ISSN 1000-0526
CN 11-2282/P

Volume 38,Issue 11,2012 Table of Contents

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  • 1  Investigation of Beijing Extreme Flooding Event on 21 July 2012
    YU Xiaoding
    2012, 38(11):1313-1329. DOI: 10.7519/j.issn.1000-0526.2012.11.001
    [Abstract](4155) [HTML](1378) [PDF 6.03 M](5937)
    On 21 July 2012 Beijing experienced the most severe rainfall event since August 1963. The extreme rainfall induced flooding killed over 100 people and the property damage is over 11.64 billion RMB yuan (about 2 billion U.S. dollars). Based on the routine upper level and surface observation, the satellite and radar data, a detailed analysis and investigation have been done on this event. The major results are as following: (1) The upper level trough accompanied by surface cold front moving toward east blocked by the subtropical high provides favorable synoptic scale conditions for torrential rain event in Beijing area. (2) The presence of a tropical cyclone over the South China Sea near the coastline led to the establishment and enhancement of southeastward and southward low level jet toward Beijing area, providing plenty of water vapor to Beijing area. (3) The development of Hetao vertex on 20 July led to the formation of a meso α scale MCS over that area, and its high value of vertical helicity made it well organized and longlived. This MCS moved with the upper level trough eastward, and was over Huabei region (including Beijing area) on the second day (21 July), producing extreme rainfall over Beijing area. (4) The south east low level jet constantly triggered new convective cells on the east slope of the Taihang Mountain Range, then moved to northeast direction into Beijing area, leading to the torrential rainfall and severe flooding there.
    2  The Characteristics of the Mesocyclone and Severe Weather Associated with Convective Storms
    WU Fangfang YU Xiaoding ZHANG Zhigang ZHOU Xiaogang WEI Yingying
    2012, 38(11):1330-1338. DOI: 10.7519/j.issn.1000-0526.2012.11.002
    [Abstract](1477) [HTML](135) [PDF 1.04 M](1326)
    Based on 4 year observation data (2005—2008) acquired by Doppler weather radar located at Yancheng, the relationship between mesocyclones and the severe convective weather is analyzed. The results show: (a) There is a high probability of large hail occurring on the right flank of the storms with high top and bottom of mesocyclones; (b) A storm with lower bottom and smaller diameter of mesocyclone is favorable for tornado; (c) Rear inflow jet can intensify the wind shear of mesocyclone, make the mesocyclone descending, thus produce downdraft and strong wind; (d) The mesocyclones located on the front flank of storm with lower bottom and weaker wind shear usually cause heavy rain. Convective storm containing mesocyclone usually occurs in the environment with high CAPE and strong vertical wind shear.
    3  Spatiotemporal Variations of Heavy Rain’s Frequency in the Early Rainy Season in Guangdong
    LI Xiaojuan JIAN Maoqiu FANG Yichuan LUO Wen
    2012, 38(11):1339-1347. DOI: 10.7519/j.issn.1000-0526.2012.11.003
    [Abstract](871) [HTML](98) [PDF 4.06 M](1246)
    Based on the observed data of precipitation in Guangdong Province, the characteristics of spatiotemporal variations of heavy rain in early rainy season (April-June) were studied. The results show: (1) The spatial distribution of heavy rain frequency is consistent with the rainfall and has obvious regional characters. The heavy rain frequency can represent the drought and flood trend in the early rainy season. By REOF method, the heavy rain distribution can be divided into 4 regions: East Guangdong, the Pearl River Delta region, Northwest Guangdong and Leizhou Peninsula. (2) The main periods in the frequency variation of heavy rain are 2-3 a and 6-10 a. The period of each region has shortened since 1985, with the main period of 4-5 a. (3) The frequency of heavy rain in the Pearl River Delta and the region south to it has an increasing trend, which is more obvious in the center of Peal River Delta region, and passed a confidence level test at 0.05. The most obvious change happened in June.
