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

Pre-processing: Source code for preparation of the original dataset for redistribution in Ensaio

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

Load the netCDF grid with xarray.

<xarray.DataArray 'geoid' (latitude: 1081, longitude: 2161)> Size: 9MB
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 17kB -180.0 -179.8 -179.7 ... 179.8 180.0
  * latitude   (latitude) float64 9kB -90.0 -89.83 -89.67 ... 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

Total running time of the script: (0 minutes 8.040 seconds)

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