need accessor to transform wind to earth relative

[blaylockbk]

This is needed for models like the HRRR, RTMA, URMA, etc. if ds['v10'].attrs["GRIB_uvRelativeToGrid"] = 1 if you want to plot vectors (barbs or quivers) on a PlatteCarree projection)

# Transform Latitude and Longitude coordinate points (PlateCarree)
# to the source projection coordinates. We need the lat/lon in the
# projection coordinate space before we do the vector transform.
srcProj = ds.herbie.crs
srcProj_coords = srcProj.transform_points(
    pc, srcData.longitude.data, srcData.latitude.data
)

# Extract the X and Y coordinate arrays for the src projection.
X = srcProj_coords[:, :, 0]
Y = srcProj_coords[:, :, 1]

# Transform the U and V vectors to the earth-relative orientation
U_t, V_t = pc.transform_vectors(srcProj, X, Y, srcData[u].data, srcData[v].data)

ds["u10"].values = U_t
ds["v10"].values = V_t
ds['u10'].attrs["GRIB_uvRelativeToGrid"] = 0
ds['v10'].attrs["GRIB_uvRelativeToGrid"] = 0