    4  Application of Low Latitude South and North Wind Indices to Prediction of Rainstorm in Guangxi
    CHEN Jian LIU Couhua GAO Anning LIANG Weiliang
    2012, 38(11):1348-1354. DOI: 10.7519/j.issn.1000-0526.2012.11.004
    [Abstract](784) [HTML](55) [PDF 2.46 M](918)
    An experiential index for prediction of regional rainstorm in Guangxi has been found, by analyzing EC wind data and defining the south and north wind indices of low latitudes. The wind indices in the cases that regional rainstorms occur or not are collected based on 1115 front cases during 1970-2009. The distribution of probability of regional rainstorm versus the wind indices is calculated, while the wind indices are combined with experiential corrections. As a result of examining 440 front rainstorm cases from 1970 to 2009, the proportion of the experiential index corresponding to the time of rainstorm happening is 74.5%, the corresponding to the position of rainstorm is 75.9%, and the corresponding to the intensity of rainstorm is 67%. These facts manifest that the experiential index is reasonable and available in actual predictions.
    5  Impact of Low Frequency Oscillation Intensity and Phases in Tropics on the Winter Precipitation in Southern China
    FENG Junyang XIAO Ziniu
    2012, 38(11):1355-1366. DOI: 10.7519/j.issn.1000-0526.2012.11.005
    [Abstract](875) [HTML](93) [PDF 5.32 M](949)
    The relationship of the low frequency oscillation (LFO) intensity and phases in tropics and the winter precipitation in southern China has been investigated based on the NOAA outgoing longwave radiation (OLR) data, NCAR/NCEP data and observed precipitation data in China. The phase composites of the low frequency precipitation for the high index years show that the phase changes are significantly correlated with the low frequency changes of the circulation systems in the subtropical and Philippines and they can affect the precipitation in southern China for different phases. For the high index years when the active convection center is located in tropical Indian Ocean (western Pacific), the Arabian trough and the Bay of Bengal trough are deepened (weakened), and the anticyclone (cyclone) circulation appears near Philippines. Such environment leads to the south (north) wind anomaly to appear in southern China, the moisture and upward motion are increased (decreased) and the precipitation is more (less). The anomalies in convection, precipitation and other factors are not obvious in each phase for the low index years.
    6  Abnormality of General Circulation with LFO During the Torrential Rainstorms over Southern China in 2010
    ZHANG Yaohua ZHOU Bing ZHANG Yaocun
    2012, 38(11):1367-1377. DOI: 10.7519/j.issn.1000-0526.2012.11.006
    [Abstract](1155) [HTML](68) [PDF 3.13 M](1147)
    By using NCEP/NCAR daily reanalysis data and NCC station precipitation data, the authors analyze the abnormality of general circulation with LFO during the torrential rainstorms over southern China in 2010 with the application of multivariate empirical orthogonal function (MV EOF). Results show that: the East Asian summer monsoon to be exceptionally weak, the West Pacific subtropical anticyclone to be exceptionally southerly, the emergence of three monsoon surges, the abnormal activities of upper level westerly jet and divergence field and their interactions with one another, are the main affecting systems of precipitation abnormality over southern China in 2010. To the MV EOF spatial distributions of wind and precipitation fields, the centers of low frequency precipitation always correspond to those of 200 hPa flow divergence and 850 hPa convergence. The first MV EOF mode of precipitation field reflects the climatic evolution of East Asian summer monsoon, while the second and third modes reflect the LFOs on different time scales of summer monsoon during the seasonal advancing process. The second mode is in positive phase of LFO during the first half of July while the third mode during the middle and later part of June, so that the ends of Jiang huai Meiyu season and early flood season of southern China are put off and Meiyu precipitation in the middle and lower reaches of the Yangtze River is enhanced. The climatic evolution of summer monsoon coincided with LFO ultimately leads to the frequent rainstorms over southern China in 2010.
