## 3 Results
### Water Isotopic Composition of Snowpack  
The spread in the values of the water isotopic composition in the snowpack (bulk samples) in the studied area (Figure 1b) during the period of maximum snow accumulation varied in winter 2019-2020 from \(-\)21.9% to \(-\)18.6% for \(\delta^{18}\)O and from \(-\)170.3% to \(-\)144.6% for \(\delta\)D, and in winter 2020-2021 from \(-\)23.2% to \(-\)18.7% for \(\delta^{18}\)O and from \(-\)179.7% to \(-\)141.5% for \(\delta\)D (Table 1). The calculated depth-weighted (mm of weq) mean values of the water isotopic composition of the snow cover were \(-\)20.0% and \(-\)20.4% for \(\delta^{18}\)O and \(-\)155% and \(-\)157% for \(\delta\)D, respectively, for the cold period 2019-2020 and 2020-2021. Figure S2a,b (Supplementary Materials), show the LMWL for snow samples taken at the end of winter 2019-2020 and 2020-2021. Relationship \(\delta\)D-\(\delta^{18}\)O in snow cover is calculated by the equation \(\delta\)D = 7.9 \(\times\)\(\delta^{18}\)O + 2.9 (R\({}^{2}\) = 0.98) for winter 2019-2020 and by the equation \(\delta\)D = 7.7 \(\times\)\(\delta^{18}\)O + 0.4 (R\({}^{2}\) = 0.98) for winter 2020-2021, which are located below LMWL for the winter precipitation in the corresponding cold period (Figure S2a,b). The statistical estimates of LMWL for snowpack samples (errors of the estimates for slopes and intercepts) are given in Table S1 in Supplementary Materials.  
At the end of winter 2019-2020, the snowpack's lower layers (depth hoar) were taken at all sampling sites in addition to the bulk samples. The isotopic composition of water in the bottom layers of snow adjacent to unfrozen soils was noticeably heavier (on average by 4.5% for \(\delta^{18}\)O and by 33% for \(\delta\)D) relative to the corresponding bulk samples (Table 2), while the lower layers of snow on frozen soil differed insiginificantly (on average by 0.8%  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & \multicolumn{2}{c}{\(\delta^{18}\)O, \%\(\infty\)} & \multicolumn{2}{c}{\(\delta\)D, \%\(\infty\)} & \multicolumn{2}{c}{D-Excess, \%\(\infty\)} \\ \cline{2-6}  & **1** & **2** & **1** & **2** & **1** & **2** \\ \hline \hline \multicolumn{6}{c}{Snowpack, n = 14 (sampling points 1–14, Figure 1b)} \\ max & \(-\)18.6 & \(-\)18.7 & \(-\)144.6 & \(-\)141.5 & 6.4 & 8.4 \\ min & \(-\)21.9 & \(-\)23.2 & \(-\)170.3 & \(-\)179.7 & 2.2 & 4.2 \\ mean 1  & \(-\)20.0 & \(-\)20.4 & \(-\)155 & \(-\)157 & 4.7 & 6.4 \\ SDOM 2  & 0.6 & 0.7 & 4.3 & 5.6 & 0.6 & 0.8 \\ \multicolumn{6}{c}{Atmospheric precipitation (n = 47 for 2019–2020; n = 50 for 2020–2021)} \\ max & \(-\)12.0 & \(-\)11.6 & \(-\)90.7 & \(-\)79.8 & 11.3 & 17.2 \\ min & \(-\)30.3 & \(-\)35.6 & \(-\)235.4 & \(-\)277.3 & \(-\)6.1 & \(-\)9.5 \\ mean 3  & \(-\)19.2 & \(-\)21.5 & \(-\)147.4 & \(-\)166.6 & 5.9 & 5.7 \\ SDOM 2  & 0.1 & 0.1 & 0.4 & 0.4 & 0.8 & 0.8 \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison of the isotopic composition of the bulk snowpack samples with the initial atmospheric precipitation for the winter period 2019–2020 (1) and 2020–2021 (2).  
for \(\delta^{18}\)O and by 9% for 8D). The LMWLs for the lower layers of snow are presented in Figure S2a separately for those on frozen and non-frozen soil.