Mean Sea Level(glossary)
(1)The average level of the surface of the sea over all stages of tide and seasonal variations.
(2)The average height of the surface of the sea at a tide station for all stages of the tide over a 19-year period, usually determined from hourly height readings measured from a fixed predetermined reference level.
Note to definition (1): Mean sea level in a local context normally means mean sea level for the region calculated from observations at one or more points over a given period of time. Mean sea level in a global context differs from a global geoid by not more than 2 m.
ISO TC211. "Mean sea level." In: ISO TC211 Multilingual Glossary. Version from 2020-06-02. Concept ID: 284. Available at: https://isotc211.geolexica.org/concepts/284/
ISO TC211. "Mean sea level." In: ISO TC211 Multilingual Glossary. Version from 2020-06-02. Concept ID: 1562. Available at: https://isotc211.geolexica.org/concepts/1562/, referencing to IHO Hydrographic Dictionary S-32, Fifth Edition.