Understanding northeastern tropical atlantic ocean dynamics in relation to climate indices

Abstract

Since 1993, Satellite Altimetry greatly enhanced the ability to study and understand ocean dynamics, particularly in the context of climate change. Though relatively low-energy and understudied, the Northeast Tropical Atlantic Ocean (NTAO) plays a crucial role in the Earth’s climate system. This study aims to deepen understanding of the NTAO region using the satellite altimetry-derived daily sea level gridded data set provided by the Copernicus Climate Change Service (C3S).The analysis of long-term regional Sea Level Anomaly (SLA) signals in the NTAO reveals a higher rate of sea level rise compared to the global average. The same analysis for regional Eddy Kinetic Energy (EKE) per unit mass and surface geostrophic currents shows declining rates, in contrast to global counterparts.Correlation analysis between SLA and climate indices (CI) uncovered significant links with the North Atlantic Oscillation, Tropical North/South Atlantic, Western Hemisphere Warm Pool, and Southern Oscillation Index. Composite maps of sea surface temperature (SST), sea level pressure (SLP), and wind anomalies, as well as complementary maps with anomalies of SLA, EKE, and ocean circulation, were examined to understand the primary mechanisms behind these correlations. SST emerged as the main forcing factor, with SLP and wind anomalies also contributing to specific regional and index correlations. EKE anomalies further elucidate differences in the anomalies of the surface geostrophic currents in the areas influenced by the key currents in the study region. The findings of this study show an intricate interplay between oceanic dynamics and climate phenomena, shedding light on the complex mechanisms driving changes in the Northeast Tropical Atlantic Ocean.