    7  Study on Numerical Simulation of Wind Energy Resources Based on WRF and CFD Models
    FANG Yanying XU Haiming ZHU Rong WANG Peng HE Xiaofeng Didier Delaunay FU Bin WANG Li
    2012, 38(11):1378-1389. DOI: 10.7519/j.issn.1000-0526.2012.11.007
    [Abstract](1618) [HTML](138) [PDF 5.55 M](1059)
    A combined model system (WRF/WT) of the mesoscale model WRF and the Meteodyn WT, a CFD model from France, was carried out the numerical simulation experiments of regional wind resources over Hailing Island of Guangdong Province with a horizontal resolution of 100 m × 100 m. The observational data from 7 wind towers in Hailing Island were used to test the results modeled by WRF/WT, and compared with the simulated errors to the single point wind parameters, thus studying the feasibility of WRF/WT model system in micro siting for wind farm and the application of distributed development of wind power and utilization. The results showed that, the combined model system of mesoscale model and CFD model in simulating the trends of the regional wind energy resource distribution is more accurate than CFD model used only; the WRF/WT model system used in complex terrain for wind resource numerical simulated evaluation is feasible, and its accuracy in simulating the parameters of the regional wind energy resource distribution is close to the result of WRF/WAsP simulating within 2 km. The WRF/WT model system compared to WRF/WAsP has obvious advantages when the frequency distribution does not meet the Weibull distribution or in a steep terrain. In the future, we need to further research in the interface methods of mesoscale model and CFD models, and the error correction of mesoscale model simulations.
    8  Homogeneity Study and Comparison Analysis on Precipitation Series over China
    WANG Qiuxiang LI Qingxiang ZHOU Haonan WEI Na XING Xuhuang WU Sheng’an
    2012, 38(11):1390-1398. DOI: 10.7519/j.issn.1000-0526.2012.11.008
    [Abstract](819) [HTML](126) [PDF 1.71 M](1079)
    Based on the precipitation data during 1951-2009 for all the 2415 stations in China, an SNHT (Standard Normal Homogeneity Test) method is used to test the homogeneity of annual data series. The result shows that about 114 stations contain data discontinuities, which covers about 4.72 percent of the total. In the following step, the inhomogeneous series at the 70 stations where the candidate series have good correlation with the reference stations with correlation coefficients above 0.7, have been adjusted in annual, monthly and daily time scales. Further comparison and analysis show that, the adjustment effects on winter precipitation series are much more than those on summer precipitation series. Finally the raw and adjusted data over plain, mountainous and station denser or sparser areas have been analyzed, and the result shows that the adjustment is reasonable. The variation coefficients, precipitation anomalies and linear trends have not changed greatly for the most of the adjusted series, with an exception in mountainous areas, the changes are slightly larger.
    9  Causative Analysis of Continuous Drought in Southwest China from Autumn 2009 to Spring 2010
    WANG Xiaomin ZHOU Shunwu ZHOU Bing
    2012, 38(11):1399-1407. DOI: 10.7519/j.issn.1000-0526.2012.11.009
    [Abstract](1029) [HTML](59) [PDF 2.34 M](1136)
    Based on the 1951—2010 daily Compound Index (CI) and atmospheric circulation monitoring index provided by National Climate Center, the daily precipitation data of the 335 stations in the Southwest China, the daily NCEP/NCAR reanalysis data and the daily OLR data of NOAA, the distribution of the drought patterns in the Southwest China was analyzed by using the REOF method, and the characteristics of atmospheric circulation anomalies such as western Pacific subtropical high (WPSH), Indian Burma trough, convection activities, water vapor transportation, and vertical motion of the continued drought from autumn 2009 to spring 2010 in the Southwest China were revealed according to the composite analysis and correlation analysis methods. It was found that the extreme drought occurred in the medium strength and central pattern El Ni〖AKn~D〗o background, instead of statistical typical La Ni〖AKn~D〗a background. The results indicated that influenced by the central type El Ni〖AKn~D〗o, the anti Walker circulation caused the significantly abnormal sinking movement around 120°E in the equator and a strong abnormal anti cyclone in the South China Sea and the surrounding areas of Southeast Asia. At the same time, the Southwest China was affected by the abnormal northwest air stream. By both influences, an obvious airflow divergence area occurred in the lower troposphere and its persistence was the key cause for the extreme drought.
