AN OBSERVATIONAL STUDY ON DISTRIBUTION OF PRECIPITATION ASSOCIATED WITH LANDFALLING TROPICAL CYCLONES AFFECTING CHINA     

舒守娟  许音  宋金杰  喻自凤 《热带气象学报(英文版)》2012,18(3):275-283

In order to provide an operational reference for tropical cyclone precipitation forecast,this study investigates the spatial distributions of precipitation associated with landfalling tropical cyclones(TCs) affecting China using Geostationary Meteorological Satellite 5(GMS5)-TBB dataset.All named TCs formed over the western North Pacific that made direct landfall over China during the period 2001-2009 are included in this study.Based on the GMS5-TBB data,this paper reveals that in general there are four types of distribution of precipitation related to landfalling TCs affecting China.(a) the South-West Type in which there is a precipitation maximum to the southwestern quadrant of TC;(b) the Symmetrical South Type in which the rainfall is more pronounced to the south side of TC in the inner core while there is a symmetrical rainfall distribution in the outer band region;(c) the South Type,in which the rainfall maxima is more pronounced to the south of TC;and(d) the North Type,in which the rainfall maxima is more pronounced to the north of TC.Analyses of the relationship between precipitation distributions and intensity of landfalling TCs show that for intensifying TCs,both the maximum and the coverage area of the precipitation in TCs increase with the increase of TC intensity over northern Jiangsu province and southern Taiwan Strait,while decreasing over Beibu Gulf and the sea area of Changjiang River estuary.For all TCs,the center of the torrential rain in TC shifts toward the TC center as the intensity of TC increases.This finding is consistent with many previous studies.The possible influences of storm motion and vertical wind shear on the observed precipitation asymmetries are also examined.Results show that the environmental vertical wind shear is an important factor contributing to the large downshear rainfall asymmetry,especially when a TC makes landfall on the south and east China coasts.These results are also consistent with previous observational and numerical studies.  相似文献   

The Impact of Horizontal Resolution on the CNOP and on Its Identified Sensitive Areas for Tropical Cyclone Predictions   总被引：1，自引：0，他引：1  

ZHOU Feifan  MU Mu 《大气科学进展》2012,29(1):36-46

In this study,the impacts of horizontal resolution on the conditional nonlinear optimal perturbation (CNOP) and on its identified sensitive areas were investigated for tropical cyclone predictions.Three resolutions,30 km,60 km,and 120 km,were studied for three tropical cyclones,TC Mindulle (2004),TC Meari (2004),and TC Matsa (2005).Results show that CNOP may present different structures with different resolutions,and the major parts of CNOP become increasingly localized with increased horizontal resolution.CNOP produces spiral and baroclinic structures,which partially account for its rapid amplification.The differences in CNOP structures result in different sensitive areas,but there are common areas for the CNOP-identified sensitive areas at various resolutions,and the size of the common areas is different from case to case.Generally,the forecasts benefit more from the reduction of the initial errors in the sensitive areas identified using higher resolutions than those using lower resolutions.However,the largest improvement of the forecast can be obtained at the resolution that is not the highest for some cases.In addition,the sensitive areas identified at lower resolutions are also helpful for improving the forecast with a finer resolution,but the sensitive areas identified at the same resolution as the forecast would be the most beneficial.  相似文献   

Modulation of Western North Pacific Tropical Cyclone Genesis by Intraseasonal Oscillation of the ITCZ: A Statistical Analysis   总被引：1，自引：0，他引：1  

CAO Xi  HUANG Ping  CHEN Guanghu  CHEN Wen 《大气科学进展》2012,29(4):744-754

The present study investigates modulation of western North Pacific(WNP) tropical cyclone(TC) genesis in relation to different phases of the intraseasonal oscillation(ISO) of ITCZ convection during May to October in the period 1979-2008.The phases of the ITCZ ISO were determined based on 30-80-day filtered OLR anomalies averaged over the region(5-20 N,120-150 E).The number of TCs during the active phases was nearly three times more than during the inactive phases.The active(inactive) phases of ISO were characterized by low-level cyclonic(anticyclonic) circulation anomalies,higher(lower) midlevel relative humidity anomalies,and larger(smaller) vertical gradient anomalies of relative vorticity associated with enhanced(weakened) ITCZ convection anomalies.During the active phases,TCs tended to form in the center of the ITCZ region.Barotropic conversion from the low-level mean flow is suggested to be the major energy source for TC formation.The energy conversion mainly depended on the zonal and meridional gradients of the zonal flow during the active phases.However,barotropic conversion weakened greatly during the inactive phases.The relationship between the meridional gradient of absolute vorticity and low-level zonal flow indicates that the sign of the absolute vorticity gradient tends to be reversed during the two phases,whereas the same sign between zonal flow and the absolute vorticity gradient is more easily satisfied in the active phases.Thus,the barotropic instability of low-level zonal flow might be an important mechanism for TC formation over the WNP during the active phases of ISO.  相似文献   

