pydda.constraints.add_hrrr_constraint_to_grid#

pydda.constraints.add_hrrr_constraint_to_grid(Grid, file_path, method='nearest', lov=-97.5, truelat1=38.5, truelat2=38.5)[source]#

This function will read an HRRR GRIB2 file and create the constraining u, v, and w fields for the model constraint.

The u and v winds in the HRRR GRIB2 file are relative to the HRRR’s Lambert Conformal Conic grid rather than true north. This function rotates them to true north (earth-relative) components before interpolating them onto the analysis grid.

Parameters:

  • Grid (Py-ART Grid) – The Py-ART Grid to use as the grid specification. The HRRR values

  • will be interpolated to the Grid’s specficiation and added as a field.

  • file_path (string) – The path to the GRIB2 file to load.

  • method (str) – Interpolation method: ‘nearest’ for nearest neighbor, ‘linear’ for linear.

  • lov (float) – The standard longitude (center longitude) of the HRRR’s Lambert Conformal Conic projection, in degrees. Only change this if the input file uses a different Lambert Conformal Conic grid than the operational CONUS HRRR.

  • truelat1, truelat2 (float) – The two standard (true) latitudes of the HRRR’s Lambert Conformal Conic projection, in degrees. Only change these if the input file uses a different Lambert Conformal Conic grid than the operational CONUS HRRR.

Returns:

Grid (Py-ART Grid) – This returns the Py-ART grid with the HRRR u, and v fields added.