Topography of the Earth at 10 arc-minute resolution¶

The grid is grid-node registered and stored in netCDF with CF-compliant metadata. The values are derived from a spherical harmonic model of the ETOPO1 bedrock grid. Topography values are referenced to “sea level” and are positive upwards.

Original source: ETOPO1

import pygmt
import xarray as xr

import ensaio.v1 as ensaio

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

fname = ensaio.fetch_earth_topography()
print(fname)

Out:

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

Load the netCDF grid with xarray.

data = xr.load_dataarray(fname)
data

<xarray.DataArray 'topography' (latitude: 1081, longitude: 2161)>
array([[ 2742.,  2742.,  2742., ...,  2742.,  2742.,  2742.],
       [ 2768.,  2768.,  2768., ...,  2768.,  2768.,  2768.],
       [ 2822.,  2822.,  2821., ...,  2822.,  2822.,  2822.],
       ...,
       [-4243., -4244., -4245., ..., -4242., -4243., -4243.],
       [-4156., -4157., -4157., ..., -4156., -4156., -4156.],
       [-4237., -4237., -4237., ..., -4237., -4237., -4237.]],
      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:           Topographic and bathymetric height of ETOPO1 (ice surfac...
    crs:             WGS84
    source:          Generated from a spherical harmonic model by the ICGEM C...
    license:         public domain
    references:      https://doi.org/10.7289/V5C8276M
    long_name:       topographic height above mean sea level
    standard_name:   height_above_mean_sea_level
    description:     height topography/bathymetry referenced to mean sea level
    units:           m
    actual_range:    [-10023.   6082.]
    icgem_metadata:  generating_institute: gfz-potsdam\ngenerating_date: 2021...

xarray.DataArray

'topography'

latitude: 1081
longitude: 2161

2.742e+03 2.742e+03 2.742e+03 ... -4.237e+03 -4.237e+03 -4.237e+03

array([[ 2742.,  2742.,  2742., ...,  2742.,  2742.,  2742.],
       [ 2768.,  2768.,  2768., ...,  2768.,  2768.,  2768.],
       [ 2822.,  2822.,  2821., ...,  2822.,  2822.,  2822.],
       ...,
       [-4243., -4244., -4245., ..., -4242., -4243., -4243.],
       [-4156., -4157., -4157., ..., -4156., -4156., -4156.],
       [-4237., -4237., -4237., ..., -4237., -4237., -4237.]],
      dtype=float32)

Coordinates: (2)
- longitude
  (longitude)
  float64
  -180.0 -179.8 ... 179.8 180.0
  long_name :
  longitude
  standard_name :
  longitude
  units :
  degrees_east
  actual_range :
  [-180. 180.]
```
array([-180.      , -179.833333, -179.666667, ...,  179.666667,  179.833333,
        180.      ])
```
- latitude
  (latitude)
  float64
  -90.0 -89.83 -89.67 ... 89.83 90.0
  long_name :
  latitude
  standard_name :
  latitude
  units :
  degrees_north
  actual_range :
  [-90. 90.]
```
array([-90.      , -89.833333, -89.666667, ...,  89.666667,  89.833333,
        90.      ])
```
Attributes: (12)
Conventions :
CF-1.8
title :
Topographic and bathymetric height of ETOPO1 (ice surface) at 10 arc-minute resolution
crs :
WGS84
source :
Generated from a spherical harmonic model by the ICGEM Calculation Service (http://icgem.gfz-potsdam.de)
license :
public domain
references :
https://doi.org/10.7289/V5C8276M
long_name :
topographic height above mean sea level
standard_name :
height_above_mean_sea_level
description :
height topography/bathymetry referenced to mean sea level
units :
m
actual_range :
[-10023. 6082.]
icgem_metadata :
generating_institute: gfz-potsdam generating_date: 2021/06/11 product_type: topography body: earth modelname: etopo1-2250 max_used_degree: 720 gentlecut: 540 to 720 functional: topography_shm (from shm) unit: meter refsysname: WGS84 radiusrefsys: 6378137.000 m flatrefsys: 3.352810664747480E-03 (1/298.25722356300) long_lat_unit: degree latlimit_north: 90.000000000000 latlimit_south: -90.000000000000 longlimit_west: -180.00000000000 longlimit_east: 180.00000000000 gridstep: 0.16666666666667 latitude_parallels: 1081 longitude_parallels: 2161 number_of_gridpoints: 2336041 gapvalue: 99999.0000 weighted_mean: -2.3852244E+03 meter maxvalue: 6.0816327E+03 meter minvalue: -1.0023309E+04 meter signal_wrms: 2.5003302E+03 meter grid_format: long_lat_value attributes: longitude latitude topography_shm attributes_units: deg. deg. meter

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="etopo1", shading="+nt0.5")
fig.colorbar(frame='af+l"topography [m]"')
fig.coast(shorelines=True, resolution="c", area_thresh=1e4)
fig.show()

Out:

<IPython.core.display.Image object>

Total running time of the script: ( 0 minutes 9.534 seconds)

Gallery generated by Sphinx-Gallery

Ensaio v0.1.0

Topography of the Earth at 10 arc-minute resolution¶