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1.
Variations in Typhoon Landfalls over China 总被引：1，自引：1，他引：1
Emily A. FOGARTY James B. ELSNER Thomas H. JAGGER Kam-biu LIU Kin-sheun LOUIE 《大气科学进展》2006,23(5):665-677
The interannual variability in typhoon landfalls over China is investigated using historical and modern records. For the purpose of substantiating and elaborating upon the claim of north to south variation in tropical cyclone activity over China, a north-to-south anti-correlation in yearly activity is confirmed in the historical cyclone records. When cyclone activity over the province of Guangdong is high （low）, it tends to be low （high） over the province of Fujian. A similar spatial variation is identified in the modern records using a factor analysis model, which delineates typhoon activity over the southern provinces of Guangdong and Hainan from the activity over the northern provinces of Fujian, Taiwan, Zhejiang, Shanghai, Jiangsu, and Shandong. A landfall index of typhoon activity representing the degree to which each year follows this pattern of activity is used to identify correlated climate variables. A useful statistical regression model that includes sea-level pressure differences between Mongolia and western China and sea-surface temperature （SST） over the northwestern Pacific Ocean during the summer explains 26% of the interannual variability of the landfall index. It is suggested that a stronger than normal north-south pressure gradient increases the surface easterly wind flow over northern China： this, coupled with lower SST over the Pacific, favors typhoons taking a more westerly track toward southern China. 相似文献
2.
The Effect of Intensity： Typhoon-Induced SST Cooling on Typhoon The Case of Typhoon Chanchu （2006） 总被引：4，自引：0，他引：4
In order to investigate air-sea interactions during the life cycle of typhoons and the quantificational effects of typhoon-induced SST cooling on typhoon intensity, a mesoscale coupled air-sea model is developed based on the non-hydrostatic mesoscale model MM5 and the regional ocean model POM, which is used to simulate the life cycle of Typhoon Chanchu （2006） from a tropical depression to a typhoon followed by a steady weakening. The results show that improved intensity prediction is achieved after considering typhoon-induced SST cooling; the trend of the typhoon intensity change simulated by the coupled model is consistent with observations. The weakening stage of Typhoon Chanchu from 1200 UTC 15 May to 1800 UTC 16 May can be well reproduced, and it is the typhoon-induced SST cooling that makes Chanchu weaken during this period. Analysis reveals that the typhoon-induced SST cooling reduces the sensible and latent heat fluxes from the ocean to the typhoon＇s vortex, especially in the inner-core region. In this study, the average total heat flux in the inner-core region of the typhoon decrease by 57.2%, whereas typhoon intensity weakens by 46%. It is shown that incorporation of the typhoon-induced cooling, with an average value of 2.17℃, causes a 46-hPa weakening of the typhoon, which is about 20 hPa per 1℃ change in SST. 相似文献
3.
4.
This paper presents a study on the statistical forecasts of typhoon tracks. Numerical models have their own systematic errors, like a bias. In order to improve the accuracy of track forecasting, a statistical model called DLM (dynamic linear model) is applied to remove the systematic error. In the analysis of typhoons occurring over the western North Pacific in 1997 and 2000, DLM is useful as an adaptive model for the prediction of typhoon tracks. 相似文献
5.
The climatology of near-equatorial typhoons over the western-north
Pacific are fully investigated using the JTWC (Joint Typhoon Warning Center)
typhoon record from 1951 to 2006. The result shows that there are seasonal and
decadal variations, as well as a distinctive spatial distribution, of such
events. Among them, Typhoon Vamei is an example of a near-equatorial typhoon
that occurred near Singapore in December of 2001. Using the WRF (Weather and
Research Forecast) model, we attempt to find out how the well known ``wind
surge" of this event contributes to the development of Typhoon Vamei. It is
found that the strong wind surge not only helps to provide advection of
positive vorticity to Vamei between 800 and 500 hPa, but also increases the
convective instability of the lower troposphere, and thus helps to induce
convective outbreaks and rapid intensification. Furthermore, sensitivity
experiments show that terrain and the land-sea distribution have very limited
effects on the formation of Typhoon Vamei in the simulation, but an adequate
Coriolis parameter ($f)$ is still needed for the development of Vamei. 相似文献
6.
