RTTOV v13.0 has been released. Updates from v12.3 include: new gas optical depth coefficients based on updated spectroscopy and new optical depth predictors; new “all trace gas” coefficients for various hyperspectral and non-hyperspectral VIS/IR sensors; for visible channels, a new parameterisation of Rayleigh extinction that may now optionally be excluded from simulations; option to treat Rayleigh multiple scattering in the DOM solver; updated VIS/IR cloud liquid water optical properties based on a newer refractive index dataset; new parameterisation for cloud liquid water effective diameter; optimisation of the MFASIS fast model and the DOM solver AD/K models; and RTTOV-SCATT updates to allow an arbitrary number of hydrometeor species, option to input per-hydrometeor cloud fraction profiles, new approximate treatment of polarised scattering by frozen hydrometeors, new options for generating MW scattering optical property tables, and an active MW sensor capability. See the RTTOV pages for more information.