pygmt.datasets.load_earth_relief

pygmt.datasets.load_earth_relief(resolution='01d', region=None, registration=None, data_source='igpp', use_srtm=False)[source]

Load Earth relief grids (topography and bathymetry) in various resolutions.

The grids are downloaded to a user data directory (usually ~/.gmt/server/earth/earth_relief, ~/.gmt/server/earth/earth_gebco, ~/.gmt/server/earth/earth_gebcosi, or ~/.gmt/server/earth/earth_synbath) the first time you invoke this function. Afterwards, it will load the grid from the data directory. So you’ll need an internet connection the first time around.

This module downloads the grids that can also be accessed by passing in the file name @earth_relief_type_res[_reg] to any grid plotting/processing function. earth_relief_type is the GMT name for the dataset. The available options are earth_relief, earth_gebco, earth_gebcosi, and earth_synbath. res is the grid resolution (see below), and reg is grid registration type (p for pixel registration or g for gridline registration).

The default color palette table (CPT) for this dataset is geo. It’s implicitly used when passing in the file name of the dataset to any grid plotting method if no CPT is explicitly specified. When the dataset is loaded and plotted as an xarray.DataArray object, the default CPT is ignored and GMT’s default CPT (turbo) is used. To use the dataset-specific CPT, you need to explicitly set cmap="geo".

Refer to https://www.generic-mapping-tools.org/remote-datasets/earth-relief.html for more details about available datasets, including version information and references.

Parameters

resolution (str) – The grid resolution. The suffix d, m and s stand for arc-degrees, arc-minutes, and arc-seconds. It can be "01d", "30m", "20m", "15m", "10m", "06m", "05m", "04m", "03m", "02m", "01m", "30s", "15s", "03s", or "01s".
region (str or list) – The subregion of the grid to load, in the form of a list [xmin, xmax, ymin, ymax] or a string xmin/xmax/ymin/ymax. Required for Earth relief grids with resolutions higher than 5 arc-minutes (i.e., "05m").
registration (str) – Grid registration type. Either "pixel" for pixel registration or "gridline" for gridline registration. Default is "gridline" for all resolutions except "15s" which is "pixel" only.
data_source (str) –
Select the source for the Earth relief data. Available options are:
- "igpp": IGPP Global Earth Relief [Default option]. See https://www.generic-mapping-tools.org/remote-datasets/earth-relief.html.
- "synbath": IGPP Global Earth Relief dataset that uses stastical properties of young seafloor to provide a more realistic relief of young areas with small seamounts.
- "gebco": GEBCO Global Earth Relief with only observed relief and inferred relief via altimetric gravity. See https://www.generic-mapping-tools.org/remote-datasets/earth-gebco.html.
- "gebcosi": GEBCO Global Earth Relief that gives sub-ice (si) elevations.
use_srtm (bool) – By default, the land-only SRTM tiles from NASA are used to generate the "03s" and "01s" grids, and the missing ocean values are filled by up-sampling the SRTM15 tiles which have a resolution of 15 arc-seconds (i.e., "15s"). If True, will only load the original land-only SRTM tiles. Only works when data_source="igpp".

Returns

grid (xarray.DataArray) – The Earth relief grid. Coordinates are latitude and longitude in degrees. Relief is in meters.

Note

The registration and coordinate system type of the returned xarray.DataArray grid can be accessed via the GMT accessors (i.e., grid.gmt.registration and grid.gmt.gtype respectively). However, these properties may be lost after specific grid operations (such as slicing) and will need to be manually set before passing the grid to any PyGMT data processing or plotting functions. Refer to pygmt.GMTDataArrayAccessor for detailed explanations and workarounds.

Examples

>>> from pygmt.datasets import load_earth_relief
>>> # load the default grid (gridline-registered 1 arc-degree grid)
>>> grid = load_earth_relief()
>>> # load the 30 arc-minutes grid with "gridline" registration
>>> grid = load_earth_relief(resolution="30m", registration="gridline")
>>> # load high-resolution (5 arc-minutes) grid for a specific region
>>> grid = load_earth_relief(
...     resolution="05m",
...     region=[120, 160, 30, 60],
...     registration="gridline",
... )
>>> # load the original 3 arc-seconds land-only SRTM tiles from NASA
>>> grid = load_earth_relief(
...     resolution="03s",
...     region=[135, 136, 35, 36],
...     registration="gridline",
...     use_srtm=True,
... )

Examples using `pygmt.datasets.load_earth_relief`

Calculating grid gradient and radiance

Calculating grid gradient with custom azimuth and normalize parameters

Clipping grid values

Cross-section along a transect

Sampling along tracks

Multiple colormaps

Creating a 3-D perspective image

Creating a map with contour lines

Interactive data visualization using Panel

Performing grid histogram equalization

Plotting Earth relief

2. Create a contour map

pygmt.datasets.load_earth_relief

Examples using pygmt.datasets.load_earth_relief

Examples using `pygmt.datasets.load_earth_relief`