0608号超强台风"桑美"的主要特点和风暴潮影响特征分析

0608号超强台风"桑美"正面袭击了温州,给温州造成了严重的人员伤亡和经济损失。本文利用相关气象和海洋资料分析了台风"桑美"的主要特点及其风暴潮影响特征。     

The effect of wave-induced radiation stress on storm surge during Typhoon Saomai (2006)

The effects of wave-induced radiation stress on storm surge were simulated during Typhoon Saomai using a wave-current coupled model based on ROMS (Regional Ocean Modeling System) ocean model and SWAN (Simulating Waves Nearshore) wave model.The results show that radiation stress can cause both set-up and set-down in the storm surge.Wave-induced set-up near the coast can be explained by decreasing significant wave heights as the waves propagate shoreward in an approximately uniform direction;wave-induced set-down far from the coast can be explained by the waves propagating in an approximately uniform direction with increasing significant wave heights.The shoreward radiation stress is the essential reason for the wave-induced set-up along the coast.The occurrence of set-down can be also explained by the divergence of the radiation stress.The maximum wave-induced set-up occurs on the right side of the Typhoon path,whereas the maximum wave induced set-down occurs on the left side.     

“圣帕”与“桑美”台风成功决策服务对比分析

从台风影响长沙前的气候背景、预报服务背景、预报依据结论、决策服务及效果等方面分析了"圣帕""桑美"影响期间的决策服务情况.结论表明:两个台风影响前气候背景不同,但预报服务背景相似;对长沙造成的影响、决策气象服务的重点不同;把握好当前的气候背景与预报服务背景,做好做准台风预报,是台风决策服务的关键.     

简化VVP反演算法在台风风场反演中的应用

多普勒雷达资料的体积速度处理VVP(Volume Velocity Processing)风场反演方法可反演风场的3维结构,但由于算法的系数矩阵病态问题易导致反演风场产生误差。本文针对VVP算法中反演参数的性质,进行了简化算法的模拟检验和误差分析。选取量级最大的3个主要参量进行反演,引入随机的观测误差,通过改变模拟风速确定了反演算法的适用范围。对比结果发现,简化算法的反演结果对观测误差并不敏感,而且从低仰角到高仰角的均方根误差基本不变,当风速较大时,反演的精度会更准确。对0608"桑美"台风的风场反演表明,该算法较真实地反演出了台风中心及眼区外围的风场,并与Rankine台风模型相符。研究表明,简化VVP算法可清晰地揭示台风内部水平风场的3维结构,可以应用于台风等灾害性天气的风场反演与分析。     

中国热带气旋潜在影响力指数分析(英文)

Tropical cyclone,a high energy destructive meteorological system with heavy rainfall and gale triggered massive landslides and windstorms,poses a significant threat to coastal areas.In this paper we have developed a Tropical Cyclone Potential Impact Index (TCPI) based on the air mass trajectories,disaster information,intensity,duration,and frequency of tropical cyclones.We analyzed the spatial pattern and interannual variation of the TCPI over the period 1949-2009,and taking the Super Typhoon Saomai as an example have examined the relationship between the TCPI and direct economic losses,total rainfall,and maximum wind speed.The results reveal that China’s TCPI appears to be a weak decreasing trend over the period,which is not significant overall,but significant in some periods.Over the past 20 years,the TCPI decreased in the southern China coastal provinces of Hainan,Guangdong and Guangxi,while it increased in the southeastern coastal provinces of Zhejiang,Fujian and Taiwan.The highest values of TCPI are mainly observed in Taiwan,Hainan,the coastal areas of Guangdong and Fujian and Zhejiang’s southern coast.The TCPI has a good correlation (P=0.01) with direct economic loss,rainfall,and maximum wind speed.     

超强台风桑美（2006）登陆前后低层风廓线数值模拟分析

利用ARW-WRF模式,以垂直方向40个模式层（对低层加密）、水平方向最高1 km的分辨率,对台风桑美（2006）进行数值模拟,模拟结果与实况基本一致。基于台风桑美（2006）1 km分辨率的模拟结果,对台风低层（海面或地表以上1500 m以下）风场结构进行了分析。结果表明,在台风登陆前,其最大风速半径附近存在水平风速在垂直方向有很强变化的风廓线,该类型风廓线的最大风速高度有明显变化,表现出类似急流的特征;而台风登陆后,其水平风速垂直变化明显减弱,即风廓线类型发生较大变化;另有一种水平风速在高层少变的风廓线类型在台风中是普遍存在的。还根据高层和低层两个切变因子,将台风登陆前的风廓线分为急流型、普通型和过渡型,并进一步分析各类风廓线在台风中出现的位置和急流高度。对急流型风廓线的形成原因也进行了初步探讨,结果表明,超/次梯度风在垂直方向上的变化是形成急流型风廓线的原因,而外围绝对角动量的输送在其中起关键作用。     

