Why do I get the warning "Radial position is less than equatorial radius of planetary model" when using the "gravitysp​hericalhar​monic" function?

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The aerospace toolbox function "gravitysphericalharmonic" issues a warning when the radius of the ecef coordinates is less than the equatorial axis.
"Warning: Radial position is less than equatorial radius of planetary model, 6.37814e+06."
What is the reason for the warning?

Accepted Answer

MathWorks Support Team
MathWorks Support Team on 18 Jan 2024
Edited: MathWorks Support Team on 1 Mar 2024
The warning message states that the radius used in error handling is the equatorial radius, and provides the numerical value for the radius used in the validation:
>> gx = gravitysphericalharmonic( [-6378.1363e3 0 0] )
"Warning: Radial position is less than equatorial radius of planetary model, 6.37814e+06."
The documentation page for the function provides additional information in the following limitation:
"Spherical harmonic gravity model is valid for radial positions greater than the planet equatorial radius. Minor errors might occur for radial positions near or at the planetary surface. The spherical harmonic gravity model is not valid for radial positions less than planetary surface."
This limitation is derived from the underlying gravity models outlined in the block's references. In order to look at the references, please run the below command in the MATLAB R2018b command window to get the release specific documentation:
web(fullfile(docroot, 'aerotbx/ug/gravitysphericalharmonic.html#References'))
You can pass the function an "action" input set to "None" to suppress this warning. This is the recommended action if you would like to calculate gravitational acceleration between R_e and R_p.
Please follow the below link to search for the required information regarding the current release:

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