Earth gravity grid at 10 arc-minute resolution

Earth gravity grid at 10 arc-minute resolution

The grid is grid-node registered and stored in netCDF with CF-compliant metadata. The gravity values are derived from the EIGEN-6C4 spherical harmonic model. Here “gravity” refers to the combined gravitational and centrifugal accelerations.

The data are calculated uniformly at 10 km above the WGS84 ellipsoid.

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.

Out:

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

Load the netCDF grid with xarray.

<xarray.DataArray 'gravity' (latitude: 1081, longitude: 2161)>
array([[980106.5 , 980106.5 , 980106.5 , ..., 980106.5 , 980106.5 ,
        980106.5 ],
       [980108.25, 980108.25, 980108.25, ..., 980108.25, 980108.25,
        980108.25],
       [980108.8 , 980108.8 , 980108.8 , ..., 980108.75, 980108.75,
        980108.8 ],
       ...,
       [980153.8 , 980153.75, 980153.6 , ..., 980153.94, 980153.8 ,
        980153.8 ],
       [980160.44, 980160.44, 980160.44, ..., 980160.44, 980160.44,
        980160.44],
       [980157.5 , 980157.5 , 980157.5 , ..., 980157.5 , 980157.5 ,
        980157.5 ]], 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
    height     (latitude, longitude) float32 1e+04 1e+04 1e+04 ... 1e+04 1e+04
Attributes:
    Conventions:     CF-1.8
    title:           Gravity acceleration (EIGEN-6C4) at a constant geometric...
    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:       gravity acceleration
    description:     magnitude of the gravity acceleration vector (gravitatio...
    units:           mGal
    actual_range:    [974748.6 980201.9]
    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="viridis", shading="+nt0.5")
fig.colorbar(frame='af+l"gravity [mGal]"')
fig.coast(shorelines=True, resolution="c", area_thresh=1e4)
fig.show()
earth gravity

Out:

<IPython.core.display.Image object>

Total running time of the script: ( 0 minutes 10.521 seconds)

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