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1.
理想海域中台风引起的潮、流及波的分析 Ⅱ.海岸及陆架的影响 总被引：2，自引：0，他引：2
采用理想的大陆架地形和台风模型计算了不同方向登陆的台风所激发的海洋响应。结果表明,岸边的潮位变化主要是由于台风引起的强迫振动造成的。而对于登陆型台风来说,在远离台风路径的地方,潮位的变化则是由于边缘波效应。对地平直海岸和二维大陆架,自由边缘波的振幅远小于强迫波的振幅。平行海岸移行台风在岸边产生随台风一起移动的强制波,其中当台风沿着与Kelvin波相同的方向移行时,岸边有陆架波产生,反之则没有陆架波。此外,还讨论了与风暴潮相关的近岸环流。 相似文献
2.
一次超级单体分裂过程的雷达回波特征分析 总被引：2，自引：0，他引：2
2007年7月9日16—20时（北京时）在河北南部非常罕见地观测到了多个超级单体风暴在相近地点连续生成及分裂的过程。利用石家庄新乐SA型多普勒天气雷达资料、地面自动站及常规天气资料,对超级单体分裂过程及环境条件做了分析。表明这次的多个超级单体风暴是在强的对流有效位能和垂直风切变的环境条件下发生的。由于垂直风切变矢量方向随高度逆时针旋转,因此,分裂后左移的反气旋风暴得到加强,发展成为具有深厚中反气旋的左移超级单体风暴,而右移的气旋性风暴受到抑制,与理论研究结果一致。但也有不同之处,沿着地面高湿区内热力边界偏暖一侧移动的气旋性风暴没有受到明显抑制,有利的地面环境条件抵消了气旋性风暴受抑制的程度,使气旋性风暴能够持续更长的时间。该强烈发展的带有明显中反气旋的超级单体风暴具有低层钩状回波和入流缺口、中高层有界弱回波区及位于有界弱回波区之上的高层具有反射率因子核心和强烈风暴顶辐散,与经典的气旋式右移超级单体风暴的回波特征非常类似,除了是反气旋涡旋外,其回波特征与气旋式超级单体近似成镜像。风暴分裂是在单体形成不久的发展初期开始的。分裂先从中高层开始,然后迅速向下延伸。分裂后相对于0—6 km风切变矢量,左侧的单体为反气旋左移风暴,右侧的为气旋性右移风暴。 相似文献
3.
《Dynamics of Atmospheres and Oceans》1999,29(2-4):397-413
A coastal shallow water model generally involves at least one coastal boundary which is curvilinear in nature. Representation of this curvilinear boundary needs special attention when a finite difference scheme is used. To incorporate the curvilinear coastal boundary and off-shore islands properly in the numerical scheme, we need fine resolution which may not be necessary away from the coast. In order to tackle this problem, a nested numerical scheme may be used where fine resolution for the coastal boundary region is nested into a course resolution scheme covering the whole analysis area. But this involves comparatively more memory and CPU time in the solution process. The present study aims at developing a storm surge model that may subsequently be modified for operational forecasting purpose for the coast of Bangladesh. A vertically integrated model is developed in a cylindrical polar coordinate system capable of incorporating bending of the coastline and off-shore islands with considerable accuracy without using any nesting. A comparison of CPU time and memory in the numerical computations between two types of modelling is described and it is found that the cylindrical polar coordinates model is economic. The model is applied for estimating the water levels at different coastal and island stations associated with a few storms that hit the coast of Bangladesh. It is found that the computed and observed water levels are in good agreement. Considering the computing time and other factors, it is found that the Polar Coordinates model is more suitable for operational forecasting purpose along the coast of Bangladesh. 相似文献
4.
Summary The Australian east coast is subject to a range of synoptic/mesoscale weather systems ranging from low-pressure troughs, small
explosive low-pressure systems near the Australian east coast, to synoptic scale maritime low-pressure systems, and both tropical
and extra-tropical cyclones. These systems vary dynamically in intensity and structure across a spectrum that includes both
weak and intense cold-cored systems, to warm-cored tropical cyclones and “hybrid” systems. A preliminary 10 year climatology,
from 1992 to 2001, is presented that concentrates on those cyclones in open waters that threaten life and property as a result
of heavy coastal rain or the combined effects of wind, sea state and swell, including both long fetch and storm surges. There
are 28 systems in the 10-year climatology. In terms of their development, the most numerous were the 50% of storms that occurred
as systems within an easterly trough, followed by 21% that occurred as circulations on decaying Tasman Sea cold fronts.
