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Article Dans Une Revue Journal of Geophysical Research. Oceans Année : 2020

Spatial and Temporal Variability of the North Atlantic Eddy Field From Two Kilometric‐Resolution Ocean Models

Julien Le Sommer
Eric Chassignet
Jean‐marc Molines
  • Fonction : Auteur
Xiaobiao Xu
Aurelie Albert
  • Fonction : Auteur
Emmanuel Cosme
  • Fonction : Auteur

Résumé

Ocean circulation is dominated by turbulent geostrophic eddy fields with typical scales ranging from 10 to 300 km. At mesoscales (>50 km), the size of eddy structures varies regionally following the Rossby radius of deformation. The variability of the scale of smaller eddies is not well known due to the limitations in existing numerical simulations and satellite capability. Nevertheless, it is well established that oceanic flows (<50 km) generally exhibit strong seasonality. In this study, we present a basin‐scale analysis of coherent structures down to 10 km in the North Atlantic Ocean using two submesoscale‐permitting ocean models, a NEMO‐based North Atlantic simulation with a horizontal resolution of 1/60 (NATL60) and an HYCOM‐based Atlantic simulation with a horizontal resolution of 1/50 (HYCOM50). We investigate the spatial and temporal variability of the scale of eddy structures with a particular focus on eddies with scales of 10 to 100 km, and examine the impact of the seasonality of submesoscale energy on the seasonality and distribution of coherent structures in the North Atlantic. Our results show an overall good agreement between the two models in terms of surface wave number spectra and seasonal variability. The key findings of the paper are that (i) the mean size of ocean eddies show strong seasonality; (ii) this seasonality is associated with an increased population of submesoscale eddies (10–50 km) in winter; and (iii) the net release of available potential energy associated with mixed layer instability is responsible for the emergence of the increased population of submesoscale eddies in wintertime.

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Océanographie
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Dates et versions

hal-03084224 , version 1 (30-12-2020)

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Adekunle Ajayi, Julien Le Sommer, Eric Chassignet, Jean‐marc Molines, Xiaobiao Xu, et al.. Spatial and Temporal Variability of the North Atlantic Eddy Field From Two Kilometric‐Resolution Ocean Models. Journal of Geophysical Research. Oceans, 2020, 125 (5), ⟨10.1029/2019JC015827⟩. ⟨hal-03084224⟩
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