.. DO NOT EDIT.
.. THIS FILE WAS AUTOMATICALLY GENERATED BY SPHINX-GALLERY.
.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "gallery/plot_stations.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_stations.py>`
        to download the full example code

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

.. _sphx_glr_gallery_plot_stations.py:


Evaluate CHAOS at a Ground Observatory
======================================

This script creates a time series plot of the first time-derivative of
the magnetic field components (SV) by evaluating the CHAOS geomagnetic field
model.

In this example the location of the ground observatory in Niemegk (Germany)
is used. The spherical harmonic coefficients of the SV are truncated
at degree 16. Note that the SV vector components are spherical geographic and
not geodetic.

.. GENERATED FROM PYTHON SOURCE LINES 15-65



.. image-sg:: /gallery/images/sphx_glr_plot_stations_001.png
   :alt: SV components at Niemegk given by CHAOS-7, d$B_r$/d$t$, d$B_t$/d$t$, d$B_p$/d$t$
   :srcset: /gallery/images/sphx_glr_plot_stations_001.png
   :class: sphx-glr-single-img





.. code-block:: Python


    import chaosmagpy as cp
    import matplotlib.pyplot as plt
    import numpy as np

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

    height = 0.  # geodetic height of the observatory in Niemegk (WGS84)
    lat_gg = 52.07  # geodetic latitude of Niemegk in degrees
    lon = 12.68  # longitude in degrees

    radius, theta = cp.coordinate_utils.gg_to_geo(height, 90. - lat_gg)

    data = {
        'Time': np.linspace(cp.mjd2000(1998, 1, 1), cp.mjd2000(2018, 1, 1), 500),  # time in mjd2000
        'Radius': radius,  # spherical geographic radius in kilometers
        'Theta': theta,  # spherical geographic colatitude in degrees
        'Phi': lon  # longitude in degrees
    }

    # compute SV components up to degree 16 (note deriv=1)
    dBr, dBt, dBp = model.synth_values_tdep(
        data['Time'], data['Radius'], data['Theta'], data['Phi'], nmax=16, deriv=1)

    fig, axes = plt.subplots(1, 3, figsize=(12, 5))
    fig.subplots_adjust(
        top=0.874,
        bottom=0.117,
        left=0.061,
        right=0.985,
        hspace=0.2,
        wspace=0.242
    )

    fig.suptitle(f'SV components at Niemegk given by {model.name}', fontsize=14)

    axes[0].plot(cp.timestamp(data['Time']), dBr)
    axes[1].plot(cp.timestamp(data['Time']), dBt)
    axes[2].plot(cp.timestamp(data['Time']), dBp)

    axes[0].set_title('d$B_r$/d$t$')
    axes[1].set_title('d$B_t$/d$t$')
    axes[2].set_title('d$B_p$/d$t$')

    for ax in axes:
        ax.grid()
        ax.set_xlabel('Year')
        ax.set_ylabel('nT/yr')

    plt.show()


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

   **Total running time of the script:** (0 minutes 0.222 seconds)


.. _sphx_glr_download_gallery_plot_stations.py:

.. only:: html

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

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

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

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

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


.. only:: html

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

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