[FEAT] Improve dipole field specification

[aburrell]

Is your feature request related to a problem? Please describe.
In src/bfield.cpp, the following lines state:

else if (input.get_bfield_type() == "dipole") {
    // This is an approximation right now, due to the fact that the
    // pole on some planets (including Earth), have an offset, so the
    // pole location should be altitude dependent.  For many planets,
    // this is a very small error, but should be fixed at some point.

Describe the solution you'd like
I would like this error to be fixed at some point.

Describe alternatives you've considered
Leaving only a simple dipole field

[aaronjridley]

In general, we should implement different magnetic field models. For example: http://superdarn.thayer.dartmouth.edu/aacgm.html
or
https://www.ngdc.noaa.gov/geomag/models.shtml

[aburrell]

I would recommend using apex coordinates of AACGM-V2 coordinates, as they are undefined near the SAA.

[aaronjridley]

Do you know if we can get apex coordinates in C? (GITM uses APEX, so I am very used to APEX...) I am hoping to keep as much in C / C++ as possible. If we have to use fortran, we can figure out how to compile it in, but it would be nice to isolate is as much as possible.

[aburrell]

As far as I know it’s only in Fortran, but Leslie Lamarche just recently made it modern fortran! Could be possible to wrap or re-write, depending on the needs/resources of the project. From: Aaron Ridley ***@***.***> Reply-To: AetherModel/Aether ***@***.***> Date: Friday, April 14, 2023 at 08:09 To: AetherModel/Aether ***@***.***> Cc: "Burrell, Angeline G CIV USN NRL (7633) Washington DC (USA)" ***@***.***>, Author ***@***.***> Subject: Re: [AetherModel/Aether] [FEAT] Improve dipole field specification (#43) Do you know if we can get apex coordinates in C? (GITM uses APEX, so I am very used to APEX...) I am hoping to keep as much in C / C++ as possible. If we have to use fortran, we can figure out how to compile it in, but it would be nice to isolate is as much as possible. — Reply to this email directly, view it on GitHub<#43 (comment)>, or unsubscribe<https://github.com/notifications/unsubscribe-auth/ABVYF7XVCVXCYGR7P2BNMPDXBE47ZANCNFSM4ZLC2WJQ>. You are receiving this because you authored the thread.Message ID: ***@***.***>