Sea Levels and Coastal Inundation Due to Tropical Cyclones in Indian Coastal Regions of Andhra and Orissa

Coastal inundation associated with extreme sea levels is the main factor which leads to the loss of life and property whenever a severe tropical cyclonic storm hits the Indian coasts. The Andhra and Orissa coasts are most vulnerable for coastal inundation due to extreme rise in sea levels associated with tropical cyclones. Loss of life may be minimized if extreme sea levels and associated coastal flooding is predicted well in advance. Keeping this in view, location specific coastal inundation models are developed and applied for the Andhra and Orissa coasts of India. Several numerical experiments are carried out using the data of past severe cyclones that struck these regions. The simulated inland inundation distances are found to be in general agreement with the reported flooding.     

Extreme Sea Levels Associated With Severe Tropical Cyclones Hitting Orissa Coast of India

Extreme sea levels associated with severe cyclonic storms are common occurrences along the east coast of India. The coastal districts of Orissa have experienced major surges in the past. The recent Paradip super cyclone is one of the most severe cyclones, causing extensive damage to property and loss of lives. Extreme sea levels are major causes for coastal flooding in this region. Damages can be minimized if the extreme sea levels are forecast well in advance. In the present study, we develop a location specific, fine resolution model for the Orissa coast on the lines similar to that of IIT-D storm surge model (Dube et al. 1994). The model runs on a personal computer. The bathymetry for the model is extracted from very fine resolution naval hydrographic charts for the region extending from the south of Orissa to south of West Bengal. A simple drying scheme has also been included in the model in order to avoid the exposure of land near the coast due to strong negative sea surface elevations. An attempt was made in this study to simulate extreme sea levels along the Orissa coast using the data of past severe cyclones. The model results reported in the present study are in good agreement with available observations or estimates.     

可能最大风暴潮风险评估中各等级热带气旋设定方法

可能最大热带气旋的设定是可能最大风暴潮计算的基础,对风暴潮灾害应急疏散具有重要意义。利用1949~2011年中国气象局(CMA)西北太平洋热带气旋最佳路径数据集、美国联合台风预警中心(JTWC)以及美国国家海洋和大气管理局(NOAA)最大风速半径数据集,基于各等级热带气旋参数之间的定量关系,建立了各等级可能最大热带气旋最大风速、中心气压、最大风速半径、移动速度、移动方向等参数设定及路径合成的方法。以福建省连江县为例,按照台风、强台风及超强台风强度等级,分强度衰减和不衰减2种情况,设定3种移动方向,合成了共216场热带气旋作为可能最大风暴潮的计算输入。另外,对参数敏感性、风场参数设定、参数设定与计算量的关系、叠加天文潮以及溃堤等问题进行了讨论。     

三维激光扫描技术应用于沙丘监测的研究

着重论述三维点云数据获取、拼接、坐标转换、去噪、DEM的生成方法,以及通过两次监测结果对比沙丘的变化情况,目的是研究三维激光扫描技术在沙丘变形监测方面的可行性.     

位涡塔结构及演变对飓风Wilma(2005)强度变化的影响

本文利用高分辨率模式输出资料,对飓风Wilma(2005)不同发展阶段内位涡塔(Potential Vorticity Tower: PVT)的结构和演变进行诊断分析,并讨论位涡塔分布特征对飓风快速增强(Rapid Intensification: RI)过程的影响.研究结果表明,内核区域位涡的强度和结构变化主要取决于高层的暖心下传、中层的凝结潜热释放和低层的动力稳定性,而低层切向平均位涡的结构及其稳定性变化,对飓风快速增强的不同发展阶段具有很好的指示意义.飓风Wilma增强过程中,在高层增温、潜热释放和对流垂直混合作用下,PVT的结构出现单极位涡塔(Monopole PVT: MPVT)和中空位涡塔(Hollow PVT: HPVT)的相互转化,也造成了涡旋系统动力稳定性的变化.在实际个例中,重新定义位涡环的结构参数,即相对厚度和中空度,这两个参数能够表征系统的稳定性,将其在RI过程中的变化与飓风Wilma强度变化作相关性分析,表明结构参数能够表征PVT结构的不稳定性,且与飓风系统强度变化参数具有很好的相关性,结构参数与海平面气压变化率的相关性能够通过显著性检验.     

