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

100%|██████████████████████████████████████| 1.34M/1.34M [00:00<00:00, 857MB/s]
grdproject [WARNING]: x_inc does not divide 180; geographic boundary condition changed to natural.
grdsample [WARNING]: Output sampling interval in x exceeds input interval and may lead to aliasing.
grdsample [WARNING]: Output sampling interval in y exceeds input interval and may lead to aliasing.

<xarray.DataArray 'z' (y: 1401, x: 1401)> Size: 8MB
array([[-30.30672  , -30.331656 , -30.378214 , ...,  48.04059  ,
         48.028038 ,  48.024025 ],
       [-30.294294 , -30.303253 , -30.33566  , ...,  48.007965 ,
         47.999096 ,  48.0013   ],
       [-30.327927 , -30.32653  , -30.343807 , ...,  47.99285  ,
         47.988316 ,  47.992607 ],
       ...,
       [ -3.2417529,  -3.207609 ,  -3.1544657, ..., -51.43643  ,
        -51.65334  , -51.86358  ],
       [ -3.3159869,  -3.2748904,  -3.2315264, ..., -51.456768 ,
        -51.677677 , -51.8906   ],
       [ -3.387241 ,  -3.3402357,  -3.2906868, ..., -51.47565  ,
        -51.697647 , -51.91267  ]], shape=(1401, 1401), dtype=float32)
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:
    actual_range:  [-52.08355713  68.41519928]
    long_name:     z

xarray.DataArray

'z'

• y: 1401
• x: 1401

• -30.31 -30.33 -30.38 -30.42 -30.44 ... -51.25 -51.48 -51.7 -51.91

  array([[-30.30672  , -30.331656 , -30.378214 , ...,  48.04059  ,
           48.028038 ,  48.024025 ],
         [-30.294294 , -30.303253 , -30.33566  , ...,  48.007965 ,
           47.999096 ,  48.0013   ],
         [-30.327927 , -30.32653  , -30.343807 , ...,  47.99285  ,
           47.988316 ,  47.992607 ],
         ...,
         [ -3.2417529,  -3.207609 ,  -3.1544657, ..., -51.43643  ,
          -51.65334  , -51.86358  ],
         [ -3.3159869,  -3.2748904,  -3.2315264, ..., -51.456768 ,
          -51.677677 , -51.8906   ],
         [ -3.387241 ,  -3.3402357,  -3.2906868, ..., -51.47565  ,
          -51.697647 , -51.91267  ]], shape=(1401, 1401), dtype=float32)

• 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.],
          shape=(1401,))

  • 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.],
          shape=(1401,))

• 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

  description :

  actual_range :

  [-52.08355713 68.41519928]

  long_name :

  z

_ = 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: -52.0835571289
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)