In addition, a numerical weather prediction (NWP) modelling case study of the ‘hybrid’ sub-tropical cyclone system of March
2001 was carried out using archived real-time data. Operational numerical weather prediction (NWP) model forecasts of this
system, which was not named in accordance with Australian classification policy, were all poor except for the US MRF model,
which provided marginally useful guidance. None of the operational global and regional models available to forecasters predicted
an intense cyclone, and only the US MRF model predicted landfall. A high-resolution forecast using all available data produced
significantly improved predictions over the operational models up to four days before landfall. 相似文献
5.
Understanding the impact of climate change on Northern Hemisphere extra-tropical cyclones 总被引：3，自引：2，他引：1
Ruth E. McDonald 《Climate Dynamics》2011,37(7-8):1399-1425
Extra-tropical cyclones strongly influence weather and climate in mid-latitudes and any future changes may have large impacts on the local scale. In this study Northern Hemisphere storms are analysed in ensembles of time-slice experiments carried out with an atmosphere only model with present day and future anthropogenic emissions. The present day experiment is forced by observed sea-surface temperature and sea-ice. The sea-surface temperatures and sea-ice for the future experiment are derived by adding anomalies, from parallel but lower resolution coupled model experiments, to the observed data. The storms in the present day simulation compare fairly well with observations in all seasons but some errors remain. In the future simulations there is some evidence of a poleward shift in the storm tracks in some seasons and regions. There are fewer cyclones in the Northern Hemisphere in winter and spring. The northeast end of the North Atlantic storm track is shifted south in winter giving more storms and increased frequency of strong winds over the British Isles. This shift is related to an increase in baroclinicity and a southward shift of the jet that occurs as a response to a minimum in ocean warming in the central North Atlantic. An increase in the frequency of storms over the UK is likely to cause enhanced levels of wind and flood damage. These results concur with those from some other models, however, large uncertainties remain. 相似文献
6.
Jacques C.J. Nihoul 《Dynamics of Atmospheres and Oceans》1977,2(1):29-47
A three-dimensional “long waves” model is discussed for the study of tides and storm surges in a shallow well-mixed continental sea. Emphasis is placed on the North Sea where tidal and storm currents constitute the essential part of the circulation and estimates from observations in the North Sea and, more especially, the Southern Bight are used to assess the relative importance of different effects and derive a simple set of equations by which vertical profiles of tidal and storm currents can be predicted, at each points, as functions of time. 相似文献
7.
广东台风特大暴雨预报 总被引：1，自引：0，他引：1
使用台风年鉴，天气图，天星云图等气象资料，对１９６０－１９９１年影响广东的３９例特大暴雨台风进行了对比分析，台风特大暴雨主要是由其云系中的中尺度强降水系统造成，归纳出形成发展的概仿模式和相应环境流场特征，建立预报思路与方法。１９９４年作１５次预报试验，其准确率达７３％。 相似文献
8.
This study focuses on the evaluation of 3-hourly 0.25° × 0.25° satellite-based rainfall estimates produced by the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA). The evaluation is performed during six heavy rainfall events that were generated by tropical storms passing over Louisiana, United States. Two surface-based rainfall datasets from gauge and radar observations are used as a ground reference for evaluating the real-time (RT) version of the TMPA product and the post-real-time bias adjusted research version. The evaluation analysis is performed at the native temporal and spatial scales of the TMPA products, 3-hourly and 0.25° × 0.25°. Several graphical and statistical techniques are applied to characterize the deviation of the TMPA estimates from the reference datasets. Both versions of the TMPA products track reasonably well the temporal evolution and fluctuations of surface rainfall during the analyzed storms with moderate to high correlation values of 0.5–0.8. The TMPA estimates reported reasonable levels of rainfall detection especially when light rainfall rates are excluded. On a storm scale, the TMPA products are characterized by varying degrees of bias which was mostly within ± 25% and ± 50% for the research and RT products, respectively. Analysis of the error distribution indicated that, on average, the TMPA products tend to overestimate small rain rates and underestimate large rain rates. Compared to the real-time estimates, the research product shows significant improvement in the overall and conditional bias, and in the correlation coefficients, with slight deterioration in the probability of detecting rainfall occurrences. A fair agreement in terms of reproducing the tail of the distribution of rain rates (i.e., probability of surface rainfall exceeding certain thresholds) was observed especially for the RT estimates. Despite the apparent differences with surface rainfall estimates, the results reported in this study highlight the TMPA potential as a valuable resource of high-resolution rainfall information over many areas in the world that lack capabilities for monitoring landfalling tropical storms. 相似文献
9.
