ISSN 1000-0526
CN 11-2282/P

Volume 36,Issue 11,2010 Table of Contents

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  • 1  The Corner Stone in Facilitating the Transition from Deterministic to Probabilistic Forecasts-Ensemble Forecasting and Its Impact on Numerical Weather Prediction
    DU Jun CHEN Jing
    2010, 36(11):1-11. DOI: 10.7519/j.issn.1000-0526.2010.11.001
    [Abstract](1917) [HTML](466) [PDF 2.61 M](1856)
    Given the nonlinear and complex nature of atmospheric system combined with the uncertainties associated with initial conditions and models, it is not only a requirement from science but also a necessity to better serve user community to transit weather prediction from deterministic to probabilistic format. However, the rational behind the transition is not clear but full of debate and confusion to many including public, endusers and even meteorologists themselves. To clarify some of these and to expedite the transition, a few issues were discussed. Since the ensemble forecasting is a central technique to facilitate such a transition, it is first discussed in this paper by focusing on the following five aspects: (1) why is ensemble forecasting needed? (2) what is the primary mission of ensemble forecasting? (3) what are common misunderstandings about it? (4) what is the impact it will bring to numerical weather prediction system as a whole? and (5) what is the forecaster’s new role in the “ensemble forecasting” era?
    2  Investigations on the Precedent Strong Influence Signal for the  Anomalous Precipitation in Rainy Season over Tianjin Area
    WANG Jing LV Jiangjin
    2010, 36(11):12-17. DOI: 10.7519/j.issn.1000-0526.2010.11.002
    [Abstract](1098) [HTML](94) [PDF 880.56 K](1134)
    Based on the 1958-2007 monthly precipitation data at 4 stations over Tianjin area and the NCEP/NCAR reanalysis data set, the precedent strong influence signal for the anomalous precipitation in rainy season over Tianjin area is investigated by employing the simple correlation and composite analysis. The results show that the annual precipitation over Tianjin area is mainly concentrated in the rainy season. There exists pronounced interannual variability and certain interdecadal variations about the rainfall in rainy season. Additionally, there is a significant negative correlation between the precipitation and NAO in the preceding February. The anomalous NAO in the preceding February has a good potential to be the precedent strong influence signal for the abnormal precipitation over Tianjin area. In the years of weak NAO, the low value systems develop on Tianjin upstream, the South Asia high, the subtropical upper westerly jet and the tropical upper easterly jet lie more northward, and the developments of monsoon depression and trough are noticeable from the Arabian Sea to the Bay of Bengal. The rainfall is likely to be more than normal due to the distribution of the abovementioned synoptic systems. The situations are just opposite in the years of strong NAO.
    3  Comparison of Different Types of Heavy Rainfall Events in Chuzhou Region, Anhui Province
    YAO Chen ZHANG Xuechen MAO Dongyan
    2010, 36(11):18-25. DOI: 10.7519/j.issn.1000-0526.2010.11.003
    [Abstract](1233) [HTML](110) [PDF 2.88 M](1183)
    Based on the conventional observation data, Doppler radar data and NCEP (1°×1°) reanalysis data, the causes for weakened typhoongenerated heavy rainfall on 8 August, 2008 (called “0808” process for short) and Meiyuperiod heavy rainfall on 4 July, 2003 (called “0307” process for short) in Chuzhou, Anhui Province are diagnosed and analyzed. The diagnostic results show that the enhancing of lowlevel jet can prompt heavy rainfall, especially heavy rainfall happening during night. In these two heavy rainfall events there exist secondary circulations, but the modes of their action are different, they both enhance high and lowlevel weather systems. A great amount of water vapor from the weakened typhoon plays an important role in the “0808” process, and a strong water vapor transport is not necessary for producing heavy precipitation. Meanwhile the strong water vapor convergence center of heavy rainfall is located in the boundary layer, and cold air is important for heavy rainfall. During the “0307” process, radar precipitation echoes stay for long time. And the main feature of “0808” process in Doppler radar is that severe storms lead to convective precipitation.
