Predicting East African spring droughts using Pacific and Indian Ocean sea surface temperature indices
Predicting East African spring droughts using Pacific and Indian Ocean sea surface temperature indices
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DOI：
10.5194/hess-18-4965-2014
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发表时间：
2014-01-01
影响因子：
6.3
通讯作者：
Husak, G.
中科院分区：
文献类型：
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作者：
Funk, C.;Hoell, A.;Husak, G.
在东非东部（埃塞俄比亚南部、肯尼亚东部和索马里南部地区），1999年、2000年、2004年、2007年、2008年、2009年和2011年北方春季（漫长的雨季）降雨量少，造成粮食严重不安全和营养不良程度高。预测该地区季节性和十年期的降雨量不足可以帮助决策者实施减少灾害风险措施，同时指导气候智能型适应和农业发展。建立在最近的研究，链接更频繁的东非干旱到一个更强的步行者流通，导致在印度洋-太平洋暖池变暖和增加的东西海表面温度（SST）梯度在西太平洋，我们表明，东非北部春季降雨变化的两个主要模式是与SST波动在中西部太平洋和印度洋中部，分别。因此，这两种降雨模式的变化可以使用两个SST指数-西太平洋梯度（WPG）和印度洋中部指数（CIO）进行预测，我们的统计预报表现出合理的交叉验证技能（r（cv）近似为0.6）。相比之下，目前这一代的耦合预报模型在长时间的降雨中表现得毫无技巧。我们的SST指数似乎也捕捉到了最近的大部分主要干旱事件，如2000年，2009年和2011年。基于这些简单指数的预测可用于支持区域预报工作和地表数据同化，以帮助提供预警信息和指导气候展望。
In eastern East Africa (the southern Ethiopia, eastern Kenya and southern Somalia region), poor boreal spring (long wet season) rains in 1999, 2000, 2004, 2007, 2008, 2009, and 2011 contributed to severe food insecurity and high levels of malnutrition. Predicting rainfall deficits in this region on seasonal and decadal time frames can help decision makers implement disaster risk reduction measures while guiding climate-smart adaptation and agricultural development. Building on recent research that links more frequent East African droughts to a stronger Walker circulation, resulting from warming in the Indo-Pacific warm pool and an increased east-to-west sea surface temperature (SST) gradient in the western Pacific, we show that the two dominant modes of East African boreal spring rainfall variability are tied to SST fluctuations in the western central Pacific and central Indian Ocean, respectively. Variations in these two rainfall modes can thus be predicted using two SST indices - the western Pacific gradient (WPG) and central Indian Ocean index (CIO), with our statistical forecasts exhibiting reasonable cross-validated skill (r(cv) approximate to 0.6). In contrast, the current generation of coupled forecast models show no skill during the long rains. Our SST indices also appear to capture most of the major recent drought events such as 2000, 2009 and 2011. Predictions based on these simple indices can be used to support regional forecasting efforts and land surface data assimilations to help inform early warning and guide climate outlooks.