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1.
To address the deficiency of climatological research on tropical cyclones(TCs) influencing China, we analyze the distributions of TCs with different intensities in the region, based on the best-track TC data for1949–2011 provided by the Shanghai Typhoon Institute. We also present the distributions of 50- and 100-yr return-period TCs with different intensities using the Gumbel probability distribution. The results show that TCs with different intensities exert distinctive effects on various regions of China and its surrounding waters. The extreme intensity distributions of TCs over these different regions also differ. Super and severe typhoons mainly influence Taiwan Island and coastal areas of Fujian and Zhejiang provinces, while typhoons and TCs with lower intensities influence South China most frequently. The probable maximum TC intensity(PMTI) with 50- and 100-yr return periods influencing Taiwan Island is below 890 hPa; the PMTI with a50-yr return period influencing the coastal areas of Fujian and Zhejiang provinces is less than 910 hPa, and that with a 100-yr return period is less than 900 hPa; the PMTI with a 50-yr return period influencing the coastal areas of Hainan, Guangdong, and the northern part of the South China Sea is lower than 930 hPa,and that with a 100-yr return period is less than 920 hPa. The results provide a useful reference for the estimation of extreme TC intensities over different regions of China.  相似文献   

2.
The NCEP 1°×1°reanalysis of June-to-September dataset between 2002 to 2009 is used in this study to conduct statistical analysis of the relationship between the environmental potential vorticity(PV)on 150 hPa located at the south edge of South Asia High(SAH)and TCs making landfall.The results show that 23 of the TCs are affected by the PV on 150 hPa located at the south edge of SAH between 2002 to2009,and three TCs'center pressure decline after the high-value environmental PV moves to the center of the TCs.These three TCs are Senlaku(0216),Bilis(0604)and Linfa(0903).Through diagnostic analysis from the viewpoint of isolines,we determined the relationship between the intensification of these TCs and the PV anomaly at high levels;the isentropic surface is close to the high level’s PV anomaly under the influence of the 150-hPa PV anomaly,leading to the decline of isentropic surfaces on both sides of the PV anomaly.Then the warm core of the middle and high levels of the TC strengthens and PV increases at the middle level,and both of them are beneficial to the reinforcement of the cyclonic vorticity in the low level.As a result,the center pressure of the TC declines.According to Wu’s theory of Slantwise Vorticity Development(SVD),the incline of the isentropic surfaces leads to the development of vertical vorticity,contributing to the vertical motion and the release of the latent heat.Then the warm core of the TC strengthens and the TC strengthens,too.Otherwise,piecewise PV inversion also shows that the high-level PV influences the mid-level more than the low level.  相似文献   

3.
A new Tropical Cyclone (TC) initialization method with the structure adjustable bogus vortex was applied to the forecasts of track, central pressure, and wind intensity for the 417 TCs observed in the Western North Pacific during the 3-year period of 2005–2007. In the simulations the Final Analyses (FNL) with 1° × 1° resolution of National Center for Environmental Prediction (NCEP) were incorporated as initial conditions. The present method was shown to produce improved forecasts over those without the TC initialization and those made by Regional Specialized Meteorological Center Tokyo. The average track (central pressure, wind intensity) errors were as small as 78.0 km (11.4 hPa, 4.9 m s?1) and 139.9 km (12.4 hPa, 5.5 m s?1) for 24-h and 48-h forecasts, respectively. It was found that the forecast errors are almost independent on the size and intensity of the observed TCs because the size and intensity of the bogus vortex can be adjusted to fit the best track data. The results of this study indicate that a bogus method is useful in predicting simultaneously the track, central pressure, and intensity with accuracy using a dynamical forecast model.  相似文献   