    10  Econometric Analysis on the Effects of Meteorological Factors on Daily Visitors to Expo 2011 Xi’an and Its Application for Predicting the Number of Visitors
    LUO Hui LIU Jie GONG Zaiwu SHEN Jin YANG Shengli DU Yanxiu XIAO Bo DENG Xiaoli MA Xiaomei YAO Dongsheng GAO Wuhu
    2012, 38(11):1408-1416. DOI: 10.7519/j.issn.1000-0526.2012.11.010
    [Abstract](886) [HTML](169) [PDF 1.18 M](1022)
    An applied meteorological econometric model was built by using real time data of daily number of visitors and meteorological factors from April 28 to August 15, 2011. The factors in the model included the number of daily visitors, the daily weather data during this period, and the quantitative explanatory variables of the daily high temperature, mean wind speed and mean relative humidity, meanwhile, the virtual explanatory variables were considering the precipitation, holidays, daily variables, and monthly variables. Besides, a random error factor of AR(2) was introduced. With the above, the meteorological econometric model was created. Furthermore, the special meteorological service system for predicting the number of visitors of the Expo was developed and the operational tests as well as application were carried out. The system for predicting the number of daily visitors has been built and applied in predicting the number of visitors with quantitative analysis on different weather conditions, and this helped the decision makers of the Executive Committee of Expo 2011 Xi’an control the number of individual visitors in daily and safely operating. The system has been proved to be successful in the short range and medium range predictions which simulated the characteristics of the daily and monthly changes of the numbers, and predicted the number of visitors in 15 days accurately, while the 1-7 d prediction was even better than that of 8-15 d. The result offered continuous support to the Executive Committee for decision making. According to the prediction of October 2011, 10 million visitors were expected till 22 of October, and the total (including the securities, staff) would exceed 16 million, which was very close to the actual total number, roughly 15.73 million.
    11  Path Analysis on Negative Air Ion Concentration and the Meteorological Environment in Urban and Forest Zones
    HUANG Shicheng XU Chunyang ZHOU Jialing
    2012, 38(11):1417-1422. DOI: 10.7519/j.issn.1000-0526.2012.11.011
    [Abstract](852) [HTML](170) [PDF 533.91 K](1110)
    There are many uncertainties in the relationship between meteorological environment and the negative air ion (NAI) concentration. Previous research has confirmed that the NAI concentration changes with time and environment. Based on the observation data of NAI concentration in one year in Suqian City, this study investigated the distributions of NAI concentration in urban and forest zones and explored the roles played by the meteorological factors in the NAI concentration. The results show that the NAI concentration in forest zone is higher than that in the urban zone, particularly in seasons summer and autumn. The results also indicate that the total cloud amount, the average wind speed and the percentage of sunshine are not significantly correlated with urban and forest NAI concentrations. With the aid of a path analysis method, it is found that in the meteorological factors, which may influence the NAI concentration, the vapour pressure is either the superior direct factor or the greatly indirect factor, and the air temperature is the secondary factor, which has important direct effect on NAI concentration in forest and city sections. Because the remaining path coefficient of meteorological elements on NAI concentration in urban and forest areas is more than 0.8, this suggests that meteorological factors present less influence on the NAI concentration in this study, the authors suggest that in the environment there are still some other important factors that have direct effect on NAI concentration.