0608号超强台风"桑美"强度变化位涡诊断分析

利用位涡(PV)收支诊断和质点轨迹追踪等方法对2006年影响中国最严重的超强台风"桑美"强度变化的成因进行了分析和研究.结果表明:台风中心四周的垂直风切变、涡度、散度变化对台风强度变化有重要影响;通过位涡诊断揭示出在台风增强和减弱时,凝结潜热、垂直平流和水平平流起着不同的作用.在台风迅速发展之前和迅速发展初期,凝结潜热...     

BOUNDARY LAYER STRUCTURE IN TYPHOON SAOMAI (2006): UNDERSTANDING THE EFFECTS OF EXCHANGE COEFFICIENT

Recent studies have shown that surface fluxes and exchange coefficients are particularly important to models attempting to simulate the evolution and maintenance of hurricanes or typhoons.By using an advanced research version of the Weather Research and Forecasting(ARW)modeling system,this work aims to study the impact of modified exchange coefficient on the intensity and structures of typhoon Saomai(2006)over the western North Pacific.Numerical experiments with the modified and unmodified exchange coefficients are used to investigate the intensity and structure of the storm,especially the structures of the boundary layer within the storm.Results show that,compared to the unmodified experiment,the simulated typhoon in the modified experiment has a bigger deepening rate after 30-h and is the same as the observation in the last 12-h.The roughness is leveled off when wind speed is greater than 30 m/s.The momentum exchange coefficient(CD)and enthalpy exchange coefficient(CK)are leveled off too,and CD is decreased more than CK when wind speed is greater than 30 m/s.More sensible heat flux and less latent heat flux are produced.In the lower level,the modified experiment has slightly stronger outflow,stronger vertical gradient of equivalent potential temperature and substantially higher maximum tangential winds than the unmodified experiment has.The modified experiment generates larger wind speed and water vapor tendencies and transports more air of high equivalent potential temperature to the eyewall in the boundary layer.It induces more and strong convection in the eyewall,thereby leading to a stronger storm.     

超强台风Saomai(0608)加强成因分析及 海温影响的数值试验研究*

以严重影响我国的2006年8号超强台风Saomai为研究对象,首先从大尺度环流特征和物理量场对其登陆前强度不断加强成因作诊断分析,指出台风加强与副高的加强和南落、低空持续加强的水汽输送、高空流出气流的强辐散、台风移向垂直切变小值区和暖洋面密切相关。然后,利用中尺度数值模式MM5分析了海温高低对台风强度变化的影响,试验结果表明台风强度对海温十分敏感,海温改变可以引起台风强度的迅速变化,海温降低2℃将使台风最终减弱19hPa。边界层通量的分析表明,海温变化对台风强度的影响中潜热通量的作用是主要的,而感热输送的作用较小。就海温变化是否引起诸多台风强度影响因子分析发现,高海温使台风区域低空气旋式环流和高层辐散流出加强,导致低空更多的水汽向该区辐合,暖海面上空潮湿空气的辐合上升释放大量的凝结潜热为台风的发展加强提供了更多的水汽和能量。对比试验还表明,正位涡向下输送预示着台风将快速加强。另外,本次试验中海温变化对台风移动路径影响不明显, 因而对环境风的垂直切变影响较小。     

我国热带气旋潜在影响力指数分析

利用热带气旋路径资料和灾情资料,综合考虑热带气旋的频数、强度、范围以及持续时间,建立热带气旋潜在影响力指数,分析了1949-2009 年我国热带气旋的潜在影响力的空间格局和年际变化特征,并以0608 号超强台风“桑美”为例分析了该指数与灾害损失、过程极大风速、过程雨量的关系。研究结果表明：1949-2009 年间,我国的热带气旋的潜在影响力呈现出弱减少的趋势,这种趋势并不显著,但各阶段性的趋势比较明显;近20 年来,我国海南、广东、广西等华南沿海受热带气旋潜在影响力在下降,而浙江、福建、台湾等东南沿海省份受热带气旋潜在影响力在上升;潜在影响力指数最高的区域主要分布在台湾、海南、广东沿海、福建沿海以及浙江南部沿海等地;TCPI 与灾害损失、过程极大风速、过程降水量等有较好的相关性,并都通过了0.01 的显著性检验。