    4  Analysis of the Meridional Heterogeneous Distribution of Summer Heat Wave over Eastern China
    ZHU Zhouping QIAN Bingqiang
    2010, 36(11):26-31. DOI: 10.7519/j.issn.1000-0526.2010.11.004
    [Abstract](1041) [HTML](90) [PDF 1.52 M](1143)
    With the analysis on the high temperature days(≥35.0 ℃) from 102 observational stations over eastern China (25°-35°N,110°-122°E) in 1958-2007, it is found that the high temperature weather in eastern China has the same rate of change in most years, but some years it has a contrary distribution in south and north, and this distribution has no relation with the high temperature intensity. Using the NCEP/NCAR monthly mean reanalysis data, the typical year circulation backgrounds are analyzed. The results show: in the anomalous years that the heat wave mainly concentrates in south, it has a “positivenegative” pattern of geopotential height anomaly in 500 hPa from south to north in East Asian,and there is a vertical counterclockwise cycle from north to south in 25°-35°N compared with normal years. In the years that the heat wave mainly concentrates in north, it is opposite. The EOF analysis of the numbers of annual high temperature days reveals that the second leading mode respectively indicate the heat wave’s contrary distribution in meridional direction and its time series can reflect the intensity of this deviation as an index. The correlation analyses denote that the variation of this distribution is well related to the December 500 hPa geopotential height anomaly and the SST anomaly in the tropical Indian Ocean in May last year. It is also related to the many atmospheric circulation indexes of spring and precedent winter. 
    5  The Impact of Temperature Mutation on the Seasonal Start Date over China
    YU Zhenyan FANG Guangzhou HUA Wei ZHOU Dingwen LAI Xin LIU Yaxing
    2010, 36(11):32-37. DOI: 10.7519/j.issn.1000-0526.2010.11.005
    [Abstract](1291) [HTML](87) [PDF 971.45 K](1213)
    The daily temperature data at 599 stations during 1961-2007 are utilized to analyze the multispatial scale, multitime scale changes of seasonal start date based on wavelet analysis. The results show that the changes of seasonal start date are accordant with the changes of temperature over China. On national average, the seasonal start date all has a time period of nearly 20 years, and show a clear trend that spring and summer became earlier, autumn and winter became later in the late 1980s. After doing a wavelet transform to the major cycle over all regions, the trends are the same as the national average basically. However, some differences are still existing in varied regions. For example, in Northeast China there was a phenomenon of summer occurring later during 2005-2007. Winter occurring earlier in Northwest China and spring occurring later in South China during 2004-2007. In the Plateau spring also occurred later during 2003-2007, combined with the other seasonal changes, the changes of seasonal start date in these regions are also corresponding to the changes of temperature well.
    6  Variations of Frost Under the Background of Climate Change in Liaoning Province in Recent 50 Years
    LI Ji YAN Xiaoyu WANG Ying
    2010, 36(11):38-45. DOI: 10.7519/j.issn.1000-0526.2010.11.006
    [Abstract](1529) [HTML](255) [PDF 3.90 M](1457)
    Based on the surface observational data of frost from 1957 to 2006 at 35 basic stations of Liaoning Province and the corresponding temperature data, the variation characteristics of frost and the effect of climate change on frost were analyzed. The result shows that the first frost delayed about 10 days in these 50 years, and the last frost brought forward 17 days, thus the frostless period extended 26 days. Besides, there was a break point in the 1990s for the first frost, last frost and frostless period. The areas in which the first frost significantly delayed, last frost significantly brought forward, and frostless period significantly extended, are mainly distributed in the middle part and the west part of Liaoning Province and the partial area of Liaodong Peninsula. The first frost date is more related to the temperature of September, the last frost date is markedly correlated with the temperature of April, while the frostless period is significantly correlated to the temperature from April to September. First frost delaying, last frost bringing forward and frostless period extending are all mainly attributed to temperature increases, especially the increases of the average minimum surface temperature and the average minimum air temperature. Due to temperature increasing, the spatial distributions of the first frost, last frost and frostless period all displayed the characteristics of moving from southwest to northeast.
    7  Experimental Study on Nucleation Rate of Artificial Ice Nuclei
    SU Zhengjun ZHENG Guoguang GUAN Liyou
    2010, 36(11):46-49. DOI: 10.7519/j.issn.1000-0526.2010.11.007
    [Abstract](1082) [HTML](126) [PDF 723.54 K](1214)
    As nucleation effectiveness, the nucleation rate of artificial ice nuclei (AIN) also is one of the most important properties of seeding agents in weather modification. But it was rarely paid attention in the bypast field experiments and operations. The chemical kinetic approach is employed in this study. The results show that the nucleating rate, efficiency and even the nucleating mechanism of these pyrotechnics are different. For different aims of weather modification operating and different type clouds, we shall choose different seeding agents with different nucleating rates.
