Reconstruction of the 3-D Dynamics From Surface Variables in a High-Resolution Simulation of North Atlantic

S. Fresnay , A. L. Ponte (1) , S. Le Gentil (1) , J. Le Sommer (2)

1 LOPS - Laboratoire d'Océanographie Physique et Spatiale
2 IGE - Institut des Géosciences de l’Environnement

Several methods that reconstruct the three-dimensional ocean dynamics from sea level are presented and evaluated in the Gulf Stream region with a 1/60° realistic numerical simulation. The use of sea level is motivated by its better correlation with interior pressure or quasi-geostrophic potential vorticity (PV) compared to sea surface temperature and sea surface salinity, and, by its observability via satellite altimetry. The simplest method of reconstruction relies on a linear estimation of pressure at depth from sea level. Another method consists in linearly estimating PV from sea level first and then performing a PV inversion. The last method considered, labeled SQG for surface quasi-geostrophy, relies on a PV inversion but assumes no PV anomalies. The first two methods show comparable skill at levels above -800 m. They moderately outperform SQG which emphasizes the difficulty of estimating interior PV from surface variables. Over the 250-1,000 m depth range, the three methods skillfully reconstruct pressure at wavelengths between 500 and 200 km whereas they exhibit a rapid loss of skill between 200 and 100 km wavelengths. Applicability to a real case scenario and leads for improvements are discussed.

Keywords: ocean dynamics; quasi-geostrophy; potential vorticity; sea surface height; correlation analysis; spectral analysis

Domains: Sciences of the Universe [physics]; Oceanography

S. Fresnay, A. L. Ponte, S. Le Gentil, J. Le Sommer. Reconstruction of the 3-D Dynamics From Surface Variables in a High-Resolution Simulation of North Atlantic. Journal of Geophysical Research: Oceans, 2018, 123, pp.1612-1630. ⟨10.1002/2017JC013400⟩. ⟨insu-03683084⟩