This version adds the SAR altimetry from the sarm-v0 branch. It is not mainstream and official, associated with the GMD paper Picard, G., Murfitt, J., Zakharova, E., Zeiger, P., Arnaud, L., Aublanc, J., Landy, J. C., Scagliola, M., and Duguay, C.: Simulating SAR altimeter echoes from cryospheric surfaces with the Snow Microwave Radiative Transfer (SMRT) model version sarm-v0, EGUsphere [preprint], doi:10.5194/egusphere-2025-6056, 2026.