Oral Session 11

Tropical Gyre Dynamics in the Atlantic: NAO’s Impact Explored Through Guinea Dome Analysis

The North Atlantic tropical gyre plays a crucial role in the exchange of physical and biogeochemical properties between the subtropical gyre and the equatorial region, thereby influencing ocean circulation and climate variability. In this context, the North Atlantic Oscillation (NAO) index serves as a valuable tool to investigate potential mechanisms which may be influencing the interannual variability observed in the Guinea Dome, the dynamical center of the tropical gyre. This study aims to examine the impact of high NAO intensity years on the tropical gyre, focusing particularly on the Guinea Dome and its associated phytoplankton blooms. To address this question, we combine Sea Surface Temperature and Chlorophyll-a satellite data with global ocean reanalysis products to analyze in detail the seasonal and interannual evolution of the Guinea Dome, and its relationship with the different phases of the NAO. Preliminary results reveal significant changes in the spatial scales and strength of the upwelling dome with a stronger (weaker) signal in years of positive (negative) NAO. Both satellite observations and the reanalysis products agree on this pattern, which also displays stronger (weaker) phytoplankton blooms during years of positive (negative) NAO. We attribute these variations in the Guinea Dome dynamics to a direct connection between the NAO intensity and the tropical gyre dynamics. Ongoing analyzes aim to uncover the role that the equatorial currents play under this scenario.

*Alex Urbaneja, Universidad de las Palmas de Gran Canaria, Spain, https://orcid.org/0009-0006-5365-7323

Marina Gutiérrez-García, Universidad de las Palmas de Gran Canaria, Spain, https://orcid.org/0009-0000-5809-9048

Borja Aguiar-González, Universidad de las Palmas de Gran Canaria, Spain, https://orcid.org/0000-0002-2064-1724

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