    8  The Method of Cloud Vertical Structure Analysis Using  Rawinsonde Observation and Its Applied Research
    ZHOU Yuquan OU Jianjun
    2010, 36(11):50-58. DOI: 10.7519/j.issn.1000-0526.2010.11.008
    [Abstract](2014) [HTML](260) [PDF 3.00 M](2263)
    The vertical structure characteristics of clouds play an important role no matter in the weather, in the climate or in the weather modification, while there are few direct and valid observation methods in the meteorological operation. In this paper several Cloud Vertical Structure (CVS) analysis methods by rawinsonde observation (RAOBS) are compared and from which the relative humidity (RH) threshold method is chosen to analyze the CVS. The seconddata of our national RAOBS network are used to analyze multicase cloud vertical structure, which are then compared with CVS from CloudSatborne cloud radar. Results prove the feasibility to identify CVS by using a relative humidity threshold, and the usability of this method in routine work. For operational applications, the methods of reading and calculating RAOBS are developed, the pictures of analyzing CVS are designed, so that a cloud structure analysis technique is founded based on RAOBS of China. This technique is used in studying temporal and spatial evolutions of cloud system coupling with different weather systems during the 60th anniversary national period day, and valuable results are achieved.
    9  Analysis on Conditions of Precipitation Enhancement Catalyzing  Operation Based on Mesoscale Model, CINRAD, and Satellite
    ZHAI Jing HUANG Yong HU Wen JIANG Nianchong CHEN Xiaohong ZENG Guangping
    2010, 36(11):59-67. DOI: 10.7519/j.issn.1000-0526.2010.11.009
    [Abstract](957) [HTML](93) [PDF 5.60 M](1162)
    The artificial precipitation condition of a case during November 15-16, 2006 in Anhui Province is studied based on the mesoscale model data, CINRAD data, geostationary meteorological satellites data, etc. First, the model results are validated by observed data, such as rainfall, the characteristics of cloud system’s radar echo, and the moving trend. The analysis on the structure of the cloud and precipitation shows that the existence of supercooled cloud water with updraft is favorable for artificial precipitation operation. Then, an index for artificial precipitation condition is calculated based on the model results, which actually include the ice supersaturation, K index, divergence difference, and the 850 hPa specific humidity. All these indexes are contrasted between the cloud structure, rainfall, and other observed data such as radar, satellite, the results show that these indexes illuminate the favorable dynamic, thermodynamic, and microphysical conditions in cloud system, which could be a precursor to the cloud system’s moving and developing, and also these indexes fit with the observed data well. At last, the characteristics of satellite retrival data, radar echo, and radar retrieval data such as ET (echo top), VIL (vertical integrated liquid), are in accord with the model’s results, so the accurate position and time for artificial precipitation could be given. This is how the model results are used with observed data in this case for artificial precipitation.
    10  Analysis on the Doppler Weather Radar Characteristics  of the 20 July 2009 Tornado in Chengde
    ZHAO Ruijin HAO Xueming YANG Xiangdong YANG Leibin
    2010, 36(11):68-76. DOI: 10.7519/j.issn.1000-0526.2010.11.010
    [Abstract](1332) [HTML](88) [PDF 3.01 M](1282)
    In order to study the Doppler weather radar characteristics of the 20 July 2009 tornado in Chengde, the CINRAD/CB, weather charts,wind profile radar,and automatic weather station observation data are analyzed synthetically. The results show as follows: Before the tornado, the lowlevel air is wet and warm. Affected by the upper cold vortex,the strong cold air at the middle troposphere descends, and there are strong vertical shears in the uppermiddle troposphere. There are strong cyclonic vortices from low level to 6.8 km at Doppler weather radar radial velocity products when tornado appears.The top height of the cell, maximum reflectivity, and echo centroid are higher also. VIL value abruptly increases before the tornado appears, but the sustaining time above 40 kg·m-2 is short. Orientation analysis shows that affected by movement and storm structure, the tornadic vortex signature is at the southeast of real tornadic position.
    11  Characteristics Analysis on Heat Island Effect in Yangtze Delta  Urban Agglomerations in Recent 8 Years by MODIS Data
    GE Weiqiang ZHOU Hongmei YANG Hequn
    2010, 36(11):77-81. DOI: 10.7519/j.issn.1000-0526.2010.11.011
    [Abstract](1117) [HTML](96) [PDF 911.88 K](1313)
    Retrieving the land surface temperature by hdf data in MODIS receiver system, first the few cloudy data were selected, and then cloud be removed by means of multiband combination. The average temperature figures of Yangtze Delta were retrieved by split window algorithm, the distribution characteristics of Yangtze Delta area were analyzed, and the heat islands are arranged in “Z” distribution. In Yangtze Delta area, the heat island intensity is the strongest in summer, then in spring and most areas are in weak or no heat island except few areas in strong heat island in winter. By GIS geographic statistics, the strong heat island areas were compared. And the change trend of heat island of each city from 2001 to 2008 were also being analyzed. The data were processed in Delphi and IDL languages including data projection, inversion, cartography. The analysis of island heats was independently conducted, and average retrieval results were more objective.
