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

.. only:: html

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

        Click :ref:`here <sphx_glr_download_gallery_earth-geoid.py>`
        to download the full example code

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

.. _sphx_glr_gallery_earth-geoid.py:


Earth geoid height grid at 10 arc-minute resolution
---------------------------------------------------

The grid is grid-node registered and stored in netCDF with CF-compliant
metadata. The geoid height is derived from the EIGEN-6C4 spherical harmonic
model of the Earth's gravity field.

**Original source:** `EIGEN-6C4 model
<https://doi.org/10.5880/icgem.2015.1>`__

.. GENERATED FROM PYTHON SOURCE LINES 19-24

.. code-block:: default

    import pygmt
    import xarray as xr

    import ensaio








.. GENERATED FROM PYTHON SOURCE LINES 25-26

Download and cache the data and return the path to it on disk.

.. GENERATED FROM PYTHON SOURCE LINES 26-29

.. code-block:: default

    fname = ensaio.fetch_earth_geoid(version=1)
    print(fname)





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

 Out:

 .. code-block:: none

    /home/runner/work/_temp/cache/ensaio/v1/earth-geoid-10arcmin.nc




.. GENERATED FROM PYTHON SOURCE LINES 30-31

Load the netCDF grid with xarray.

.. GENERATED FROM PYTHON SOURCE LINES 31-34

.. code-block:: default

    data = xr.load_dataarray(fname)
    data






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    </style><pre class='xr-text-repr-fallback'>&lt;xarray.DataArray &#x27;geoid&#x27; (latitude: 1081, longitude: 2161)&gt;
    array([[-29.5     , -29.5     , -29.5     , ..., -29.5     , -29.5     ,
            -29.5     ],
           [-29.5     , -29.5     , -29.5     , ..., -29.5     , -29.5     ,
            -29.5     ],
           [-29.6     , -29.6     , -29.6     , ..., -29.6     , -29.6     ,
            -29.6     ],
           ...,
           [ 14.7     ,  14.7     ,  14.7     , ...,  14.7     ,  14.7     ,
             14.7     ],
           [ 15.2     ,  15.2     ,  15.2     , ...,  15.2     ,  15.2     ,
             15.2     ],
           [ 15.400001,  15.400001,  15.400001, ...,  15.400001,  15.400001,
             15.400001]], dtype=float32)
    Coordinates:
      * longitude  (longitude) float64 -180.0 -179.8 -179.7 ... 179.7 179.8 180.0
      * latitude   (latitude) float64 -90.0 -89.83 -89.67 -89.5 ... 89.67 89.83 90.0
    Attributes:
        Conventions:     CF-1.8
        title:           Geoid height (EIGEN-6C4) with respect to WGS84
        crs:             WGS84
        source:          Generated from the EIGEN-6C4 model by the ICGEM Calculat...
        license:         Creative Commons Attribution 4.0 International Licence
        references:      https://doi.org/10.5880/icgem.2015.1
        long_name:       geoid height
        standard_name:   geoid_height_above_reference_ellipsoid
        description:     height of the geoid with respect to the WGS84 ellipsoid
        units:           m
        actual_range:    [-106.5   86. ]
        icgem_metadata:  generating_institute: gfz-potsdam\ngenerating_date: 2021...</pre><div class='xr-wrap' style='display:none'><div class='xr-header'><div class='xr-obj-type'>xarray.DataArray</div><div class='xr-array-name'>'geoid'</div><ul class='xr-dim-list'><li><span class='xr-has-index'>latitude</span>: 1081</li><li><span class='xr-has-index'>longitude</span>: 2161</li></ul></div><ul class='xr-sections'><li class='xr-section-item'><div class='xr-array-wrap'><input id='section-aae6ab7c-f8f9-48a6-b742-530d3c2b3bb9' class='xr-array-in' type='checkbox' checked><label for='section-aae6ab7c-f8f9-48a6-b742-530d3c2b3bb9' title='Show/hide data repr'><svg class='icon xr-icon-database'><use xlink:href='#icon-database'></use></svg></label><div class='xr-array-preview xr-preview'><span>-29.5 -29.5 -29.5 -29.5 -29.5 -29.5 ... 15.4 15.4 15.4 15.4 15.4 15.4</span></div><div class='xr-array-data'><pre>array([[-29.5     , -29.5     , -29.5     , ..., -29.5     , -29.5     ,