4.
本文基于兰州市国家基本气象站1960~2014年降雨资料,通过直接拟合、耿贝尔分布、皮尔逊-Ⅲ型分布研究兰州市暴雨强度公式。选用芝加哥雨型来研究兰州市雨峰系数,结合暴雨强度公式确定短历时暴雨雨型。结果表明:(1)皮尔逊-Ⅲ型分布要优于耿贝尔分布和直接拟合,其调整后的兰州市暴雨公式中1年雨力参数A1为5.532mm/min,重现期调整参数c为3.198,降雨历时偏移参数b为14.92min,n为0.942,平均绝对均方差为0.036mm/min;(2)皮尔逊-Ⅲ分布能够满足不同的降雨历时以及更久的重现期。降雨历时小于90min或者重现期大于20年的暴雨模拟精确度更高,重现期在2~20a的暴雨平均绝对均方差最小为0.03mm/min。   相似文献   

5.
云迹风在热带气旋路径数值预报中的应用研究   总被引：13，自引：3，他引：10  
通过一系列四维变分同化试验对GMS5卫星资料反演的云迹风资料在西北太平洋热带气旋的初始化及路径数值预报中的作用进行研究,同化资料为中国国家卫星气象中心提供的GMS5水汽和红外云迹风资料,其中70%在400hPa以上,50%集中在200～300hPa。应用美国NCAR/PSU中尺度模式MM5及其四维变分同化系统,同化窗口为6h,对初始时刻和6h后的云迹风进行同化。同化前对云迹风资料进行了简单的类似ECMWF初值检验方法的质量控制。对2002年8个西北太平洋热带气旋共进行了22组试验。结果表明,采用四维变分同化技术同化云迹风对热带气旋路径预报有一定改善,12,24,36和48h预报的平均距离误差分别降低5%,12%,10%和7%,但同化云迹风的作用与初始气旋强度有关。选择初始中心海平面气压960hPa作为强、弱气旋的分类标准,则11个较强气旋平均路径误差12h减小了13%,12h以后的预报误差减小率维持在20%以上。而对于11个较弱气旋,平均路径误差反而略有增加,说明同化云迹风资料对不同初始强度的气旋作用也有所不同。其主要原因是由于强度较强的热带气旋往往具有较为深厚的垂直结构,因此受高层大气流场的影响更明显;同时,较弱热带气旋的云迹风观测相对稀少且凌乱,并且更容易受环境气流的影响,因此对于较弱的热带气旋,当模式变量与模式或变量之间在同化后不够协调的话,就会产生负效应。  相似文献   

6.
The interdecadal variations of tropical cyclones(TCs) and their precipitation over Guangdong Province are investigated using the observational data of TCs and precipitation from 26 observational stations in the province from 1951 to 2005.The results show that the TCs precipitation shows an oscillation with a peak value of about 25 years,with both the numbers of the Guangdong-influencing TCs and TCs formed in the western North Pacific oscillating with a peak value of about 23 years.The correlations are highly positive between the interdecadal variation of TC precipitation over the province and these numbers.The interdecadal variation of TC precipitation in the province shows significant negative correlations with the interdecadal variation of annual mean SST in some parts of the western North Pacific and the interdecadal variation of annual mean 500 hPa geopotential heights in some parts of the middle and high latitudes over the North Pacific.In general,there are high mean SSTs on the equator from central to eastern Pacific,low mean SSTs in the middle and high latitudes over the North Pacific and a main strong East Asian trough over the North Pacific in the period of less TC precipitation as compared with the period of more TC precipitation over the province.  相似文献   

7.
热带气旋强度的卫星探测客观估计方法研究   总被引：3，自引：1，他引：3       下载免费PDF全文
运用2001～2002年6月10日到8月10日西北太平洋上15个热带气旋的日本静止气象卫星（GMS-5）高分辨率红外辐射亮温（TBB）资料，从代表热带气旋强度的热带气旋云系特征中选取多个TBB因子及热带气旋中心所在纬度等因子，结合《热带气旋年鉴》资料，采用逐步回归方法，经多次试验求得热带气旋强度的客观估计算式，复相关系数达到0.80以上。由此式估计的热带气旋中心气压，经24 h滑动平均后的结果与年鉴气压的复相关系数提高到0.89，且两者之间的气压差在±10 hPa之内的占整个样本数的83%以上，与美国新近展示的相关研究结果十分接近。用2000年两个热带气旋作检验，结果很好。该客观方法有望替代目前的Dvorak主观估计方法，成为一种新的业务方法。  相似文献   

