What does altimetry mean?
Altimetry is the science and practice of measuring altitude — the height of an object or surface relative to a reference level, usually mean sea level. The term arises most prominently in two domains: aviation, where aircraft determine their height using barometric or radio altimeters, and geoscience, where satellite altimetry bounces radar or laser pulses off the Earth's surface to map oceans, ice sheets, and terrain with remarkable precision. Satellite altimetry has become indispensable for monitoring global sea-level rise, charting deep-ocean currents, and measuring changes in polar ice. Closely related to surveying and geodesy, it contrasts with bathymetry, which measures water depth rather than height. Though technical in register, altimetry underpins some of the most consequential climate data gathered today, making it a quietly vital word in modern Earth science.
nounThe science or practice of measuring altitude, especially the height of an aircraft above sea level or of a terrain or ocean surface above a reference datum.
- The scientific discipline of measuring altitude or elevation, particularly of land surfaces, ice sheets, and the ocean surface using instruments such as radar or laser altimeters.
- The measurement of an aircraft's height above sea level or above the ground, typically by means of an altimeter.
"Satellite altimetry allows scientists to track subtle changes in global sea level."
"Radar altimetry from satellites revealed that the Greenland ice sheet is losing mass at an accelerating rate."
"The pilot relied on barometric altimetry to maintain a safe cruising altitude during the flight."
The plural is rare and generally limited to technical literature referring to multiple altimetric methods or datasets.
"Comparing radar and laser altimetries helps scientists validate measurements across different surfaces."
By bouncing radar pulses off the ocean surface from orbit, satellite altimetry can measure sea level to within a few centimetres — from hundreds of kilometres away in space.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of altimetry
Altimetry derives from the Latin 'altus', meaning high or deep, combined with the Greek-derived '-metry' suffix denoting measurement, as in other scientific disciplines such as geometry and bathymetry. The word took shape as a technical term alongside the development of precision altitude-measuring instruments, becoming widespread with the growth of aviation in the early twentieth century and later with satellite remote sensing. It shares its Latin root with cognates such as 'altitude', 'altimeter', and 'exalt'.
Related word forms
How altimetry is actually used
A technical term used chiefly in aviation, geodesy, oceanography, and remote sensing; rarely encountered in everyday conversation. In modern usage it most often appears in the context of satellite-based Earth observation.
Easily confused with altimetry
Altimetry measures height above a reference level such as sea level, while bathymetry measures the depth of water below the surface.
An altimeter is the instrument that measures altitude, whereas altimetry is the broader science and practice of making such measurements.