ISSN 1000-0526
CN 11-2282/P

Volume 33,Issue 8,2007 Table of Contents

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  • 1  Weather Forecaster and Numerical Weather Prediction
    Xue Jishan
    2007, 33(8):3-11. DOI: 10.7519/j.issn.1000-0526.2007.08.001
    [Abstract](675) [HTML](96) [PDF 1.83 M](965)
    The status and applications of numerical weather predictions are intro duced to weather forecasters in operational posts in a way of nonspecialist te rminology. Following a historical review with the stress on the achievements and unsolved issues in the latest decade, the merits and shortcomings of forecasts by numerical models and experiencesbased methodologies are compared. The combi nation of the superiorities of two kinds of approaches is emphasized. The impact s of technical developments of numerical weather prediction on the interpretatio n and application of model outputs, and the possible roles the forecaster may pl ay in the further development of NWP are also discussed.
    2  Mechanism Analysis of Rainfall in the Far Distance of Typhoon AERE
    Fan Xuefeng Wu Zhen Xi Shiping
    2007, 33(8):12-16. DOI: 10.7519/j.issn.1000-0526.2007.08.002
    [Abstract](702) [HTML](134) [PDF 2.02 M](1076)
    By using the helicity and moist potential vorticity (MPV) theory 1° ×1° reanal ysis data of NCEP was calculated to diagnose the heavy rain process of NO.18 Typ hoon AERE in the east of Henan. The dynamical and thermodynamic mechanisms of t his process' formation and development were discussed. The results show that so utheast jet in the typhoon inverted trough periphery supplied vapor and thermody namic conditions for the heavy rain. Strong convergence action on the top of typ hoon inverted trough was the dynamical mechanism of the rainstorm' happening and developing. Because of weak cool air intrusion in the low level the MPV1 o f ra instorm area turned from negative to positive, which led vertical vortexes to en hance and hasten precipitation developing. So the weak cool air intrusion increa sed the precipitation in some extent. Moreover, the moving and developing of big value band of the vertical helicity of 925hPa could dictate the place of invert ed trough and had better indicative meaning for rainstorm falling area. When the rainstorm happened the area was in the negative big value area of MPV1.
    3  The Mesoscale System Character Analysis of Far  Distance Typhoon Haitang Rainstorm
    Li Gaiqin Liang Haihe Wang Shuwen Wang Yunxing Zhang Chunyun Zhong Tianhua
    2007, 33(8):17-22. DOI: 10.7519/j.issn.1000-0526.2007.08.003
    [Abstract](1591) [HTML](66) [PDF 1.86 M](1097)
    By means of routine sounding and intensive surface observation data, satellite c loud pictures and new generation weather radar products, a diagnosis is performe d to the heavy rainstorm process induced by typhoon Haitang inverted trough on J uly 22, 2005. The results suggest that:1) This process is generated because northward inverted trough of typhoon Haita ng combines with weak cold air in we s terly belt, which is a classical reciprocity process between mid and low latitud e weather systems. 2) Abundant heat and vapor are transported from low latitude sea by the lowlevel jet in the east of inverted trough, and the left to invert e d trough becomes the headspring of mesoscale system. 3) The intensifying highl e vel anticyclone enhances the pumping effect, which strengthens convergence of ai r and rainstorm. 4) In the satellite cloud pictures, it is seen that the direct cause of the heavy rainstorm is the genesis and evolution of conglomeration and closegrained intensive mesoβ convective system. 5) In Doppler radar ref l ectivity field a lot of mesoscale echo belts converge, which induces the echo an d rainfall increasing. 6) During rainstorm, it is obvious nonuniform in horizo n tal wind according to the Doppler radar radial velocity field, there is large sc ales intensive convergence in mid and low levels, and wind direction are discont inuous in vertical. The vertical wind shear can provide kinetic energy for the d evelopment of convective cloud, which is advantageous to large thunderstorm clou d evolution and rainstorm occurrence. The reversed wind appears in the inflow a rea many times, rotates northwards in the form of cyclonic rotation and merges w ith the positive speed area. The strong echo and rainstorm appear in the area a nd passing way of reversed wind.
