Impact of vertical wind shear in modulating tropical cyclones eye and rainfall structure

Tropical cyclones (TCs) are primarily characterised by strong winds and torrential rain. Often, strong environmental vertical wind shear (EVWS) displaces the location of TC’s eye at the cloud level from that near the surface and modulates its rain structure significantly. Thus, knowledge of EVWS and its role in displacing TC’s eye at vertical level is important to resolve rain structure of TC. Present study examines the role of EVWS in displacing TC’s eye location and associated rainfall distribution by analysing 27 TCs over global ocean basins in the Northern Hemisphere from October 2016 to December 2019. Study utilizes Indian Space Research Organisation’s Scatsat-1 Ku-band (13.53 GHz) scatterometer derived global ocean surface vector winds, National Oceanic and Atmospheric Administration provided global merged Infra-Red imagery product, U and V components of winds from Global Forecast System, and rainfall from Integrated Multi-satellitE Retrieval for Global Precipitation Measurement mission. High intensified TCs that developed in strong EVWS (> 10 ms−1) show eye dislocation of > 30 km. However, this locational displacement is negligible for severe TCs strengthen in weak EVWS (≤ 10 ms−1). Rain structure of TC is controlled by the direction of shifted eye, particularly when a severe TC exhibits significant shift of > 30 km. On the other hand, rainfall distribution is nearly uniform around the TC’s eye that has a marginal dislocation of < 15 km. Findings of this study are not only important to understand rain structure of TC but also beneficial for saving coastal lives and properties that are often impacted by torrential rain from TC.