The East Asian Subtropical Jet Stream and Atlantic Tropical Cyclones

Wei Zhang,Gabriel A Vecchi,Gabriele Villarini

doi:10.1029/2020gl088851

Wei Zhang, Gabriel A Vecchi + Show 1 more

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https://doi.org/10.1029/2020gl088851

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Abstract

AbstractAtlantic tropical cyclones (TCs) can cause significant societal and economic impacts, as 2019's Dorian serves to remind us of these storms' destructiveness. Decades of effort to understand and predict Atlantic TC activity have improved seasonal forecast skill, but large uncertainties still remain, in part due to an incomplete understanding of the drivers of TC variability. Here we identify an association between the East Asian Subtropical Jet Stream (EASJ) during July–October and the frequency of Atlantic TCs (wind speed ≥34 knot) and hurricanes (wind speed ≥64 knot) during August–November based on observations for 1980–2018. This strong association is tied to the impacts of EASJ on a stationary Rossby wave train emanating from East Asia and the tropical Pacific to the North Atlantic, leading to changes in vertical wind shear in the Atlantic Main Development Region (80–20°W, 10–20°N).

Highlights

Atlantic tropical cyclones (TCs) receive significant interest both from the scientific community and the general public because of their large societal and economic impacts in terms of fatalities and property damage [Czajkowski et al, 2011; 2017; Klotzbach et al, 2018; Pielke Jr et al, 2008]
We have identified a significant correlation between the East Asian Subtropical Jet Stream (EASJ) in July-October and the frequency of Atlantic TCs and hurricanes in August-November in observations, which is robust across four different reanalysis data sets
The one-month lag in the peak correlation, which indicates causality moving from the EASJ to Atlantic TCs, may arise from the EASJ and the propagation of Rossby waves from East Asia to the North Atlantic (Figure 3)

Summary

Introduction

Atlantic tropical cyclones (TCs) receive significant interest both from the scientific community and the general public because of their large societal and economic impacts in terms of fatalities and property damage [Czajkowski et al, 2011; 2017; Klotzbach et al, 2018; Pielke Jr et al, 2008]. As a prominent component of the weather and climate system in the Asia–Pacific sector [Thompson et al, 2003], the East Asian Subtropical Jet stream (EASJ) is associated with precipitation and temperature in North America. The Rossby wave energy can be trapped by the EASJ in East Asia, triggering the downstream development of a Rossby wave train along the EASJ towards North America and the North Atlantic [Graf and Zanchettin, 2012; Swanson et al, 1997; Zhu and Li, 2016]. We examine whether and the extent to which the EASJ is associated with the frequency of Atlantic TCs and hurricanes The remainder of this manuscript is organized as follows.

Data and Methodology

Results

Conclusion