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

近几十年来，水文极端事件在全球范围内发生得更频繁、更严重，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，对全球气候模型的模拟一致表明，温室气体增加的人为强迫在近几十年来造成了前所未有的、可观测到的全球范围的气温上升。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性。换句话说，全球变暖可能会改变加拿大各个城市未来的强度-持续时间-频率(IDF)曲线，包括埃德蒙顿。在这项研究中，我们将根据中尺度大气模式MM5模拟的极端降雨，使用一般极值(GeV)概率分布的多站点、区域频率分析和概率加权矩(PWM)方法，推导出未来艾伯塔省中部可能的IDF曲线。这些新的IDF曲线将根据IPCC选定的全球气候监测机制(2007年)预测的各种SRES(排放情景特别报告)气候情景反映全球变暖的可能影响，三个30年期间(2010-2039年、2040-2069、2070-2099)。除了第一阶段考虑的加拿大CGCM2外，为了考虑气候预测的不确定性，在第二阶段，针对四个SRES气候情景(A1FI、A1、B1和B2)的CCSRNIES(日本)、ECHAM4(德国)、HadCM3(英国)、CSIRO(澳大利亚)、GFDLR(美国)和NCAR-PCM(美国)等主要GCMM也将应用于以独立模式运行的MM5，以模拟艾伯塔省埃德蒙顿极端降雨未来可能的变化。总共将进行54次GCM模拟。反映气候变化可能影响的新的IDF曲线将有助于该市避免未来基础设施和排水服务发展中可能存在的设计不足问题的陷阱。

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.