8.
Based on the Tropical Cyclone(TC briefly thereafter)Yearbook 1980-2009,this paper first analyzes the number and intensity change of the TCs which passed directly over or by the side of Poyang Lake(the distance of TC center is less than 1°longitude or 1°latitude from the Lake)among all the landfalling TCs in China during the past 30 years.Two cases are examined in detail in this paper.One is severe typhoon Rananim with a speed of 3.26 m/s and a change of 1 hPa in intensity when it was passing the Lake.The other is super typhoon Saomai with a faster moving speed of 6.50 m/s and a larger change in intensity of 6 hPa.Through numerical simulation experiments,this paper analyzes how the change of underlying surface from water to land contributes to the differences in intensity,speed and mesoscale convection of the two TCs when they passed the Lake.Results show that the moisture and dynamic condition above the Lake were favorable for the maintenance of the intensity when Rananim was passing through Poyang Lake,despite the moisture supply from the ocean was cut off.As a result,there was strong convection around the lake which led to a rainfall spinning counter-clockwise as it was affected by the TC movement.However,little impact was seen in the Saomai case.These results indicate that for the TCs coming ashore on Poyang Lake with a slow speed,the large water body is conducive to the sustaining of the intensity and strengthening of the convection around the TC center and the subsequent heavy rainfall.On the contrary,a fast-moving TC is less likely to be influenced by the underlying surface in terms of intensity and speed.  相似文献   

9.
影响我国热带气旋活动的气候特征及其与太平洋海温的关系   总被引：23，自引：14，他引：23  
利用1956~2000年的热带气旋(简称TC,下同)资料对影响我国TC活动的气候特征进行了初步的统计分析,结果发现影响我国的TC活动具有明显的阶段性特征,1960年代影响我国的TC数明显偏少,而后进入偏多期,1990年代又相对偏少。影响我国的TC强度多集中于980~999 hPa,华东的闽、浙一带TC登陆比华南晚,但强度较大。在此基础上通过对影响我国的TC年个数与太平洋海温场进行相关分析,发现两个相关较密切的区域: 西太平洋暖池(120~150 E, 10~20 N)正相关区、赤道中东太平洋(180 ~90 W, 10 S~5 N)负相关区,这两个相关区具有较好的持续性。进一步分析影响我国的TC在El Ni駉年与La Ni馻年的气候特征发现,El Ni駉年影响我国的TC数较少,但强度较大,La Ni馻年则相反,影响我国TC多年和少年对应的太平洋海温距平分布形势分别与La Nia年和El Nio年的海温距平分布形势类似。  相似文献   

10.
Using the T63L16 analysis data with the resolution of 1.875╳1.875 degree of latitude and longitude obtained from National Meteorological Center (NMC) and the real central position information of tropical cyclone (referred to as TC hereafter) numbered by NMC, the basic environmental geostrophic flow at 126 time levels of 25 TCs in 1996 are calculated. The vertical distribution features of the flows are analyzed. Besides, the deviation of real TC tracks from the flows (referred as steering deviation hereafter, namely, the deviation between the real central position of TC and the position calculated according to the steering flow) is also investigated. The result shows that the steering deviation would be different if the domain used to calculate the steering flow is different. The present paper obtains the optimum domain size to calculate the steering flow. It is found that the steering deviation is related to the velocity of steering flow and the initial latitude and intensity of TC itself, and that TC motion has relationship with the vertical shear structure of environmental geostrophic flow. The result also shows that the optimum steering flow is the deep-layer averaged basic flow from 1000 hPa to 200 hPa. Having the knowledge of these principle and features would help make accurate forecast of TC motion.  相似文献   

