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How satellites measure the sea from space

Transcript

From their orbit high above the Earth, satellites send thousands of microwave pulses down to the ocean every second. They precisely time how long it takes for these signals to bounce off the surface and return, calculating the distance to the sea. While a single measurement is accurate to a few centimeters, averaging hundreds of thousands of these readings allows scientists to determine the global mean sea level with a precision of just a few millimeters.