Jonville T., Cornillault E., Lavaysse Christophe, Peyrillé P., Flamant C. (2024). Distinguishing north and south African Easterly Waves with a spectral method : Implication for tropical cyclogenesis from mergers in the North Atlantic. Quarterly Journal of the Royal Meteorological Society, [Early access], p. [25 p.]. ISSN 0035-9009.
Titre du document
Distinguishing north and south African Easterly Waves with a spectral method : Implication for tropical cyclogenesis from mergers in the North Atlantic
Jonville T., Cornillault E., Lavaysse Christophe, Peyrillé P., Flamant C.
Source
Quarterly Journal of the Royal Meteorological Society, 2024,
[Early access], p. [25 p.] ISSN 0035-9009
African Easterly Waves (AEWs) are mixed barotropic-baroclinic instabilities, propagating both north (AEW-N) and south (AEW-S) of the African Easterly Jet. They are an important component of the North Atlantic region meteorology, influencing precipitation and convection, and are primary seeds for tropical cyclones (TCs) over the North Atlantic. In this study, a novel tracking protocol is introduced based on filtering of the 700-hPa vorticity over two frequency ranges, suited for each wave track: 2.95-4.55 days (quicker propagating mode) and 4.55-6.35 days (slower propagating mode). It is applied to a 31-year reanalysis dataset, the European Centre for Medium-range Weather Forecasts (ECMWF) Fifth Reanalysis. This method effectively isolates north-track activity even amidst dominant south-track signals, enabling better identification and tracking of northward vortices. An analysis of the climatological structure of the two modes is conducted. The slower mode propagates around 24