11.
登陆台湾岛热带气旋强度和结构变化的统计分析   总被引：2，自引：0，他引：2  
利用1949—2008年共60年的《台风年鉴》、《热带气旋年鉴》资料及CMA-STI热带气旋最佳路径数据集,2001—2008年美国联合台风警报中心(JTWC)热带气旋尺度相关资料及日本气象厅(JMA)的TBB资料,统计分析西北太平洋(包括南海)热带气旋(TC)在登陆台湾过程中强度和结构变化的基本特征,主要结论有:(1)TC登陆台湾时强度为台风及以上级别的样本数占总样本数约60%,主要出现在6—9月,东部登陆TC的强度一般比在西部登陆的强;(2)大部分TC在岛上维持6 h左右,登陆时最大风速≤5级和强度为超强台风的TC穿越台湾岛时移动比较缓慢;(3)126个登陆台湾的TC样本过岛后近中心海平面气压平均增加5.61 hPa,近中心最大风速平均减小3.58 m/s,在台湾东部地区登陆TC的衰减率比在西部登陆的大3倍左右;(4)TC在登陆台湾前6 h至离岛后6 h期间其8级和10级风圈半径均明显减小,TC形状略呈长轴为NE-SW向的椭圆状,而其最大风速的半径却逐渐增大;(5)TBB分析结果显示,TC登陆台湾前,其外围对流主要出现在南侧和西侧,结构不对称,登陆以后,TC北部及东部的对流显著发展,外围结构区域对称;但中心附近的强对流则从登陆前6 h开始逐渐减弱消失。表明TC穿越台湾过程中内核结构松散、强度减弱。  相似文献   

12.
Atmospheric Infrared Sounder (AIRS) temperature profiles during the period 2003–2013 are used to examine the warm core structures and evolution characteristics associated with the formation and development of western North Pacific (WNP) tropical cyclones (TCs). The warm core with a steady 1.5-K warming in the layer of 500–300 hPa occurs 24 h prior to tropical storm formation. Apparent eye warming extends upward to upper troposphere and downward to near surface after tropical storm formation. TC intensity shows a robust positive correlation with the warm core strength and has a weaker but still significant positive correlation with the warm core height (the weaker correlation is primarily attributed to the scattered warm core heights of weak TCs). Future 24-h intensity change of TCs has little correlation with the warm core height while it has a significant negative correlation with the warm core strength. Weak to moderate warm core at 500–200 hPa may be a necessary but not sufficient initial condition for TC rapid intensification. AIRS-observed warm core structures, in combination with other environmental factors, have the potential to improve the prediction of tropical storm formation and rapid intensification of WNP TCs.  相似文献   

13.
Recent trends and variability in tropical cyclone (TC) frequency and intensity are examined for TCs that affected China, with particular focus on those TCs that affected China’s key economic zones (e.g., the Yangtze River Delta, the Pearl River Delta, and the Beijing-Tianjin area). The results show that the frequency of TCs affecting China weakly declined during the 1980s and 2000s, followed by a slight increase. The time series of TC frequency shows insignificant variations at periods of 2–6 yr during the past 60 years; these variations are significantly correlated with ENSO activity. The frequency of TCs affecting the Pearl River Delta area is strongly correlated with the ENSO cycle while the frequency of TCs affecting the Yangtze River Delta is not. The TC frequency varies differently for TCs of different intensities. Tropical storms (TSs) affecting China were small in total number, but have clearly increased in frequency. The frequencies of severe tropical storm (STS), typhoon (TY), severe typhoon (STY), and super typhoon (super TY) affecting China declined significantly during the 1970s and 1980s, but the numbers of STY and super TY have increased over the 2000s. The typical intensity of TCs affecting China declined over the 60-yr timeframe, but increased over the most recent 10 years (2000–2010). This increase in the intensity of TCs has particularly impacted the Yangtze River Delta area, which has experienced increased numbers of STYs and super TYs. These tendencies are observed in changes of the maximum intensity of TCs affecting both China in general and the Yangtze River Delta in particular during both the full 60-yr analysis period and the latest 10-yr period; however, these tendencies are not observed in changes of the average intensity of TCs. By contrast, both the extreme intensity and the average intensity of TCs affecting the Pearl River Delta have decreased throughout the analysis period, including the most recent decade.  相似文献   

