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

.. only:: html

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

        Click :ref:`here <sphx_glr_download_sample_data_earth_geoid.py>`
        to download the full example code

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

.. _sphx_glr_sample_data_earth_geoid.py:


Earth Geoid
===========

The geoid is the equipotential surface of the Earth's gravity potential that
coincides with mean sea level. It's often represented by "geoid heights", which
indicate the height of the geoid relative to the reference ellipsoid (WGS84 in
this case). Negative values indicate that the geoid is below the ellipsoid
surface and positive values that it is above. The data are on a regular grid
with 0.5 degree spacing and was generated from the spherical harmonic model
EIGEN-6C4 [Forste_etal2014]_.

.. GENERATED FROM PYTHON SOURCE LINES 19-38



.. image-sg:: /sample_data/images/sphx_glr_earth_geoid_001.png
   :alt: Geoid heights (EIGEN-6C4)
   :srcset: /sample_data/images/sphx_glr_earth_geoid_001.png
   :class: sphx-glr-single-img


.. rst-class:: sphx-glr-script-out

 Out:

 .. code-block:: none

    <xarray.Dataset>
    Dimensions:    (latitude: 361, longitude: 721)
    Coordinates:
      * longitude  (longitude) float64 -180.0 -179.5 -179.0 ... 179.0 179.5 180.0
      * latitude   (latitude) float64 -90.0 -89.5 -89.0 -88.5 ... 89.0 89.5 90.0
    Data variables:
        geoid      (latitude, longitude) float64 -29.5 -29.5 -29.5 ... 15.37 15.37
    Attributes: (12/37)
        generating_institute:  gfz-potsdam
        generating_date:       2018/12/13
        product_type:          gravity_field
        body:                  earth
        modelname:             EIGEN-6C4
        max_used_degree:       1277
        ...                    ...
        maxvalue:              8.4722744E+01 meter
        minvalue:              -1.0625734E+02 meter
        signal_wrms:           3.0584191E+01 meter
        grid_format:           long_lat_value
        attributes:            longitude latitude geoid
        attributes_units:      deg. deg. meter






|

.. code-block:: default

    import cartopy.crs as ccrs
    import matplotlib.pyplot as plt

    import harmonica as hm

    # Load the geoid grid
    data = hm.datasets.fetch_geoid_earth()
    print(data)

    # Make a plot of data using Cartopy
    plt.figure(figsize=(10, 10))
    ax = plt.axes(projection=ccrs.Orthographic(central_longitude=100))
    pc = data.geoid.plot.pcolormesh(ax=ax, transform=ccrs.PlateCarree(), add_colorbar=False)
    plt.colorbar(
        pc, label="meters", orientation="horizontal", aspect=50, pad=0.01, shrink=0.6
    )
    ax.set_title("Geoid heights (EIGEN-6C4)")
    ax.coastlines()
    plt.show()


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

   **Total running time of the script:** ( 0 minutes  0.666 seconds)


.. _sphx_glr_download_sample_data_earth_geoid.py:


.. only :: html

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



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

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



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

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


.. only:: html

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

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