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Height above mean sea level (AMSL) is the elevation (on the ground) or altitude (in the air) of an object, relative to a reference datum for mean sea level (MSL). It is also used in aviation, where some heights are recorded and reported with respect to mean sea level (contrast with flight level ), and in the atmospheric sciences , and in land ...
Altimetry is the measurement of altitude or elevation above sea level. Common techniques are: [8] [9] Surveying, especially levelling. Global Navigation Satellite System (such as GPS), where a receiver determines a location from pseudoranges to multiple satellites. A geoid is needed to convert the 3D position to sea-level elevation.
This is a list of countries and territories by their average elevation above sea level based on the data published by Central Intelligence Agency, [1] unless another source is cited. The list includes sovereign states and self-governing dependent territories based upon the ISO standard ISO 3166-1.
These island countries also have the smallest range between their lowest (sea level) and highest points, and are very sensitive to changes in sea level. The highest and lowest points in China constitute the greatest elevation range within any single country at 9,002 metres (29,534 ft).
This is a list of places on land below mean sea level. Places artificially created such as tunnels, mines, basements, and dug holes, or places under water, or existing temporarily as a result of ebbing of sea tide etc., are not included.
Enlargeable map of the 50 U.S. states by mean elevation. This list includes the topographic elevations of each of the 50 U.S. states, ... sea level: NA 57 280 ft
The elevation of a geographic location is its height above or below a fixed reference point, most commonly a reference geoid, a mathematical model of the Earth's sea level as an equipotential gravitational surface (see Geodetic datum § Vertical datum).
It superseded the National Geodetic Vertical Datum of 1929 (NGVD 29), [2] previously known as the Sea Level Datum of 1929. NAVD 88, along with North American Datum of 1983 (NAD 83), is set to be replaced in 2025 with a new geometric reference frame and geopotential datum, based on GPS and gravimetric geoid models.