    4  An Analysis of a Tornado in Yongzhou, Hunan Province
    Tang Xiaoxin Liao Yufang
    2007, 33(8):23-28. DOI: 10.7519/j.issn.1000-0526.2007.08.004
    [Abstract](700) [HTML](155) [PDF 1.00 M](1053)
    The severe wind which took place in the morning of April 10, 2006 in Lij iaping town, Shuangpai County, Hunan Province was analyzed based on the postdi saster inspection data, conventional weather data and Yongzhou Doppler radar dat a. It shows that the severe wind was the first confirmed tornado in Yongzhou Cit y in normal meteorological records. It was a supercell tornado, and had classica l tornado hook characteristics in the radar base reflectivity. The strong vertic al wind shear and thermodynamic instability resulted in a mesocyclone in the s upercell. The convergence of on low and middlelevel atmosphere in the mesocycl one resulted in the tornado finally.
    5  MesoScale Analysis of a Regional Heavy Rain Using Doppler Radar Data
    Wang Nan Liu Yong Guo Damei
    2007, 33(8):29-34. DOI: 10.7519/j.issn.1000-0526.2007.08.005
    [Abstract](885) [HTML](124) [PDF 1.36 M](930)
    There was a regional heavy rain in the middle of Shannxi Province at the night o f June 2, 2006. The rain was analyzed by using Doppler data. The result shows t hat the mesoscale convergence line, which was the result of interaction betwee n the lowlevel warm/wet jet and weak cold air, directly produced the heavy rai n. Lowlevel jet provided not only ample of vapor but also instability energy , so it was the main matter which resulted in so heavy rain. The directions of lowlevel jet and mesoscale convergence line that affects the developing of convergence line. At the night, lowlevel jet will become more intensive, that is why lots of heavy rain occurred in the evening.
    6  Analysis of the Special“人”Character Structure of a Strong SeaBreeze Event near Qingdao Coast
    Sheng Chunyan Chen Youkuan
    2007, 33(8):35-39. DOI: 10.7519/j.issn.1000-0526.2007.08.006
    [Abstract](611) [HTML](203) [PDF 1.78 M](970)
    Using the automatic weather stations, island stations, buoys,Doppler radar data and FY-2C satellite image around Qingdao Olympic sailing spots, a strong sea breeze event during 2006 sailing test period is analyzed. Results show that ther e are several sea breezes near Qingdao. The sea breeze front in the eastern part is from NE to SE, while the sea breeze front near the Jiaozhou Bay in the west is circle. The strong seabreeze front in the eastern part pushes inland and me ets the seabreeze near the Jiaozhou Bay, where the seabreeze develops signif icantly and has a special structure like “人" character as displayed in Doppler radar image. The northern part is the boundary from NE to SW and the southern pa rt is halfcircle. The seabreeze is very shallow in the vertical direction below the height of 1.5 km. It is difficult to identify the seabreeze front from the FY-2C cloud image due to the obstacle of alt ostratus fractus.
    7  Causality Analysis of Super Rainstorm and Mountain Torrents by Strong T ropical Storm “BILIS”
    Yao Rong Li Zuxian Ye Chengzhi Huang Xiaoyu Xu Lin
    2007, 33(8):40-46. DOI: 10.7519/j.issn.1000-0526.2007.08.007
    [Abstract](886) [HTML](110) [PDF 3.41 M](1045)
    Based on the weather background, atmospheric circulation evolution and the meteo rological conditions, including dynamic, thermodynamic, water vapor and the inst ability condition, the torrential rain in the southeast of Hunan Province caused by “BILIS” (the No.4 strong tropical storm in 2006) is examined by using the conventional observations and pentadaveraged meteorological elements. Results show that the ascending motion generated by the surface mesoscale convergence line and the dynamic lifting of topography strengthened the dynamic force of tor rential rain. In addition, the high temperature and high humidity provided ext remely good thermal energy, which is propitious to the development and the gener ation of convective instability ener gy. The eruption of the South China Sea m onsoon and the formation of monsoon trough in the southwest offered water vapor co ntinuously. Moreover, the continental high and subtropical high confronted each other and slow down the westward drift of “BILIS”. Besides the meteorological fact ors, the frangible geology environmental condition is the internal cause of the geological disaster induced by “BILIS”.
