“…Correspondence to: F. C. Seidel (felix.seidel@geo.uzh.ch) 6S (Second Simulation of a Satellite Signal in the Solar Spectrum) (Vermote et al, 1997), SCIATRAN , SHARM (Muldashev et al, 1999;Lyapustin, 2005), RT3 (Evans and Stephens, 1991), RTMOM (Govaerts, 2006), RAY (Zege and Chaikovskaya, 1996), STAR (Ruggaber et al, 1994) and Pstar2 (Nakajima and Tanaka, 1986;Ota et al, 2010), as well as DISORT (Stamnes et al, 1988), which is used in MODTRAN (Berk et al, 1989), STREAMER (Key and Schweiger, 1998) and SBDART (Ricchiazzi et al, 1998). These accurate but complex RTMs are frequently run in a forward mode, generating look-up tables (LUTs), which are later used during the inversion process for atmospheric compensation (Gao et al, 2009) or aerosol retrieval (Kokhanovsky, 2008;Kokhanovsky and Leeuw, 2009;Kokhanovsky et al, 2010), for instance.…”