altitude 0.73 # Altitude of IFU, Garmisch-PartenkirchenThe profiles of pressure, temperature, molecular absorbers, ice and water clouds are cut at the specified altitude. The aerosol profile is not affected by altitude but starts right from the model surface. This is a convenient way for the user to calculate the radiation at other altitudes than sealevel. Note that altitude is very different from zout where the radiation is calculated at an altitude of zout above the surface. E.g. to calculate the radiation field 1 km above the surface at a location at 0.73 km above sealevel, one would specify 'altitude 0.73' and 'zout 1.0'. If an altitude is specified which is below the lowest level in the atmosphere_file, the atmospheric profiles are extrapolated assuming a constant gradient for temperature and mixing ratios. A second optional argument may be given to altitude as e.g.
altitude 0.73 0.5Here the bottom level will be at 0.73 km and the vertical resolution of the model atmosphere will be redistributed to have a spacing between levels specified by the second number, here 0.5 km. (Levels 0.73, 1.23, 1.73 ... will be added to the original atmosphere grid and optical properties are devided into the new layers. In order to use interpolated properties use zout_interpolate. See verbose output for details.) Be aware that specifying a fine vertical spacing will produce many layers thus increasing the computing time. Also the radiative transfer equation solvers implemented in Fortran 77 might need to have some array sizes increased (see src_f/DISORT.MXD).