Set up a default aerosol according to Shettle (1989). The default properties are
a rural type aerosol in the boundary layer, background aerosol above 2km,
spring-summer conditions and a visibility of 50km. These settings may
be modified with aerosol_haze, aerosol_vulcan, aerosol_season,
and aerosol_visibility.
Arve Kylling
2010-03-10