Evaluation of the ocean heat budget with ERA5 since 1980 to 2024 in the Eastern North Atlantic Ocean

Abstract

This study evaluates the ocean heat budget within a defined region of the Eastern North Atlantic Ocean by analyzing the physical variables that control its four main heat flux components, using ERA5 data from 1980 to 2024. Spatial and seasonal variability are assessed through meridional and monthly meridional climatologies, while the impact of climate change is incorporated via trend analyses and time series. Additionally, relative contributions of each heat flux to the overall budget are quantified. Results reveal pronounced latitudinal variability, delineating three distinct regions: the tropical zone, influenced by atmospheric phenomena such as hot towers and persistent cloud cover; the subtropical zone, governed by the stabilizing presence of the Azores High; and the subpolar zone, controlled by seasonal fluctuations of the Icelandic Low. Furthermore, while strong trends are evident in many physical variables, the ocean heat budget and its constituent fluxes display significant trends only at specific latitudes. Throughout the domain, surface net shortwave radiation constitutes the dominant contributor to the heat budget, followed by surface latent heat flux, with surface net long-wave radiation and sensible heat flux playing smaller roles.