geoidheight

Calculate geoid height

Syntax

N = geoidheight(latitude,longitude)

N = geoidheight(latitude,longitude,modelname)

N = geoidheight(latitude,longitude,action)

N = geoidheight(latitude,longitude,modelname,action)

N = geoidheight(latitude,longitude,'custom',datafile)

N = geoidheight(___,action)

Description

N = geoidheight(latitude,longitude) calculates the geoid height using the EGM96 Geopotential Model. For this geopotential model, the function calculates the geoid heights to an accuracy of 0.01 m and interpolates an array of m geoid heights at m geodetic latitudes, latitude, and m longitudes, longitude.

N = geoidheight(latitude,longitude,modelname) calculates the geoid height using the geopotential model, modelname.

N = geoidheight(latitude,longitude,action) calculates the geoid height and performs action if latitude or longitude are out of range.

N = geoidheight(latitude,longitude,modelname,action) calculates the geoid height using modelname and performs action if latitude or longitude are out of range.

N = geoidheight(latitude,longitude,'custom',datafile) calculates the geoid height using the custom model specified by datafile.

N = geoidheight(___,action) calculates the geoid height using the custom geopotential model and performs function performs action if latitude or longitude are out of range. Specify action as the last input argument preceded by any of the input argument combinations in the previous syntaxes.

Examples

Calculate EGM96 Geoid Height with Warning

This example shows how to calculate the EGM96 geoid height at 42.4 degrees N latitude and 71.0 degrees W longitude. A warning, enabled by default, is returned for the out-of-range longitude value:

N = geoidheight(42.4,71.0)

N = 
-36.5900

Calculate Custom Geoid Height at Two Locations

This example shows how to calculate a custom geoid height at two different locations:

N = geoidheight([39.3,33.4],[-77.2,36.5],'custom',...
'geoidegm96grid','none')

N = 1×2

  -33.0100   25.5500

Input Arguments

latitude — Geodetic latitudes

array

Geodetic latitudes, specified as an array of m geodetic latitudes, in degrees, where north latitude is positive and south latitude is negative.

If latitude is not within the range –90 to 90, inclusive, this function wraps the value to be within the range when action is set to 'None' or 'Warning'. It does not wrap when action is set to 'Error'.

Data Types: double | single

longitude — Longitudes

array

Longitudes, specified as an array of m longitudes, in degrees, where east longitude is positive and west longitude is negative. If longitude is not within the range 0 to 360 inclusive, this function wraps the value to be within the range.

If longitude is not within the range –90 to 90, inclusive, this function wraps the value to be within the range when action is set to 'None' or 'Warning'. It does not wrap when action is set to 'Error'.

Data Types: double | single

modelname — Geopotential model

'EGM96' (default) | 'EGM2008' | 'custom'

Geopotential model, specified as:

Geopotential Model	Description
'EGM96'	EGM96 Geopotential Model to degree and order 360. This model uses a 15-minute grid of point values in the tide-free system. This function calculates geoid heights to an accuracy of 0.01 m for this model.
'EGM2008'	EGM2008 Geopotential Model to degree and order 2159. This model uses a 2.5-minute grid of point values in the tide-free system. This function calculates geoid heights to an accuracy of 0.001 m for this model. Note This function requires that you download EGM2008 Geopotential Model data with the Add-On Explorer. For more information, see aeroDataPackage.

Data Types: char | string

datafile — Custom geopotential model definitions

scalar

Custom geopotential model definitions, specified as a scalar file of definitions for a custom geopotential model.

This file must contain these variables:

Variable	Description
'latbp'	Array of geodetic latitude breakpoints.
'lonbp'	Array of longitude breakpoints.
'grid'	Table of geoid height values.
'windowSize'	Even integer scalar greater than 2 for the number of interpolation points.

Data Types: char | string

action — Action

'Warning' (default) | 'Error' | 'None'

Action for out-of-range input, specified as:

• 'Error' — Displays warning and indicates that the input is out of range

• 'Warning' — Displays error and indicates that the input is out of range

• 'None' — Does not display warning or error

Data Types: char | string

Output Arguments

N — Geoid heights

array | same data type as latitude argument

Geoid heights, returned as an array of M geoid heights, in meters.

Tips

• This function interpolates geoid heights from a grid of point values in the tide-free system.

• When using the EGM96 Model, this function has the limitations of the 1996 Earth Geopotential Model.

• When using the EGM2008 Model, this function has the limitations of the 2008 Earth Geopotential Model.

• The interpolation scheme wraps over the poles to allow for geoid height calculations at and near pole locations.

• The geoid undulations for the EGM96 and EGM2008 models are relative to the WGS84 ellipsoid.

• The WGS84 EGM96 geoid undulations have an error range of +/– 0.5 to +/– 1.0 m worldwide.

References

[1] Vallado, D. A. "Fundamentals of Astrodynamics and Applications." McGraw-Hill, New York, 1997.

[2] NIMA TR8350.2: "Department of Defense World Geodetic System 1984, Its Definition and Relationship with Local Geodetic Systems."

Version History

Introduced in R2010b