Storm-related sea level variations along the North Sea coast as simulated by a high-resolution model 1958–2002     

Ralf Weisse  Andreas Plüβ 《Ocean Dynamics》2006,56(1):16-25

Storm-related sea level variations 1958–2002 along the North Sea coast from a high-resolution numerical hindcast are investigated and compared to the results of earlier studies. Considerable variations were found from year to year and over the entire period. The large-scale pattern of these variations is consistent with that derived from previous studies, while the magnitudes of the long-term trends differ. The latter is attributed to different analysis periods, improvements in the atmospheric forcing, and the enhanced spatial resolution of the numerical simulation. It is shown that the different analysis periods, in particular, represent an issue as the increase in storm-related sea levels was found to be weaker over the last few years that have not been included in earlier studies. These changes are consistent with observed changes of the storm climate over the North Sea. It is also shown that observed and hindcast trends may differ significantly. While the latter are in agreement with observed changes in the storm climate, it may be concluded that observed sea level changes along the North Sea coast comprise a considerable fraction that cannot be attributed to changes in the large-scale atmospheric circulation.

Ralf WeisseEmail:

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“天绘一号”卫星基于摄影任务的轨道维持策略   总被引：1，自引：1，他引：0  

冯宁  元朝鹏  宫轶松  黄显安  邢坤 《遥感学报》2012,16(S1):108-111

针对靶标场等摄影任务受轨道维持影响大的现状, 提出基于摄影任务的轨道维持策略。分析了卫星轨道特性和轨道维持对重要摄影任务的影响, 提出利用邻轨搭接特性对摄影区域完成两次摄影的方法。通过某靶标场摄影试验, 比较分析得到最优摄影方案, 验证了本文方法的可行性。同时完善卫星轨道维持策略, 作为卫星实施轨道维持的重要参考依据。  相似文献   

大气Rossby波动力学的研究进展   总被引：5，自引：0，他引：5  

谭本馗 《气象学报》2008,66(6):870-879

Rossby波是旋转大气和海洋中的一类重要波动,在天气和气候演变中起有重要的作用。该文介绍了北半球中纬度地区的两类重要Rossby波——斜压不稳定波和准定常行星波,在最近20余年来取得的一些重要研究进展。文中涉及的主要研究领域有:斜压不稳定波包动力学、湿斜压过程对斜压不稳定波的作用、北半球风暴轴动力学、斜压波包与高影响天气的预报、准定常行星波的形成机理、准定常行星波的水平传播与能量频散、准定常行星波的垂直传播与能量频散、三维准定常行星波的传播与能量频散。  相似文献   

都安一次特大暴雨过程卫星和雷达图像特征分析   总被引：1，自引：1，他引：0  

唐新  林宗桂  黎家宜  林墨  罗红磊 《气象研究与应用》2010,31(3)

利用彩色增强显示的卫星云图、雷达和自动气象站资料对2010年5月31日22时至6月1日11时都安县出现的特大暴雨进行分析,发现这次暴雨过程由2个强降雨阶段组成,造成都安县特大暴雨的原因是1个形成于滇黔桂交界处的低涡在南移过程中,低涡东边缘对流强烈发展,对流云团主体移过都安而产生了强降雨,对应着这2个强降雨阶段,在卫星云图上分析出是由2个对流云团前后移过所造成的,在雷达回波图上可分析出对流云团中又先后有多个对流单体移过都安县上空,所以造成了这次特大暴雨过程  相似文献   

北半球冬季风暴轴与ENSO循环的关系及其能量平衡特征   总被引：1，自引：0，他引：1  

何花  聂绩  谭本馗 《气象学报》2009,67(2):210-217

利用欧洲中期天气预报中心的再分析资料,分析了北半球冬季对流层上层300 hPa面上风暴轴与ENSO循环的关系以及风暴轴的能量平衡特征.研究表明,由于El Nino年北太平洋的哈德莱环流增强,导致北太平洋西风急流向赤道和向东伸展,进而引起了北太平洋风暴轴的增强并向赤道和向东伸展;而La Nina年事件期间情形正好相反.在北大西洋,El Nino年其西风急流中心最大值有所减小,但整个西风急流区域有所扩大并向西和向赤道伸展,相应北大西洋风暴轴强度在El Nino年也有所减弱并向西和向赤道方向伸展;La Nina事件的情形正好相反.能量分析表明,斜压转换的正值中心位于风暴轴及其上游区域.在El Nino年,北太平洋斜压转换的正值中心向赤道和向下游伸展,而北大西洋斜压转换的正值中心向赤道和向西伸展,这与北太平洋风暴轴和北大西洋风暴的变化趋势是一致的.行星尺度扰动对斜压转换的贡献比天气尺度扰动的贡献要小,而行星尺度-天气尺度扰动的相互作用项对斜压转换的贡献更小.研究还表明,能量正压转换的正中心化于风暴轴的上游,负中心位于风暴轴区域.相对于La Nina年,El Nino年北太平洋东部的正压转换负值中心偏北,北美的正值中心位置偏南,而北大西洋的负值中心强度减弱范围变小.这些变化与从La Nina年剑El Nino年北太平洋和北大西洋风暴轴的变化是一致的.在能量的正压转换过程中,天气尺度扰动的贡献要大于行星尺度扰动,而行星尺度-天气尺度扰动的相互作用项的贡献更小.  相似文献   

