OCEAN · CURRENTS — GEOSTROPHIC

Currents — Geostrophic

The surface current field of the whole ocean, drawn with direction arrows — the geostrophic currents, computed from the slope of the sea surface itself. Where the sea piles into a bulge, water flows around it, balanced between gravity and Earth’s rotation; almost all the large-scale surface flow of the ocean is geostrophic, so this one calculation recovers the great currents: the Gulf Stream, the Kuroshio, the Agulhas, the Antarctic Circumpolar. The satellite-measured companion to the animated particle currents — same ocean, a different instrument. Updated daily.