A satellite Sentinel-6 "Michael Freilich" that will be critical to the understanding of climate change has blasted skyward from California.

Sentinel-6 "Michael Freilich" is set to become the primary means of measuring the shape of the world's oceans.

Its data will track not only sea-level rise but reveal how the great mass of waters is moving around the globe.

The Sentinel is a joint endeavour between Europe and the US, and will continue the measurements that have been made by a succession of spacecraft, called the Jason-Topex/Poseidon series, going back to 1992.

Sentinel-6 will, however, fly with a much improved capability, which will allow it to see more clearly what seas are doing right up against coastlines; and also how inland water features - rivers and lakes - are behaving.