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Linkage between Westerly Wind Bursts and Tropical Cyclones

2018-10-18

Lian, T., D. Chen, Y. Tang, X. Liu, J. Feng and L. Zhou. Linkage between Westerly Wind Bursts and Tropical Cyclones. Geophysical Research Letters, https://doi.org/10.1029/ 2018GL079745.


The westerly wind burst (WWB) in the equatorial Pacific strongly impacts on the genesis and diversity of El Niño, as manifested by its crucial role in the 2014–2016 El Niño events. However, the origin of WWB is still far from clear, rendering El Niño 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 Niño prediction.

 

Figure 1. Composites of anomalous wind fields of WWBs (a) and TCs (b) in WNP. Colors and contours are for the zonal wind anomaly (m/s) and the stream function, respectively. Gray columns represent the center of cyclone with a radius of 5°, where the purple arrows denote the vertical velocity averaged in the column. WWBs = westerly wind bursts; TCs = tropical cyclones; WNP = western North Pacific.