Speed-up of the Madeira tip jets in the ERA5 climate highlights the decadal variability of the Atlantic subtropics

Abstract

During the summer months, the northeasterly trade winds impinging on Madeira Island lead to the establishment of a quasi-permanent wind pattern with two tip jets emerging near the western and eastern island tips. These jets respond to subtle changes of the upstream flow with an amplified signal, and a high-resolution simulation of the regional atmospheric flow is found to indicate an intensification, associated with a lowering of the atmospheric boundary layer and a slight realignment of the background flow. These results are validated by observations at Madeira Airport, where the proximity of the East Jet has led to less favourable wind conditions for aircraft operations in the last decade. It is suggested that these trends may be explained by large-scale changes in the structure of the Hadley Cell in the North Atlantic basin.