东海近海热带气旋及天气数值预报系统

以ＭＭ４模式为框架,研制并建立了东海近海热带气旋及天气数值预报系统,将对热带气旋的预报和一般天气的预报统一在一个模式中,并实现了业务自动化控制,自１９９４年台风季节起投入了业务试验和准业务的运行。结果表明：该系统对东海近海热带气旋路径、风场、降水及江淮梅雨降水具有较好的预报能力     

涡旋初始化对T639模式热带气旋路径预报影响的数值试验

为了探讨涡旋初始化对T639L60模式热带气旋路径预报的影响程度,以1002号台风康森为个例进行数值试验,结果表明:在涡旋初始化中采用新的初始涡旋形成技术,能减小TC路径预报误差;从初始涡旋形成方案中通过改变七级风半径、涡旋外围尺度半径大小参数和有无进行涡旋强度调整方案进行敏感性试验,得到TC路径的预报对TC涡旋外围半径和TC强度较敏感,其路径会因涡旋外围半径大小和其强度的不同而有所差异。     

复杂地形对西南低涡生成和移动影响的数值试验分析

为探讨四川盆地周边复杂地形对西南低涡发生发展以及移动的影响,利用NCEP 1°×1°再分析资料和中尺度非静力平衡模式WRF V3.4.1,对2010年7月16日至18日发生在四川盆地的一次西南低涡暴雨过程进行了再现模拟(控制试验)以及降低盆地周边不同地形高度的3组敏感性试验。结果表明,控制试验模拟出的西南低涡位置和强度与实况基本吻合。秦岭、大巴山山脉对西南低涡的形成不具有决定性影响,但对西南低涡的维持和发展具有非常重要的作用;横断山脉、云贵高原对西南低涡的生成位置、强度以及移动路径均很重要;青藏高原大地形对偏东气流的阻挡而产生的绕流有利于西南低涡的生成,对西南低涡的移动也有重要影响。除西南低涡以外,四川盆地周边地形所产生的一些局地小低涡的现象也值得关注。     

近30年西北太平洋热带气旋时空特征分析

 本文利用近30年热带气旋年鉴建立了西北太平洋热带气旋灾害数据库,以.NET和ArcGIS Engine搭建了二次开发平台(其包括登录界面、图查属性、 属性查图、数据库分析处理等功能),分析了西北太平洋热带气旋的时间特征、空间特征,以及时空变化特征。结果表明,30年来西北太平洋共生成905次热带气旋,年均30.2次/年。其中,7-10月最容易发生热带气旋,占所有热带气旋的35.7%,8月份达到峰值,达21.5%,2月最不容易发生热带气旋,发生频率仅为0.6%,而8-10月是强台风和超强台风发生的月份。热带气旋源地集中区位于(10°~22°N,112°~120°E)、(8°~20°N,126°~134°E)和(6°~20°N,136°~150°E),具有纬度带和经度带的分布特性。源地的空间分布存在明显的季节变化和月变化特征,在季节尺度上,夏季主要集中在偏北偏西位置,并向南向东偏移,冬季向北向西偏移;在月尺度上,1-4月源地相对分散;5-6月相对于1-4月的源地位置发生向西向北方向转移;7月向东向北扩散,8-9月向西扩散,9月源地相对集中,10月热带气旋源地南移, 11-12月热带气旋源地范围明显减小。     

基于3维GIS的热带气旋路径动态演化模拟方法研究

我国是世界上受热带气旋影响最为严重的国家之一,因此研究其机理演变规律将更有利于指导做好防灾减灾工作。本文利用GIS的显示功能,重建和再现热带气旋的登陆路径全过程,在空间格局上,进行时间维的动态演化模拟,为更好地研究热带气旋的演化机理提供一种实用的分析手段。结果表明,该方法对在时空上了解和认识气旋登陆演化全过程的研究具有一定意义。     

