The June 2013 extreme precipitation event in Alberta resulted in devastating flash floods that caused significant economic losses and societal disruption. In this study, two high-resolution experiments were conducted using the Weather Research and Forecasting (WRF) model to study the change of the 2013 Alberta extreme precipitation event in a warmer climate. The control experiment was forced with 6-hourly ERA-Interim reanalysis data, while the sensitivity experiment was forced with perturbed ERA-Interim reanalysis data with climate change signals derived from ten global climate models under the Representative Concentration Pathway 8.5 emission scenario. The results indicate that the 2013 Alberta extreme precipitation event is projected to exhibit two significant characteristics in a warming climate. First, precipitation is expected to increase over the Canadian Rocky Mountain region and eastern British Columbia. Second, the precipitation is expected to decrease over the Alberta and Saskatchewan Prairies. Future changes in the extreme precipitation event are associated with changes in the cyclone evolution, moisture transport, and atmospheric stability change caused by climate change. We also found that the increase in atmospheric stability due to the decrease of relative humidity in the lower atmosphere cause less precipitation to form over the plains and later enhance the orographic precipitation in the Canadian Rockies. In addition to the general increase of precipitable water under global warming, this mechanism causes the storm's precipitation to be more concentrated near the Canadian Rockies. The findings from this study could be beneficial for understanding future changes in extreme precipitation events that share similar characteristics.

中文翻译：

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使用伪全球变暖方法预测极端降水的未来——以 2013 年阿尔伯塔省洪水事件为例


2013 年 6 月阿尔伯塔省的极端降水事件导致了毁灭性的山洪暴发，造成了重大的经济损失和社会混乱。在本研究中，使用天气研究和预报 （WRF） 模型进行了两个高分辨率实验，以研究 2013 年阿尔伯塔省极端降水事件在温暖气候下的变化。对照实验被迫使用 6 小时 ERA-Interim 再分析数据，而敏感性实验被迫使用扰动的 ERA-Interim 再分析数据，这些数据来自代表性浓度途径 8.5 排放情景下的 10 个全球气候模型得出的气候变化信号。结果表明，预估 2013 年阿尔伯塔省极端降水事件在气候变暖时表现出两个显著特征。首先，预计加拿大落基山脉地区和不列颠哥伦比亚省东部的降水将增加。其次，预计阿尔伯塔省和萨斯喀彻温省大草原的降水将减少。极端降水事件的未来变化与气候变化引起的气旋演变、水汽输送和大气稳定性变化的变化有关。我们还发现，由于低层大气中相对湿度的降低，大气稳定性的增加导致平原上形成的降水减少，随后增加了加拿大落基山脉的地形降水。除了在全球变暖下可降水的普遍增加外，这种机制还导致风暴的降水更加集中在加拿大落基山脉附近。这项研究的结果可能有助于理解具有相似特征的极端降水事件的未来变化。