Source code for pygmt.datasets.earth_relief

"""
Function to download the Earth relief datasets from the GMT data server, and load as
:class:`xarray.DataArray`.

The grids are available in various resolutions.
"""

from collections.abc import Sequence
from typing import Literal

import xarray as xr
from pygmt.datasets.load_remote_dataset import _load_remote_dataset
from pygmt.exceptions import GMTInvalidInput

__doctest_skip__ = ["load_earth_relief"]


[docs] def load_earth_relief( resolution: Literal[ "01d", "30m", "20m", "15m", "10m", "06m", "05m", "04m", "03m", "02m", "01m", "30s", "15s", "03s", "01s", ] = "01d", region: Sequence[float] | str | None = None, registration: Literal["gridline", "pixel", None] = None, data_source: Literal["igpp", "gebco", "gebcosi", "synbath"] = "igpp", use_srtm: bool = False, ) -> xr.DataArray: r""" Load the Earth relief datasets (topography and bathymetry) in various resolutions. .. figure:: https://www.generic-mapping-tools.org/remote-datasets/_images/GMT_earth_gebco.jpg :width: 80 % :align: center Earth relief datasets (topography and bathymetry). 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 processing function or plotting method. *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 the 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 :class:`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 :gmt-datasets:`earth-relief.html` for more details about available datasets, including version information and references. Parameters ---------- resolution The grid resolution. The suffix ``d``, ``m`` and ``s`` stand for arc-degrees, arc-minutes, and arc-seconds. region The subregion of the grid to load, in the form of a sequence [*xmin*, *xmax*, *ymin*, *ymax*] or an ISO country code. Required for grids with resolutions higher than 5 arc-minutes (i.e., ``"05m"``). registration Grid registration type. Either ``"pixel"`` for pixel registration or ``"gridline"`` for gridline registration. Default is ``None``, means ``"gridline"`` for all resolutions except ``"15s"`` which is ``"pixel"`` only. data_source Select the source for the Earth relief data. Available options are: - ``"igpp"``: IGPP Earth Relief. See :gmt-datasets:`earth-relief.html`. - ``"synbath"``: IGPP Earth Relief dataset that uses stastical properties of young seafloor to provide a more realistic relief of young areas with small seamounts. - ``"gebco"``: GEBCO Earth Relief with only observed relief and inferred relief via altimetric gravity. See :gmt-datasets:`earth-gebco.html`. - ``"gebcosi"``: GEBCO Earth Relief that gives sub-ice (si) elevations. use_srtm 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 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 :class:`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 :class:`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, ... ) """ # resolutions of original land-only SRTM tiles from NASA land_only_srtm_resolutions = ["03s", "01s"] # Map data source to prefix prefix = { "igpp": "earth_relief", "gebco": "earth_gebco", "gebcosi": "earth_gebcosi", "synbath": "earth_synbath", }.get(data_source) if prefix is None: raise GMTInvalidInput( f"Invalid earth relief data source '{data_source}'. " "Valid values are 'igpp', 'gebco', 'gebcosi', and 'synbath'." ) # Use SRTM or not. if use_srtm and resolution in land_only_srtm_resolutions: if data_source != "igpp": raise GMTInvalidInput( f"Option 'use_srtm=True' doesn't work with data source '{data_source}'." " Please set 'data_source' to 'igpp'." ) prefix = "srtm_relief" # Choose earth relief dataset match data_source: case "igpp" | "synbath": name = "earth_igpp" case "gebco" | "gebcosi": name = "earth_gebco" grid = _load_remote_dataset( name=name, prefix=prefix, resolution=resolution, region=region, registration=registration, ) return grid