    8  Spatial-Temporal Characteristics of Precipitation in  Flood Season in Huangshan Mountains
    Liu Yulu Xu BaiLin Xu Jianyong
    2007, 33(8):47-51. DOI: 10.7519/j.issn.1000-0526.2007.08.008
    [Abstract](555) [HTML](172) [PDF 1.06 M](886)
    The spatialtemporal distribution characteristics of precipita tion in the flood season (from May to September) of past 45 years in Huangshan are analyzed with spectral analysis, continuous wavelet transformation and empirical orthogo nal function (EOF) decomposition techniques. The results indicated that there ar e obvious drought/flood cycle about 3- to 4- year and 16- to 20- year in Huang shan as a whole, while there is drought/flood cycle about 10 year in its northwester n region. At present, Huangshan is in the third drought period during the past 45 years. By the first space mode decomposed with EOF, it is found that the spatial distribution of precipitation has close relationship with the orientation of Hu angshan mountain. The spatial anomaly of precipitation can be divided into three patterns, i.e., the midwest type, south type and northeast type.
    9  Transition Precipitation Analysis During Defend against the Great  Xing’an Mountain Forest Conflagration in Inner Mongolia
    Han Jingwei Wu Xuehong Song Guiying
    2007, 33(8):52-59. DOI: 10.7519/j.issn.1000-0526.2007.08.009
    [Abstract](611) [HTML](97) [PDF 7.64 M](1068)
    By using basic data, nephanalysis and T213 numerical prediction products, transi tion precipitation was diagnosed and analyzed during key period of defend agains t puff the “5·25” big forest fire in 2006. The study shows that the air tempe rature in fire region of Hulun Buir City is about 3~4 degrees higher than the no rmal. The precipitation is 90%~100% less than the surrounding area. The vapor re source during defend against puff fire is mainly from the Bay of Bengal and low latitude areas of China. The vapor flux value at 700hpa is 19.7g·s-1·cm-1·hPa-1. At the same time, moisture was added in low level of Jianghuai Valley. The transport of positive vortex advection maintains and strengthens the east wind she ar in fire region. There is an increased vertical velocity zone in this area. Th e value is -15.6×10-3hPa·s-1.The vertical distribution of diverge nce field has good suction effect. The guide role of divergence at high level for precipita tion is obvious. Thermodynamic factors increase the precipitation in fire area . Results indicate that abnormal atmospheric circulation results in high tempera ture and drought at the earlier stage of fire. The long distance transport of va por is the most important factor for the transition precipitation. The dynamic r ole is notable during key period of defend against puff the “5·25” big fo rest fire.
    10  Causality Analysis of Snowstorm in Xizang  Plateau in Autumn of 2005
    Kang Zhiming Luo Jinxiu Guo Wenhua Yang Keming
    2007, 33(8):60-67. DOI: 10.7519/j.issn.1000-0526.2007.08.010
    [Abstract](893) [HTML](116) [PDF 3.16 M](1213)
    Based on the observation data and NCEP (1°×1°)6 h reanalysis data, the synop tic dynamic analysis of the snowstorm process in Xizang Plateau in October 2005 was made. The result shows that several factors have play important roles in the snowstorm process as follows: the instable atmospheric stratification fo rmed by the coaction of upward moist airflow and downward cold airflow at the uplevel, the pumping effect of the divergence at upper level and the specific t errain of Xizang Plateau. Bay of Bengal and South China sea are the sources of th e vapor of the snowstorm. The vapor is transported to the Xizang Plateau throug h two passages. The vertical profile of helicity, with positive and negative hel icities respectively in the low and upper level over snowstorm area, and the exc eptional area of moist potential vorticity are both closely related to the snows torm.
