geocat.comp.rgrid2rcm#

geocat.comp.rgrid2rcm(lat1d, lon1d, fi, lat2d, lon2d, msg=None, meta=False)#

Interpolates data on a rectilinear lat/lon grid to a curvilinear grid like those used by the RCM, WRF and NARR models/datasets.

Interpolates data on a rectilinear lat/lon grid to a curvilinear grid, such as those used by the RCM (Regional Climate Model), WRF (Weather Research and Forecasting) and NARR (North American Regional Reanalysis) models/datasets. No extrapolation is performed beyond the range of the input coordinates. The method used is simple inverse distance weighting. Missing values are allowed but ignored.

Parameters:

  • lat1d (xarray.DataArray, numpy.ndarray) – A one-dimensional array that specifies the latitude coordinates of the regular grid. Must be monotonically increasing.

    Note: It should only be explicitly provided when the input (fi) is numpy.ndarray; otherwise, it should come from fi.coords.

  • lon1d (xarray.DataArray, numpy.ndarray) – A one-dimensional array that specifies the longitude coordinates of the regular grid. Must be monotonically increasing.

    Note: It should only be explicitly provided when the input (fi) is numpy.ndarray; otherwise, it should come from fi.coords.

  • fi (xarray.DataArray, numpy.ndarray) – A multi-dimensional array to be interpolated. The rightmost two dimensions (latitude, longitude) are the dimensions to be interpolated.

  • lat2d (xarray.DataArray, numpy.ndarray) – A two-dimensional array that specifies the latitude locations of the input (fi). Because this array is two-dimensional it is not an associated coordinate variable of fi.

  • lon2d (xarray.DataArray, numpy.ndarray) – A two-dimensional array that specifies the longitude locations of the input (fi). Because this array is two-dimensional it is not an associated coordinate variable of fi.

  • msg (numpy.number) – A numpy scalar value that represents a missing value in fi. This argument allows a user to use a missing value scheme other than NaN or masked arrays, similar to what NCL allows.

  • meta (bool) – If set to True and the input array is an Xarray, the metadata from the input array will be copied to the output array; default is False. Warning: this option is not currently supported.

Returns:

fo (xarray.DataArray, numpy.ndarray) – The interpolated grid. A multi-dimensional array of the same size as fi except that the rightmost dimension sizes have been replaced by the sizes of lat2d (or lon2d).

Examples

Example 1: Using rgrid2rcm with xarray.DataArray input

import numpy as np
import xarray as xr
import geocat.comp

# Open a netCDF data file using xarray default engine and load the data stream
# input grid and data
ds_rect = xr.open_dataset("./DATAFILE_RECT.nc")

# [INPUT] Grid & data info on the source rectilinear
ht_rect   =ds_rect.SOME_FIELD[:]
lat1D_rect=ds_rect.gridlat_[:]
lon1D_rect=ds_rect.gridlon_[:]

# Open a netCDF data file using xarray default engine and load the data stream
# for output grid
ds_curv = xr.open_dataset("./DATAFILE_CURV.nc")

# [OUTPUT] Grid on destination curvilinear grid (or read the 2D lat and lon from
#          an other .nc file
newlat2D_rect=ds_curv.gridlat2D_[:]
newlon2D_rect=ds_curv.gridlat2D_[:]

ht_curv = geocat.comp.rgrid2rcm(lat1D_rect, lon1D_rect, ht_rect, newlat2D_curv, newlon2D_curv)