SWOT delivers its first data

A new milestone has been reached after all the instruments have been switched on, with the reception of the first data from SWOT, the Franco-American satellite for measuring water on the Earth’s surface!

The Maroni River as seen by SWOT’s Poseidon-3C altimeter. Credits: CNES (Sophie Le Gac & Alexandre Guérin)

After a month of intensive commissioning by teams from CNES, JPL and Thales Alenia Space at the Toulouse space center, the Surface Water & Ocean Topography (SWOT) altimetry satellite is delivering its first nadir data. Developed jointly with NASA, SWOT is now in its calibration orbit, giving it a revisit period of only one day.

The Poseidon-3C altimeter is the first instrument to provide data on water level rise, here from the Maroni River and its tributaries in French Guiana on January 20, 2023.

Processed by the CNES SWOT expertise center and analyzed by the teams in charge of quality and performance monitoring, the radar waveforms represented by the colored images can be seen on the map.

Called “level 2 products”, the information generated will make it possible to monitor the rise in water levels in many of the rivers overflown by SWOT.

Sophie Le Gac, NADIR altimetry studies and development specialist at CNES, said: “These first measurements already show the excellent performance of Poseidon-3C in orbit. This first result is very promising for the upcoming calibration/validation phase for this new Nadir altimeter, in addition to the other altimeters currently in flight!”

The Poseidon-3C altimeter also transmitted information on ocean height, particularly during its passage over the Atlantic on January 19. The figure illustrates very well the consistency between the elevations in red and the troughs in blue observed by the SWOT instrument (darker trace), and the map from other altimeters in the altimetry constellation (Jason-3, SARAL, Sentinel-6…) for the same day.

The in-flight acceptance phase of the satellite now begins, which will last 3 months. It consists in checking and validating the behavior of the satellite platform and all its instruments in the hostile conditions of space.

Source: CNES

The height of the Atlantic measured by Poseidon-3C. Credits: CNES (Gérald Dibarboure)