The impact of cloud microphysical processes on the simulated intensity and track of Typhoon Rananim is discussed and analyzed in the second part of this study.The results indicate that when the cooling effect due to evaporation of rain water is excluded,the simulated 36-h maximum surface wind speed of Typhoon Rananim is about 7 m s-1 greater than that from all other experiments; however,the typhoon landfall location has the biggest bias of about 150 km against the control experiment.The simulated strong outer rainbands and the vertical shear of the environmental flow are unfavorable for the deepening and maintenance of the typhoon and result in its intensity loss near the landfall.It is the cloud microphysical processes that strengthen and create the outer spiral rainbands,which then increase the local convergence away from the typhoon center and prevent more moisture and energy transport to the inner core of the typhoon.The developed outer rainbands are supposed to bring dry and cold air mass from the middle troposphere to the planetary boundary layer (PBL).The other branch of the cold airflow comes from the evaporation of rain water itself in the PBL while the droplets are falling.Thus,the cut-off of the warm and moist air to the inner core and the invasion of cold and dry air to the eyewall region are expected to bring about the intensity reduction of the modeled typhoon.Therefore,the deepening and maintenance of Typhoon Rananim during its landing are better simulated through the reduction of these two kinds of model errors. 相似文献
7.
Diagnostic analysis of the balance of kinetic energy (KE) is made for a decaying onland typoon, its external torrential rain area and environment. Results show that, besides low-level frictional dissipation as an energy sink, upper-level horizontal export of KE is another important one for the typhoon. In its decaying KE grows in the external torrential rain area, and the KE production term Gk represents the chief energy source for the torrential rain. The growth of Gk is attributed to the development of the heavy rain and to the heating effect of released latent heat, and the external torrential rain owes its evolution to the exported KE from the strong windbelt in the east of the typhoon and the conversion of synoptic KE into mesoscale perturbation KE. The development of the torrential rain results in the KE feedback to its environment. The KE transfer from the typhoon to the external torrential rain area and then to the environmental region as a mechanism constitutes one of the causes for the rapid d 相似文献
8.
YU Zhenshou XU Wenming JI Chunxiao ZHAO Fang LOU Liyin 《Acta Meteorologica Sinica》2006,20(4):500-511
Using the high-resolution non-hydrostatic model ARPS (Advanced Regional Prediction System),the Typhoon Rananim (0414) was simulated by using the CINRAD Doppler radar data.The results before and after typhoon landfall show that model ARPS performs well to simulate the track,the variation of center pressure,as well as severe heavy rain of Rananim.Meanwhile,the simulated composite reflectivity was compared with the observed radar composite reflectivity.The numerical results reveal that the asymmetrical structure of Rananim plays an important role in its westward deflecting after landfall.The sensitivity simulation experiments of terrain effects on Rananim (0414) were also investigated,and the terrain of the southeastern China has important effects on Rananim turning right slightly of its track and increasing its intensity obviously,but when typhoon is far away from the coastline,the terrain only impacts slightly on the storm intensity during its landfall.The results show that topographic lifting contributes greatly to precipitation enhancement,and makes the distribution of precipitation more uneven. 相似文献
9.
10.
Typhoon Rananim (2004) was one of the severest typhoons landfalling the Chinese mainland
from 1996 to 2004. It brought serious damage and induced prodigious economical loss. Using a new
generation of mesoscale model, named the Weather Research and Forecasting (WRF) modeling system,
with 1.667 km grid horizontal spacing on the finest nested mesh, Rananim was successfully simulated
in terms of track, intensity, eye, eyewall, and spiral rainbands. We compared the structures of
Rananim to those of hurricanes in previous studies and observations to assess the validity of
simulation. The three-dimensional (3D) dynamic and thermal structures of eye and eyewall were
studied based on the simulated results. The focus was investigation of the characteristics of
the vortex Rossby waves in the inner-core region. We found that the Rossby vortex waves propagate
azimuthally upwind against the azimuthal mean tangential flow around the eyewall, and their
period was longer than that of an air parcel moving within the azimuthal mean tangential flow.
