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Sea level. This marker indicating sea level is situated between Jerusalem and the Dead Sea. Mean sea level (MSL, often shortened to sea level) is an average surface level of one or more among Earth 's coastal bodies of water from which heights such as elevation may be measured. The global MSL is a type of vertical datum – a standardised ...
Height above mean sea level. Height above mean sea level is a measure of a location's vertical distance (height, elevation or altitude) in reference to a vertical datum based on a historic mean sea level. In geodesy, it is formalized as orthometric height. The zero level varies in different countries due to different reference points and ...
The National Geodetic Vertical Datum of 1929 is the official name since 1973 [1] of the vertical datum established for vertical control surveying in the United States of America by the General Adjustment of 1929. Originally known as Sea Level Datum of 1929, NGVD 29 was determined and published by the United States Coast and Geodetic Survey [2 ...
A nautical chart or hydrographic chart is a graphic representation of a sea region or water body and adjacent coasts or banks. Depending on the scale of the chart, it may show depths of water (bathymetry) and heights of land (topography), natural features of the seabed, details of the coastline, navigational hazards, locations of natural and ...
It superseded the National Geodetic Vertical Datum of 1929 (NGVD 29), [2] previously known as the Sea Level Datum of 1929.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.
The orthometric height (symbol H) is the vertical distance along the plumb line from a point of interest to a reference surface known as the geoid, the vertical datum that approximates mean sea level. [1][2] Orthometric height is one of the scientific formalizations of a layman's "height above sea level", along with other types of heights in ...
The largest absolute deviation can be found in the Indian Ocean Geoid Low, 106 meters below the average sea level. [18] Another large feature is the North Atlantic Geoid High (or North Atlantic Geoid Swell), caused in part by the weight of ice cover over North America and northern Europe in the Late Cenozoic Ice Age .
Established in 1985, The Global Sea Level Observing System ( GLOSS) is an Intergovernmental Oceanographic Commission (IOC) program whose purpose is to measure sea level globally for long-term climate change studies. The program's purpose has changed since the 2004 Indian Ocean earthquake and the program now collects real time measurements of ...