近58年来登陆中国热带气旋气候变化特征   总被引：12，自引：1，他引：11  

杨玉华  应明  陈葆德 《气象学报》2009,67(5):689-696

利用1949-2006年<台风年鉴>和<热带气旋年鉴>资料,主要分析了1949-2006年登陆中国热带气旋的频数、登陆位置、登陆季节延续期和登陆强度等要素及其概率分布的年际和年代际变化特征.结果表明:近58年来,登陆中国热带气旋年频数有减少趋势,但登陆时达台风强度的年频数变化不明显;按登陆地点分区统计发现,登陆华南地区的热带低压及(强)热带风暴年频数以减少为主,而登陆东部地区的热带气旋年频数变化不明显.登陆点历年最北位置(最南位置)有南移(弱的北移)趋势,导致登陆点历年南北最大纬度差逐渐减小,这表明热带气旋登陆区域更为集中,在23°-35°N增多,而在35°N以北和23°N以南以减少为主.登陆中国热带气旋季节延续期缩短了近1个月.热带气旋年平均登陆强度及其概率分布偏度有增加趋势,表明登陆的强台风有增加;登陆中国华南和东部地区的台风强度都有增强趋势,前者比后者趋势更明显.另外,热带气旋年最大登陆强度差长期呈现减小的趋势.  相似文献   

全球数值模式中的台风初始化Ⅱ: 业务应用   总被引：2，自引：0，他引：2  

瞿安祥  麻素红  李娟  胡江凯  LIU Qingfu 《气象学报》2009,67(5):727-735

由于缺少大量有效的观测资料,台风初始化对数值天气预报业务模式而言,仍然是一个悬而末决的难题.中国国家气象中心自从1996年将台风数值预报系统投入业务运行以来,一直使用经验的人造bogus涡旋台风初始化技术.实际上,不同时期的台风有着不同的环流结构,即使同一个台风在不同的生命期也具有不同的结构特征,而这些结构特征的差异并不能依靠现有的bogus涡旋技术体现出来,这种主观方法的统一性与台风在时空上的差异性形成了强烈的反差.最近,基于国家气象中心全球资料分析同化-预报循环系统,设计和发展了一套新的台风初始化业务方案,它主要由初始涡旋形成、涡旋重定位和涡旋调整3部分过程组成.相比于业务中使用的人造bogus涡旋台风初始化方案,新方案在很大程度上减少了人为因素对台风涡旋结构的影响,而更多地是依靠数值模式自身的动力和物理过程来协调约束产生三维空间的涡旋结构.应用新方案,文中对生成于西北太平洋的2006年0605号台风格美(Kaemi)进行了数值试验,初步分析表明,新方案在实现台风涡旋环流结构的初始化方面效果较好,同时,对台风格美多个时次的预报结果也显示,相比于业务使用的bogus方案而言,新方案对台风路径平均预报误差有了大幅度的降低.  相似文献   

西北太平洋热带气旋源地变化特征及与局地海表温度的关系   总被引：2，自引：0，他引：2  

杨亚新  邱新法 《气象》2009,35(5):83-90

为提高热带气旋的短期气候预测水平,利用1950-2005年西北太平洋热带气旋(TC)和表层水温(SST)资料,分析了西北太平洋TC生成位置分布的一般气候特征,季节、年际变化特征及其与局地SST之间的关系,同时还探讨了TC强度、路径与TC生成位置之间的关系.结果表明,西北太平洋存在4个TC高频源地,分别是南海中北部偏东洋面、菲律宾以东附近洋面、关岛附近洋面和马绍尔群岛附近洋面,其中关岛附近洋面TC发生数最多,是TC发生的一个主要源地.TC生成位置分布存在显著的季节和年际变化特征,这种变化与局地SST存在密切的关系,局地SST升高,TC生成位置偏西、偏北,反之,则偏东、偏南.同时发现,TC生成位置西北边界与月平均SST的27.5℃等温线具有较好的匹配关系,绝大多数TC都发生在月平均SST≥27.5℃的海区.TC强度、路径与TC生成位置之间存在一定的关系.TC生成位置偏东偏南,其发展强度相对较强,路径偏东偏南,可导致影响我国南部海区和日本东部沿海的TC个数增加;TC生成位置偏西偏北,其发展强度相对较弱,路径偏西北,可导致影响我国东部和北部沿海的TC个数增加.  相似文献   

