孟加拉湾热带风暴活动路径的客观分类

利用热带气旋路径客观分析方法,将1972—2011年间共131个孟加拉湾热带风暴的移动路径分为3类:西行(A类)、北行(B类)和西北行(C类)。类型A主要生成于孟加拉湾西南部,占全部TS的16%(21次),季节分布为单峰型,主要在秋季,有90%(18次)登陆,登陆点大部分为孟加拉湾海岸西段(85 °E以西),有5%达到2级飓风以上强度,对西藏基本没有影响;类型B主要生成于孟加拉湾中部,约占全部TS的56.6%(74次),是主要的风暴移动路径,呈双峰型季节分布,是春季TS的主要路径类型,有91%(67次)登陆,登陆点大部分为孟湾海岸中段(85～95 °E),有19%达到2级飓风以上强度,对西藏影响最大,是造成西藏强降水的主要TS路径类型;类型C主要生成于孟加拉湾南部,约占全部TS的27.5%(36次),主要形成于秋季,是冬季TS的主要路径类型,有64%(23次)登陆,大部分在西段登陆,持续时间较长,对西藏影响很小。      

9216号热带风暴的初步分析

对9216号热带风暴在9月1日02时中心分裂的原因,作了初步探讨,认为东南低空急流使热带风暴倒槽区的气旋性环流加强,以及低涡的吸引合并,是产生新中心的原因。青岛产生大暴雨的条件,是充沛的水汽,强烈的上升运动和长波槽东移影响。     

9516号热带风暴路径异常的初步分析

９５１６号热带风暴属径路异常的南海热带风暴，路径呈准抛物线状。从大气形势和卫星去图两方面进行分析，寻找其右折的原因及前兆；与历史上两个相似个例的异同进行分析，可使我们加深对秋冬季路径异常的热带风暴的认识和了解，对今后提高路径异常的热带风暴的分析预报水平都有一定的参考价值。     

9516号热带风暴路径异常的初步分析

9516号热带风暴属路径异常的南海热带风暴，路径呈准抛物线状。从大气形势和卫星云图两方面进行分析，寻找其右折的原因及前兆；与历史上两个相似个例的异同进行分析，可使我们加深对秋冬季路径异常的热带风暴的认识和了解，对今后提高路径异常的热带风暴的分析预报水平都有一定参考价值．     

孟加拉湾季风爆发可预测性的分析和初步应用

基于季风区对流层中高层副高脊附近的经向温度梯度能表征季节转换和季风爆发的物理本质这一事实,使用1980—1999年过渡季节期间(3～5月)逐日和月平均的NCEP／NCAR高空温度场再分析资料,对该温度梯度潜在的预报季风爆发进行了分析。结果表明：在已知初始时刻孟加拉湾季风区对流层中高层经向温度梯度的前提下,依据初始时刻的经向温度梯度和气候平均的经向增温率梯度,可以对孟加拉湾季风爆发的迟早做出定性预测。另外,由于孟加拉湾地区季风爆发日期与3月份青藏高原上空对流层中高层气温有显著相关,故前期高原上空对流层中高层的气温高低也是判断孟加拉湾季风爆发迟早的重要因子。对2000年和2001年孟加拉湾季风爆发迟早定性预测的结果表明,这两种预报方法具有潜在的应用价值。     

9905号热带风暴分析

７月２７日受９９０５号热带风暴影响,粤东和闽南地区普降暴雨到大暴雨,梅州有５个县降了暴雨,其中大埔日降水量达９６．９ｍｍ。降水量主要集中在２７日的白天（表１）。 由于梅州市前期降水量偏少,较为干旱,因此９９０５号热带风暴带来的降水解除或缓解了干旱现象。本文着重从天气图、卫星云图等资料对９９０５号热带风暴的生成、路径及降水进行分析,从中汲取预报经验。１　９９０５号热带风暴的生命史 ２４日１４时,西太平洋赤道辐合带活跃在１７～１８°Ｎ,其中不断有对流云团生成发展。在这种环流背景下,热带低压在南海中部（…     

热带风暴的命名

我国气象工作者对发生在西太平洋上的热带风暴——台风,采用编号的办法来识别。而国外的气象工作者则给热带风暴命名来识别。 一、早期命名 在国外给热带风暴命名已有长久的历史,甚至可回溯到十九世纪末以前。当时由于科学技术水平的限     

9711号热带风暴登陆定位分析

9711号台风自1997年8月10日08时在太平洋生成时,正处于西太平洋副热带高压稳定偏北期间,该台风在副高南侧东风气流引导下,持续向西移动,于8月18日21时30分在浙江省温岭市一带登陆。     

远离热带风暴中心的大暴雨个例分析

2010年9月2-3日江苏淮北出现了较罕见的大暴雨过程,暴雨中心雨量为244.7 mm.分析表明,这次大暴雨过程产生在南海登陆的热带风暴“狮子山”倒槽中,暖湿气流在北上中与对流层低层相对冷的气团相遇,在暴雨区产生局地锋生,中层干冷空气的倾斜下侵,促使大气的斜压性增强,不仅产生了对流性不稳定,而且提供了有利于暖湿气流抬升的动力条件.在锋生作用下,气旋性涡度沿锋区发展.在暴雨发生过程中,西行热带风暴倒槽东部的偏南风和副热带高压西部的偏南气流,构成了一支补偿性质的低空急流,向暴雨区输送了充足的暖湿气流.     