            -29.5     ],
           [-29.5     , -29.5     , -29.5     , ..., -29.5     , -29.5     ,
            -29.5     ],
           [-29.6     , -29.6     , -29.6     , ..., -29.6     , -29.6     ,
            -29.6     ],
           ...,
           [ 14.7     ,  14.7     ,  14.7     , ...,  14.7     ,  14.7     ,
             14.7     ],
           [ 15.2     ,  15.2     ,  15.2     , ...,  15.2     ,  15.2     ,
             15.2     ],
           [ 15.400001,  15.400001,  15.400001, ...,  15.400001,  15.400001,
             15.400001]], dtype=float32)</pre></div></div></li><li class='xr-section-item'><input id='section-93520fc5-a769-455e-aec7-4a0583c88324' class='xr-section-summary-in' type='checkbox'  checked><label for='section-93520fc5-a769-455e-aec7-4a0583c88324' class='xr-section-summary' >Coordinates: <span>(2)</span></label><div class='xr-section-inline-details'></div><div class='xr-section-details'><ul class='xr-var-list'><li class='xr-var-item'><div class='xr-var-name'><span class='xr-has-index'>longitude</span></div><div class='xr-var-dims'>(longitude)</div><div class='xr-var-dtype'>float64</div><div class='xr-var-preview xr-preview'>-180.0 -179.8 ... 179.8 180.0</div><input id='attrs-3284c575-0d3b-4285-8c0d-de3f2a4e5661' class='xr-var-attrs-in' type='checkbox' ><label for='attrs-3284c575-0d3b-4285-8c0d-de3f2a4e5661' title='Show/Hide attributes'><svg class='icon xr-icon-file-text2'><use xlink:href='#icon-file-text2'></use></svg></label><input id='data-1452278e-ceb2-4184-8d91-71c4c9ef64c9' class='xr-var-data-in' type='checkbox'><label for='data-1452278e-ceb2-4184-8d91-71c4c9ef64c9' title='Show/Hide data repr'><svg class='icon xr-icon-database'><use xlink:href='#icon-database'></use></svg></label><div class='xr-var-attrs'><dl class='xr-attrs'><dt><span>long_name :</span></dt><dd>longitude</dd><dt><span>standard_name :</span></dt><dd>longitude</dd><dt><span>units :</span></dt><dd>degrees_east</dd><dt><span>actual_range :</span></dt><dd>[-180.  180.]</dd></dl></div><div class='xr-var-data'><pre>array([-180.      , -179.833333, -179.666667, ...,  179.666667,  179.833333,
            180.      ])</pre></div></li><li class='xr-var-item'><div class='xr-var-name'><span class='xr-has-index'>latitude</span></div><div class='xr-var-dims'>(latitude)</div><div class='xr-var-dtype'>float64</div><div class='xr-var-preview xr-preview'>-90.0 -89.83 -89.67 ... 89.83 90.0</div><input id='attrs-e8fc6273-8a0a-4bde-be2b-7a96fe0bf46d' class='xr-var-attrs-in' type='checkbox' ><label for='attrs-e8fc6273-8a0a-4bde-be2b-7a96fe0bf46d' title='Show/Hide attributes'><svg class='icon xr-icon-file-text2'><use xlink:href='#icon-file-text2'></use></svg></label><input id='data-8c439a40-80ad-47f0-9a5e-3f016cd6ddde' class='xr-var-data-in' type='checkbox'><label for='data-8c439a40-80ad-47f0-9a5e-3f016cd6ddde' title='Show/Hide data repr'><svg class='icon xr-icon-database'><use xlink:href='#icon-database'></use></svg></label><div class='xr-var-attrs'><dl class='xr-attrs'><dt><span>long_name :</span></dt><dd>latitude</dd><dt><span>standard_name :</span></dt><dd>latitude</dd><dt><span>units :</span></dt><dd>degrees_north</dd><dt><span>actual_range :</span></dt><dd>[-90.  90.]</dd></dl></div><div class='xr-var-data'><pre>array([-90.      , -89.833333, -89.666667, ...,  89.666667,  89.833333,
