Hazard warnings and responses to evacuation orders: the case of Bangladesh's cyclone Sidr

On 15 November 2007 Cyclone Sidr, a category 4 storm, struck the southwestern coast of Bangladesh. Despite early cyclone warnings and evacuation orders for coastal residents, thousands of individuals stayed in their homes. This study examines dissemination of the warning, assesses the warning responses, and explores the reasons why many residents did not evacuate. Field data collected from 257 Sidr survivors in four severely affected coastal districts revealed that more than three-fourths of all respondents were aware of the cyclone warnings and evacuation orders. Despite the sincere efforts of the Bangladesh government, however, lapses in cyclone warnings and evacuation procedures occurred. Field data also revealed several reasons why evacuation orders were not followed. The reasons fell into three broad groups: those involving shelter characteristics; the attributes of the warning message itself; and the respondents' characteristics. Based on our findings, we recommend improved cyclone warnings and utilization of public shelters for similar events in the future.     

Factors contributing to the development of extreme North Atlantic cyclones and their relationship with the NAO

The occurrence of extreme cyclones is analysed in terms of their relationship to the NAO phase and the dominating environmental variables controlling their intensification. These are latent energy (equivalent potential temperature 850 hPa is used as an indicator), upper-air baroclinicity, horizontal divergence and jet stream strength. Cyclones over the North Atlantic are identified and tracked using a numerical algorithm, permitting a detailed analysis of their life cycles. Extreme cyclones are selected as the 10% most severe in terms of intensity. Investigations focus on the main strengthening phase of each cyclone. The environmental factors are related to the NAO, which affects the location and orientation of the cyclone tracks, thus explaining why extreme cyclones occur more (less) frequently during strong positive (negative) NAO phases. The enhanced number of extreme cyclones in positive NAO phases can be explained by the larger area with suitable growth conditions, which is better aligned with the cyclone tracks and is associated with increased cyclone life time and intensity. Moreover, strong intensification of cyclones is frequently linked to the occurrence of extreme values of growth factors in the immediate vicinity of the cyclone centre. Similar results are found for ECHAM5/OM1 for present day conditions, demonstrating that relationships between the environment factors and cyclones are also valid in the GCM. For future climate conditions (following the SRES A1B scenario), the results are similar, but a small increase of the frequency of extreme values is detected near the cyclone cores. On the other hand, total cyclone numbers decrease by 10% over the North Atlantic. An exception is the region near the British Isles, which features increased track density and intensity of extreme cyclones irrespective of the NAO phase. These changes are associated with an intensified jet stream close to Europe. Moreover, an enhanced frequency of explosive developments over the British Isles is found, leading to more frequent windstorms affecting Europe.

Recent Sea Level and Sea Surface Temperature Trends Along the Bangladesh Coast in Relation to the Frequency of Intense Cyclones

The French Transportable Laser Ranging System (FTLRS) was deployed in the calibration site of satellite radar altimeters in Corsica over the 2002 and 2005 campaigns. The paper describes the different steps of SLR data processing. The average arcs RMS obtained are about 1–2 cm for Lageos-1&;-2, Starlette and Stella satellites; it is shown that the best results of satellite orbits determination and geocentric positioning are obtained with Eigen-Grace03s gravity model. The difference of FTLRS absolute 3D positioning, between 2002 and 2005, of about 7.7 mm (i.e., 2.6 mm/yr) is less than residual errors of ITRF2005 velocities (of about 4.3 mm/yr).     

基于Cyclone和PolyWorks的三维建模实现

从数据采集到数据处理,再到最后的模型重建,以实例详细介绍了地面激光扫描三维建模的整个流程。利用LeicaHDS6000地面激光扫描仪进行点云数据采集,针对规则和不规则建筑物的特点,分别基于Cyclone和PolyWorks软件实现了三维建模。     

气旋波动研究进程及研究方法

较全面地回顾与阐述了气旋波动研究进程及研究方法, 其中包括Bjerknes气旋模式, 以及Bjerknes and Solherg (1922) 提出的温带气旋生命循环和Petterssen (1956) 对气旋温度结构的描述, 并指出凝结潜热及地形对气旋发展的作用。还较详细地介绍了Petterssen (1956) 气旋发展理论、倾斜涡度发展理论、来自准地转 方程及位涡思考的气旋生成理论, 以及高空超长波系统发展与高空急流加强有利于低层爆发性气旋发展的学术观点, 为气旋的研究提供了历史研究背景、研究思想及方法。     

利用雷达回波特征和地面资料确定0312号台风"科罗旺"强度

通过分析0312号台风"科罗旺"过程的雷达回波特征和地面资料,应用"热带气旋强度综合判据表"的办法,确定该台风的强度,并分析其大风分布的特点.为将来雷达探测台风业务,分析回波资料积累一些经验和方法,从而能更好的利用雷达回波应用于台风预报业务.     