“海上丝绸之路”主要海域热带气旋时空分布特征及其危险性

热带气旋作为一种海上灾害性天气,对“海上丝绸之路”海上航运影响重大。本文基于西北太平洋和北印度洋1990—2017年的热带气旋路径数据,结合热带气旋风场参数模型,利用缓冲区分析、叠加分析等GIS空间分析技术,系统研究了“海上丝绸之路”主要海域、主要海区、关键通道受热带气旋影响频次以及热带气旋危险性的时空分布特征。主要结论：① “海上丝绸之路”主要海域受热带气旋影响严重,表现在热带气旋影响范围广、影响频次高,其中西北太平洋较北印度洋受热带气旋影响更为严重,危险性更大;② 西北太平洋的15°N—30°N,120°E-—145°E海域热带气旋危险性最高;③ 热带气旋危险性季节变化较为明显,秋夏两季危险性较高,冬春两季危险性较低,在夏秋两季各月份中,7、8、9、10月危险最高;④ 在各海区中,中国东部海区热带气旋危险最高,其次是南海、日本海、孟加拉湾、阿拉伯海,而红海和波斯湾不受热带气旋影响;在各关键通道中,吕宋海峡热带气旋危险性最高,其次是台湾海峡、对马海峡、宗谷海峡、鞑靼海峡、保克海峡、霍尔木兹海峡,而马六甲海峡和曼德海峡无热带气旋危险。     

适用于移动平台的快速生成地形剖面线方法

本文针对移动平台内外存储容量小,处理器相对较弱的特点,通过数字高程模型（DEM,包括不规则三角网和规则格网）,提出一种适用于移动平台的等高线直接生成剖面线的方法。与其他2种数字高程模型的剖面线生成方法的对比表明,本方法计算简单、运算量小、操作方便、成果图精度适宜,非常适合用于移动GIS。另外,针对在等高线生成剖面线过程中,路线处于2条等高线之间（即与等高线没有交点）,无法求得路线高程值的情况,提出了通过作路线上任意点的水平和垂直方向直线,求得该直线与最邻近等高线的交点,利用4个交点的高程值求出路线上该点的高程值的方法。通过该方法,求出足够多高程点,进而生成剖面线。将本文提出的移动平台快速生成地形剖面线算法,应用于区域地质调查,较好地解决了实际应用中遇到的问题,取得了良好的效果。     

广东近海油类漂流扩散的试验和实践

根据海上溢油试验结果，结合20a来对海上溢油事故的观察结果分析了油类入海后漂流和扩散过程。经分析认为：1)海面油类漂流的速度和方向取决于风和表层海流的速度和方向，海面油类漂流的速度和方向基本符合Uo=Uc ζW和D=C流 r；2)海面油类扩散的形状与油类漂流的速度有关。油膜的扩散速度与时间可以用U扩=at^-b来表达，油类漂流速度越大，油膜的形状就越呈长而窄，反之则呈短而宽；3)经两起海上沉船溢事故的实例检验．结果比较接近；4)在1996年珠江口惠洲26—1油田海底输油管线溢油漂流预测分析过程中进行尝试，收到比较好的效果。     

广东近海油类漂流扩散的试验和实践

根据海上溢油试验结果，结合20a来对海上溢油事故的观察结果分析了油类入海后漂流和扩散过程。经分析认为1）海面油类漂流的速度和方向取决于风和表层海流的速度和方向，海面油类漂流的速度和方向基本符合UO=UC+ζW和D=C     

复杂地形下冰雹预报的数值试验研究

充分考虑贵州低纬、高原山区特色,首先模拟由于下垫面的热力和动力不均匀造成的强对流云的初始扰动.在此初始扰动的基础上,用完全弹性三维冰雹云数值模式,模拟雹云的发生发展过程,对冰雹进行数值预报研究.通过现场试验和个例分析,发现模式能反映雹云的发生、发展等变化规律,并能对冰雹天气作预报,预报概括率为81%.     