10.
Estimating present day extreme water level exceedance probabilities around the coastline of Australia: tropical cyclone-induced storm surges 总被引：2，自引：0，他引：2
Ivan D. Haigh Leigh R. MacPherson Matthew S. Mason E. M. S. Wijeratne Charitha B. Pattiaratchi Ryan P. Crompton Steve George 《Climate Dynamics》2014,42(1-2):139-157
The incidence of major storm surges in the last decade have dramatically emphasized the immense destructive capabilities of extreme water level events, particularly when driven by severe tropical cyclones. Given this risk, it is vitally important that the exceedance probabilities of extreme water levels are accurately evaluated to inform risk-based flood and erosion management, engineering and for future land-use planning and to ensure the risk of catastrophic structural failures due to under-design or expensive wastes due to over-design are minimised. Australia has a long history of coastal flooding from tropical cyclones. Using a novel integration of two modeling techniques, this paper provides the first estimates of present day extreme water level exceedance probabilities around the whole coastline of Australia, and the first estimates that combine the influence of astronomical tides, storm surges generated by both extra-tropical and tropical cyclones, and seasonal and inter-annual variations in mean sea level. Initially, an analysis of tide gauge records has been used to assess the characteristics of tropical cyclone-induced surges around Australia. However, given the dearth (temporal and spatial) of information around much of the coastline, and therefore the inability of these gauge records to adequately describe the regional climatology, an observationally based stochastic tropical cyclone model has been developed to synthetically extend the tropical cyclone record to 10,000 years. Wind and pressure fields derived for these synthetically generated events have then been used to drive a hydrodynamic model of the Australian continental shelf region with annual maximum water levels extracted to estimate exceedance probabilities around the coastline. To validate this methodology, selected historic storm surge events have been simulated and resultant storm surges compared with gauge records. Tropical cyclone induced exceedance probabilities have been combined with estimates derived from a 61-year water level hindcast described in a companion paper to give a single estimate of present day extreme water level probabilities around the whole coastline of Australia. Results of this work are freely available to coastal engineers, managers and researchers via a web-based tool (www.sealevelrise.info). The described methodology could be applied to other regions of the world, like the US east coast, that are subject to both extra-tropical and tropical cyclones. 相似文献
11.
Synoptic analysis of dust storms in the Middle East 总被引：4，自引：0，他引：4
Mehdi Hamidi Mohammad Reza Kavianpour Yaping Shao 《Asia-Pacific Journal of Atmospheric Sciences》2013,49(3):279-286
Dust storm in the Middle East and south-west Asia is a natural hazard and the Tigris-Euphrates alluvial plain has been recognized as the main dust source in this area. In this study, more than 60 dust storms that occurred during the period 2003–2011 are investigated on the basis of MODIS satellite images, and 12 of the dust storms are selected for synoptic analysis using the NCEP-NCAR Reanalysis Data. The potential dust sources in the Middle East and south-west Asian region (20°E to 80°E, 5°N to 50°N) are analyzed and used in the synoptic analysis. Dust storms in the region can be grouped into two main categories, i.e., the Shamal dust storms and the frontal dust storms. Synoptic systems, associated with the two categories, are distinguished and the frequency of the patterns is identified. For 68% of the Shamal dust storms, a high pressure system is situated between 0°E to 30°E and 27°N to 45°N, and a low pressure system between 50°E to 70°E and 23°N to 43°N. For 86% of the frontal dust storms, a high is located between 51°E to 67°E and 18°N to 33°N and a low between 28°E to 48°E and 32°N to 43°N. Three main patterns for Shamal dust storms are identified, which represent about 60% of the Shamal dust storms. This analysis confirms that the Shamal is related to the anticyclones located over northern Africa to Eastern Europe and the monsoon trough over Iraq, southern Iran, Pakistan and the Indian Subcontinent. The analysis also shows that the main dust sink for the frontal dust storms in Tigris and Euphrates alluvial plain extends from center of Iraq to west and center of Iran and, in most severe cases, to northern Iran and the southern coast of the Caspian Sea. 相似文献
12.
