Earth & Cosmos / Earth, Climate & Environment

SWOT Wide-Swath Water Survey

NASA and CNES's SWOT satellite (December 2022) is the first to survey nearly all surface water, with ocean detail about ten times finer than earlier altimeters.

SWOT carries the Ka-band Radar Interferometer (KaRIn), which measures water height across a 120 km wide swath instead of along a single track as earlier altimeters did. It covers 78°S to 78°N, at least 86% of the globe, revisiting every 21 days, and resolves ocean circulation at 15-25 km scales and rivers wider than 100 m. NASA and CNES lead the mission with the Canadian and UK space agencies; science operations began in mid-2023, and visualisations released in May 2025 show ocean waves, internal solitary waves and eddies as small as a mile across.