Reference tool for simulation of VIS/NIR spectral radiances

To facilitate the generation of mission requirements from user requirements it is necessary to  prepare  adequate  radiative  transfer   modelling  tools.   This   document   describes   the  objectives  and   the   results   of   a   study  performed   under  EUMETSAT   Contract  EUM/CO/06/1529/PS  Reference   Tool   for   Simulation   of  VIS/NIR  Spectral   Radiances,  in   support   of   the   Post­EPS  mission   on   Cloud,   Precipitation,   and   large­scale   Land   surface   imaging   (CPL).   The   CPL  mission  will   require  a  capability  to  co­process  data  from  passive  instruments  working  in  the  broadest possible spectral range.  The   purpose   of   the   study   is   to   extend   the   existing   validated   line­by­line   model   LBLMS   to  develop towards a unified scheme to compute radiance and fluxes from UV to far infrared in  any  direction  in  space   for   a  plane­parallel   atmosphere.   The  scheme  is   based   on  line­by­line  methods   to   compute   optical   depths   at   high  spectral   resolution  and  on  the  adding/doubling  method to solve the radiative transfer equation in a scattering atmosphere.