**Appendix A**


**Table A1.** Date of all analyzed Sentinel-1 (S1) scenes for this study.


**Table A1.** *Cont.*

**Figure A1.** Picture of snow and perennial firn on Vernagtferner recorded in September 2018. The pole in the center is an accumulation stake, which used to be an ablation stake in summer 2018. See the backpack and ski poles for roughness height estimates. The red surface color has been spread out in previous years to detect the previous fall surface for winter field campaigns.
