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Publication Date
8 December 2023

The Effects of African Easterly Wave Suppression by Wave Track on Atlantic Tropical Cyclones

In the absence of African easterly waves (AEWs), tropical cyclone activity is enhanced, with the largest increase occurring when AEWs in the south wave track are suppressed.
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Power spectral density plots of the control, both, north, and south filter ensemble-averaged 700 hPa meridional wind averaged between 5oS-15oN at (a)(c)(e) 35oW and (b)(d)(f) 20oW for the years (a)(b) 2003, (c)(d) 2010, and (e)(f) 2011. Note the increase in the 2-10 day signal between 20 and 35oW for the both and south filter experiments.

African easterly waves (AEWs) are observed in two tracks and can serve as precursors to Atlantic tropical cyclones (TCs). It has been shown, however, that the seasonal number of TCs is not affected by the absence of AEWs. This research examines the effects of suppressing AEW activity by wave track (north, south, or both tracks) on TC activity. We found that AEWs are not a requirement for TC development, and that suppressing AEWs, specifically in the south wave track, can enhance TC activity as well as environmental conditions favorable for TC development.


TCs have the potential to be both deadly and destructive, and their impacts may worsen with future climate change. Although TC development involves the co-occurrence of many factors, AEWs often serve as the initial disturbances required for these storms to form. In this study, we found that Atlantic TC activity was enhanced in the absence of AEWs, with the largest increase occurring when AEWs in the south wave track were suppressed. This demonstrates the importance of examining environmental conditions as well as other mechanisms that may lead to TC development when considering the future of Atlantic TC activity.


In this study, we examined the effects of AEW suppression by wave track on Atlantic TC activity. We ran a suite of TC-permitting regional model simulations in which AEWs were either prescribed (control) or suppressed (experiments) through the lateral boundary conditions. We ran three experiments in which AEWs were suppressed in either the north, south, or both wave tracks. In all simulations, TCs were objectively tracked in the model data. Measures of TC activity as well as environmental conditions were compared in the control and experiments. We found that AEWs are not necessary to maintain basin-wide Atlantic TC frequency and that AEW suppression, specifically in the south wave track, can lead to an increase in TC activity. This increase in TC activity coincided with more favorable environmental conditions for TC genesis and the strengthening of disturbances associated with increased Atlantic rainfall when AEWs were suppressed in the south wave track.

Point of Contact
Emily Bercos-Hickey
Lawrence Berkeley National Laboratory
Funding Program Area(s)
Additional Resources:
NERSC (National Energy Research Scientific Computing Center)