"""
Function to download the IGPP Global Earth Vertical Gravity Gradient from the
GMT data server, and load as :class:`xarray.DataArray`.
The grids are available in various resolutions.
"""
from pygmt.datasets.load_remote_dataset import _load_remote_dataset
from pygmt.helpers import kwargs_to_strings
[docs]@kwargs_to_strings(region="sequence")
def load_earth_vertical_gravity_gradient(
resolution="01d", region=None, registration=None
):
r"""
Load the IGPP Global Earth Vertical Gravity Gradient in various
resolutions.
The grids are downloaded to a user data directory
(usually ``~/.gmt/server/earth/earth_vgg/``) 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.
These grids can also be accessed by passing in the file name
**@earth_vgg**\_\ *res*\[_\ *reg*] to any grid plotting/processing
function. *res* is the grid resolution (see below), and *reg* is grid
registration type (**p** for pixel registration or **g** for gridline
registration).
Refer to :gmt-datasets:`earth-vgg.html` for more details.
Parameters
----------
resolution : str
The grid resolution. The suffix ``d`` and ``m`` stand for
arc-degrees and arc-minutes. It can be ``"01d"``, ``"30m"``,
``"20m"``, ``"15m"``, ``"10m"``, ``"06m"``, ``"05m"``, ``"04m"``,
``"03m"``, ``"02m"``, or ``"01m"``.
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 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 ``"01m"`` which is ``"pixel"`` only.
Returns
-------
grid : :class:`xarray.DataArray`
The Earth vertical gravity gradient grid. Coordinates are latitude and
longitude in degrees. Units are in Eotvos.
Note
----
The :class:`xarray.DataArray` grid doesn't support slice operation, for
Earth vertical gravity gradient grids with resolutions of 5 arc-minutes or
higher, which are stored as smaller tiles.
"""
grid = _load_remote_dataset(
dataset_name="earth_vgg",
dataset_prefix="earth_vgg_",
resolution=resolution,
region=region,
registration=registration,
)
return grid