Analyses of Orissa Super Cyclone using TRMM (TMI), DMSP (SSM/I) and OceanSat-I (MSMR) Derived Data

The super cyclone in October 1999 was the most intense tropical cyclone in the last century in Orissa, a coastal state in India. This state was battered for more than two days by strong winds and intense rain killing thousands of people. The main objective of this study is to examine the impact of total precipitable water content (TPWC) and surface wind speed data from sensors on board the Tropical Rainfall Measuring Mission (TRMM), Defense Meteorological Satellite Project (DMSP), and Indian Remote Sensing Satellite (OceanSat-I) satellites on the data assimilation system at NCMRWF, New Delhi during the Orissa cyclone period. Comparison of various assimilation experiments suggests that the utilization of TRMM Microwave Imager (TMI) data in the assimilation produced the best analyses. However, in all the forecasts, the storm was predicted to weaken and did not have a reasonably good track. Assimilation experiments with the other two satellite data showed the cyclone track much to the south of the observed track and also it was a weak storm. Biases in the data, when compared with each other, are evident in the analyses also. Better analyses are obtained when the satellite data are used in the originally obtained resolution than when reduced by averaging. A forecast experiment with assimilated data, utilizing the Cloud Motion Vectors (CMVs) from METEOSAT along with TMI data, produced the best forecast among all the experiments. However, the forecast quality was poor. A high-resolution data assimilation experiment was carried out to see the impact of model resolution on the analyses of the cyclone. The strength of the cyclone further increased when higher resolution TMI data were included. The study highlights the need for more satellite data over the Indian Ocean, where conventional data coverage is too poor to define the vertical structure of the atmosphere.     

人工神经网络与符号推理在江淮气旋预报中的应用研究

本文通过对符号推理及神经网络系统的剖析，实现了神经网络与符号推理的有机结合，并成功地运用到天气预报中去。提出了一种新的，充分利用预报经验，数值预报产品及计算机计算能力的预报方法。     

2000年两次沙尘暴天气过程的分析研究

本文根据探空资料（TTAA），利用数值模式的客观和诊断分析结果、高空气象探测数据处理系统（T－lnp图）及天气图进行天气形势、物理量场的定量分析及单站气象要素的演变分析等对2000年4月4－6日两次沙尘暴天气过程进行了分析。结果表明：两次沙尘暴过程的形成是由于生成于蒙古地区的蒙古气旋进入东北后强烈发展，在华北、东北、内蒙南部地区形成大范围的强西北风而引起的。地面锋线及高空槽后都为偏北大风区，强劲的空中风使沙尘迅速向前方扩展。地面锋线与850、700、500hPa槽线上、下位置重合较好，槽后各层均存在大风区及下沉运动区，二者配合有利于高层动量下传，形成地面辐散大风直接导致了沙尘暴的形成。陡峭的锋面使得锋前有强励的上升气流，将沙尘粒子源源不断地输送到高空，使地面和空中沙尘连成一体。利用高空气象探测数据处理系统对探空资料（TTAA报）处理的结果表明：整层大气比较稳定，对流不易发展。近地面大气较干燥，无法形成降水，疏松的沙土易被大风扬起，这也是沙尘暴形成的主要原因之一。     

东北暴雨的研究

系统性研究东北暴雨将提高对东北灾害性天气的认识,有利于加深对中国暴雨的全面研究。对我国气象工作者在东北暴雨研究方面的工作进行了综述,并回顾了影响东北暴雨的几类主要天气系统,分别为气旋、台风、冷涡,着重回顾了在过去几十年中东北冷涡暴雨方面研究的进展。指出目前待解决的问题是：影响东北地区台风暴雨强度、分布及转向问题;东北冷涡的内部结构特征及其发生发展的物理机制、东北冷涡下中尺度对流系统的结构特征与暴雨的关系;引发东北地区强暴雨过程的水汽源地等问题。这些问题需要通过今后深入和细致的加密观测分析研究,以及利用长时间卫星遥感观测资料和雷达资料的论证才能逐渐认识清楚。