    12  The Performance Verification of Medium Range Forecast for T639, ECMWF and Japan Models from June to August 2012
    ZHAO Xiaolin
    2012, 38(11):1423-1428. DOI: 10.7519/j.issn.1000-0526.2012.11.012
    [Abstract](852) [HTML](143) [PDF 4.25 M](925)
    The performance of medium range forecast is verified and compared for the models of T639, ECMWF and Japan from June to August 2012. The results show that the three models have good performance on predicting the variation and adjustment of atmospheric circulation over Asian middle and high latitude areas. Comparatively speaking, EC has better performance on forecasting synoptic systems and elements than T639 and JP models, and is the best at the prediction of the track and intensity of typhoon Haikui among all models.
    13  Analysis of the August 2012 Atmospheric Circulation and Weather
    TAO Yiwei
    2012, 38(11):1429-1435. DOI: 10.7519/j.issn.1000-0526.2012.11.013
    [Abstract](850) [HTML](161) [PDF 2.69 M](993)
    The following are the main characteristics of the general atmospheric circulation in August 2012. There was one polar vortex center in the Northern Hemisphere and its intensity is stronger than normal. The circulation presents a five wave pattern in the middle high latitudes. In comparison with the sates of normal years, the western ridge spot of West Pacific subtropical high is further west and north. The monthly mean temperature is 21.4℃, and is 0.6℃ higher than normal (20.8℃). The monthly mean precipitation is 92.1 mm, and is 12.4% less than normal (105.1 mm).There are 8 precipitation processes, and 7 tropical cyclones have acted in the western North Pacific. There are 5 tropical cyclones landed China. Besides, tropical cyclone “Bolaven” seriously affected Northeast of China. Extreme high temperature weather occurred in areas of Jiangnan, Huanan, Jianghan, Sichuan Basin and Xinjiang. The hail storm disasters happened in 19 provinces, regions and cities in China.
    14  Using Quality Assessment Method to Test the Data of Eddy Covariance
    JIANG Ming GUO Jianxia JING Yuanshu
    2012, 38(11):1436-1442. DOI: 10.7519/j.issn.1000-0526.2012.11.014
    [Abstract](657) [HTML](150) [PDF 1.81 M](895)
    The quality assessment (QA) method which includes the steady state test of the CO2 flux, sensible/latent heat flux and integral turbulence characteristic test of the vertical velocity was used to analyze the turbulence flux data observed by eddy covariance at Xilinhot, 2009. The main results are as follows. The data are good on the whole and there are 80% data well assessed by the QA method. The good data size in daytime is more than in nighttime and in summer is more than in winter. From the comparative analysis, the pre processing work can eliminate most bad data. Furthermore, the quality of the data assessed by the QA method will be obviously improved. Using these good data to analyze the energy balance, the closure of the local energy balance has increased by more than 2%.
    15  Developing of an Airborne Seeding Device for Powdered Agents and Its Application in Cloud Modification During Beijing Olympic and Paralympic Games
    JIN Hua ZHANG Qiang HE Hui MA Xincheng HUANG Mengyu TIAN Haijun LIU Liwei
    2012, 38(11):1443-1448. DOI: 10.7519/j.issn.1000-0526.2012.11.015
    [Abstract](750) [HTML](59) [PDF 890.80 K](916)
    The methods to destroy developing convective clouds, using artificially generated downdrafts, were theoretically justified and thoroughly tested under laboratory and field conditions. It is based on artificial initiation of downdrafts in convective clouds by releasing large doses of powdered agents into their tops. Beijing Weather Modification Office developed a new seeding device to release large doses of powdered agents in field experiments. This is the first device that seeds powdered agents by airdropping in the weather modification field experiments of China. Pollution to the aircraft could be relieved when releasing powdered agents with the device. The powdered agents should be packaged with special box before airdrop. The new device was used at Beijing Olympic Games and Paralympic Games opening and closing days. The total 34 tons of hygroscopic powdered agents were released in 9 flights.

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