The Productive Ligurian Pool

TL;DR

This study investigates how rim-like sub-mesoscale eddy activity in the Ligurian Basin sustains a productive central area by trapping nutrients and chlorophyll, combining satellite data and realistic numerical modeling.

Contribution

It reveals the role of rim eddies in maintaining the Ligurian Pool through nutrient import and concentration, using satellite observations and high-resolution ocean modeling.

Findings

Higher chlorophyll concentrations in the basin center.

Eddy activity concentrated in the rim during 2009-2010.

Eddies contribute to basin-scale cyclonic gyre formation.

Abstract

In contrast with the behavior of the eddies in the open-ocean, the sub-mesoscale eddies generated in the constricted Ligurian Basin (NW Mediterranean), are unproductive but their combined effect, arranged in a rim-like fashion, contributes to the containment of a Productive Ligurian Pool (PLP). Data de- rived from MODIS satellite sensor showed persistent higher chlorophyll con- centrations in the centre of the basin, concurrent with high EKE values in its surroundings, derived from AVISO altimetry merged products. This sug- gested that this 'productive pool' is maintained by the intense (sub)mesoscale eddy activity in the rim. Numerical realistic experiments, using a Regional Ocean Model System, forced by MERCATOR and by a high-resolution COSMO- l7 atmospheric model, also showed that most of the sub-mesoscale eddies, during 2009 and 2010, are concentrated in the rim surrounding the basin, contributing to the formation of a basin-scale cyclonic gyre. We hypothesized that the interaction between eddies in the rim might contribute to import of nutrients into the pool in two ways: (i) by advection of nutrients from the nearby coastal regions into the pool; (ii) by concentrating eddy upwelled nu- trients inside the pool; or by a combination thereof.