the 25-point smooth filter methods. Results show that the spatial and temporal characteristics of the mesoscale convective system that associated with the mesoscale rain mass has significant day variation, and the mesoscale rain mass often appear in the area of the center of low TBB and the lower TBB band, the sharp and dense TBB on the north of the low center and the area where the TBB curve is the larger;the evolution of the mesoscale vortex filtered from large scale SW stream has great impact on the maintaining and development of the mesoscale convective cloud mass over Xijiang River in South China, which is the direct causes for the heavy flooding rainstorm process;the low-level-jet give the rich moisture to the heavy rainfall and the convective instability and the strong vertical shear of horizontal wind are the important condition of the explosive and persistent heavy flooding rainstorm process.

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