This is a Python wrapper for the Apex fortran library by Emmert et al. [2010] [1], which allows converting between geodetic, modified apex, and quasi-dipole coordinates as well as getting modified apex and quasi-dipole base vectors (Richmond [1995] [2]). MLT calculations are also included. The package is free software (MIT license).
Install (requires NumPy before installation):
pip install apexpy
This assumes that the same version of libgfortran is installed in the same location as when the pip wheel was built. If not, you may have trouble importing apexpy and you will have to build apexpy yourself using:
pip install --global-option='build_ext' apexpy
which requires both libgfortran and gfortran to be installed on your system.
Conversion is done by creating an Apex object and using its methods to
perform the desired calculations. Some simple examples:
>>> from apexpy import Apex
>>> from __future__ import print_function
>>> A = Apex(date=2015.3) # datetime objects are also supported
>>> # geo to apex, scalar input
>>> mlat, mlon = A.convert(60, 15, 'geo', 'apex', height=300)
>>> print("{:.12f}, {:.12f}".format(mlat, mlon))
57.469573974609, 93.633583068848
>>> # apex to geo, array input
>>> glat, glon = A.convert([90, -90], 0, 'apex', 'geo', height=0)
>>> print(["{:.12f}, {:.12f}".format(ll, glon[i]) for i,ll in enumerate(glat)])
['83.099594116211, -84.594589233398', '-74.388267517090, 125.714927673340']
>>> # geo to MLT
>>> import datetime as dt
>>> mlat, mlt = A.convert(60, 15, 'geo', 'mlt', datetime=dt.datetime(2015, 2, 10, 18, 0, 0))
>>> print("{:.12f}, {:.12f}".format(mlat, mlt))
56.590423583984, 19.108103879293
>>> # can also convert magnetic longitude to mlt
>>> mlt = A.mlon2mlt(120, dt.datetime(2015, 2, 10, 18, 0, 0))
>>> print("{:.2f}".format(mlt))
20.89
If you don't know or use Python, you can also use the command line. See details in the full documentation.
https://apexpy.readthedocs.org/
| [1] | Emmert, J. T., A. D. Richmond, and D. P. Drob (2010), A computationally compact representation of Magnetic-Apex and Quasi-Dipole coordinates with smooth base vectors, J. Geophys. Res., 115(A8), A08322, doi:10.1029/2010JA015326. |
| [2] | Richmond, A. D. (1995), Ionospheric Electrodynamics Using Magnetic Apex Coordinates, Journal of geomagnetism and geoelectricity, 47(2), 191–212, doi:10.5636/jgg.47.191. |
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