Earth geoid height grid at 10 arc-minute resolution

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

import pygmt
import xarray as xr

import ensaio

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

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

Out:

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

Load the netCDF grid with xarray.

<xarray.DataArray 'geoid' (latitude: 1081, longitude: 2161)>
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...


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

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()
earth geoid

Out:

<IPython.core.display.Image object>

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

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