A global increase in nearshore tropical cyclone intensification

Abstract

Tropical Cyclones (TCs) inflict substantial coastal damages, making it pertinent to understand changing storm characteristics in the important nearshore region. While past studies examined several aspects of landfalling TCs, storm intensification nearshore has hitherto not been explored at the global scale. Here, we address this using a suite of observations and numerical model simulations. Over the historical period 1979-2020, observations reveal a global mean TC intensification rate increase of about 3 kt per 24-hr in regions close to the coast. Analysis of the observed large-scale environment shows that stronger decreases in vertical wind shear and larger increases in relative humidity relative to the open oceans are responsible. Further, climate model simulations suggest that nearshore TC intensification will continue to rise under global warming. Decreasing shear near coastlines, driven by amplified warming in the upper troposphere and changes in heating patterns, is the likely pathway for these projected increases in TC intensification nearshore.