Stationary waves and tropical cyclone variability

Researchers report a link between atmospheric stationary waves and tropical cyclone (TC) activity. TC impacts are expected to worsen in a warming climate, and seasonal prediction of TC activity will be crucial for preparedness and mitigation. Prediction of TC activity over long time scales relies primarily on the association between tropical atmospheric circulation and slowly varying tropical ocean conditions, but recent studies suggest that extratropical processes also influence TC activity. Zhuo Wang and colleagues investigated the role of summer stationary waves, particularly the tropical upper-tropospheric troughs (TUTTs), in integrating tropical and extratropical influences on TC activity. TUTTS are subject to the modulation of diabatic heating in the tropics, and strong TUTTS are associated with increased frequency of extratropical Rossby wave breaking, which alters tropical atmospheric conditions in ways that modulate TC activity. The authors found significant correlations between TUTT strength and variability in TC activity. Additionally, TUTT strengths, and hence TC activities, in the North Atlantic and North Pacific are out of phase with each other, which reduces the global variability in TC activity. The results provide a hemispheric perspective on TC variability and predictability that may help future TC activity projections, according to the authors.

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Article #20-10547: "Summertime stationary waves integrate tropical and extratropical impacts on tropical cyclone activity," by Zhuo Wang, Gan Zhang, Timothy J. Dunkerton, and Fei-Fei Jin.

MEDIA CONTACT: Zhuo Wang, University of Illinois at Urbana-Champaign, IL; tel: 217-244-4270, 217-979-0376; e-mail: <zhuowang@illinois.edu>