14.
An observational study focusing on the contribution of tropical cyclones(TCs)that form over the western North Pacific(WNP)to the synoptic-scale transient eddy activity(STEA)over the North Pacific during the boreal autumn and early winter in the period 1979–2019 is presented in this paper.Statistical results show that WNP TCs entering the midlatitudinal North Pacific provide significant positive effects on the pentad mean strength of STEA,which is primarily concentrated over the Kuroshio/Oyashio Extensions(KOE)and regions from east of Japan to 160°W in the lower and midto-upper troposphere,respectively.TC intensity is highly indicative of the subsequent STEA with a correlation coefficient of 0.37/0.33/0.45 at 300 hPa/500 hPa/850 hPa exceeding the 99%confidence level for the period 1979–2019.The strength of STEA in the upper troposphere associated with TCs presents a more significant linear growth with TC intensity than that at the mid-to-lower levels after the cyclones enter the KOE region,suggesting that the impact of TCs on STEA gradually increases with height.Further analyses reveal that the contribution of TCs accounts for 4%–6%of the total STEA change over the KOE region during the late autumn and early winter.In addition,the influence of TCs on STEA experienced an interdecadal decrease from the early 2000 s through the early 2010 s.  相似文献   

15.
Analyzed in this paper are the 20-yr(1991-2010)tropical cyclone(TC)intensity from three forecast centers in the Western North Pacific,i.e.China Meteorological Administration(CMA),Japan Meteorological Agency(JMA),and Joint Typhoon Warning Center(JTWC)of the United States.Results show that there is more or less discrepancy in the intensity change of a TC among different datasets.The maximum discrepancy reaches 22 hPa/6h(42 hPa/6h,33 hPa/6h)between CMA and JMA(CMA and JTWC,JMA and JTWC).Special attention is paid to the records for abrupt intensity change,which is currently a difficult issue for forecasters globally.It is found that an abrupt intensity change process recorded by one dataset can have,in some extreme cases,intensity change in another dataset varying from 0 to≥10 hPa/6h with the same sign or the opposite sign.In a total of 2511 cases experiencing rapid intensity change,only 14%have consensus among all the three datasets and 25%have agreement between two of the three datasets.In spite of such a significant uncertainty,the three datasets agree on the general statistical characteristics of abrupt intensity change,including regional and seasonal distribution,the relationship with initial intensity and TC moving speed,and persistence features.Notable disagreement is on very strong systems(SuperTY)and TCs moving very fast.  相似文献   

16.
In this study, three tropical cyclones (TCs) that passed through the Taiwan Strait were analyzed; our results show that precipitation is not directly related to the intensity of TCs. From the perspective of water budget, moisture flux convergence was dominant and contributed ～70% of the moisture for TC precipitation over the ocean and almost all over the land, especially inside the TC circulation. Their spatial distributions were also similar. Evaporation contributed ～30% of the moisture for precipitation over the ocean but changed little with the time. Moisture flux convergence can be divided into two parts: wind convergence and moisture advection. Moisture flux convergence was mostly due to wind convergence, which was dominant in the southwestern quadrants of the TCs. Moisture advection was located in the northern area, and becomes relatively important when the TCs approached the land. The moisture flux convergence and its two parts varied during TC movement, with strengthening and contraction of moisture convergence present near landfall. The vertical structure of the three TC cases all indicated that the moisture convergence was mainly confined to the lower atmosphere under 800 hPa and a weak divergence region was present in the middle troposphere around 550 hPa.  相似文献   