卫星云图,雷达数字化回波图在预报徐州暴雨中的应用

本文使用历史暴雨天气过程的卫星云图资料,进行数字处理,统计归纳,并结合雷达数字化资料和天气分析、数值预报产品、能量场分析,总结出一些以卫星资料为主,能使用于日常短期到短时预报暴雨的结论。     

Participatory exclusion – Cyclone Sidr and its aftermath

‘Nature does not discriminate, but humans do’ – this deliberately echoed sentiment in an area affected by Cyclone Sidr problematizes the practice of resource distribution in post-disaster situations. While relief and rehabilitation services have the objective of ‘building back better’, the possibility of elite-capture of resource distribution channels, jeopardizes both humanitarian initiatives as well as future development. This paper explores the political economy of post-Sidr interventions from an ethnographic account. The paper establishes links between power networks and access to resources in the study area, finding that marginality is a production of ongoing disaster interventions which favour the relatively well-off over the structurally poor. Ultimately, humanitarian assistance channels resources through established power networks, thus reinforcing them and producing uneven resilience among different social strata. This paper offers important insights for redesigning the distribution of humanitarian assistance.     

上层海洋对热带气旋的响应与反馈研究进展

对60年来有关上层海洋与热带气旋(Tropical Cyclone,TC)的响应与反馈的研究进行了回顾,通过观测手段的完善和改进模式的应用,人们的认识不断提高:TC直接激发的近惯性流最大可达1 m/s,其导致的强烈的剪切造成混合层对下层冷水的夹卷是引起混合层降温的主要原因,并往往伴随着混合层深度的增加,这一影响在TC右侧更为最著,并可延续几天到几十天不等。TC导致的混合层降温会使得海洋输出的热通量减少,反过来削弱TC的强度,形成一个负反馈,而海洋特殊的热力和环流结构(如暖涡、洋流等)则对TC有正反馈。所以了解TC经过前的海洋初始场对研究TC与海洋之间的相互作用、对预测,TC的强度、路径变化等尤其重要;通过准确的初始场结合越来越完善的模式可以对TC进行更真实的模拟和预测,使得对TC准确的预报和预警成为可能。     

Simulation Study on the Impact of Taihang Mountain Slopes on Downhill Front Cyclone Rainstorm

The statistical and diagnostic analysis of precipitation in Hebei Province in the past six years shows that the mid-south of the North China Plain on the east side of the Taihang Mountains is an area of frequent rainstorm disasters in summer. The rain belt is mostly distributed along the Taihang Mountains, and the rainfall is often over 700mm. Focus was on the summer downhill frontal Yellow River cyclone, which accounted for 20% of the 73 storm days in the statistical samples. The analysis of the typical frontal cyclone heavy rain in 2016 shows that the meridional distribution of the Taihang Mountains cooperates with the climbing mountain jet in the north of the cyclone and the southward flow in the west of the cyclone, leading to the formation of a deep narrow cold temperature trough along the mountain orientation. It enhances the temperature gradient in the frontal cyclone, enhances the baroclinicity of the cyclone and the intensity of the rotating wind, resulting in augmentation of the cyclone and slowing of the eastward movement. Through the cooperation of the entanglement of the cyclone jet and the mountain block, a deep and abundant water vapor environment is formed, and the moving westward of water vapor flux and the low-level water vapor main body are hindered; The high-energy tongue convection instability on the eastern side of the mountain range is formed, a strong uplift with abundant water vapor masses is triggered, and three critical areas of vertical motion occurred, which restricts the rainstorm locations. Numerical experiments on the mechanism of the influence of the slope of the Taihang Mountains on heavy rain show that the downhill rainstorm area is parallel to the mountain range, and the meridional mountain range can cause a greater range of heavy precipitation. It is also easy to cause double frontal precipitation locally by a same cyclonic warm front and cold front, resulting in a long duration of heavy rain. The slope of the mountain is proportional to the intensity of the mountain block and forms the wet convection instability with the dry at lower and wet at upper overlapping on a thermal instability of the front zone with cold at lower and warm at upper, such as the total instability is stronger. The slope of the mountain is proportional to the increase and maintenance time of the cyclone decompression during downhill. It is inversely proportional to the decline to the North China Plain, which affects the path and speed of the cyclone eastward movement.     

The next step in shallow coral reef monitoring: Combining remote sensing and in situ approaches

Most current coral reef management is supported by mapping and monitoring limited in record length and spatial extent. These deficiencies were addressed in a multidisciplinary study of cyclone impacts on Aboré Reef, New-Caledonia. Local knowledge, high thematic-resolution maps, and time-series satellite imagery complemented classical in situ monitoring methods. Field survey stations were selected from examination of pre- and post-cyclone images and their post-cyclone coral communities documented in terms of substrata, coral morphologies, live coral cover, and taxonomy. Time-series maps of hierarchically defined coral communities created at spatial scales documenting the variability among communities (29-45 classes) and suggesting the processes that affected them. The increased spatial coverage and repeatability of this approach significantly improved the recognition and interpretation of coral communities’ spatio-temporal variability. It identified precise locations of impacted areas and those exhibiting coral recovery and resilience. The approach provides a comprehensive suite of information on which to base reef-scale conservation actions.