Identification of changing precipitation extremes and attribution to atmopsheric, oceanic and climatic changes

气候变化的一些最关键的影响可能会由于水文循环极端事件（干旱和洪水）的变化而发生，但未来降水及其极端事件的预期变化目前还相当不确定。未来变化的情景是从全球和区域气候模式的模拟中得出的，我们对未来极端降水情景的信心取决于我们对这些模式可靠性的评估。我们建议通过将这些模式的模拟结果与观测到的极端降水事件的变化进行仔细比较来评估这些模式。我们的比较将远远超出对模拟和观测事件的统计数据的简单比较，而且还将评估大气环流变异性（风速和风向、稳定性、辐合和上升）、大气湿度以及模型和现实世界中由此产生的极端降水之间的联系。然后，我们将扩展评估，以考虑在模式模拟中包括温室气体（和其他外部气候影响）的变化是否能改善与观测资料中检测到的变化的一致性。

Some of the most critical impacts of climate change will probably occur due to changes in the extremes of the hydrological cycle (droughts and floods), yet the expected changes in future precipitation and its extremes are currently quite uncertain. Scenarios of future change are derived from simulations with global and regional climate models, and our confidence in scenarios of future precipitation extremes rests on our assessment of the reliability of those models. We propose to evaluate these models by careful comparison of their simulations with observed variations in extreme precipitation events. Our comparisons will go far beyond simple comparisons of the statistics of simulated and observed events, but will in addition assess the linkages between atmospheric circulation variability (wind speeds and directions, stability, convergence and uplift), atmospheric humidity, and resulting precipitation extremes in both models and the real world. We will then extend the assessment to consider whether including changes in greenhouse gases (and other external climate influences) in the model simulations improves the agreement with changes detected in the observational data.