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

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

.. _sphx_glr_gallery_plot_spectrum.py:


Spatial Power Spectra
=====================

This script creates a plot of the spatial power spectrum of the time-dependent
internal field from the CHAOS geomagnetic field model.

.. GENERATED FROM PYTHON SOURCE LINES 9-40



.. image-sg:: /gallery/images/sphx_glr_plot_spectrum_001.png
   :alt: Spatial power spectra at Earth's surface
   :srcset: /gallery/images/sphx_glr_plot_spectrum_001.png
   :class: sphx-glr-single-img





.. code-block:: Python


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

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

    nmax = 20
    time = cp.data_utils.mjd2000(2018, 1, 1)
    degrees = np.arange(1, nmax+1, dtype=int)

    fig, ax = plt.subplots(1, 1, figsize=(12, 7))

    for deriv, label in enumerate(['nT', 'nT/yr', 'nT/yr$^2$']):

        # get spatial power spectrum from time-dependent internal field in CHAOS
        spec = model.model_tdep.power_spectrum(time, nmax=nmax, deriv=deriv)
        ax.semilogy(degrees, spec, label=label)

    ax.legend()
    ax.grid(which='both')

    ax.yaxis.set_major_locator(ticker.LogLocator(base=10.0, numticks=15))
    ax.xaxis.set_major_locator(ticker.MultipleLocator(1))

    ax.set_title("Spatial power spectra at Earth's surface", fontsize=14)
    ax.set_xlabel('Spherical harmonic degree')

    plt.tight_layout()
    plt.show()


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

   **Total running time of the script:** (0 minutes 0.444 seconds)


.. _sphx_glr_download_gallery_plot_spectrum.py:

.. only:: html

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

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

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

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

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


.. only:: html

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

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