热带风暴的模拟实验研究

一、引言 这里,热带风暴一词包括台风,飓风以及有些国家称之为热带气旋和强热带气旋的低压天气系统。由于我们的模拟实验研究多数成果不带有地区性,所以用热带风暴一词是比较恰当的。 我们进行热带风暴的模拟实验研究已经有七年多时间了,也取得了一些使人感兴趣的成果。它们包括了在实验室里实验研究的理论基础,实验装置的设计,以及风暴宏观和微观结构、风暴的运动、风暴内的波动、地形对风暴的影响、风暴的螺旋云带     

孟加拉湾风暴Mala结构及对云南强降水的影响

利用实时观测资料和NCEP(1°×1°)的6 h再分析资料,对2006年春季发生在孟加拉湾的超强风暴Mala的移动路径、强度变化、环流背景以及风暴温湿场、动力场特征等进行分析。结果表明:Mala在阿拉伯副热带高压和西太平洋副热带高压两高间辐合区生成、加强,并沿西太平洋副热带高压西侧西南或偏南气流移动。风暴发展、成熟到消亡,湿度对风暴的作用比温度明显;动力场结构除具有台风结构的一般特征外,在风暴发展期,中心附近散度场从低层到高层为辐合和辐散交替结构,表明风暴内部高空辐散抽吸作用对于风暴发展起到重要作用。登陆后风暴低压内自身能量和水汽与冷空气共同作用下,在冷暖交汇处出现强烈的上升运动和激发出中尺度辐合线是造成云南强降水主要原因。     

Variation of the total ozone column during tropical cyclones over the Bay of Bengal and the Arabian Sea

The variation of the total ozone column (TOC) before, during, and after tropical cyclones occurring in the pre-monsoon and post-monsoon periods over the Bay of Bengal and the Arabian Sea for the period 1997–2009 is presented. From the analysis, it is concluded that TOC decreases steadily before and during the formation of a cyclone, followed by a more or less increasing trend after dissipation of the cyclone. It is also observed that, when the cyclone reaches its peak intensity indicated by its maximum wind speed, there is a sudden fall in TOC over those regions where the cyclone has intensified. The observed variation of TOC is consistent with existing chemical and dynamical theories.     

孟加拉湾春季小型暖池对热带气旋的影响研究

本文研究了2017年春季孟加拉湾小型暖池对热带气旋Maarutha（4月14-17日）以及热带气旋Mora（5月27-30日）的影响.利用卫星遥感和现场观测数据分析发现,尽管春季孟加拉湾热带气旋确实能引起海洋上层冷却效应,但是其冷却强度受到暖池强度的影响.本文进一步对比孟加拉湾小型暖池对两个热带气旋的响应情况,发现当春季小型暖池的温度大于31℃（热带气旋Mora期间）,暖池效应能有效抑制海洋上层混合层的加深,降低热带气旋引起的潜热通量损失带来的冷却效应,并在一定程度上加强了热带气旋.     

Evaluation of different versions of NCUM global model for simulation of track and intensity of tropical cyclones over Bay of Bengal

The global UK Met office Unified Model (UM) is currently operational at National Centre for Medium Range Weather Forecasting (NCMRWF), the global model named as NCUM. An inter-comparison of two different versions of NCUM has been carried out for simulating the track and intensity of Tropical Cyclones (TCs), which formed over the Bay of Bengal (BoB). For this purpose, two series of numerical experiments named as NCUM25 (New Dynamical core with NCUM N512 resolution) and NCUM17 (ENDGame core with NCUM N768 resolution and upgraded physics and data assimilation scheme) are carried out with seven different initial conditions (ICs) for two TCs. The results suggested that the location, intensity, and vertical structure of the TCs are reasonably well predicted by the NCUM17 over the NCUM25. The Direct Position Error (DPE) and landfall error of TCs are reduced in the NCUM17 in comparison to the NCUM25 for all initial conditions. The mean DPEs and intensity error are reduced by 21–41% and 18–21% in NCUM17 over NCUM25 in both the cases respectively. Improvements in mean landfall position errors are shown to range from 43 to 65% in the NCUM17 as compared to the NCUM25. The mean statistical skill scores for rainfall are considerably improved in NCUM17.     