17.
The present study elucidated the fact that remarkable interdecadal variation exists in the time series of the tropical cyclone (TC) frequency that affects Korea during June–October. These variations were identified through statistical change-point analysis, and the results showed that significant variation existed in 1983 and 2004. Therefore, data in 2005 and thereafter were excluded and differences in TC activities during the period after 1983 (1984–2004) and a period before 1983 (1968–1983), as well as differences in large-scale environments were analyzed. During the period of 1984–2004, TCs mainly occurred in the northwest quadrant of the subtropical western North Pacific (SWNP). The TCs move from the east sea of Philippines, pass the East China Sea, recurved, and moved to Korea and Japan. During the period of 1968–1983, TCs occurred in the southeast quadrant of the SWNP and showed a characteristic westward movement from the southeast of Philippines toward the southern coast of China and the Indochina Peninsula. Therefore, the intensity of TCs during the former period, which were supplied with greater heat and water vapor from the sea, were stronger, while TCs during the latter period quickly dissipated after landing in the southern coast of China and the Indochina Peninsula due to the effects of topography. Thus, the lifetimes of the TCs were short and their intensities were weak. The cause of these differences in TC activities between the two periods was identified through differences in stream flows between the 850 hPa level and the 500 hPa level. At the 850 hPa level, anomalous cyclonic (anticyclonic) circulations are reinforced in most waters north (south) to 10° N, and thus, more (fewer) TCs occur in the northwest (southeast) quadrant of the SWNP during the period of 1984–2004 (1968–2003). At the 500 hPa level, since the center of anomalous cyclonic circulation is located in the southeastern region of China southeast to the east sea of the Philippines, anomalous southerlies from the east sea of Philippines to Korea and Japan are predominant. Due to the anomalous steering flows of these anomalous southerlies, the TCs during the period of 1984–2004 show the aforementioned paths. On the other hand, anomalous northerlies or northeasterlies are reinforced in regions in the west of the center of these anomalous cyclonic circulations, and thus, these anomalous steering flows serve the role of preventing TCs from moving toward the southern coast of China the Indochina Peninsula during the period of 1984–2004. During the period of 1984–2004, vertical wind shears and sea surface temperatures are high and low, respectively, in most waters of the SWNP. Therefore, more TCs occur and are reinforced during this period.  相似文献   

18.
Intensity variation of tropical cyclones(TCs),especially that of coastal or landfalling TCs,is of great concern in current research.Most of the research papers,however,focus on intensification processes of TCs;only a few discuss decay processes in the lifetime of a TC.In the daily weather operation related to TCs,it is challenging when a TC weakens and/or disappears suddenly,because it brings more difficulties than the forecast of intensifying TCs does.Overestimation of a decaying landfalling TC would lead to over-preparation of defensive measures and result in"crying wolf"mentality with adverse effects.This study summarized physical mechanisms that dominate the decaying process of TCs and listed several possible dynamical factors:reduced level of air temperature,too large or too small speed,contraction of TC size amplification of TC’s core,and lightning number in a TC.  相似文献   

19.
西北太平洋变性台风时空分布特征   总被引：3，自引：0，他引：3  
钟颖旻  徐明  王元 《气象学报》2009,67(5):697-707
利用中国气象局上海台风研究所整编的1961-2000年共40 a热带气旋年鉴资料,对发生在西北太平洋上的变性台风的时空分布特征进行了诊断分析和研究.研究发现,发生于西北太平洋上的变性台风的年频数呈现出明显的年代际变化特征,主要特征是20世纪60年代偏多,70至80年代显著减少,90年代初又略有回升,至90年代下半期每年发生变性的台风个数均极少;年际变化趋势呈现出逐年减少的特征,与西北太平洋上生成的总台风频数的变化趋势一致;西北太平洋上的变性台风多发生于夏、秋两季,特别集中于夏季与秋季的转换时期(变性比例分别达到40%及46%);秋季较夏季台风发生变性的位置整体偏东;台风变性前移动路径主要集中于朝鲜半岛以南及日本海附近,变性后路径多北上偏东;西北太平洋各月变性台风在变性后6小时内平均强度均减弱,变性后12小时内平均强度仍继续减弱,变性后强度加强的气旋的最低平均气压仅在6、7月份较变性前最明显.进一步通过对NCEP/NCAR月平均再分析资料的500 hPa高度场的EOF分析,发现夏、秋两季,纬向环流指数与台风变性频数呈显著负相关;中高纬度500hPa距平高度场在夏半年为正距平区,对应着高压,宜于冷空气入侵向高纬地区北上的台风,促进台风发生变性.  相似文献   

20.
利用1949～2001年热带气旋年鉴资料,对53年登陆我国并经过内陆湖泊的热带气旋特征进行统计分析.结果表明:登陆过湖泊热带气旋在陆上维持时间长,登陆时强度较强;湖泊地带能延缓登陆TC强度的衰减;热带气旋经过内陆湖泊时大多表现为中心气压维持不变或降低,风速增大;长江中游地区是登陆过湖泊热带气旋消失数最多的区域.  相似文献   

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