This image is a combination of altimeter data from both the Sentinel-6 sea-level tracking satellites: Sentinel-6B and its twin, Sentinel-6 Michael Freilich, which was launched in 2020. The image shows the Gulf Stream current in the North Atlantic Ocean, off the eastern coasts of the US and Canada. The ‘ground tracks’ for Sentinel-6B (S6B) and Sentinel-6 Michael Freilich (S6MF) are shown as thick strips on the map.
Colours along the tracks show sea level relative to a long-term average: red indicates higher-than-usual sea level, blue indicates lower-than-usual. Knowledge of Gulf Stream current systems is important for both ship routing and fisheries. The background image shows a global map of sea-surface height anomalies based on satellite altimeter data produced by the Copernicus Marine Service for 26 November 2025. All altimeter tracks display data collected on that same day. Image illustrative and not for operational use.
The image was created using data from the mission’s Poseidon-4 dual-frequency (C- and Ku-band) radar altimeter, which uses an innovative mode that has improved performance compared to previous satellite altimeter designs. Radar altimeter instruments measure the time it takes for radar pulses to reach Earth’s surface and bounce back to the satellite.
Read full story: First image from Sentinel-6B extend sea-level legacy