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Above mean sea level” (AMSL) is a measurement used to indicate the height or altitude of a location relative to the average sea level. It is a standard reference point used in geography, aviation, and various other fields to describe elevation.

Key Points:

  1. Mean Sea Level (MSL): This is the average height of the surface of the sea at a specific location over a period of time, typically measured over many years to account for tidal variations.
  2. Elevation Reference: AMSL is used as a reference point for measuring the height of geographical features such as mountains, hills, cities, and other points of interest relative to sea level.
  3. Applications:
  • Geography and Cartography: AMSL is crucial for mapping and defining the topography of regions, continents, and countries.
  • Aviation: Pilots use AMSL to determine the altitude of aircraft above ground level (AGL) during flight.
  • Meteorology: Weather stations often report temperatures, atmospheric pressure, and other data with reference to AMSL.
  1. Accuracy: Measurements of altitude AMSL are typically made using altimeters, which calculate the height based on atmospheric pressure and compare it to the known pressure at sea level.


  • Mount Everest: The highest mountain peak in the world, Mount Everest, has an elevation of 8,848 meters above mean sea level.
  • Cities: For example, Mexico City is located approximately 2,240 meters above mean sea level.
  • Flight: During a flight, pilots might report their altitude as 30,000 feet above mean sea level.

Above mean sea level (AMSL) provides a standardized way to communicate and measure altitude or elevation relative to the average sea level, serving essential roles in various fields from navigation and geography to aviation and meteorology. It allows for accurate spatial understanding and facilitates safe operations in transportation and other activities dependent on precise altitude measurements.

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