.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/plot_global_polar.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download_gallery_plot_global_polar.py>`
        to download the full example code

.. rst-class:: sphx-glr-example-title

.. _sphx_glr_gallery_plot_global_polar.py:


Create a Global Map and Polar Views
===================================

This script creates a map of the first time-derivative of the radial field
component from the CHAOS geomagnetic field model on the core surface
in 2016. The map projections are handled by the Cartopy package, which you
need to install in addition to ChaosMagPy to execute the script.

.. GENERATED FROM PYTHON SOURCE LINES 11-85



.. image-sg:: /gallery/images/sphx_glr_plot_global_polar_001.png
   :alt: plot global polar
   :srcset: /gallery/images/sphx_glr_plot_global_polar_001.png
   :class: sphx-glr-single-img





.. code-block:: Python


    # Copyright (C) 2024 Clemens Kloss
    #
    # This script is free software: you can redistribute it and/or modify it under
    # the terms of the GNU Lesser General Public License as published by the Free
    # Software Foundation, either version 3 of the License, or (at your option) any
    # later version.
    #
    # This script is distributed in the hope that it will be useful, but WITHOUT
    # ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
    # FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
    # details.
    #
    # You should have received a copy of the GNU Lesser General Public License
    # along with this script. If not, see <https://www.gnu.org/licenses/>.

    import chaosmagpy as cp
    import numpy as np
    import matplotlib.pyplot as plt
    import matplotlib.gridspec as gridspec
    from mpl_toolkits.axes_grid1.inset_locator import inset_axes
    import cartopy.crs as ccrs

    model = cp.CHAOS.from_mat('CHAOS-7.mat')  # load the mat-file of CHAOS-7

    time = cp.data_utils.mjd2000(2016, 1, 1)  # convert date to mjd2000
    radius = 3485.  # radius of the core surface in km
    theta = np.linspace(1., 179., 181)  # colatitude in degrees
    phi = np.linspace(-180., 180, 361)  # longitude in degrees

    # compute radial SV up to degree 16 using CHAOS
    B, _, _ = model.synth_values_tdep(time, radius, theta, phi,
                                      nmax=16, deriv=1, grid=True)

    limit = 30e3  # nT/yr colorbar limit

    # create figure
    fig = plt.figure(figsize=(12, 8))

    fig.subplots_adjust(
        top=0.98,
        bottom=0.02,
        left=0.013,
        right=0.988,
        hspace=0.0,
        wspace=1.0
    )

    # make array of axes
    gs = gridspec.GridSpec(2, 2, width_ratios=[0.5, 0.5], height_ratios=[0.35, 0.65])

    axes = [
        plt.subplot(gs[0, 0], projection=ccrs.NearsidePerspective(central_latitude=90.)),
        plt.subplot(gs[0, 1], projection=ccrs.NearsidePerspective(central_latitude=-90.)),
        plt.subplot(gs[1, :], projection=ccrs.Mollweide())
    ]

    for ax in axes:
        pc = ax.pcolormesh(phi, 90. - theta, B, cmap='PuOr', vmin=-limit,
                           vmax=limit, transform=ccrs.PlateCarree())
        ax.gridlines(linewidth=0.5, linestyle='dashed', color='grey',
                     ylocs=np.linspace(-90, 90, num=7),  # parallels
                     xlocs=np.linspace(-180, 180, num=13))  # meridians
        ax.coastlines(linewidth=0.8, color='k')

    # inset axes into global map and move upwards
    cax = inset_axes(axes[-1], width="45%", height="5%", loc='upper center',
                     borderpad=-12)

    # use last artist for the colorbar
    clb = plt.colorbar(pc, cax=cax, extend='both', orientation='horizontal')
    clb.set_label('nT/yr', fontsize=14)

    plt.show()


.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 4.154 seconds)


.. _sphx_glr_download_gallery_plot_global_polar.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: plot_global_polar.ipynb <plot_global_polar.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: plot_global_polar.py <plot_global_polar.py>`


.. only:: html

 .. rst-class:: sphx-glr-signature

    `Gallery generated by Sphinx-Gallery <https://sphinx-gallery.github.io>`_