Sting jets in severe Northern European windstorms

点击翻译按钮获取中文摘要

Three extremely strong storms (including those named Lothar and Martin) hit Europe in December 1999 claiming more than 130 lives and causing about 13 billion Euros total economic losses. These storms were each associated with violent gusts exceeding 78 knots. Significant property damage occurred, vast areas of forest were destroyed and transport and power outages lasted for days. The storm surge associated with Martin led to flooding along several parts of the Atlantic coast. While larger-scale aspects of these storms are generally forecast with reasonable skill, the occurrence, location, and severity of the local regions of major wind damage are not. A broad region of moderately strong winds is found in the warm sector of the storm for most of its lifecycle. Some, but not all, storms have a second localised region of strong winds, and especially strong gusts, which may be short lived (a few hours) but especially damaging. This has been termed a 'sting jet' and its structure has only recently been identified by numerical model simulations of an intense storm. The term 'sting jet' has captured media attention (e.g. the Telegraph newspaper, BBC radio 4, 2003 Royal Society Summer Science Exhibition). However, it is remarkable that at present this research is based on detailed analysis of only a single storm and we do not know the characteristics of storms that exhibit sting jets. Sting jets are also not represented in the climate models used to predict changes to storminess under future climate scenarios. We propose to determine the mechanisms that lead to sting jets, develop diagnostics that can be used to predict the development and presence of a sting jet in a given storm, determine the climatology of these storms in the current climate and consider the possible changes to these storms under further climate scenarios. This will be achieved through analysis of high-resolution case study and idealised numerical model forecasts. The socio-economic implications of these severe storms means that the findings will be of relevance to users with the responsibility for mitigation of and response to the impacts of these events (e.g., DEFRA, the Environment Agency, utilities providers such as power companies).