西北太平洋台风活动的年代际变化与大尺度环流因子的关系

用多项式拟合和统计分析的方法对1960～2005年西北太平洋台风年频数资料进行分析表明：台风活动存在明显的年代际变化,46a间台风活动存在两个高频期和两个低频期,高低频期台风频数的差异主要集中在7～10月（称为台风活跃季）,利用台风活跃季的NCEP／NOAA资料对影响台风年代际变化的大尺度环流因子进行分析,结果表明：与低频期相比,在台风生成的高频期出现了较高的海表温度、较低的海平面气压、较大的高层散度和低层相对涡度、较小的垂直风切变,而且500hPa风场利于台风的生成和向西北太平洋移动。西太平洋副热带高压偏北,100hPa南亚高压偏弱。西北太平洋海盆的总降水量的年代际变化与台风的年代际变化关系不明显。     

西北太平洋台风频数异常年的气候背景分析

利用中国气象局整编的热带气旋资料、NCEP再分析资料和Scripps海温资料,分析了台风季西北太平洋台风频数发生年代际和年际异常时的气候背景特征,并且比较分析了造成台风频数发生年代际和年际异常的影响因子的异同。结果表明:台风频数的年代际变化主要和副热带高压和赤道西太平洋的温跃层海温有非常显著的关系,而年际变化则与副高、季风槽、越赤道气流以及赤道中东太平洋的混合层海温都有着密切的联系。     

PDO对西北太平洋热带气旋活动与大尺度环流关系的影响

利用NCEP再分析资料和上海台风研究所整编的热带气旋资料,研究了在太平洋年代际振荡(PDO)冷暖位相中西北太平洋热带气旋频数与太平洋海表温度(SST)年际相关的分布差异,以及500 hPa高度场对热带气旋频数和生成源地的影响.结果表明,在PDO冷位相时期,热带气旋频数与赤道东太平洋SST存在显著相关,副热带高压位置偏东...     

西北太平洋热带气旋频数异常与五类主要大尺度环流型的关系

利用Yoshida and Ishikawa(2013)提出的一套客观分类方法对1979-2013年夏季(5-10月)共796个热带气旋(Tropical Cyclone,TC)生成前的大尺度环流背景场进行了分型,主要包括了季风切变线型(monsoon Shear Line,SL)、季风涡旋区(monsoon Gyre...     

夏季西北太平洋台风生成数的敏感性因子

比较了台风生成参数中各因子与西北太平洋7-9月台风生成数(WNPSTYN)的相关关系,也比较各因子在北半球台风主要源区的纬向距平分布特征,发现涡度因子与WNPSTYN的关系最好,在台风生成条件中相对富有但不特别富足的特性决定了其是WNPSTYN年际变化的敏感性因子.同时还分析了西北太平洋关键区涡度因子年际变化的来源和表征台风生成数的优越性,发现关键区涡度因子年际变化与南方涛动、南极涛动和澳洲东部高度场的年际变化有关,体现了南半球两大系统和ENSO对WNPSTYN的影响；涡度因子与WNPSTYN的显著相关区与台风生成源地集中区一致,表征台风年际变化有明显的优越性.这些特性对关于WNPSTYN的影响机制研究和气候模式模拟有非常重要的意义.     

西北太平洋环流特点和远东南部天气条件之间的关系

按照现代观点,要成功地编制天气预报必须考虑海洋环流以及海洋和大气相互作用的过程。洋流在地球上的热量再分配中起着重要作用,它把大量的热量从一个地区输送到另一个地区。已有许多研究讨论洋流对大陆气候和天气的影响。近年来关于洋流性质的概念有了重大变化。涡旋系统概念代替了“平滑的”大尺度洋流的旧概念。1970年在热带大西洋实验区进行的试验和最近的研究表明,大洋中的动能的主要负荷者是顺时针的(暖性反气旋式)和逆时针的(冷性气旋式)洋流涡     

西北太平洋台风路径与厄尼诺关系初步分析

本文分析了近百年西北太平洋台风路径与厄尼诺的关系,得出了在厄尼诺年,西太平洋(120°E以东)转向的台风路径比在反厄尼诺年偏多,而西行路径则偏少。厄尼诺与反厄尼诺年的台风路径差异主要是受副高形势的影响,有明显的月际差异。      

厄尔尼诺现象与西北太平洋台风活动关系的初步分析

本文分析了1950年以来厄尔尼诺现象与西北太平洋台风活动之间的关系,发现中等强度以上的厄尔尼诺当年夏季(6—8月)的台风活动与厄尔尼诺次年夏季具有不同的特点。通过对1972—1973,1982—1983年两次强厄尔尼诺现象分析表明这种差异与赤道太平洋东部SST异常增暖、西北太平洋低纬度夏季环流特征有密切关系。本文还讨论了厄尔尼诺现象与西北太平洋台风活动之间可能存在的联系。     