They also propagated outward against the boundary layer inflow of the azimuthal mean vortex.
Futhermore, we studied the connection between the spiral potential vorticity (PV) bands and
spiral rainbands, and found that the vortex Rossby waves played an important role in the
formation process of spiral rainbands. 相似文献
11.
“莫拉克”是2009年登陆我国热带气旋中影响范围最广、造成损失最大的台风.“莫拉克”带来的强降水导致台湾南部发生50年来最严重的水灾,福建、浙江等省的部分站点过程雨量超过50年一遇.因此,在台风暴雨(强降水)预报中,能否准确把握其落区就显得尤为重要.本文首先利用中尺度非静力数值模式WRF对台风“莫拉克”进行高分辨率数值模拟(三层嵌套,最高分辨率为2 km).模式较好地再现了台风中心的移动路径、强度;模拟的降水分布区域与实况也较为相符.利用再分析资料及模拟的高分辨率资料对暴雨成因进行诊断分析,表明造成此次强降水过程的水汽主要由西南季风输送,并且垂直运动旺盛,贯穿整个对流层.根据集合动力因子预报方法,运用广义湿位温、对流涡度矢量垂直分量及水汽散度通量对暴雨落区进行了诊断和预报,发现广义湿位温等值线的“漏斗状”区域与暴雨落区对应关系显著;基于NCEP-GFS每日四次的预报场资料,利用对流涡度矢量和水汽散度通量做出的降水落区预报表明,二者对降水落区均有一定的指示意义.强降水主要位于对流层中低层对流涡度矢量垂直积分量的梯度大值区附近,其时间演变与观测降水的演变具有相当高的一致性;水汽通量散度抓住了垂直运动和水汽散度这两个引发暴雨的关键因子,对降水的发生范围和强降水极值中心的判断更为准确.这三个动力因子都可以为“莫拉克”台风暴雨(强降水)落区提供信号,对台风暴雨落区具有一定的诊断和预报意义. 相似文献
12.
我国台风灾害特征及风险防范策略 总被引：5，自引：0，他引：5
对登陆我国台风气候特征及灾害发生特点进行了分析,表明台风登陆我国时间集中于每年的7—9月,年均登陆数量广东最多,而最强登陆台风出现在台湾。台风灾害导致的直接经济损失总量呈现缓慢增加趋势,人员死亡数明显下降。但死亡100人以上的特别重大台风灾害平均每年发生一次,且造成的灾情占比很大。台风灾害影响主要是其伴随的大风、暴雨及引起的滑坡、泥石流、风暴潮等次生灾害共同造成的,重大灾害往往由突发性、极端性风雨引起。为了最大限度地降低和减轻台风灾害损失和社会影响,可依靠基于风险区划的防灾能力建设降低风险,依据准确的风险预评估避让风险,依赖保险特别是政策性巨灾保险的开展转移风险。 相似文献
13.
中国台风降水的气候特征 总被引：17，自引：5，他引：12
对中国台风降水的时空分布特征进行研究,发现台风降水分布在中国中东部广大地区,台风降水量自东南沿海向西北内陆逐渐减少.台风降水最大值出现在台湾岛的中东部地区和海南岛的个别地区,年平均台风降水量大于700 mm,最小值出现在内蒙古、山西、陕西、四川的部分地区,年平均台风降水量不足10 mm.台风降水一般出现在4～12月,峰值出现在8月.1957～2004年期间台风降水呈下降趋势.台风降水的异常主要由于亚洲地区大气环流和赤道中东太平洋沃克环流的异常变化所引起.进一步分析发现,台风降水在中国大部分地区为减少趋势,且这种趋势在台湾岛、海南岛、东南沿海部分地区和东北南部较显著.台风暴雨是我国东南沿海及部分内陆地区的极端强降水事件之一,这些地区的暴雨和大暴雨很大程度上是台风带来的. 相似文献
14.
