Improved global sea surface height and currents maps from remote sensing and in situ observations
Event: 2022 Ocean Surface Topography Science Team Meeting
Session: Science III: Mesoscale and sub-mesoscale oceanography
Presentation type: Type Poster
Contribution: PDF file
We present a new gridded sea surface height (SSH) and current dataset produced by combining observations from nadir altimeters and drifting buoys. This product is based on a multiscale/multivariate mapping approach, which aims to improve the resolution of operational products provided by Copernicus services and offers the possibility to study mesoscale circulations, equatorial wave dynamics and Arctic Sea level variability. The dataset covers the entire global ocean and spans from 2016-01-15 to 2020-06-30. The multi-scale approach decomposes the observed signal into different physical contributions. In the present study, we simultaneously estimate the mesoscale ocean circulations as well as part of the equatorial wave dynamics (e.g., tropical instability and Poincaré waves). The multivariate approach is able to exploit the geostrophic signature resulting from the synergy of altimetry and drifter observations. In addition, sea level observations of Arctic leads are also used in the merging to improve the SSH in this poorly mapped region. A quality assessment of this new product is proposed against the product distributed in the Copernicus Marine Service. We show that the multi-scale mapping approach offers promising perspectives for surface ocean circulation reconstructions. The geostrophic circulation is better mapped in the new product. The mapping errors are significantly reduced in regions of high variability and in the equatorial band. The drifters help to refine the mapping in the in regions of intense dynamics where the temporal sampling must be accurate enough to properly map the rapid mesoscale dynamics. The effective resolution of this new product is hence between 5% and 10% finer than the Copernicus product.