RTTOV v13.1 has been released. Updates from v13.0 include: basic UV simulation capability, MFASIS simulations extended to 1.6 micron channels and MFASIS treatment of mixed phase cloud improved, new subroutines to obtain emissivities/BRDFs from the RTTOV sea surface models without running full simulations, new option to output transmittances only from the forward model (more efficient if radiances are not required), overcast and secondary radiance outputs now calculated for aerosol simulations with the fast “Chou-scaling” IR solver, and various other minor technical improvements. See the RTTOV pages for more information.