Specifies an altitude map which is used in combinition with latitude, longitude in order to select the altitude for the simulation. No interpolation is done between the pixels of the map. The format of the call is:
altitude_map file [variable_name]
where file is the location of the altitude map file. The map is expected to be in netCDF format. The file must contain double lat(lat), double lon(lon), and the altitude variable, where variable_name is the name of the surface elevation variable in the netCDF file. The default name is Z. The altitude variable must be altitude(lat, lon). For format discribtion see also the example map included in libRadtran, data/altitude/ELEVATION_GTOPO_10min.cdf. To use this map in uvspec, you may also use altitude_map GTOPO. This map has a resolution of 10 arc minutes and the unit of the altitude is meter. Please note that this resolution might not ne adequate for your application. If an altitude in the map is below the lowest level of the atmosphere_file, the atmospheric profiles are extrapolated assuming a constant gradient for temperature and mixing ratios.





Arve Kylling 2010-03-10