Linking extreme precipitation in Southeast Asia to equatorial waves
Linking extreme precipitation in Southeast Asia to equatorial waves
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DOI：
10.1002/qj.3699
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发表时间：
2019-12-25
影响因子：
8.9
通讯作者：
Holloway, Christopher E.
中科院分区：
文献类型：
--
作者：
Ferrett, Samantha;Yang, Gui-Ying;Holloway, Christopher E.
赤道陷波（英语：Equatorial-trapped waves），如开尔文波、赤道罗斯比波和西移混合罗斯比重力波（英语：Mixed Rossby-Gravity waves），在天气尺度到亚季节尺度的热带对流中扮演重要角色。这些波有可能为东南亚和更广泛的热带地区的高影响天气提供重要的可预测性来源。为了帮助理解这种波在高影响天气中所起的作用，研究了1998-2016年期间在东南亚确定的赤道波和暴雨之间观察到的统计关系。东南亚降水量的增加和极端降水的可能性与分析中包括的所有三种类型的波有关;开尔文波，赤道Rossby波和WMRG波。当高振幅波在东南亚传播时，平均降雨量增加，暴雨发生的概率也增加。特别是，在赤道波期间，东南亚地区的强降水可能性高达三倍，包括马来西亚，印度尼西亚和菲律宾。Kelvin波对印度尼西亚的强降雨有很大的影响，WMRG和Kelvin波影响马来西亚的降雨，赤道Rossby和WMRG波与菲律宾的降雨增加有关。根据这项研究，它可以得出结论，极端降水的概率在该地区是依赖于赤道波活动。因此，东南亚极端降水的概率预测技术预计将取决于赤道波预测技术以及赤道波和对流之间的模拟关系。
Equatorially trapped waves, such as Kelvin Waves, Equatorial Rossby Waves and Westward-moving Mixed Rossby-Gravity (WMRG) Waves, play a major role in organising tropical convection on synoptic to sub-seasonal time-scales. These waves have the potential to provide an important source of predictability for high-impact weather in Southeast (SE) Asia and the Tropics more widely. To aid understanding of the role played in high-impact weather by such waves, the observed statistical relationship between identified equatorial waves and heavy rainfall in SE Asia is examined for the period 1998-2016. Increases in the amount of precipitation and the likelihood of extreme precipitation in SE Asia are linked to all three types of waves that are included in analysis; Kelvin, equatorial Rossby and WMRG waves. There is both increased mean rainfall and increased probability of occurrence of heavy rainfall on days when high-amplitude waves propagate over SE Asia. In particular, heavy precipitation can be up to three times more likely in regions of SE Asia during equatorial waves, including Malaysia, Indonesia and the Philippines. Kelvin waves have a large influence on heavy rainfall over Indonesia, WMRG and Kelvin waves impact Malaysia rainfall, and equatorial Rossby and WMRG waves are linked to increased rainfall over the Philippines. Based on this study it can be concluded that the probability of extreme precipitation in this region is dependent on equatorial wave activity. Therefore, the skill in probabilistic prediction of extreme precipitation in SE Asia would be expected to be conditional on the skill in equatorial wave prediction, and the modelled relationship between equatorial waves and convection.