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Using Observational Evidence and Process Understanding to Improve Predictions of Extreme Rainfall Change

利用观测证据和过程理解来改进对极端降雨变化的预测

基本信息

批准号：
NE/I006680/1
负责人：
Hayley Jane Fowler
金额：
$ 59.2万
依托单位：
Newcastle University
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2011
资助国家：
英国
起止时间：
2011 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FI006680%2F1
关键词：
Using Observational Evidence Process Understanding

项目摘要

Climate change is one of the most important challenges facing societies in the coming century but there are important gaps in our understanding of how climate change might affect local and regional scale hydrology. In particular, we do not know how European rainfall patterns might change. Observations of rainfall suggest that there have been increases in northern and central Europe, especially in winter, and also increases in rainfall intensity. These changes are consistent with atmospheric physics which indicate that warmer air can hold more moisture. We use climate models to examine how climate might change in the future and these suggest more frequent and intense heavy rainfall even in regions experiencing lower rainfall totals. This may cause an increase in the risk of flooding of the sort witnessed over the last decade across the UK and Europe. Although climate model ability to simulate observed processes has improved in recent years, there are still biases in their outputs due to uncertainties in the levels of future greenhouse gas emissions, due to the large-scale resolution of climate models compared to many natural processes and due to natural variations in the climate. There is also a lack of climate model simulations on the small scale needed to model some of the heaviest rainfall events, in particular summer storms. This research advances the study of extreme climate events by looking at the causes of climate model biases in the simulation of extreme rainfall, particularly with regards to heavy summer storms. We will first identify the historical characteristics of heavy rainfall using observed storms and, after we have identified the atmospheric causes for these events, we will try to provide physically-based explanations for any detected trends. Climate models represent physical processes in different ways and this can have an important influence on the simulation of heavy rainfall. We will assess which of these affect the simulation of heavy rainfall by comparing different model simulations with observations. Weather forecasting and climate models will also be run at a 1.5km resolution to see if such models are able to tell us more about how heavy rainfall events such as thunderstorms might change in the future. This research will provide new estimates of future changes to heavy rainfall and examine the atmospheric mechanisms responsible for such changes. This information will tell us which aspects of heavy rainfall and relevant processes are simulated well by models and which projections for the future we should use in informing any adaptation to climate change. Those that are not will be identified and this research will provide guidance on improvements that are needed in the next generation of climate models as well as weather forecasting models. As we use many different climate models, we can also produce estimates of how uncertain we are about future changes in extreme rainfall and flood risk. The summer 2007 floods cost the UK over £3 billion and the UK Government has announced increased annual budgets for flood risk management that will reach £800 million by 2010 but when and should this investment be prioritised. The Pitt Review in 2008 suggested that more information is needed for 'urgent and fundamental changes in the way the country is adapting to the likelihood of more frequent and intense periods of heavy rainfall'. We need to know how heavy rainfall and flood risks may change in the future, particularly for surface water flooding which is very poorly understood. The information provided by this research is vital for agencies responsible for future flood risk planning and management such as the Environment Agency, DEFRA and the Emergency Services and crucial for updating the climate change allowances used in flood risk management.

气候变化是未来世纪社会面临的最重要的挑战之一，但我们对气候变化如何影响地方和区域尺度水文的理解存在重大差距。特别是，我们不知道欧洲的降雨模式可能会如何变化。对降雨量的观测表明，北方和中欧的降雨量有所增加，特别是在冬季，降雨强度也有所增加。这些变化与大气物理学是一致的，这表明温暖的空气可以容纳更多的水分。我们使用气候模型来研究未来气候可能如何变化，这些模型表明，即使在降雨总量较低的地区，也会出现更频繁和更强烈的暴雨。这可能会导致过去十年英国和欧洲发生洪水的风险增加。虽然近年来气候模型模拟观测过程的能力有所提高，但由于未来温室气体排放水平的不确定性，由于气候模型与许多自然过程相比具有大尺度分辨率，以及由于气候的自然变化，其输出结果仍然存在偏差。此外，还缺乏模拟一些最严重降雨事件，特别是夏季风暴所需的小规模气候模型模拟。这项研究通过研究极端降雨模拟中气候模型偏差的原因，特别是关于夏季暴雨的原因，推进了极端气候事件的研究。我们将首先使用观测到的风暴来确定暴雨的历史特征，在我们确定了这些事件的大气原因之后，我们将尝试为任何检测到的趋势提供基于物理的解释。气候模式以不同的方式代表物理过程，这对暴雨的模拟有重要影响。我们将通过比较不同的模式模拟与观测结果来评估这些影响暴雨的模拟。天气预报和气候模型也将以1.5公里的分辨率运行，看看这些模型是否能够告诉我们更多关于雷暴等强降雨事件在未来可能如何变化的信息。这项研究将为未来强降雨的变化提供新的估计，并研究造成这种变化的大气机制。这些信息将告诉我们，暴雨和相关过程的哪些方面被模型模拟得很好，以及我们应该使用哪些预测来为气候变化的适应提供信息。那些没有被识别的将被识别，这项研究将为下一代气候模型和天气预报模型所需的改进提供指导。当我们使用许多不同的气候模型时，我们还可以估算出我们对未来极端降雨和洪水风险变化的不确定性。2007年夏季的洪水使英国损失超过30亿英镑，英国政府宣布增加洪水风险管理的年度预算，到2010年将达到8亿英镑，但何时以及是否应该优先考虑这项投资。2008年的《皮特评论》建议，需要更多的信息来“紧急和根本性地改变国家适应更频繁和更激烈的严重冲突时期的方式”。我们需要知道未来强降雨和洪水风险可能如何变化，特别是对地表水洪水的了解非常少。这项研究提供的信息对于负责未来洪水风险规划和管理的机构（如环境局，DEFRA和紧急服务）至关重要，对于更新洪水风险管理中使用的气候变化津贴至关重要。