4A/OP
4A/OP or, Automatized Atmospheric Absorption Atlas, is an operational fast and accurate radiative transfer model for the infrared. 4A/OP is a user-friendly software for various scientific applications (surface, balloon or space-based observations), co-developed by LMD (Laboratoire de Meteorologie Dynamique) and NOVELTIS with the support of CNES (the French Space Agency).