2008年7月14—15日川西暴雨过程的温度层结变化分析     

肖递祥  顾清源  祁生秀 《湖北气象》2009,28(1)

2008年7月14-15日,四川盆地西部"5.12"汶川大地震重灾区在非典型热力条件下出现了一次暴雨天气过程.本文利用常规观测资料和NCEP 1°×1°再分析资料,对其天气形势及温度层结变化特征进行了详细分析.结果表明:(1)暴雨发生在副热带高压不断西伸的环流背景下,低层偏南气流及其风速脉动对暴雨产生具有重要作用.(2)暴雨开始于850hPa θse下降及大气层结为弱稳定的非典型热力条件下,但700 hPa θse突增使得700-500 hPa对流性不稳定层建立,从而利于对流运动发展;暴雨过程后期,因850 hPa和700 hPa θse急剧下降和大气层结稳定度增大,对流上升受到明显抑制.(3)低层θse锋区和水汽辐合对强降水具有指示意义,暴雨落区位于850 hPa和700 hPa θse锋区前沿,降水中心位于水汽汇合中心附近.  相似文献   

ANALYSIS OF RAINSTORMS ASSOCIATED WITH SIMILAR TRACK TROPICAL CYCLONES HAITANG (0505) AND BILLS (0604)     

YU Zhen-shou  CHEN Xuan-miao  NI Dong-hong  JI Chun-xiao  XIE Hai-hua 《热带气象学报(英文版)》2009,15(1)

It is generally thought that the influence of comparable track typhoons is approximately similar,but in fact their wind and especially their rainstorm distribution are often very different. Therefore,a contrastive analysis of rainstorms by tropical cyclones (TCs) Haitang (0505) and Bilis (0604),which are of a similar track,is designed to help understand the mechanism of the TC rainstorm and to improve forecasting skills. The daily rainthll of TC itaitang (0505) and Bills (0604) is diagnosed and compared.The result indicates that these two TCs have similar precipitation distribution before landtall but different precipitation characteristics after landthll. Using NCEP/GFS analysis data,the synoptic situation is analyzed; water vapor transportation is discussed regarding the calculated water vapor flux and divergence.The results show that the heavy rainfall in the Zhejiang and Fujian Provinces associated with Haitang (0505) and Bitis (0604) before landlhll results ti'om a peripheral easterly wind,a combination of the tropical cyclone and the terrain. After landthll and moving far inland of the storm,the precipitation of Haitang is caused by water vapor convergence carried by its own circulation; it is much weaker than that in the coastal area. One of the important contributing thctors to heavy rainstorms in southeast Zhejiang is a southeast jet stream,which is maintained over the southeast coast. In contrast,the South China Sea monsoon circulation transports large amounts of water vapor into Bills - when a water-vapor transport belt south of the tropical cyclone significantly strengthens - which strengthens the transport. Then,it causes water vapor flux to converge on the south side of Bilis and diverge on the north side. Precipitation is much stronger on the south side than that on the north side. After Bilis travels far inland,the cold air guided by a north trough travels into the TC and remarkably enhances precipitation. In summary,combining vertical wind shear with water vapor transportation is a good way to predict rainstorms associated with landing tropical cyclones.  相似文献   

一次华南暴雨过程中不同区域降水特征的模拟分析   总被引：6，自引：5，他引：1  

史荟燕  潘晓滨  谢海军  臧增亮  何亿强 《气象科学》2009,29(1):58-63

通过对2005年6月19-20日的一次华南大暴雨过程的诊断分析表明,本次降水过程的水汽来源有两个,一是来自于印度洋上的印度季风,另一个是来自于澳大利亚的东南信风.对不同暴雨中心的分析表明,福建北部的降水带为华南准静止锋锋面上的系统性降水,假相当位温的经向垂直剖面呈明显的Ω型结构,而广东河源附近的暴雨中心为暖区对流性降水,低层为强的不稳定.利用ARPS模式对这次暴雨过程进行了数值模拟,结果表明,锋面雨带主要来自于网格降水的贡献,而对流性降水主要来自于次网尺度降水的贡献.  相似文献   

