How Satellites Map the Ocean Floor Indirectly

Satellite Altimetry Reveals Seafloor Topography

Radar cannot penetrate water, but satellites measure sea-surface height with centimeter precision. The sea surface mirrors seafloor gravity anomalies:

• Seamounts/ridges → excess mass → stronger gravity → water piles up → sea-surface highs.
• Trenches/abyssal plains → mass deficit → weaker gravity → water depresses → sea-surface lows.

By mapping these geoid anomalies, satellites (e.g., GEOSAT, ERS-1, CryoSat, Jason series) infer bathymetry. Combined with ship soundings and gravity data, global models like SRTM15+ and GEBCO achieve ~100–500 m resolution.