Abstract ID: 148
Equatorial waves: precursors to tropical cyclone occurrence and intensification
Lead Author: Xiangbo Feng
National Centre for Atmospheric Science, University of Reading, United Kingdom
Keywords: medium range prediction, tropical cyclone, equatorial waves
Abstract: Understanding and prediction of tropical cyclone (TC) activity on the medium range remains challenging. Here, we find that the pre-existing westward-moving equatorial waves can inform the risk of TC occurrence and intensification, based on a dataset obtained by synchronising objectively identified TCs and equatorial waves in a climate reanalysis. Globally, westward-moving equatorial waves can be precursors to 60–70% of pre-tropical cyclogenesis events, and to >80% of the events with the strongest vorticity, related to the favourable environmental conditions within the pouch of equatorial waves. We further find that when storms are in-phase with westward-moving equatorial waves, the intensification rate of TCs is augmented, whilst in other phases of the waves, storm intensity grows more slowly, or even decays. Coherent wave packets associated with TCs are identifiable up to two weeks ahead. Our findings show that westward-moving equatorial waves can be useful medium-range precursors to TC activity.
Co-authors:
Gui-Ying Yang (National Centre for Atmospheric Science and Department of Meteorology, University of Reading)
Kevin I. Hodges (National Centre for Atmospheric Science and Department of Meteorology, University of Reading)
John Methven (Department of Meteorology, University of Reading)