Study of the total lightning activity in a hailstorm   总被引：1，自引：0，他引：1  

Joan Montany  Serge Soula  Nicolau Pineda  Oscar van der Velde  Pere Clapers  Glria Sol  Joan Bech  D. Romero 《Atmospheric Research》2009,91(2-4):430-437

A thunderstorm that developed over northeastern Spain on 16 June 2006 is analyzed. This severe thunderstorm produced hailstones as large as 40 mm and had a lifetime of 3 h and 30 min. Radar cross-sections show strong vertical development with cloud echo tops reaching an altitude of 13 km. The specific characteristics of the lightning activity of this storm were: (i) a large amount (81%) of negative cloud-to-ground (−CG) flashes with very low peak currents (< 10 kA in absolute value), (ii) a very large proportion of intra-cloud (IC) flashes with an IC/CG ratio reaching about 400, (iii) a large number of “short” IC flashes (with only 1-VHF source according to SAFIR detection), (iv) a large increase of the −CG flash rate and of the CG proportion near the end of the storm. The rate of −CG flashes with a low peak current were observed to evolve similarly to the rates of IC flashes. Most of them have been assumed to be IC flashes misclassified by the Spanish Lightning Detection Network (SLDN). They have been filtered as it is usually done for misclassified +CG flashes. After this filtering, CG flash rates remained very low (< 1 min^− 1) with +CG flashes sometimes dominant. All the particular lightning activity characteristics similar to those observed in the Severe Thunderstorm Electrification and Precipitation Study (STEPS) campaigns support the hypothesis that this thunderstorm could have had an inverted-polarity or complex charge structure. The maximum IC flash rate (67 min^− 1) peaked 24 min before the presence of reflectivity higher than 60 dBZ. The IC activity abruptly decreased during the period when reflectivity was dramatically increasing. The time of maximum reflectivity observed by radar was consistent with the times of reported hail at the ground.  相似文献   

相似路径热带气旋“海棠”(0505)和“碧利斯”(0604)暴雨对比分析   总被引：12，自引：3，他引：9  

余贞寿  陈敏  叶子祥  陈宣淼  庄千宝 《热带气象学报》2009,25(1):37-47

一般认为相似路径台风的影响大致相似,但实际上相似路径台风的风雨分布尤其是暴雨分布往往有很大差异,因此,对相似路径热带气旋“海棠”(0505)和“碧利斯”(0604)暴雨成因的对比分析有助于加强台风暴雨发生机制的认识和预报。“海棠”(0505)和“碧利斯”(0604)逐日降水分布对比分析表明,两者登陆前降水分布类似,而登陆后降水分布差异比较大。利用NCEP/GFS 1 °×1 °分析资料对热带气旋登陆前后天气形势、水汽通量和水汽通量散度进行诊断分析,结果表明：“海棠”(0505)和“碧利斯”(0604)登陆前引起浙闽沿海地区大降水主要是热带气旋外围偏东气流和地形共同影响下形成。“海棠”登陆后,维持在浙江东部沿海东南风急流不断输送水汽到“海棠”倒槽内引起浙东南沿海强降水,深入内陆后,降水主要由“海棠”自身环流携带的水汽辐合引起的,降水比沿海地区明显减弱;而“碧利斯”登陆后,有明显的南海季风环流输送水汽并入热带气旋南侧环流,在其南侧形成偏南风急流,使南侧水汽输送得到明显加强,造成“碧利斯”南侧水汽通量辐合,北侧水汽通量辐散,南侧降水比北侧降水强很多;深入内陆后,“碧利斯”环流仍维持并引导北方槽后弱冷空气渗透到其西南侧,使南侧降水进一步增幅。本文还探讨了包括热带气旋外核在内区域平均垂直风切变和热带气旋强降水落区的关系,结果表明：“海棠”和“碧丽斯”大暴雨落区均对应于暴雨区区域平均垂直风切矢量左侧水汽通量散度负值区。“海棠”垂直风切变矢量平行于移动路径并指向移动路径后方是造成“海棠”强降水分布在其移动路径右侧的重要原因,“碧利斯”垂直风切变矢量平行于移动路径并指向移动路径前方是造成“碧利斯”强降水分布在其移动路径左侧的重要原因。因此,利用垂直风切结合水汽输送条件可以作热带气旋大暴雨落区预报可能是一种比较有效的方法。  相似文献