    12  Research on MedicalMeteorological Forecast Models of CardiovascularCerebrovascular Diseases in Nanjing
    MAO Yuqing YIN Dongping SUN Ning SUN Yan
    2010, 36(11):82-87. DOI: 10.7519/j.issn.1000-0526.2010.11.012
    [Abstract](993) [HTML](84) [PDF 632.52 K](1327)
    Forecast models of cardiovescular and cerebrovescular diseases in Nanjing are separately built. First we select 22 dummy variables including holidays as nonmeteorological factors according to the time distributive characters of the daily hospital visit numbers from January 2003 to July 2007. Then we choose meteorological and nonmeteorological factors with stepwise regression method so as to obtain the explanatory variables which are finally used to build forecast models based on the SVM regression method. The daily hospital visit numbers are divided into five grades and the results show that the precisions of grade prediction in cardiovascular and cerebrovascular diseases are 87.91% and 84.62% respectively. Therefore, the models perform satisfactorily and can be applied to actual predictions. 
    13  Trends in Climate Extremes in Association with Climate Warming in Wuhan
    YAO Wangling CHEN Zhenghong XIANG Yuchun
    2010, 36(11):88-94. DOI: 10.7519/j.issn.1000-0526.2010.11.013
    [Abstract](1295) [HTML](281) [PDF 1002.93 K](1439)
    Based on the data series of the annual mean, highest, and lowest temperatures and annual day numbers for 8 kinds of extreme weather events from 1951 to 2007 in Wuhan City, the trend and the relationship between annual mean temperatures and the day numbers with extreme weather are analyzed. By introducing the Granger causality detection algorithm, the relationship between climatic warming and extreme weather events is studied. The results show that: (1) the increase rate of annual mean lowest temperature in Wuhan in recent 57 years is 0.45 ℃/10a, which is much higher than that of the annual mean highest temperature of 0.19 ℃/10a. It indicates that the climatic warming is mainly caused by nighttime temperature increasing. (2) The frequency of high temperature and muggy weather events increased with year. The increasing rate of muggy weather is 2.8 d/10a and more evident than high temperature. The frequency of thunderstorm, snow, low temperature, gale, and fog decreased evidently with year. The decrease rates of thunderstorm, fog and low temperature are much larger and are 3.0, 4.0 and 2.1 d/10a respectively. The decrease rates of gale and snow events are 1.8 and 1.5 d/10a. The fluctuation of rainstorm events is small. (3) The annual mean temperature is highly correlated with the extreme weather events at time periods 0 years (concurrent) or ±(1-2) years (leading or leg). (4) The Granger causality detection results show that the climatic warming is the causes for the muggy weather increasing, snow event decreasing, and the gale and low temperature decreasing. The existence of causality is very valuable for the forecast of extreme weather events.
    14  New Developments on Subjective Operational Products of the American NationalLevel Severe Convective Weather Prediction
    ZHOU Qingliang
    2010, 36(11):95-99. DOI: 10.7519/j.issn.1000-0526.2010.11.014
    [Abstract](1188) [HTML](117) [PDF 636.75 K](1406)
    To reflect the situation of American nationallevel subjective operational products of severe convective weather prediction and provide the reference to the CMA (China Meteorological Adiministration) severe weather prediction operations, the newest developments of American nationallevel subjective operational products of severe convective weather prediction (its products, generation and issuance regulation) were analyzed. Some proposals were put forward to the further development of CMA severe weather prediction operations. The conclusion could be drawn through the analysis that American nationallevel subjective operational products of severe convective weather prediction mainly are the classified probability forecasts. They have been formed a systemic product series of shorttime, shortterm and mediumterm forecasts now. By using of contrast, CMA severe weather prediction operations should strengthen their work in these four respects as follows. First, the application of climatology, meteorology, analysis technology and diagnosis technology of severe convective weather. Second, investigations of the forecast methods and mesoscale numerical forecast products which are based on the high resolution of time and space scales. Third, construct a steadily special team. The last is the scientific operation flow and efficient transportation of integrated monitoring. 
