Geostrophic Ocean Current Balance

This simulator renders a sloping sea-surface-height feature — a warm-core dome or cold-core trough, the kind altimetry satellites map across every real ocean basin — and releases a ring of water parcels on its flank. Each parcel is integrated under two real forces: the pressure-gradient force pulling it down-slope and the Coriolis force deflecting it sideways as Earth rotates beneath it. Watch the parcels overshoot into inertial loops and then, as the spin-down drag removes their ageostrophic wobble, settle into steady flow that runs parallel to the sea-surface contours rather than down them — geostrophic balance, the mechanism that steers the Gulf Stream, the Antarctic Circumpolar Current, and the interior of every subtropical gyre.