Initial wind field structure: A crucial factor in determining tropical cyclone size and intensity

Phys.org  May 15, 2023 Researchers in China conducted experiments by varying the radius of maximum wind (RMW) and shape parameter b of the initial vortices. The size–intensity relationship was quantified by the linear regression coefficient of the azimuthally-averaged gale-force wind radius against the maximum wind during the development stage, reflecting the degree of size expansion at the same intensity increment. The regression coefficient increased with increased RMW and decreased b, with the RMW being the primary constraint. Enlarging the RMW led to a secondary circulation with a horizontally elongated structure, which retards the intensification while expanding the size. Broadening the […]

Tropical storms signaled by atmospheric waves, study finds

Phys.org February 7, 2023 Understanding and prediction of tropical cyclone (TC) activity on the medium range remains challenging. Researchers in the UK found 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. They also found that when storms are in-phase with westward-moving […]