Characteristics and trends of Atlantic tropical cyclones that do and do not develop from African easterly waves

• Published in: Quarterly journal of the Royal Meteorological Society 2024-10, Vol.150 (765), p.4951-4968
• Main Authors: Bercos‐Hickey, Emily, Patricola, Christina M.
• Format: Article
• Language: English
• Subjects: African easterly waves; Algorithms; Anthropogenic factors; Cyclones; Easterly waves; Environmental conditions; Hurricanes; observational data analysis; Statistical analysis; Trends; Tropical cyclones; tropical meteorology
• ISSN: 0035-9009; 1477-870X
• DOI: 10.1002/qj.4850

Atlantic tropical cyclones (TCs) are known to develop from African easterly waves (AEWs) that propagate across North Africa and out over the Atlantic Ocean. The relationship between AEWs and TCs has been the subject of numerous previous studies. There are, however, many Atlantic TCs that do not have AEW origins. In this study, we provide a novel analysis of the characteristics and trends of Atlantic TCs both with and without AEW origins using 43 years of observational and reanalysis data. To conduct this research, we identified TCs with and without AEW origins from the observational record between 1980 and 2022, and ran objective tracking algorithms on reanalysis data to identify the AEWs and TCs during this time period. We found statistically significant differences in the characteristics and environments of TCs with and without AEW origins. TCs with AEW origins are stronger and costlier, experience more favorable environmental conditions, and are more likely to make landfall in the Gulf of Mexico and the Caribbean when compared to TCs without AEW origins. Additionally, the 43‐year increasing trend in Atlantic TC activity is primarily driven by an increase in TCs with AEW origins that is associated with increasing AEW frequency and strength, with anthropogenic aerosols potentially driving this trend. In contrast, we found no trend in TCs without AEW origins. Hurricane Bill, September 19, 2009 ( https://earthobservatory.nasa.gov/images/39861/hurricane‐bill) Atlantic tropical cyclones (TCs) that develop from African easterly waves (AEWs) are stronger and costlier, have more favorable environments, and are more likely to make landfall in the Gulf of Mexico and the Caribbean when compared to TCs without AEW origins. TCs with AEW origins are also primarily responsible for the historical increasing trend in Atlantic TC activity. The increasing trend in TCs with AEW origins is associated with increasing AEW activity that may be related to a decrease in anthropogenic aerosols.