The structural evolution of Typhoon Morakot(2009) during its passage across Taiwan was investigated with the WRF model. When Morakot approached eastern Taiwan, the low-level center was gradually filled by the Central Mountain Range(CMR), while the outer wind had flowed around the northern tip of the CMR and met the southwesterly monsoon to result in a strong confluent flow over the southern Taiwan Strait. When the confluent flow was blocked by the southern CMR, a secondary center(SC) without a warm core formed over southwestern Taiwan. During the northward movement of the SC along the west slope of the CMR, the warm air produced within the wake flow over the northwestern CMR was continuously advected into the SC, contributing to the generation of a warm core inside the SC. Consequently, a well-defined SC with a warm core, closed circulation and almost symmetric structure was produced over central western Taiwan, and then it coupled with Morakot's mid-level center after crossing the CMR to reestablish a new and vertically stacked typhoon. Therefore, the SC inside Morakot was initially generated by a dynamic interaction among the TC's cyclonic wind, southwesterly wind and orographic effects of the CMR, while the thermodynamic process associated with the downslope adiabatic warming effect documented by previous studies supported its development to be a well-defined SC. In summary, the evolution of the SC in this study is not in contradiction with previous studies, but just a complement, especially in the initial formation stage. 相似文献
15.
2018年共有29个台风在西北太平洋和南海生成,生成台风个数偏多,南海台风活跃。有10个台风登陆我国,登陆强度整体明显偏弱,但是登陆台风个数明显偏多、登陆时间集中、登陆地段偏北、北上台风偏多,造成台风降水范围广、暴雨强度大、超警河流多。其中,“安比”、“摩羯”、“温比亚”一个月内相继在华东地区登陆并深入内陆北上,且登陆后长时间维持热带风暴级强度,给华东、华北、东北等地区带来大范围强降雨。“艾云尼”移动缓慢,与西南季风环流相结合,给广东等地区造成长时间的持续强降水。“山竹”是2018年登陆我国最强台风,其7级风圈明显偏大,给广东、香港等地区带来大范围、长时间的强风和强降水。2018年所有预报时效的路径预报误差较2017年均有所降低,路径预报水平进一步提高,但是强度预报水平仍然没有明显的进步。 相似文献
16.
台风暴雨作为台风引起的最主要灾害之一,一直被人们关注。台风常被认为是对称结构,但从实际状况来看台风的非对称性非常明显,所以有必要研究斜压性涡度在台风中的表现。在高分辨率数值模拟的基础上,通过引入斜压涡度的概念,分析和总结了斜压涡度在2009年台风“莫拉克”暴雨过程中的表现。通过模拟与分析得到如下的结果:斜压涡度和MPV对比,可以看出在登陆前和登陆后,明显低层斜压涡度有更强的异常信号,围绕台风内核呈现正负正的位相特点;从沿着台风中心时间剖面可以看出,登陆前斜压涡度低层多为负正负的位相,并且随着时间的推移,斜压涡度有从大气的高层向台风的移动中心传递的趋势,即在台风即将到达时原先的正涡度被替换为负涡度,所以对其移动有一定指示意义;在台风“莫拉克”过台湾岛时,其斜压涡度表现为负涡度消失,在山地附近有正涡度生成,完成过岛,台风中心被替换;斜压涡度的异常值主要位于大气的低层时,一般会产生较强的降水。 相似文献
17.
《热带气象学报(英文版)》2015,(2)
While previous studies indicate that typhoons can decrease sea surface temperature(SST) along their tracks, a few studies suggest that the cooling patterns in coastal areas are different from those in the open sea. However, little is known about how the induced cooling coupled with the complex ocean circulation in the coastal areas can affect tropical cyclone track and intensity. The sea surface responses to the land falling process of Typhoon Morakot(2009) are examined observationally and its influences on the activity of the typhoon are numerically simulated with the WRF model. The present study shows that the maximum SST cooling associated with Morakot occurred on the left-hand side of the typhoon track during its landfall. Numerical simulations show that, together with the SST gradients associated with the coastal upwelling and mesoscale oceanic vortices, the resulting SST cooling can cause significant difference in the typhoon track, comparable to the current 24-hour track forecasting error. It is strongly suggested that it is essential to include the non-uniform SST distribution in the coastal areas for further improvement in typhoon track forecast. 相似文献
18.
