# Is the geoid the same as MSL?

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## Is the geoid the same as MSL?

The geoid is a measurement of mean sea level (MSL). When you average out the motion of waves, the level at which water settles is MSL. The geoid is the hypothetical MSL without digging a canal… And surveyors use it to measure precise surface elevations as a true zero surface in a vertical datum.

## Is GPS altitude MSL or AGL?

The Spider GPS altitude is Above Mean Sea Level (AMSL). This means you may see a difference between pressure altitude sensors or Above Ground Level (AGL) altitude sensors. The vertical accuracy is approximately within 100 feet.

## Is airport elevation AGL or MSL?

The Federal Aviation Administration (FAA) defines the Airport Elevation as the highest point of an airport’s usable runways and is measured in height above mean sea level. AGL is the altitude expressed in the actual number of feet measured above the ground.

## Is MSL a datum?

Mean Sea Level (MSL) is a tidal datum which is computed by the National Ocean Service (NOS), Center for Operational Oceanographic Products and Services (CO-OPS) as part of the National Tidal Datum Epoch (NTDE) based on data collected over a 19-year tide cycle.

## Which is the correct solution for the EGM96 model?

EGM96 is a composite solution, consisting of: and the quadrature solution at degree 360. PGM2000A is an EGM96 derivative model that incorporates normal equations for the dynamic ocean topography implied by the POCM4B ocean general circulation model .

## How are EGM96 and WGS84 related?

Good explanation. WGS84 (elipsoid) and EGM96 (geoid) are two different models, with different applications. When you see a height in a map, it is usually a height over the geoid (orthometric height), but when you get one from a GPS device, it is usually a height over the elipsoid.

## Is there such thing as ” the ” EGM96 geoid?

Assume that measurements of mean sea level (MSL) can be made through altimetry. Define “the geoid” (G) as the particular level surface which best fits (in the least squares sense, globally)to mean sea level. (A global fit is not truly possible, as altimetric measurements do not reach to the poles.

## How are GPS and MSL related to each other?

These measurements are based on an ellipsoid surface that is a mathematically generated model of the earth obtained from a three-dimensional Cartesian coordinate system. The GPS receivers can provide only the ellipsoid (geometric) height. However, most users expect accurate elevation readings that are related to MSL.