Why does tropical cyclone Emeraude move along a small annular track?

A tropical cyclone (TC), Emeraude, exhibited a unique small annular track in the central Indian Ocean in March 2016. This study integrates high-resolution satellite remote sensing data and reanalysis data to decode the dynamic mechanisms, revealing that the synergy between atmospheric steering flows and oceanic thermal structures was pivotal. Specifically, a barrier zone formed on the TC's northern flank on March 17, intensifying the low-pressure system and steering the TC northward, while its southward shift on March 20 induced a secondary southwest turn to close the annular path, coupled with adjustments in environmental wind shear and vertical velocity fields. In addition, significant upwelling in the TC core (peak Ekman pumping velocity of 2×10−4 m · s−1) and sea surface cooling weakened thermal energy supply, with tropical cyclone heat potential (TCHP) decreased, confirming that oceanic heat content dominated track stability. Furthermore, the variation in the potential vorticity (PV) induced by the disturbances of the eddy reflect the change in TC strength. This paper provides an in-depth analysis of the dynamic mechanism of the TC annular movement trajectory, which is important for future analysis and improvement of typhoon-like path prediction. Research highlights: High divergence and low convergence of wind field favored TC Emeraude's development. Barrier zones affected TC's movement, and PV variation reflected TC strength. There was notable upwelling in the TC center, with a peak Ekman pumping velocity and maximum latent heat flux recorded on March 20. [ABSTRACT FROM AUTHOR]