    11  Comparison Study of Two Similar Rain and Snow Processes in South China
    Chen Lifang
    2007, 33(8):68-75. DOI: 10.7519/j.issn.1000-0526.2007.08.011
    [Abstract](738) [HTML](148) [PDF 3.62 M](992)
    In middle tendays and last tendays of February in 2006, there were tow preci pitation processes in Changjiang delta, i.e. snow and rain respectively, but the forecast of precipitation type was wrong. A comparison of these two processed s hows that in the snow process, there was west wind in the front of trough and th e circulation was flat, whereas in the rain process, there was southwest wind in the front of trough. Snow would happen only if the cold advection, which was r esulted from the northeast return current, generated a cold center over east Chi na. However the north and northwest wind decreased the air temperature, but no precipitation would happen at the same time, so there would be no snow in this case. Before snowing the air at 850 hPa was dry and before raining the air at lowmiddle levels was wet. Th e temperatures at 700~800 hPa and in the inversion layer were important to the precipitation type. At the end of snow process the air in high level become dry first, whereas at the end of rain process the air in middle level become dry fi st. In snow process the snow and ice crystals were centralized in the high le vel, and the center of snow content was at 600~700 hPa. In rain process, the l ower boundary of snow content lifted up and its center was in a level above 600 hPa. The center of snow content weakened very fast when it moved down northward s.
    12  Climatic Features and Previous Signal of Cold Airflow  Snowfall in Shandong Peninsula
    Yang Chengfang Zhou Xuesong Wang Yehong
    2007, 33(8):76-82. DOI: 10.7519/j.issn.1000-0526.2007.08.012
    [Abstract](695) [HTML](707) [PDF 1.22 M](1438)
    With statistical and wavelet analysis, snowfall data in recent 41a and SST of November in recent 25a are analyzed for cold airflow snowfall in Shandong Pe ninsula in winter. The results show that snow distribution has close relation to the landform with more snowfall in the northeast peninsula and less snowfall in the other areas. Cold airflow snowstorms are of remarkable mesoscale character and often occur in December. By using wavelet analysis it is also found that t he main period is about 4, 7 and 17 years. The statistical analysis shows that S ST of Bohai sea in November is remarkably useful signal for cold airflow snowfa ll prediction in winter.
    13  SVD Analysis of Precipitation in the ChangjiangHuaihe River  Valley and the Sea Surface Temperature of the Western  Pacific Ocean in Winter
    Mao Wenshu Wang Qianqian Jing Yan Li Ruqi Yang Xia
    2007, 33(8):83-89. DOI: 10.7519/j.issn.1000-0526.2007.08.013
    [Abstract](570) [HTML](182) [PDF 1.26 M](942)
    Based on the precipitation of Meiyu at 37 stations in the ChangjiangHuaihe riv er valley from 1954 to 2001 and the mean monthly reanalysis SST data (grid:2° ×2°) of NCEP/NCAR from 1953 to 2001, the relationship between Meiyu precipit ation and the sea surface temperature in the West Pacific Ocean are investigat ed in terms of empirical orthogonal function(EOF), composite analysis, singular value decomposition (SVD), and so on. Results show that the key SST region which influences lies in the warm pool of the West Pacific Ocean and the key pe riod is from December of the former year to February in the next year(simply cal led “former winter"). Meiyu precipitation is increasing (decreasing) in the cor responding period when SST of the warm pool in the West Pacific Ocean in the win ter is warmer (colder) than average. Results of SVD are consistent with those of composite analysis, which passed the prominent test of MonteCarlo at 0.0 5.
    14  Research and Application of Meteorological Drought  Monitoring Indexes in Northwest China
    Yang Xiaoli
    2007, 33(8):90-96. DOI: 10.7519/j.issn.1000-0526.2007.08.014
    [Abstract](671) [HTML](99) [PDF 764.16 K](963)
    To monitor drought in Northwest China more effectively, the drought monitoring index for east and west part of NW China was established respectively based on t he principles of Z index and Palmer index. The monthly precipitation data in 138 representative stations of NW China(1961~2000) were used as basic data. A regi onal drought monitoring index was further developed, and the grades for regional drought were also determined. Comparing the computed drought index with some re corded drought situation, it is found that these indexes can reflect the severit y of meteorological drought in NW China. Furthermore, the drought characteristic s were analyzed by using some statistical methods. The result shows that the dro ught in the east part was more severe than in the west in recent decades. In a l ong term, the drought frequency shows an increasing trend in the east part while a decreasing trend in the west. The meteorological drought in the east part fr om March to June has a period of 5 to 10 years, while the periodicity isn't evid ent in the west. These indexes have an obvious meteorology meaning and can be ap plied simply in the drought monitoring practices of NW China.
