emissivity_map file [variable_name]where file is the location of the netCDF file. With the optional argument variable_name the name of the emissivity variable in the netCDF file can be specified. (By default the expected name is EMIS.) The emissivity must be specified as function of latitude and longitude EMIS(lat, lon), or additionally may also depent on time EMIS(time, lat, lon). All grids must be provided as double lat(lat), double lon(lon), and double time(time). libRadtran reads the value at the nearest pixel to the given latitude and longitude. No spatial interpolation or averaging of the values is done. If the variable time is present in the file, the emissivity data nearest to the specified time will be selected (or interpolated if time_interpolate is switched on).