Using wrg files for WaspGridSite

Hello. I am trying to create a WaspGridSite from .wrg files instead of reading .grd files, which is what I have at my disposal. For that, I am providing the data from the .wrg files to WaspGridSite as a xarray.Dataset with the same structure as the one provided by load_wasp_grd. The problem is that the .wrg files lack some variables that the .grd files are supposed to have, and they seem to be essential in order to be able to instantiate WaspGridSite and use it in wake calculations. These variables are tke, orog_spd, obst_spd, and rgh_spd, as far as I've been able to check. Would it be possible to create a site lacking these variables, or if not, is there a way to compute them from terrain height and Weibull parameters for each grid location? On a side note, I've seen that tke is named turbulence intensity in the source code, where I would expect tke to be turbulent kinetic energy. Should I assume tke is actually ti?