NEMESIS Radiative Transfer and Retrieval Tool

NEMESIS is a general-purpose radiative transfer and retrieval code, designed to be applicable to any planetary atmosphere (solar system and exoplanets) and can handle a wide range of observation geometries. The NEMESIS code actually has two components, the NEMESIS retrieval tool itself and also the more general radiative transfer code, RADTRAN, from which it was developed. The Nemesis project is a collaborative effort and is continually being developed and extended. It is managed with Github and the repository can be found here. NEMESIS also has its own dedicated website. Scientists interested in running either NEMESIS or RADTRAN to analyse their data are very welcome to contact me.


NEMESIS (Non-linear optimal Estimator for MultivariatE spectral analySIS) is the general purpose correlated-k/LBL retrieval code developed from the RADTRAN project. The original version, developed in 2003 and used for analysing Cassini/CIRS observations of Jupiter, Saturn and Titan, was based on the correlated-k approximation. However, NEMESIS now also now works in line-by-line (LBL) mode. It has been designed to be generally applicable to any planet and with any observing mode and so is suitable for both solar-system studies and also exoplanetary studies.


RADTRAN is a general purpose planetary radiative transfer model for computing the transmission of atmospheric paths and/or the radiances emitted by planetary atmospheres. The code is general purpose and not hard-wired to any specific planet. RADTRAN evolved from Genlbl, which was a general purpose planetary line-by-line model, developed by Dr Simon Calcutt. RADTRAN extended the functionality of this program to also allow the computation of planetary spectra using both band model approximations and also the correlated-k approximation. The code has also been extended to incorporate both multiple scattering and single scattering calculations.


Irwin, P.G.J., N.A. Teanby, R. de Kok, L.N. Fletcher, C.J.A. Howett, C.C.C. Tsang, C.F. Wilson, S.B. Calcutt, C.A. Nixon, P.D. Parrish, The NEMESIS planetary atmosphere radiative transfer and retrieval tool, J. Quant. Spectrosc. and Rad. Trans., 109, 1136-1150, 2008. doi:10.1016/j.jqsrt.2007.11.006.

Irwin, P. G. J., S. B. Calcutt and F. W. Taylor, Radiative transfer models for Galileo NIMS studies of the atmosphere of Jupiter. Adv. Space. Res. 19, No. 8, pp 1149-1158, 1997. doi:10.1016/S0273-1177(97)00266-4.