资源环境科技发展态势分析平台

The westerly wind burst (WWB) in the equatorial Pacific strongly impacts on the genesis and diversity of El Nino, as manifested by its crucial role in the 2014-2016 El Nino events. However, the origin of WWB is still far from clear, rendering El Nino prediction, a persistently challenging task. Here we confirm a robust linkage between WWB and tropical cyclone (TC) from a set of observational and reanalysis data. Specifically, about 69% of WWBs were closely associated with TCs in the western tropical Pacific, and the three-dimensional structure of WWBs highly resembled that of TCs. Such a close relationship readily explains not only the unidirectional and intermittent nature of WWBs but also the state dependency, seasonality, and spatial distribution of these bursts. An important implication is that, with skillful seasonal forecast of WWB-associated TCs, we may be able to predict the seasonal activity of WWBs and thus improve El Nino prediction.

Plain Language Summary The westerly wind bursts (WWBs) frequently occur in the western-central equatorial Pacific. Previous studies have confirmed that WWBs play an important role in triggering and maintaining El Nino, including the extreme 2014-2016 El Nino events. Improving the prediction of WWBs will be no-doubt to benefit El Nino prediction, but the origin of WWB is still far from clear. Here we found that the majority of WWBs are closely associated with tropical cyclones (TCs) in the western Pacific. The existence of such a close relationship makes good sense and is easy to understand, because TCs always produce equatorial westerly winds as long as they are not too far from the equator, and because the TC movements tend to make these westerlies burst like. Aside from explaining the unidirectional and intermittent nature of WWBs, the WWB-TC linkage also explains the state dependency, seasonality, and spatial distribution of WWBs. Our results imply that one may be able to improve El Nino prediction with a skillful seasonal forecast of TCs and the consequent seasonal activity of WWBs.