Future regional intensity-duration-frequency curves of Edmonton due to potential impact of global warming

近几十年来，世界范围内的水文极端事件发生得越来越频繁，越来越严重，许多科学家将其归因于全球变暖的影响。在获得2007年诺贝尔和平奖的政府间气候变化专门委员会第四次评估报告（2007年）中，全球气候模式的模拟一致表明，近几十年来，温室气体增加的人为强迫导致了全球尺度上前所未有的、可观测到的温度上升。随着地球变暖，更高的温度将导致更高的蒸发和降水速率，更多的降水可能会在更短的时间间隔内下降，从而增加极端风暴事件的频率和严重程度。换句话说，全球变暖可能会改变包括埃德蒙顿在内的加拿大各个城市未来的强度-持续时间-频率（IDF）曲线。在这项研究中，我们将基于中尺度大气模式MM5模拟的极端降雨，利用多站点、区域频率分析一般极值（GEV）概率分布和概率加权矩（PWM）方法，推导出阿尔伯塔省中部未来可能的IDF曲线。这些新的IDF曲线将根据IPCC（2007）选定的gcm预估的三个30年期间（2010-2039、2040-2069、2070-2099）的各种SRES（排放情景特别报告）气候情景，反映全球变暖的可能影响。除了第一阶段考虑的加拿大CGCM2外，考虑到气候预估的不确定性，第二阶段还将采用CCSRNIES（日本）、ECHAM4（德国）、HadCM3（英国）、CSIRO（澳大利亚）、GFDLR（美国）和NCAR-PCM（美国）4种SRES气候情景（A1FI、A1、B1和B2）的主要gcm应用于单机模式运行的MM5，模拟埃德蒙顿极端降雨未来可能发生的变化。总共将进行54次GCM模拟。新的IDF曲线反映了气候变化可能产生的影响，将有助于伦敦金融城在未来基础设施和排水服务的发展中避免可能出现的设计不足问题。

In recent decades, hydrologic extremes have been occurring more frequently and in greater severity worldwide, which many scientists attribute to the effect of global warming. In the 4th Assessment of the Intergovernmental Panel of Climate Change report (2007) which won the Nobel Peace Prize of 2007, simulations of global climate models unanimously demonstrated that anthropogenic forcing of increased greenhouse gases have caused unprecedented, observed temperature rise at global scale in recent decades. As the Earth warms, higher temperatures will lead to higher rates of evaporation and precipitation, and more precipitation will likely fall over shorter time intervals, thus increasing the frequency and severity of extreme storm events. In other words, global warming could modify future Intensity-Duration-Frequency (IDF) curves of various Canadian cities, including that of Edmonton. In this study, we will derive possible future IDF curves of central Alberta based on extreme rainfall simulated by the mesoscale atmospheric model, MM5, using a multi-site, regional frequency analysis of the General Extreme Value (GEV) probability distribution and the probability weighted moment (PWM) method. These new IDF curves will reflect possible impact of global warming based on various SRES (Special Report on Emission Scenarios) climate scenarios projected by selected GCMs of the IPCC (2007), for three 30-year periods (2010-2039, 2040-2069, 2070-2099). Besides the CGCM2 of Canada considered in Phase I, to consider uncertainties of climate projections, in this Phase II, major GCMs such as CCSRNIES (Japan), ECHAM4 (Germany), HadCM3 (UK), CSIRO (Australia), GFDLR (USA), and NCAR-PCM (USA) for four SRES climate scenarios (A1FI, A1, B1, and B2) will also be applied to MM5 running at stand-alone mode to simulate the possible future changes to the extreme rainfall of Edmonton, Alberta. A total of 54 GCM simulations will be conducted. The new IDF curves that reflect the possible impact of climate change will help the City to avoid possible pitfalls of under-design problems in the development of its future infrastructure and drainage services.