热带太平洋对流活动与西北太平洋台风活动关系的探讨

利用１９７９～１９９５年月平均ＯＬＲ资料,分析了影响我国夏半年台风多寡的同期及前期热带太平洋地区ＯＬＲ分布特征,通过计算ＯＬＲ特征指数,探讨对流活动与台风异常变化的特征及关系．结果表明,台风活动季节,在西太平洋热带地区,ＯＬＲ强度与生成及登陆台风个数呈明显的负相关关系．不仅如此,这种相关关系在前期冬、春季ＯＬＲ强度与生成及登陆台风的相关场上就有所反映．用ＯＬＲ特征指数所表征的对流活动的强度和位置与台风活动频数有较好的正相关关系．且７～９月对流强度指数与登陆我国台风个数、６～１０月ＯＬＲ低值轴的位置与生成台风个数都具有３～５年的低频振荡周期及气候阶段性．     

THE IMPACT OF MID-LATITUDE CIRCULATION OVER THE TIBETAN PLATEAU ON THE TRACK OF TYPHOON OVER THE NORTHWEST PACIFIC

There is a close relationship between variation of middle latitude synoptic system over theTibetan Plateau and movement of typhoon over the Northwest Pacific.This paper tries to discussthe mechanism of it through the numerical simulation and dynamic diagnosis.25-year statistical results during the period from 1970 to 1995 indicate that the relationshipbetween middle latitude circulation over the Plateau and the track of typhoon over the NorthwestPacific are as follows.When longwave trough in 500 hPa isobaric surface over the Plateau.it isfavourable to typhoon's westward movement:on the contrary,large scale anticyclone over thePlateau is favourable to typhoon's recurvature.We simulated the typhoon under these two flowpatterns with MM5 model.Numerical simulation results showed that:(a)Longwave trough on500 hPa surface over the Plateau makes subtropical high extended westward so as to typhoon southto high moves westward in easterly steering flow.(b)Anticyclone over the Plateau will bringabout the longwave trough developing along the east coast of Asia,it'will usually cause typhoonrecurring in front of the developed trough.In addition,the results of dynamic diagnosis show the physical mechanism on impact ofsynoptic system over the Plateau on the downstream synoptic system,that is,the transport ofdisturbance kinetic energy over the upstream Plateau makes the downstream trough developed.And then it affects the steering flow of typhoon.Because of existence of the high ridge over thePlateau.the energy transport channel moves to north.On the contrary,the trough exists over thePlateau,the energy transport channel moves to south.The southerly in front of trough over thePlateau and the southerly in the east part of typhoon transport low potential vorticity of lowlatitude into subtropical high.That is beneficial to development of subtropical high and affectstyphoon's movement.These results fully reflect the impact of interaction between mid-latitude andlow latitude on synoptic system.     

夏季西太平洋台风频数异常与ENSO事件的关系及大气环流异常特征

根据西太平洋编号台风资料、NOAA卫星观测OLR资料和NCEP／NCAR风场再分析资料,在统计和探讨夏季西太平洋台风多（少）发年与ENSO事件的关系的基础上,分别对夏季台风异常偏多或偏少的E1Nifio、LaNifia年的OLR特征量和热带夏季风环流进行合成对比分析。分析表明：夏季当南半球马斯可林高压和澳大利亚高压无明显的系统性异常时,Walker环流异常的影响占主导作用,并遵循ENSO事件对大气环流及台风频数影响的基本规律。若E1Nifio期间澳大利亚高压环流出现系统性异常时,南半球环流异常的影响则占主导地位,台风反而异常偏多。对于1999年LaNifia特殊年份,马斯可林高压异常偏强引发的季风西风偏北偏东,台风反而异常偏少。弱风速垂直切变区、西太平洋暖池和季风槽的重叠部分是台风频发源地,本文分别对E1Nifio、LaNifia台风异常偏多（少）年台风频发源地的位詈和范围作了比较分析．     

THE RELATIONSHIP BETWEEN TROPICAL PACIFIC SEA SURFACE TEMPERATURE AND SUMMER RAINFALL OVER NORTHWEST CHINA

In this paper,the data of summer precipitation in Northwest China were expanded by means of EOF.According tomajor eigenvectors in expansion the area of Northwest China was divided into four natural rainfall regions.Amongthem the region of greatest precipitation variability is found over the East Qinghai-North Shaanxi region,includingEast Qinghai,Central and East Gansu,Ningxia and North Shaanxi.There is apparent teleconnection between the firstand second time-dependent coefficients in EOF expansion and the tropical Pacific SST in the corresponding period andearlier months.The variation of the east tropical Pacific SST in winter and spring is able to predict precipitation trend ofNorthwest China next summer.Moreover,in the El Nino years precipitation trend is opposite to the following year,andthe region from East Qinghai to North Shaanxi is most sensitive.     