While previous studies indicate that typhoons can decrease sea surface temperature(SST) along their tracks, a few studies suggest that the cooling patterns in coastal areas are different from those in the open sea. However, little is known about how the induced cooling coupled with the complex ocean circulation in the coastal areas can affect tropical cyclone track and intensity. The sea surface responses to the land falling process of Typhoon Morakot(2009) are examined observationally and its influences on the activity of the typhoon are numerically simulated with the WRF model. The present study shows that the maximum SST cooling associated with Morakot occurred on the left-hand side of the typhoon track during its landfall. Numerical simulations show that, together with the SST gradients associated with the coastal upwelling and mesoscale oceanic vortices, the resulting SST cooling can cause significant difference in the typhoon track, comparable to the current 24-hour track forecasting error. It is strongly suggested that it is essential to include the non-uniform SST distribution in the coastal areas for further improvement in typhoon track forecast. 相似文献
19.
双台风生消过程涡旋能量、水汽输送相互影响的三维物理图像 总被引：7，自引：2，他引：5
重点研究“莫拉克”台风发展并登陆台湾,以及“天鹅”台风消亡阶段两者相互作用的问题。通过诊断分析发现“莫拉克”与“天鹅”移动过程存在双台风涡旋互旋、吸引与合并现象。采用双台风中心连线的垂直剖面移动坐标分析法可揭示出双台风涡度、风场三维结构,演变过程中双台风的涡度、动能强度呈反向变化关系,在双台风生消过程中,动能、位涡场分布存在显著“连体”通道特征。并揭示出双台风涡旋各自生、消过程水汽、动能可能存在的相互影响及其涡旋结构变化的内在关联。对“天鹅”消亡、“莫拉克”引发暴雨过程,采用Flexpart-WRF耦合模式模拟“质点群”轨迹,模拟结果再现了双台风生消阶段“天鹅”台风水汽“粒子群”向“莫拉克”低层气旋式输入通道,且在“莫拉克”涡旋高层反气旋式卷出的三维立体动态图像。通过剔除“天鹅”台风涡旋数值模拟试验进一步印证了“天鹅”台风趋于消弱过程其水汽、动能输送为“莫拉克”台风发展与维持做出了一定贡献。基于以上合成分析、轨迹和数值模拟技术综合分析提出了能揭示“天鹅”消亡、“莫拉克”发展过程能量、水汽输送相互影响的三维物理图像。 相似文献
20.
CLIMATIC CHARACTERISTICS OF TYPHOON PRECIPITATION OVER CHINA 总被引：2，自引：0，他引：2
The spatio-temporal characteristics of typhoon precipitation over China are analyzed in this
study. The results show that typhoon precipitation covers most of central-eastern China. Typhoon
precipitation gradually decreases from the southeastern coastal regions to the northwestern mainland. The
maximum annual typhoon precipitation exceeds 700 mm in central-eastern Taiwan and part of Hainan,
while the minimum annual typhoon precipitation occurs in parts of Inner Mongolia, Shanxi, Shaanxi and
Sichuan, with values less than 10 mm. Generally, typhoons produce precipitation over China during April
– December with a peak in August. The annual typhoon precipitation time series for observation stations
are examined for long-term trends. The results show that decreasing trends exist in most of the stations
from 1957 to 2004 and are statistically significant in parts of Taiwan, Hainan, coastal Southeast China and
southern Northeast China. The anomaly of typhoon precipitation mainly results from that of the general
circulation over Asia and the Walker Cell circulation over the equatorial central and eastern Pacific.
Typhoon torrential rain is one of the extreme rainfall events in the southeastern coastal regions and parts of
central mainland. In these regions, torrential rains are mostly caused by typhoons. 相似文献