Improving the Altimeter-Derived Surface Currents Using Sea Surface Temperature (SST) Data: A Sensitivity Study to SST Products

• Published in: Remote Sensing
• Main Authors: Daniele Ciani, Marie-Hélène Rio, Bruno Buongiorno Nardelli, Hélène Etienne, Rosalia Santoleri
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2020
• Subjects: sea surface temperature; ocean currents; altimetry; earth observations synergy; Science; Q; Southern Ocean
• Online Access: https://doi.org/10.3390/rs12101601; https://doaj.org/article/8cabb05f3b40499394380bd7e677cb7e

Measurements of ocean surface topography collected by satellite altimeters provide geostrophic estimates of the sea surface currents at relatively low resolution. The effective spatial and temporal resolution of these velocity estimates can be improved by optimally combining altimeter data with sequences of high resolution interpolated (Level 4) Sea Surface Temperature (SST) data, improving upon present-day values of approximately 100 km and 15 days at mid-latitudes. However, the combined altimeter/SST currents accuracy depends on the area and input SST data considered. Here, we present a comparative study based on three satellite-derived daily SST products: the Remote Sensing Systems (REMSS, 1/10 <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>∘</mo> </msup> </semantics> </math> resolution), the UK Met Office OSTIA (1/20 <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>∘</mo> </msup> </semantics> </math> resolution), and the Multiscale Ultra-High resolution SST (1/100 <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>∘</mo> </msup> </semantics> </math> resolution). The accuracy of the marine currents computed with our synergistic approach is assessed by comparisons with in-situ estimated currents derived from a global network of drifting buoys. Using REMSS SST, the meridional currents improve up to more than 20% compared to simple altimeter estimates. The maximum global improvements for the zonal currents are obtained using OSTIA SST, and reach 6%. Using the OSTIA SST also results in slight improvements (≃1.3 %) in the zonal flow estimated in the Southern Ocean (45 <math display="inline"> <semantics> <msup> <mrow></mrow> <mo>∘</mo> </msup> </semantics> </math> S to 70 <math display="inline"> <semantics> <msup> ...