RELATION BETWEEN SUMMER TYPHOON FREQUENCY ANOMALIES IN WEST PACIFIC AND ENSO EVENTS AND THE ANOMALOUS ATMOSPHERIC CIRCULATION CHARACTERISTICS

By using data of serially numbered typhoons in northwestern Pacific and NOAA OLR data and NCEP/NCAR reanalysis data of wind field, based on the statistics and study of the relationship between the calendar years with more (or fewer) summer typhoons and ENSO events, we compared the composites of OLR eigenvectors and tropical summer wind fields during El Nino and La Nina events with more or fewer than normal summer typhoons, respectively. The results show that, in summer, without remarkable systematic anomalies of Mascarene High and Australia High in South Hemisphere, the anomaly of Walker circulation will dominate and follow the rule of ENSO impacts to atmospheric circulation and typhoon frequency. Otherwise, when systematic anomalies of Australia High appear during the El Nino events, circulation anomalies in the South Hemisphere will dominate, and many more typhoons will occur. In 1999, which is a special year of La Nina events, northward and eastward monsoon was induced by the stronger Mascarene High, and fewer typhoons arose. The typhoon source are regions where weak vertical wind shear, warm pool in western Pacific and the area with monsoon troughs are overlapping with each other. Finally, this paper analyzes and compares the source locations and ranges of more (fewer) typhoons in the events of El Nino and La Nina, respectively.     

MEDIUM-RANGE OSCILLATION AND TELECONNECTION OF THE ATMOSPHERIC CIRCULATION SYSTEMS OVER THE NORTHWEST PACIFIC AND SOUTH INDIAN OCEANS

This paper aims to demonstrate some characteristics of the 20-50 day oscillations of certain circulationsystems in low latitudes during the northern summer seasons.The teleconnection between the variations ofthe Mascarene high and the Northwest Pacific high and its physical mechanism are studied.How the Mas-carene high plays an important role in the interaction between the atmospheric circulations of both hemispheresis discussed.     

THE RELATIONSHIP BETWEEN GLOBAL WARMING AND THE VARIATION IN TROPICAL CYCLONE FREQUENCY OVER THE WESTERN NORTH PACIFIC

The relationship between global warming and the variation in tropical cyclone (TC) genesisfrequency is analyzed using the data of the Tropical Cyclone Year Book by the China MeteorologicalAdministration and the National Centers for Environmental Prediction (NCEP) reanalysis data from 1949to 2007. The observational results indicate that the average sea surface temperature (SST) in theIntertropical Convergence Zone (ITCZ) region (10°N – 20°N, 100°E – 140°E) increases by 0.6°C againstthe background of global warming, while the frequency of tropical cyclone geneses in this region decreasessignificantly. Generally, the rise of SSTs is favorable for the genesis of tropical cyclones, but it is nowshown to be contrary to the normal effect. Most of the tropical cyclones in the western North Pacific (WNP)are generated in the ITCZ. This is quite different from the case in the Atlantic basin in which the tropicalcyclones are mostly generated from the easterly wave. Our research results demonstrate that the ITCZ has aweakening trend in strength, and it has moved much more equatorward in the past 40 years; both aredisadvantageous to the formation of tropical cyclones. Furthermore, our study also found that the ridge ofthe subtropical high tends to shift slightly equatorward, which is another adverse mechanism for theformation of tropical cyclones.     

热带太平洋海温与中国西北夏季降水的关系

本文将中国西北(陕、甘、宁、青四省区)夏季降水资料用经验正交函数(EOF)方法展开,根据展开后的主要特征向量把西北划分为四个自然降水区,其中降水变率最大的区域是包括青海省东部、甘肃省中东部、宁夏全区和陕西省北部在内的海东—陕北区。西北夏季降水经EOF方法展开后的第一、二时间系数与同期和前期热带太平洋海温有着明显的遥相关。热带东太平洋海温冬、春季的冷暖变化程度,可以预示后期西北夏季降水的趋势变化。另外,在厄尼诺现象发生的当年和次年,西北夏季降水具有明显的相反变化,其中海东—陕北区最敏感。     

论热带大气垂直环流圈的结构和海洋加热尺度间的关系

应用本征模式的浅水运动方程,研究了热带大气中Walker环流和Hadley环流圈的垂直结构和海洋加热尺度间的关系,如热源的纬圈尺度为L,赤道Rossby变形半径为L_0,Ray-leigh摩擦和Newton冷却系数为ε,则垂直环流圈的结构依赖于加热尺度L的大小。当α(=L_0/L)>α_0(ε)时(即小尺度热源),其结果和Gill的定常解相似,即在热源中心西侧的Rossby波活动区,与Walker环流相联系的Hadley环流,是热力性的正环流。低层空气是向赤道辐合,高层空气是向极地的,并在副热带地区下沉;而在热源以东的Kelvin波活动区,经圈速度的垂直分布反过来,即低层气流是向极地的,高层气流是向赤道的。但当热源尺度变得适当大后,例如当α<α_0(ε)时,经圈环流在Rossby波和Kelvin波区的大部分地区,都是正的Hadley环流,而原来在Kelvin波区的反Hadley环流,将东移到离热源中心相当远的地区(例如超过10个赤道Rossby变形半径)。在后面这种情况下,一个大尺度的正的Hadley环流,将把大气从海洋中得到的热量或能量大量地输送到副热带或中纬度地区,使那里的大气环流发生异常性的变化。后面这一理论结果与统计事实相当符合,可以看成是对Bjerknes提出的遥相关现象的一个理论支持。