Claudio Cassardo ;Nicola Loglisci ;Min Wei Qian ;Silvia Ferrarese ;Arnaldo Longhetto ;Gianpaolo Balsamo 《气象与减灾研究》2008,31(2):6-13
对1999年圣诞期间发生在欧洲中西部的圣诞节风暴进行了分析,认为4个主要的低气压系统中的第二个给法国北部带来了强风暴雨,巴黎的Orly机场阵风速度〉47m／s;第四个低压系统沿法国西海岸产生相似的恶劣天气,并在西班牙的北部海岸及地中海沿岸国家造成了毁灭性的破坏。在法国中部风暴最剧烈的时候,最大阵风〉41m／s;在法国和德国之间的区域,达55m／s。圣诞节风暴造成欧洲国家大约140人死亡,其他损失包括树木、街道和房屋被毁,电力系统和电话中断时间长达数天,受影响的人数大约为1000万,财产损失大约为80亿美元。由于风暴的极端强度和快速发展速度,欧洲大多数国家的数值预报中心没有对这次剧烈天气提供足够的预警。为此,利用中尺度数值预报系统（RAMS）模拟圣诞节风暴,并与ECMWF分析资料以及实况观测资料进行了对比分析。结果表明,RAMS模式能够准确模拟风暴的主要特性、低气压的演变和位置移动、发展的关键时间点、风暴演化期间的平均风场;模拟的平均风场和气象观测网的观测结果相一致;模拟的风暴移动时间和主要新闻媒体的报道相吻合;模式计算的一些特定地区平均风速的时间趋势显示,在阿尔卑斯山脉地区,无论是上风区还是下风区,风暴的时间都被准确地预测;模拟的第一次风暴最低气压值较实际值偏低。 相似文献
13.
To quantitatively investigate the dynamic and thermal responses of the South China Sea (SCS) during and subsequent to the passage of a real typhoon, a three-dimensional, regional coupled air–sea model is developed to study the upper ocean response of the SCS to Typhoon Krovanh (2003). Owing to the scarcity of ocean observations, the three-dimensional numerical modeling with high resolution, as a powerful tool, offers a valuable opportunity to investigate how the air–sea process proceeds under such extreme conditions. The amplitude and distribution of the cold path produced by the coupled model compare reasonably well with the TRMM/TMI-derived data. The maximum SST cooling is 5.3 °C, about 80 km to the right of the typhoon track, which is consistent with the well-documented rightward bias in the SST response to typhoons. In correspondence to the SST cooling, the mixed layer depth exhibits an increase; the increases in the mixed layer depth on the right of typhoon track are significantly higher than those on the left, with maxima of 58 m. This correspondence indicates that the SST cooling is caused mainly by entrainment. Under the influence of typhoon, a cyclonic, near-surface current field is generated in the upper ocean layer, which moves with the typhoon. The typhoon-induced horizontal currents in the wake of the storm have strong near-inertial oscillation, which gradually propagates downward. The unique features of the SCS response to Typhoon Krovanh are also discussed, such as Kuroshio intrusion and coastal subsurface jets. 相似文献
14.
Wind data from NCEP and hydrographic data obtained during 8–27 March 1992 have been used to compute circulation in the Luzon Strait and the northern South China Sea using three-dimensional diagnostic models with a modified inverse method. Numerical results are as follows: the main Kuroshio is located above 800 m levels. It has two intrusive branches of the Kuroshio in the areas above 400 m. One part intrudes anti-cyclonically northwestward, then flows through the area above 200 m southwest of Taiwan and into the Taiwan Strait. The other part intrudes westward and flows cyclonically in the areas north of the cyclonic eddies, then flows southward through the southern boundary of the region. The net westward volume transport (VT) through Section at 120°15′E between Luzon Island and Taiwan Island is about 3.0 Sv, net northward VT through northern boundaries into the Taiwan Strait is about 1.4 Sv and net southward VT through southern boundaries is about 1.6 Sv, which finally flows into the Karimata and Mindoro Straits. In the areas above 400 m east of 117°15′E, the circulation is mainly dominated by the basin-scale cyclonic gyre, which consists of two cyclonic eddies. However, in the areas below 400 m east of 119°00′E, the circulation is mainly dominated by basin-scale anti-cyclonic gyre. The joint effect of baroclinity and relief and interaction between wind stress and relief are important in different area respectively for the pattern of the depth-averaged flow across contours of fH−1. 相似文献
15.