An interdecadal change of tropical cyclone activity in the South China Sea in the early 1990s

Tropical cyclone (TC) genesis in the South China Sea (SCS) during 1979-2008 underwent a decadal variation around 1993. A total of 55 TCs formed in the SCS from May to September during 1994- 2008, about twice that during 1979-1993 (27). During the TC peak season (July-September, JAS), there were 43TCs from 1994-2008, but only 17 during 1979-1993. For July in particular, 13TCs formed from 1994-2008, but there were none during 1979-1993. The change in TC number is associated with changes of key environmental conditions in atmosphere and ocean. Compared to 1979-1993, the subtropical high was significantly weaker and was displaced more eastward during 1994-2008. In the former period, a stronger subtropical high induced downward flow, inhibiting TC formation. In the latter period, vertical wind shear and outgoing longwave radiation all weakened. Mid-level (850-500hPa) humidity, and relative vorticity were higher. Sea surface temperature and upper layer heat content were also higher in the area. All these factors favor TC genesis during the latter period. The decadal change of TC genesis led to more landfalling TCs in Southern China during the period 1994-2008, which contributed to an abrupt increase in regional rainfall.     

Features of ocean surface winds observed by the QuikSCAT satellite before tropical cyclogenesis over the South China Sea

Ocean surface winds observed by the Quick Scatterometer (QuikSCAT) satellite prior to the geneses of 36 tropical cy- clones (TCs) in the South China Sea (SCS) are investigated in this paper. The results show that there are areas with negative mean horizontal divergence around the TC genesis locations three days prior to TC formation. The divergence term [-(f ζ)( u/ x v/ y)] in the vorticity equation is calculated based upon the QuikSCAT ocean surface wind data. The calculated mean divergence term is about 10.3 times the mean relative vorticity increase rate around the TC genesis position one day prior to TC genesis, which shows the important contributions of the divergence term to the vorticity increase prior to TC formation. It is suggested that criteria related with the divergence and divergence term be applied in early detections of tropical cyclogenesis using the QuikSCAT satellite data.     

The Upper Ocean Thermal Structure and the Genesis Locations of Tropical Cyclones in the South China Sea

The relationship between the upper ocean thermal structure and the genesis locations of tropical cyclones （TCs） in the South China Sea （SCS） is investigated by using the Joint Typhoon Warning Center （JTWC） best-track archives and high resolution （1/4 degree） temperature analyses of the world＇s oceans in this paper In the monthly mean genesis positions of TCs from 1945 to 2005 in the SCS, the mean sea surface temperature （SST） was 28.8℃ and the mean depth of 26℃ water was 53.1 m. From the monthly distribution maps of genesis positions of TCs, SST and the depth of 26℃ water in the SCS, we discovered that there existed regions with SST exceeding 26℃ and 26℃ water depth exceeding 50m where no tropical cyclones formed from 1945 to 2005 in the SCS, which suggests that there were other factors unfavorable for TC formation in these regions.     

Modulation of tropical cyclogenesis over the South China Sea by ENSO Modoki during boreal summer

This study examines the modulation of tropical cyclogenesis over the South China Sea(SCS) by the El Nio-Southern Oscillation(ENSO) Modoki during the boreal summer. Results reveal that there were more tropical cyclones(TCs) formed over the SCS during central Pacific warming years and less TC frequency during central Pacific cooling years. How different environmental factors(including low-level relative vorticity, mid-level relative humidity, vertical wind shear, and potential intensity) contribute to this influence is investigated, using a genesis potential(GP) index developed by Emanuel and Nolan. Composite anomalies of the GP index are produced for central Pacific warming and cooling years separately, which could account for the changes of TC frequency over the SCS in different ENSO Modoki phases. The degree of contribution by each factor is determined quantitatively by producing composites of modified indices in which only one of the contributing factors varies, with the others set to climatology. The results suggest that the vertical wind shear and low-level relative vorticity, which are associated with the ENSO Modoki-induced anomalous circulations in Matsuno-Gill patterns, make the largest contributions to the ENSO Modoki modulation of tropical cyclogenesis over the SCS as implied by the GP index. These results highlight the important roles of dynamic factors in the modulation of TC frequency over the SCS by the ENSO Modoki during the boreal summer.     

Statistical Analysis of Tropical Disturbances over the South China Sea During 1997-2006

Tropical disturbances over the South China Sea (SCS) during the period of 1997-2006 are analyzed using the Tropical Storm and Hurricane WX products. A total of 158 tropical disturbances were formed over the SCS from 1997 to 2006, with 54 developing tropical disturbances which developed into tropical depressions and 104 non-developing tropical disturbances which never developed into tropical depressions. The development rate of tropical disturbances into tropical depressions was 34.18% in these ten years. During the period of this study, total annual numbers of tropical disturbances and developing tropical disturbances over the SCS had significant decreasing trends; however, the development rate of tropical disturbances had an insignificant increasing trend.     

