Real-time extreme weather event attribution with forecast seasonal SSTs
Real-time extreme weather event attribution with forecast seasonal SSTs
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DOI：
10.1088/1748-9326/11/6/064006
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发表时间：
2016-06-01
影响因子：
6.7
通讯作者：
Cullen, H.
中科院分区：
文献类型：
--
作者：
Haustein, K.;Otto, F. E. L.;Cullen, H.
在过去的十年里，极端天气事件的归因已经成为一个新的科学领域，并引起了更广泛的科学界和公众的越来越多的关注。已经提出了许多方法来确定人为气候变化对个别极端天气事件的贡献。到目前为止，几乎所有此类分析都是在事件发生几个月后进行的。在这里，我们提出了一种新的方法，可以实时评估由于外部驱动因素导致的恶劣天气事件的归因风险分数。该方法建立在季节性海面温度预报（SSTs）强迫的仅大气环流模式模拟的大集合上。以2013/14年英国冬季洪水为例，我们利用观测到的或季节预报的海温，证明了英国洪水期间由于人为气候变化引起的暴雨风险的变化幅度相似。通过对模式对2014年1月异常海洋状态的动态响应进行测试，我们发现需要观测到的海温才能在特定海温型和大气响应（如模式中急流的移动）之间建立明显的联系。然而，对于发生在与已知低频气候模式相关的强烈海温异常模式下的极端事件，海温预报可以为确定事件的动力贡献提供足够的指导。
Within the last decade, extreme weather event attribution has emerged as a new field of science and garnered increasing attention from the wider scientific community and the public. Numerous methods have been put forward to determine the contribution of anthropogenic climate change to individual extreme weather events. So far nearly all such analyses were done months after an event has happened. Here we present a new method which can assess the fraction of attributable risk of a severe weather event due to an external driver in real-time. The method builds on a large ensemble of atmosphere-only general circulation model simulations forced by seasonal forecast sea surface temperatures (SSTs). Taking the England 2013/14 winter floods as an example, we demonstrate that the change in risk for heavy rainfall during the England floods due to anthropogenic climate change, is of similar magnitude using either observed or seasonal forecast SSTs. Testing the dynamic response of the model to the anomalous ocean state for January 2014, we find that observed SSTs are required to establish a discernible link between a particular SST pattern and an atmospheric response such as a shift in the jetstream in the model. For extreme events occurring under strongly anomalous SST patterns associated with known low-frequency climate modes, however, forecast SSTs can provide sufficient guidance to determine the dynamic contribution to the event.