Satellite Altimetry

Abstract

Altimetry is a technique for measuring heights. Satellite altimetry measures the time taken by an electromagnetic pulse to propagate from the satellite to the surface and back to the satellite Satellite Altimetry Satellite altimetry is a technique of measuring heights of the Earth's surface from a satellite flying approximately at an attitude of about 1000 km. The word "altimetry" originates from the Latin "altus," meaning "high" and the Greek suffix "metry" ("metrίa," as in Geometry , Trigonometry , etc.) denoting the science or scientific discipline related to measuring heights. At the beginning, the objective of altimetry has been to measure height principally of sea surface to an accuracy of about AE1 cm, continuously, objectively, and on a global scale. Altimeters measure distances, or ranges, from a satellite to the Earth's surface and principally onto the sea, inland water levels (lakes, rivers) and ice surfaces as well (Fig. 1). Measurements of altimetric heights are thus creating profiles of the Earth's surface along satellite orbits with respect to Earth's center of mass. Satellite observations coming from altimeters, like those of Sentinel-3, Jason-3, CryoSat-2, IceSat-2, HY-2, and others, address several applications in solid Earth geophysics. Gravity determination, natural resources exploration, ocean circulation and variability, ice topography, hydrology, geodesy, climate change, bathymetry, sea-floor topography, etc., are a few applications of satellite altimetry.