    15  Climatic Facts of Gale Weather of Dandong
    Gao Songying Liu Tianwei
    2007, 33(8):97-103. DOI: 10.7519/j.issn.1000-0526.2007.08.015
    [Abstract](695) [HTML](566) [PDF 910.72 K](1036)
    The temporal and spatial characteristics of gale are analyzed by using the data for 26 years of surface wind of 4 autorecorded observational station s in Dandong,some significant results are obtained. The annual frequency of gale weather may be divided into three periods from 1980 to 2005, less than normal but variable from 1980 to 1991,high frequency period from 1992 to 1998,obvious ly decrease from 1999 to 2005,and obvious reducing trend after 1999.The gale weather occurs mostly in spring,especially in April,then in winder,and the least in summer and autumn. The wind direction is most in NNW and differen t in each season. The spatial distribution of gale is closely related to the to pography.The days of gale in the coastal observational stations are more than t hat in the mountains and the direction of most gales is in the south.The gale w eather is analyzed and divided into some patterns according to the characteristi cs of the main influential systems and weather situation by using synoptic metho d.
    16  The Potential Prediction of Thunderstorm and Monitoring,  Nowcasting and Warning System in Jiaozuo, Henan Province
    Liu Yuehong Yan Xiaoli Song Zifu Li Yanhong Lu Xuefeng Xiao Jie Niu Guangshan Zhang Zhen
    2007, 33(8):104-111. DOI: 10.7519/j.issn.1000-0526.2007.08.016
    [Abstract](923) [HTML](117) [PDF 856.42 K](1089)
    Based on the thunderstorm climatic statistical characteristics in Jiao zuo area, thunderstorm trend prediction was made by means of T213 numerical pred iction products. The double criterion was adopted to modify the K exponent. The thunderstorm stability definition index was presented, then the thunderstorm pot ential prediction was made. According to historical data 1984-2000, thirty physi cal fields were calculated, 1°×1°grid data was formed and thunderstorm intens ity grades discrimination method was developed. Combined with the data of satel lite, radar, and lightning locator, thunderstorm monitoring and warning system w as established .The system is realized by visual basic language. Classified weat her types, calculated physical quantities, extracted forecast index and discrimi nated forecast method were automatically finished by using the MICAPS data of 8: 0 0 and 20:00. Therefore, early warning conclusion and regions of thunderstorm oc currence were output. The system performed well in routine forecasting during 20 05-2006.
    17  Verification of Mediumrange Forecasting Efficiency of T213 and  ECMWF and JAPAN Model from March to May 2007
    Wang Chao
    2007, 33(8):112-117. DOI: 10.7519/j.issn.1000-0526.2007.08.017
    [Abstract](740) [HTML](79) [PDF 1.84 M](944)
    From March to May every year, China usually suffers frequent cold fronts. Becaus e of active cold fronts, during these 3 months, weather in China is characterize d by sharp temperatures fluctuations and frequent dusty weather conditions. In o rder to examine the forecast effect of numerical model and accumulate a wealth o f forecasting experience, the 96hour forecasting products of T213 model were e xamined and compared with those of ECMWF model and Japan model. The result is th at T213, ECMWF and Japan models all work relatively well in midrange forecast. The ECMWF model shows a good ability in adjusting macroscale circulation and forecasting the main body of subtropical highpressure system, while the Japan model is more effective in forecasting temperatures at 850hpa than other 2 model s. In addition, we chose a dusty weather process which ever occurred in 810 Ma y , 2007 as a case study. Through analyzing this case, we found that T213 and E CMWF models are more effective than the Japan model in midrange forecast of th e strong surface winds, which caused this dusty weather process.

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