Diagnosis of seasonal variations of tropical cyclogenesis over the South China Sea using a genesis potential index

This study examines the seasonal variations of tropical cyclogenesis over the South China Sea (SCS) using a genesis potential (GP) index developed by Emanuel and Nolan. How different environmental factors (including low-level vorticity, mid-level relative humidity, vertical wind shear, and potential intensity) contribute to these variations is investigated. Composite anomalies of the GP index are produced for the summer and winter monsoons separately. These composites replicate the observed seasonal variations of the observed frequency and location of tropical cyclogenesis over the SCS. The degree of contribution by each factor in different regions is determined quantitatively by producing composites of modified indices in which only one of the contributing factors varies, with the others set to climatology. Over the northern SCS, potential intensity makes the largest contributions to the seasonal variations in tropical cyclogenesis. Over the southern SCS, the low-level relative vorticity plays the primary role in the seasonal modulation of tropical cyclone (TC) genesis frequency, and the vertical wind shear plays the secondary role. Thermodynamic factors play more important roles for the seasonal variations in tropical cyclogenesis over the northern SCS, while dynamic factors are more important in the seasonal modulation of TC genesis frequency over the southern SCS.     

EAST CHINA SEA RESPONSE TO TROPICAL CYCLONES

The response of the East China Sea (ECS) to a tropical cyclone (TC) is studied with a two-layernonlinear primitive equation ocean model. Numerica experiments indicate that there is rightward bias inocean response to a moving TC. The initial middle layer (ML) depth and stratification intensity havesubstantial impact on the Changes of SST and ML depth. The initial ML depth has large effect onthe value of the current, whereas the initial stratification intensity has slight influence on it. Thedistribution of ECS ML depth, especially the special ocean thermal structure on the continental shelf facil-itates the drop of SST. The simulation results of ocean response to Typhoon 7002 are fairly consistentwith the observation data.     

Study of the Wind Conditions in the South China Sea and Its Adjacent Sea Area

An increasing number of marine structures have been built for coastal protection and marine development in recent years,and wind,which is crucial to marine structures,should be analyzed.Therefore,typhoon frequency,wind climate,wind energy assess-ment,and extreme wind speed in the South China Sea(SCS)are investigated in detail in this study.The data are obtained from the China Meteorological Administration,the European Centre for Medium-range Weather Forecasts,and the National Centers for Envi-ronmental Prediction.The offshore wind energy potential is analyzed at five sites near the coast.The spatial and monthly frequencies of tropical cyclones for different intensity categories are analyzed.The extreme wind speed is fitted by five distribution models,and the generalized extreme value(GEV)distribution is selected as the most suitable function according to the goodness of fit.The spa-tial distributions of extreme wind speeds in the SCS are plotted on the basis of the GEV distribution and ERA5 data sets.The influ-ences of the distribution models and data sets on the calculated results are discussed.Moreover,the monthly extreme wind speed and comparison with the results of previous studies are analyzed.This study provides a reference for the design of wind turbines.     

地形对台风影响的数值模拟研究——以台风“泰利”为例

为研究台湾岛地形对台风移动路径及结构的影响,利用高分辨率中尺度MM5V3模式,设计3组敏感性试验,对“0513”号台风“泰利”在2005年8月31日00：06到9月1日18：00（世界时）影响台湾岛的过程进行数值模拟研究。主要就台湾岛地形对台风移动路径、气压场、散度场、涡度场和降水场进行分析。试验结果表明：台湾岛地形对台风“泰利”的移动路径和中心气压的影响不显著;地形的强迫作用对台风涡度场的中心强度和非对称结构有明显的影响;台湾岛地形是形成迎风坡诱生低压和背风坡诱生高压的主要因子;地形是台风外围降水加强的主要原因。     

Anomalies of asian summer monsoon related to ssta in the south China Sea and the tropical pacific

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