Modeling of radiative transfer through cryospheric Earth system: software package SCIATRAN

The cryosphere plays a crucial role in global climate change. To accurately quantify impacts of typical cryospheric surface types, such as snow, ice, and melt ponds on the radiative processes both in the atmosphere and at the surface, new developments in the radiative transfer modeling are necessary. This paper summarizes recent developments in the coupled atmosphere-snow(water)-ice-water radiative transfer model SCIATRAN, which are essential for cryospheric science applications. Novel implementations include a polarized treatment of the coupled ocean-atmosphere, support for multi-layer ice with an ice crust, a flexible interface for incorporating diverse total suspended matter, and an improved cloud parameter input for mixed clouds. We also introduce new surface reflection models and expanded databases of inherent optical properties for snow and ice. Furthermore, it includes selected verification and validation results obtained by comparing SCIATRAN simulations with benchmark data and with measurements from various campaigns. The SCIATRAN software package is freely distributed via the homepage of the Institute of Environmental Physics (IUP), University of Bremen: https://www.iup.uni-bremen.de/sciatran/ (last access: 23 June 2026.