结合“海棠”台风（2005）定量分析非绝热加热对湿 Q 矢量诊断能力的影响   总被引：3，自引：0，他引：3  

岳彩军 《气象学报》2010,68(1):59-69

湿Q矢量最大特点就是考虑了非绝热加热作用,各种湿Q矢量差异也主要表现在对非绝热加热计算处理方案的不同.因此,通过比较分析非绝热加热作用,可揭示出不同湿Q矢量之间诊断能力的差异.2005年第5号登陆台风"海棠"在7月19日08时20 H 08时,给福建省东北部及浙江省造成大范围暴雨.WRF模式成功模拟出此次台风暴雨过程.文章将结合"海棠"台风(2005)登陆台风暴雨过程,利用 WRF模式模拟输出的气象要素,通过计算降水场,定量分析了非绝热加热作用及其对湿Q矢量诊断能力的影响.结果表明:(1)对于公包括大尺度凝结加热的非绝热加热作用H1及包括了潜热加热(大尺度凝结加热和对流凝结加热)、感热加热和辐射加热的非绝热加热作用H2来讲,局地变化项的强迫作用较垂直平流项、水平平流项的强迫作用约小1-2个量级,可以忽略不计,垂直平流项的强迫作用是主要成分,对于水平平流项来讲,尽管其强迫作用明显小于垂直平流项的强迫作用,但也明显大于局地变化项的强迫作用,考虑其将更有利于充分反映H1、H2的强迫作用.对于包括非均匀饱和大气中潜热加热的H3来讲,水平平流项与垂直平流项的强迫作用相当,均为主要成分,而局地变化项的强迫作用为次要成分且不容忽视,对其考虑将有助于全面描述H2的强迫作用.(2)非绝热加热作用H1、H2以及H3强迫产生的24 h累积降水场具有相似的水平分佰特征,三者强迫产生的逐时雨量随时间演变特征也非常相似,这表明水汽凝结潜热是非绝热加热作用的主要成分.(3)进一步结合模拟降水场分析表明,相对于H1强迫产生的降水场来讲,H2与H3强迫产生的降水场更接近模拟结果,这揭示出包含H2的湿Q矢量与包含H2的湿Q矢量诊断能力相近,且对降水反映能力较包含H1的湿Q矢量诊断能力强.(4)不同湿Q矢量各自有其自身诊断特点,根据不同研究目的的需要,可有针对性的选取相应的湿Q矢量来作为研究工具.如需要具体、细敛分析水汽潜热的强迫作用,可以选朋包含H1、H3的湿Q矢量,如仅需考虑总的湿Q矢量强迫作用,则可以直接选用包含H2的湿矢量.  相似文献   

粒子群算法与支持向量机相结合的热带气旋强度预报试验     

顾锦荣  刘华强  孙预前 《气象与减灾研究》2010,33(3):22-26

支持向量机(SVM)的惩罚参数及核参数的选择直接影响到模型效果,通过粒子群算法(PSO)解决支持向量机的参数选择问题,实现了参数选择的自动化。将该方法应用于热带气旋强度预报,利用气候持续性因子,挑选了1990年的100个左右样本进行预报检验,预报时效为12 h、24 h、36 h、48 h的强度平均绝对误差分别为3.00、4.35、4.93和6.68 m/s。另外,还与国外预报结果及采用最小二乘回归法的预报结果进行了效果的比较,SVM方法显示了更好的预报能力。  相似文献   

Process‐based modeling of kilometer‐scale alongshore sandbar variability          下载免费PDF全文

D. J. R. Walstra  B. G. Ruessink  A. J. H. M. Reniers  R. Ranasinghe 《地球表面变化过程与地形》2015,40(8):995-1005

Subtidal nearshore sandbars may exhibit cyclic net offshore migration during their multi‐annual lifetime along many sandy coasts. Although this type of behavior can extend continuously for several kilometers, alongshore variations in cross‐shore bar position and bar amplitude are commonly observed. Alongshore variability is greatest when bars display km‐scale disruptions, indicative of a distinct alongshore phase shift in the bar cycle. An outer bar is then attached to an inner bar, forming a phenomenon known as a bar switch. Here, we investigate such large‐scale alongshore variability using a process‐based numerical profile model and observations at 24 transects along a 6 km section of the barred beach at Noordwijk, The Netherlands. When alongshore variability is limited, the model predicts that the bars migrate offshore at approximately the same rate (i.e. the bars remain in phase). Only under specific bar configurations with high wave‐energy levels is an increase in the alongshore variability predicted. This suggests that cross‐shore processes may trigger a switch in the case of specific antecedent morphological configurations combined with storm conditions. It is expected that three‐dimensional (3D) flow patterns augment the alongshore variability in such instances. In contrast to the observed bar behaviour, predicted bar morphologies on either side of a switch remain in different phases, even though the bars are occasionally located at a similar cross‐shore position. In short, the 1D model is not able to remove a bar switch. This data‐model mismatch suggests that 3D flow patterns are key to the dissipation of bar switches. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

1010号“莫兰蒂”台风登陆地点分析     

赵惠芳  何秀恋  蔡英群  杨建东  陈川珍 《海洋预报》2012,29(1):31-35

应用区域自动站10分钟加密的风场、气压场和变压场资料,结合雷达回波资料,对2010年10号"莫兰蒂"台风登陆地点进行综合分析表明:"莫兰蒂"台风于2010年9月10日03时(北京时)左右在福建省晋江市围头-深沪之间沿岸登陆,登陆之后沿着晋江市东部镇(街)向NE移动,于3:40前后进入石狮市宝盖镇附近,然后转NNE移动,穿过石狮西部镇(街)再次进入晋江市,之后转NE方向移动,于6时前后移出晋江市。  相似文献