Introduction

The NASA/CNES (Centre national d'études spatiales) Surface Water Ocean Topography (SWOT) satellite mission was successfully launched on December 16, 2022, and has since been capturing the height of the ocean (sea surface height or SSH) at unprecedented spatial scales. Since the early 1990s, satellite altimeters have been capturing SSH at scales of ~300 km in the 1990s to ~100 km at present. SSH data have been widely used by the climate science community to, among others, monitor the global mean sea level and El Niño Southern Oscillation, predict hurricane intensification, track large scale eddies, and estimate ocean circulation.

Using High-Resolution Data from SWOT

For the first time, thanks to SWOT and its unprecedented Ka-band Interferometer altimeters onboard, we are able to observe SSH between 78°S and 78°N at even higher resolution below 10 km. Capturing the topography of the ocean surface at fine scales is a necessity to effectively monitor the vertical transport of heat and carbon within the ocean as well as coastal sea level, which is of utmost importance to study global climate and consequences relating to its changes.

Major Findings

The map above is the first global image of SSH anomalies acquired by SWOT over its 21-day repeat cycle, between July 26 and August 16, 2023. The map shows the elevation of the surface of the ocean filtered to show scales below 2000 kilometers. The height of the sea surface has highs (red) and lows (blue) as it reacts to the atmospheric pressure on the surface, ocean tides, waves, eddies and currents. Ocean currents and eddies transport heat, nutrients, carbon, marine debris, etc. from one oceanic region to another. These small scale features that are visible in this map have never been observed before globally as they are not captured at the resolution of traditional altimeters such as Sentinel-6 Michael Freilich.

Referenced Dataset