            90.      ])</pre></div></li></ul></div></li><li class='xr-section-item'><input id='section-21c9780a-d72c-4715-b3bf-dac4da4f6967' class='xr-section-summary-in' type='checkbox'  ><label for='section-21c9780a-d72c-4715-b3bf-dac4da4f6967' class='xr-section-summary' >Attributes: <span>(12)</span></label><div class='xr-section-inline-details'></div><div class='xr-section-details'><dl class='xr-attrs'><dt><span>Conventions :</span></dt><dd>CF-1.8</dd><dt><span>title :</span></dt><dd>Geoid height (EIGEN-6C4) with respect to WGS84</dd><dt><span>crs :</span></dt><dd>WGS84</dd><dt><span>source :</span></dt><dd>Generated from the EIGEN-6C4 model by the ICGEM Calculation Service (http://icgem.gfz-potsdam.de)</dd><dt><span>license :</span></dt><dd>Creative Commons Attribution 4.0 International Licence</dd><dt><span>references :</span></dt><dd>https://doi.org/10.5880/icgem.2015.1</dd><dt><span>long_name :</span></dt><dd>geoid height</dd><dt><span>standard_name :</span></dt><dd>geoid_height_above_reference_ellipsoid</dd><dt><span>description :</span></dt><dd>height of the geoid with respect to the WGS84 ellipsoid</dd><dt><span>units :</span></dt><dd>m</dd><dt><span>actual_range :</span></dt><dd>[-106.5   86. ]</dd><dt><span>icgem_metadata :</span></dt><dd>generating_institute: gfz-potsdam
    generating_date: 2021/06/11
    product_type: gravity_field
    body: earth
    modelname: EIGEN-6C4
    max_used_degree: 720
    gentlecut: 540 to 720
    tide_system: tide_free
    functional: geoid
    zero_degree_term: included
    unit: meter
    crust_density: 2670.0 kg/m**3
    refsysname: WGS84
    gmrefpot: 3.98600441800E+14 m**3/s**2
    radiusrefpot: 6378137.000 m
    flatrefpot: 3.352810664747480E-03 (1/298.25722356300)
    omegarefpot: 7.29211500000E-05 1/s
    normal_potential: 6.263685171456948E+07 m**2/s**2
    long_lat_unit: degree
    latlimit_north: 90.000000000000
    latlimit_south: -90.000000000000
    longlimit_west: -180.00000000000
    longlimit_east: 180.00000000000
    gridstep: 0.16666666666667
    latitude_parallels: 1081
    longitude_parallels: 2161
    number_of_gridpoints: 2336041
    gapvalue: 999.0000
    weighted_mean: -5.2816814E-02 meter
    maxvalue: 8.5964166E+01 meter
    minvalue: -1.0652440E+02 meter
    signal_wrms: 3.0591615E+01 meter
    grid_format: long_lat_value
    attributes: longitude latitude geoid
    attributes_units: deg. deg. meter</dd></dl></div></li></ul></div></div>
    </div>
    <br />
    <br />

.. GENERATED FROM PYTHON SOURCE LINES 35-36

Make a PyGMT pseudo-color map of the grid in a Mollweide projection.

.. GENERATED FROM PYTHON SOURCE LINES 36-46

.. code-block:: default

    fig = pygmt.Figure()
    fig.basemap(
        region="g",
        projection="W15c",
        frame=True,
    )
    fig.grdimage(data, cmap="polar+h")
    fig.colorbar(frame='af+l"geoid height [m]"')
    fig.coast(shorelines=True, resolution="c", area_thresh=1e4)
    fig.show()



.. image-sg:: /gallery/images/sphx_glr_earth-geoid_001.png
   :alt: earth geoid
   :srcset: /gallery/images/sphx_glr_earth-geoid_001.png
   :class: sphx-glr-single-img


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

 Out:

 .. code-block:: none

    <IPython.core.display.Image object>





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

   **Total running time of the script:** ( 0 minutes  7.539 seconds)


.. _sphx_glr_download_gallery_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>`_