    15  Experiments and Analysis of Pyranometers on Nighttime Zero Offset
    YANG Yun DING Lei WANG Dong
    2010, 36(11):100-103. DOI: 10.7519/j.issn.1000-0526.2010.11.015
    [Abstract](1017) [HTML](263) [PDF 632.83 K](1227)
    The zero offset experiments for pyranometers were done outside in the night of clear day using the comparison method. On the basis of the experiments, the zero offsets of different pyranometers (the blackwhite pyranometers and allblack pyranometers, the homemade and imported pyranometers) were compared respectively. The causes for zero offset were analyzed. By analysis of the experimental data, it was shown that the zero offset of the homemade pyranometers was less than 10 W·m-2 in the night of clear day. The experiments, in which the sensing surface of pyrnaometers was installed downwards and a lid was put on the pyranometers, all demonstrated that the zero offset was caused by the cold sky effect indeed.
    16  The Performance Verification of the MediumRange Forecasting for T639, ECMWF and Japan Models from June to August 2010
    YU Chao
    2010, 36(11):104-108. DOI: 10.7519/j.issn.1000-0526.2010.11.016
    [Abstract](874) [HTML](81) [PDF 6.30 M](1088)
    In order to improve the application ability to T639 model, a synoptic verification on its mediumrange forecasting(96 h leading time) during the summer of 2010 was made in comparison with the counterparts of models of ECMWF and Japan. The results show that the three models all have good performance on predicting the largescale circulation evolution and adjustment over Asian middle and high latitude areas. As a whole, ECMWF is the best at forecasting synoptic systems and elements among all models; The three models have a bigger error on prediction of the track and intensity of typhoon Chanthu except that ECMWF performs well before typhoon landing.
    17  Analysis of the August 2010 Atmospheric Circulation and Weather
    ZHAO Wei
    2010, 36(11):109-114. DOI: 10.7519/j.issn.1000-0526.2010.11.017
    [Abstract](1262) [HTML](80) [PDF 2.35 M](1495)
    The following are the main characteristics of the general circulation of atmosphere in August 2010. The circulation presents a fourwave pattern in Eurasian high latitudes. The negative 40gpm is found near Novaya Zemlya and northwestern Europe in the 500 hPa geopotential height anomaly field. The area that the subtropical high covered is larger than normal years. The intensity of the subtropical high is stronger and the western ridge spot is wester than normal years. The monthly mean temperature (21.4 ℃) is 1.1 ℃ higher than the same period of normal years and the national mean precipitation (108.1 mm) is 5.5 mm more than the same period of normal years. There are 14 precipitation processes and 5 tropical cyclones generated with one (Namtheum, numbered 1008) landed China in this month.
    18  Research and Implementation of Chinese Character  Displaying in GrADS System
    DENG Liantang
    2010, 36(11):115-119. DOI: 10.7519/j.issn.1000-0526.2010.11.018
    [Abstract](1304) [HTML](388) [PDF 331.69 K](1512)
    Generally, the GrADS software could not set the title or notation in Chinese. It makes some inconvenience for domestic scientists. Based on the GrADS existing functions, we develop a set of key technologies, and implement the displaying Chinese character function in GrADS. These key technologies are as follows: Set up a userdefined Chinese character base which is suitable for the GrADS system, creat the index of Chinese character base, display Chinese characters along with English characters, find the exact character in the usedefined Chinese character base rapidly, decode the dotarray information of a Chinese character in the userdefined Chinese character base, and draw the Chinese character on the GrADS graphic area. The function of displaying Chinese character in GrADS is very convenient, efficient, portable, and could display Chinese along with English.
    19  Forecast Factors Selection and the ManMachine Conversation  Platform Establishment by Building Equation
    DUAN Xu DING Sheng XU Meiling
    2010, 36(11):120-125. DOI: 10.7519/j.issn.1000-0526.2010.11.019
    [Abstract](1060) [HTML](114) [PDF 1.26 M](1097)
    Using the calculator technique forecast factor selection, equation establishment and sample fitting into a composite ensemble are integrated,and the forecast factor selection and manmachine conversation platform by building forecast equation are established. This platform has three modules, i.e. document information module, factor primary election module and regression analysis module, which can be described as follows:(1)The document information module is mainly reading the forecast the object document and forecast factor document, examining and displaying the consistency of information length in file header; (2)The factor primary election module is mainly calculating the weather factor or physical quantity field’s correlativity between each of grid point factors and the amount of forecast field, and through analysis of this correlation field the combination factors are finally found out; (3) The regression analysis module is carrying on stepwise regression towards forecasting object and combination factor which has picked up from the equation by the second module, and then the forecasting equation is build up, and according to the regression equation’s parameter and the rate of sample fitting and through changing the standards for picking up and getting rid of regression results are adjusted.

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