Source code for pyrfu.pyrf.l_shell
#!/usr/bin/env python
# -*- coding: utf-8 -*-
# 3rd party imports
import numpy as np
# Local imports
from .cotrans import cotrans
__author__ = "Louis Richard"
__email__ = "louisr@irfu.se"
__copyright__ = "Copyright 2020-2023"
__license__ = "MIT"
__version__ = "2.4.2"
__status__ = "Prototype"
[docs]def l_shell(r_xyz):
r"""Compute spacecraft position L Shell for a dipole magnetic field
according to IRGF.
Parameters
----------
r_xyz : xarray.DataArray
Time series of the spacecraft position. Must have a
"COORDINATES_SYSTEM" attributes.
Returns
-------
out : xarray.DataArray
Time series of the spacecraft position L-Shell.
"""
# Transform spacecraft coordinates to solar magnetic system
r_sm = cotrans(r_xyz, "sm")
# Compute Geomagnetic latitude
lambda_ = np.arctan(r_sm[:, 2] / np.linalg.norm(r_sm[:, :2], axis=1))
# Compute L shell
out = np.linalg.norm(r_sm, axis=1) / np.cos(lambda_) ** 2
return out