Geoid Anomaly Grid

Description: Gridded geoid heights from EIGEN-6C4 originally at a 10 arc-min resolution. Can be added to a ellipsoid-referenced elevation grid to convert it to be referenced to the geoid.

Dataset:

Uieda, Leonardo. “Fatiando a Terra Data: Earth - Geoid Height Grid at 10 Arc-Minute Resolution.” Zenodo, January 20, 2022. https://doi.org/10.5281/zenodo.5882205.

Associated paper:

Förste, Christoph, Sean.L. Bruinsma, Oleg Abrikosov, Jean-Michel Lemoine, Jean Charles Marty, Frank Flechtner, G. Balmino, F. Barthelmes, and R. Biancale. “EIGEN-6C4 The Latest Combined Global Gravity Field Model Including GOCE Data up to Degree and Order 2190 of GFZ Potsdam and GRGS Toulouse.” Application/octet-stream,application/octet-stream,application/zip. GFZ Data Services, 2014. https://doi.org/10.5880/ICGEM.2015.1.

%%capture
%load_ext autoreload
%autoreload 2

from polartoolkit import fetch, maps, utils

data = fetch.geoid(
    hemisphere="north"
    # available options
    # region,
    # spacing,
    # registration ("g" for gridline or "p" for pixel),
)
data

<xarray.DataArray 'z' (y: 1401, x: 1401)> Size: 16MB
array([[-30.31243706, -30.33487129, -30.37892342, ...,  48.041008  ,
         48.02936554,  48.0265274 ],
       [-30.29789162, -30.30325317, -30.33566093, ...,  48.00796509,
         47.99909592,  48.00268555],
       [-30.33016205, -30.32653046, -30.34380722, ...,  47.99285126,
         47.98831558,  47.99351501],
       ...,
       [ -3.24265838,  -3.20760894,  -3.15446568, ..., -51.43643188,
        -51.65333939, -51.86560059],
       [ -3.31388164,  -3.27489042,  -3.23152637, ..., -51.45676804,
        -51.67767715, -51.89131546],
       [ -3.38364506,  -3.3380127 ,  -3.29133773, ..., -51.47672653,
        -51.69813156, -51.91356659]])
Coordinates:
  * y        (y) float64 11kB -3.5e+06 -3.495e+06 ... 3.495e+06 3.5e+06
  * x        (x) float64 11kB -3.5e+06 -3.495e+06 ... 3.495e+06 3.5e+06
Attributes:
    Conventions:   CF-1.7
    title:
    history:       gmt grdsample @GMTAPI@-S-I-G-M-G-N-000000 -G@GMTAPI@-S-O-G...
    description:
    long_name:     z
    actual_range:  [-52.08284378  68.41519928]

xarray.DataArray

'z'

• y: 1401
• x: 1401

• -30.31 -30.33 -30.38 -30.42 -30.44 ... -51.26 -51.48 -51.7 -51.91

  array([[-30.31243706, -30.33487129, -30.37892342, ...,  48.041008  ,
           48.02936554,  48.0265274 ],
         [-30.29789162, -30.30325317, -30.33566093, ...,  48.00796509,
           47.99909592,  48.00268555],
         [-30.33016205, -30.32653046, -30.34380722, ...,  47.99285126,
           47.98831558,  47.99351501],
         ...,
         [ -3.24265838,  -3.20760894,  -3.15446568, ..., -51.43643188,
          -51.65333939, -51.86560059],
         [ -3.31388164,  -3.27489042,  -3.23152637, ..., -51.45676804,
          -51.67767715, -51.89131546],
         [ -3.38364506,  -3.3380127 ,  -3.29133773, ..., -51.47672653,
          -51.69813156, -51.91356659]])

• Coordinates: (2)
  • y
    (y)
    float64
    -3.5e+06 -3.495e+06 ... 3.5e+06

    long_name :

    y

    axis :

    Y

    actual_range :

    [-3500000. 3500000.]

    array([-3500000., -3495000., -3490000., ...,  3490000.,  3495000.,  3500000.])

  • x
    (x)
    float64
    -3.5e+06 -3.495e+06 ... 3.5e+06

    long_name :

    x

    axis :

    X

    actual_range :

    [-3500000. 3500000.]

    array([-3500000., -3495000., -3490000., ...,  3490000.,  3495000.,  3500000.])

• Indexes: (2)
  • y
    PandasIndex

    PandasIndex(Index([-3500000.0, -3495000.0, -3490000.0, -3485000.0, -3480000.0, -3475000.0,
           -3470000.0, -3465000.0, -3460000.0, -3455000.0,
           ...
            3455000.0,  3460000.0,  3465000.0,  3470000.0,  3475000.0,  3480000.0,
            3485000.0,  3490000.0,  3495000.0,  3500000.0],
          dtype='float64', name='y', length=1401))

  • x
    PandasIndex

    PandasIndex(Index([-3500000.0, -3495000.0, -3490000.0, -3485000.0, -3480000.0, -3475000.0,
           -3470000.0, -3465000.0, -3460000.0, -3455000.0,
           ...
            3455000.0,  3460000.0,  3465000.0,  3470000.0,  3475000.0,  3480000.0,
            3485000.0,  3490000.0,  3495000.0,  3500000.0],
          dtype='float64', name='x', length=1401))

• Attributes: (6)

  Conventions :

  CF-1.7

  title :

  history :

  gmt grdsample @GMTAPI@-S-I-G-M-G-N-000000 -G@GMTAPI@-S-O-G-G-G-Y-000001 -I5000.0 -R-3500000.0/3500000.0/-3500000.0/3500000.0 -Vw -rg

  description :

  long_name :

  z

  actual_range :

  [-52.08284378 68.41519928]

_ = utils.get_grid_info(data, print_info=True)

grid spacing: 5000.0 m
grid region: (-3500000.0, 3500000.0, -3500000.0, 3500000.0)
grid zmin: -52.0828437805
grid zmax: 68.4151992798
grid registration: g

fig = maps.plot_grd(
    data,
    title="EIGEN-6C4 Geoid Height",
    cmap="balance+h0",
    coast=True,
    cbar_label="meters",
    hist=True,
    robust=True,
    hemisphere="north",
    shading="+nt.1",
)

fig.show(dpi=200)