Joan Bech Nicolau Pineda Tomeu Rigo Montserrat Aran Jéssica Amaro Miquel Gayà Joan Arús Joan Montanyà Oscar van der Velde 《Atmospheric Research》2011,100(4):621-637
This study presents an analysis of a severe weather case that took place during the early morning of the 2nd of November 2008, when intense convective activity associated with a rapidly evolving low pressure system affected the southern coast of Catalonia (NE Spain). The synoptic framework was dominated by an upper level trough and an associated cold front extending from Gibraltar along the Mediterranean coast of the Iberian Peninsula to SE France, which moved north-eastward. South easterly winds in the north of the Balearic Islands and the coast of Catalonia favoured high values of 0–3 km storm relative helicity which combined with moderate MLCAPE values and high shear favoured the conditions for organized convection. A number of multicell storms and others exhibiting supercell features, as indicated by Doppler radar observations, clustered later in a mesoscale convective system, and moved north-eastwards across Catalonia. They produced ground-level strong damaging wind gusts, an F2 tornado, hail and heavy rainfall. Total lightning activity (intra-cloud and cloud to ground flashes) was also relevant, exhibiting several classical features such as a sudden increased rate before ground level severe damage, as discussed in a companion study. Remarkable surface observations of this event include 24 h precipitation accumulations exceeding 100 mm in four different observatories and 30 minute rainfall amounts up to 40 mm which caused local flash floods. As the convective system evolved northward later that day it also affected SE France causing large hail, ground level damaging wind gusts and heavy rainfall. 相似文献
16.
We present a new event-scale catalog of stable isotopic measurements from 5?years of storm events at 4 sites in southern California, which is used to understand the storm to storm controls on the isotopic composition of precipitation and validate the event-scale performance of an isotope-enabled GCM simulation (IsoGSM) (Yoshimura et?al. 2008). These analyses are motivated to improve the interpretation of proxy records from this region and provide guidance in testing the skill of GCMs in reproducing the hydrological variability in the western US. We find that approximately 40% of event-scale isotopic variability arises from the percentage of precipitation that is convective and the near surface relative humidity in the days prior to the storms landfall. The additional isotopic variability arises from the fact that storms arriving from different source regions advect moisture of distinct isotopic compositions. We show using both field correlation and Lagrangian trajectory analysis that the advection of subtropical and tropical moisture is important in producing the most isotopically enriched precipitation. The isotopic catalog is then used along with satellite-derived δD retrievals of atmospheric moisture to benchmark the performance of the IsoGSM model for the western US. The model is able to successfully replicate the observed isotopic variability suggesting that it is closely reproducing the moisture transport and storm track dynamics that drive the large storm-to-storm isotopic range. Notably, we find that an increase in moisture flux from the central tropical Pacific leads to a convergence of isotopically enriched water vapor in the subtropics and consequently an increase in δ18O of precipitation at sites along the entire west coast. Changes in poleward moisture flux from the central Tropical Pacific have important implications for both the global hydrological cycle and regional precipitation amounts and we suggest such changes can be captured through instrumental and proxy-reconstruction of the spatiotemporal isotopic patterns in the precipitation along the west coast of the US. 相似文献
17.
