wrf.ll_to_xy_proj(latitude, longitude, meta=True, squeeze=True, as_int=True, map_proj=None, truelat1=None, truelat2=None, stand_lon=None, ref_lat=None, ref_lon=None, pole_lat=None, pole_lon=None, known_x=None, known_y=None, dx=None, dy=None, latinc=None, loninc=None)

Return the x, y coordinates for a specified latitude and longitude.

The latitude and longitude arguments can be a single value or a sequence of values. This version of the ll_to_xy routine allows users to manually specify projection parameters.

The leftmost dimension of the returned array represents two different quantities:

  • return_val[0,…] will contain the X (west_east) values.
  • return_val[1,…] will contain the Y (south_north) values.
  • latitude (float or sequence) – A single latitude or a sequence of latitude values to be converted.
  • longitude (float or sequence) – A single longitude or a sequence of latitude values to be converted.
  • squeeze (bool, optional) – Set to False to prevent dimensions with a size of 1 from being automatically removed from the shape of the output. Default is True.
  • meta (bool, optional) – Set to False to disable metadata and return numpy.ndarray instead of xarray.DataArray. Default is True.
  • as_int (bool) – Set to False to return the x,y values as float, otherwise they will be returned as int. Default is True.
  • map_proj (int) – Model projection [1=Lambert Conformal, 2=Polar Stereographic, 3=Mercator, 6=Lat-Lon]. Required.
  • truelat1 (float) – Latitude of true scale 1. Required for map_proj = 1, 2, 3 (defaults to 0 otherwise).
  • truelat2 (float) – Latitude of true scale 2. Optional for map_proj = 1 (defaults to 0 otherwise).
  • stand_lon (float) – Standard longitude. Required for map_proj = 1, 2, 6 (defaults to 0 otherwise).
  • ref_lat (float) – A reference latitude. Required.
  • ref_lon (float) – A reference longitude. Required.
  • known_x (float) – The known x-coordinate associated with ref_lon. Required.
  • known_y (float) – The known y-coordinate associated with ref_lat. Required.
  • pole_lat (float) – Pole latitude. Required for map_proj = 6 (use 90 for no rotation).
  • pole_lon (float) – Pole longitude. Required for map_proj = 6 (use 0 for no rotation).
  • dx (float) – The x spacing in meters at the true latitude. Required for all map projections.
  • dy (float) – Required for map_proj = 6 (defaults to 0 otherwise).
  • latinc (float) –

    Optional for map_proj = 6. Default is:

    latinc = (dy*360.0)/2.0/Constants.PI/Constants.WRF_EARTH_RADIUS
  • loninc (float) –

    Optional for map_proj = 6. Default is:

    loninc = (dx*360.0)/2.0/Constants.PI/Constants.WRF_EARTH_RADIUS

The x,y coordinate value(s) whose leftmost dimension is 2 (0=X, 1=Y). If xarray is enabled and the meta parameter is True, then the result will be a xarray.DataArray object. Otherwise, the result will be a numpy.ndarray object with no metadata.

Return type:

xarray.DataArray or numpy.ndarray