A preliminary study of climatological associations and characteristics of tropical cyclones in the SW Indian Ocean

Summary Tropical cyclones (TC) in the data-sparse SW Indian Ocean region are studied through climatological and statistical associations and case study structure. Differences between summers with more and less TC are identified with a view to the prediction of seasonal frequencies. In summers with more TC, upper easterlies and lower westerlies over the equatorial zone north of Madagascar form a Walker cell anomaly in conjunction with the east phase of the stratospheric quasi-biennial oscillation (QBO), while sea surface temperatures (SST) are above normal in the preceding spring (>28°C). In the sub-tropics, easterly trade winds strengthen while mid-latitude westerlies shift polewards and SST are below normal (<23°C). OLR departures in more TC summers are <–15 Wm^–2 over region frequented by tropical cyclones.Two tropical cyclone events are selected for analysis which rank highest in terms of rainfall on Mauritius. Danielle formed near 13°S, 65°E and tracked southwest across Mauritius on 19 January 1964. A radiosonde time-height section is analysed for departures from climatology and thermodynamic structure. The profile of equivalent potential temperature is rather uniform near the center of the TC, decreasing from 350°K near the surface. Dry stable air is present in the 600hPa layer around the perimeter. TC Hyacinthe was quasistationary to the east of Madagascar causing rainfall in excess of 500 cm on Reunion Island from 15–27 January 1980. OLR anomaly plots and satellite imagery indicate that Hyacinthe was spawned in association with an eastward moving convective wave and reached maximum intensity (–92 Wm^–2) and radius (>1000 km) from 21 to 26 January 1980.With 14 Figures     

一个孟加拉湾低压水汽场的初步分析

根据1979年夏季季风试验时期较稠密的高空资料,本文对7月3—9日发生在孟加拉湾地区的一个季风低压进行了水汽场的分析,计算了可降水量、垂直加权的相对湿度、水汽通量散度和海面蒸发的分布,发现随着低压环流的发展,低压由一个干涡迅速地转变成一个湿涡.在成熟期,各种湿度参数都达到低压生命期的最大值.总的来说,这个低压湿度场的演变似乎是低压环流场发展的一种结果.可降水量与低压环流很相似;平均相对湿度与ω分布有更密切的关系;水汽辐合场很不对称(主要在低压以西和以南),它与实际云区和降水区一致.研究还发现;低压的发展和     

青藏高原地形对孟加拉湾热带气旋动力影响的模拟实验研究

本文以流体动力学模拟实验的方法,初步揭示了青藏高原地形,对移到高原南侧25°N附近的孟加拉湾热带气旋的地形效应.这种大地形的动力作用,对以不同路径靠近高原的孟加拉湾热带气旋的影响是不同的. 我们给出了三种不同路径移近高原的孟加拉湾热带气旋的上、中、下层水平流场及垂直剖面结构,并计算了它们在上述各层的风速径向分布.     

Sensitivity of physical parameterizations on prediction of tropical cyclone Nargis over the Bay of Bengal using WRF model

Comprehensive sensitivity analyses on physical parameterization schemes of Weather Research Forecast (WRF-ARW core) model have been carried out for the prediction of track and intensity of tropical cyclones by taking the example of cyclone Nargis, which formed over the Bay of Bengal and hit Myanmar on 02 May 2008, causing widespread damages in terms of human and economic losses. The model performances are also evaluated with different initial conditions of 12?h intervals starting from the cyclogenesis to the near landfall time. The initial and boundary conditions for all the model simulations are drawn from the global operational analysis and forecast products of National Center for Environmental Prediction (NCEP-GFS) available for the public at 1° lon/lat resolution. The results of the sensitivity analyses indicate that a combination of non-local parabolic type exchange coefficient PBL scheme of Yonsei University (YSU), deep and shallow convection scheme with mass flux approach for cumulus parameterization (Kain-Fritsch), and NCEP operational cloud microphysics scheme with diagnostic mixed phase processes (Ferrier), predicts better track and intensity as compared against the Joint Typhoon Warning Center (JTWC) estimates. Further, the final choice of the physical parameterization schemes selected from the above sensitivity experiments is used for model integration with different initial conditions. The results reveal that the cyclone track, intensity and time of landfall are well simulated by the model with an average intensity error of about 8?hPa, maximum wind error of 12?m?s^?1and track error of 77?km. The simulations also show that the landfall time error and intensity error are decreasing with delayed initial condition, suggesting that the model forecast is more dependable when the cyclone approaches the coast. The distribution and intensity of rainfall are also well simulated by the model and comparable with the TRMM estimates.     

Effect of ENSO on landfalling tropical cyclones over the Korean peninsula

The effect of ENSO on landfalling tropical cyclones (TCs) over the Korean Peninsula is examined. It is found that although the landfalling frequency does not show any statistically significant difference among ENSO phases, the landfalling tracks are shifted northward in response to the decrease in Niño-3.4 index. In the neutral ENSO phase, many TCs pass through mainland China before landfalling over the Korean Peninsula due to the westward expansion of the western North Pacific subtropical high. Therefore, the landfalling TC intensity over the Korean Peninsula in the neutral phase is similar to that in the La Niña phase because more than half of those TCs made landfall over mainland China. However, it is found that the preceding winter ENSO phases are not related to the landfalling TC activity over the Korean Peninsula during summer.