Over south-eastern Europe, severe weather events are often associated with Mediterranean cyclones. This paper presents a climatic study of severe storms over Bulgaria produced by synoptic-scale Mediterranean cyclones, which are the main high-impact weather systems for the region during the winter season. The study is based on a synoptically oriented data set that contains systematic information about the pronounced Mediterranean cyclones including their life and trajectories over the Mediterranean area and the severe storms over Bulgaria produced by them. The definition of a severe storm is a storm in which the wind speed and precipitation exceed thresholds of 15 m/s and 30 mm/24 h, respectively. The observed severe storms were split into two groups by the number of districts where they have caused damages. During the last years a trend of decreasing numbers of initiating synoptic-scale Mediterranean cyclones has been observed. However, the number of those producing a high-impact weather phenomenon over Bulgaria has increased. In these high-impact cases, the observed paths of the cyclones are connected to the specific circulation conditions over the region. In the most severe cases, almost 80% of the cyclones move through the southernmost parts of Balkan Peninsula and for a large portion of them, this motion is associated with a blocking regime in the mid-level mass field.The development of such Mediterranean cyclone cases has been studied and results are presented here. The results illustrate the synoptic-scale mechanisms for intensification of a feeding flow of Mediterranean air towards the area affected by extremely severe weather. 相似文献
18.
该文选择了发展变化机制有一定差异的两例春季爆发性东北低压（分别是1983年4月25～26日气旋（简称A例）和1983年4月28～29日气旋（简称B例）），进行了对比诊断分析。结果表明:（1）非绝热加热和局地斜压不稳定对A例气旋发展来说是十分关键的因子，而空正IPV平流的显著增强及其与低层IPV分布中两个局地最大值的垂直耦合是B例气旋增强的一个重要原因；（2）两个风暴最大不同点在于非绝热加热效应在影响气旋增强的程度上有所不同。另外，B例事件中对流层中部产生的较强高空锋生可以在低压范围内导致深厚的上升运动并使高空锋向下游的正涡度平流得以加强，这对系统的发展是十分有利的。 相似文献
19.
In October 7–9, 2016, Hurricane Matthew moved along the southeastern coast of the U.S., causing major flooding and significant damage, even to locations farther north well away from the storm’s winds. Various observations, such as tide gauge data, cable measurements of the Florida Current (FC) transport, satellite altimeter data and high-frequency radar data, were analyzed to evaluate the impact of the storm. The data show a dramatic decline in the FC flow and increased coastal sea level along the U.S. coast. Weakening of the Gulf Stream (GS) downstream from the storm’s area contributed to high coastal sea levels farther north. Analyses of simulations of an operational hurricane-ocean coupled model reveal the disruption that the hurricane caused to the GS flow, including a decline in transport of ∼20 Sv (1 Sv = 106 m3 s−1). In comparison, the observed FC reached a maximum transport of ∼40 Sv before the storm on September 10 and a minimum of ∼20 Sv after the storm on October 12. The hurricane impacts both the geostrophic part of the GS and the wind-driven currents, generating inertial oscillations with velocities of up to ±1 m s−1. Analysis of the observed FC transport since 1982 indicated that the magnitude of the current weakening in October 2016 was quite rare (outside 3 standard deviations from the mean). Such a large FC weakening in the past occurred more often in October and November, but is extremely rare in June-August. Similar impacts on the FC from past tropical storms and hurricanes suggest that storms may contribute to seasonal and interannual variations in the FC. The results also demonstrated the extended range of coastal impacts that remote storms can cause through their influence on ocean currents. 相似文献
20.
Stanislav S. Davydenko Thomas C. Marshall Maribeth Stolzenburg 《Atmospheric Research》2009,91(2-4):165-177
This study examines the electricity in two thunderstorms, typical for their respective locales (the Great Plains and the New Mexico mountains), by modeling them as a set of steady-state horizontal layers of external currents. The model electric sources, corresponding to the charge separation processes in the thundercloud, are embedded in an exponential conducting atmosphere. The source parameters are determined by fitting the model electric field to measured profiles. The resulting currents to the ionosphere (i.e., the Wilson current) from the two storms are 0.53 A and 0.16 A, while the calculated electrical energies of the storms are 2.3 × 1010 J and 2.8 × 109 J, respectively. The more vigorous storm is estimated to transfer 16 000 C in the global circuit during 8.5 h of its lifetime, while the weaker mountain storm transferred about 1200 C in its entire 2-h lifetime. Removal of the screening charge layer from above the updraft region in one modeled storm leads to only a small increase in the net Wilson current of less than 3%, while it provides a substantial local disturbance of the electric field. Overall, the model findings indicate that differences in the Wilson currents and electrical energies of the two storms result from differences in their internal dynamical and electrical structures as well as their geographical locations. 相似文献