# Spatio-Temporal Variability of Water Temperature of Arctic Rivers in Russia over the Past 60 Years
## 3 Results
### Current River Water Temperature  
Under the current climatic conditions (i.e., after the change point years), the water temperature in the rivers of the Russian Arctic rises from just above 0 \({}^{\circ}\)C in May to a maximum of 21.4-21.6 \({}^{\circ}\)C (on the Amgas and Ob rivers) in July and August. The water temperature statistics for rivers of the Russian Arctic calculated for the period 1991-2020 are very similar (\(\pm\)0.1-0.4 K) to the statistics that are given in Table 7 (mean values of water temperature in individual months in hydrographic regions, taking into account a standard error of the mean). \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Region** & \multicolumn{2}{c}{**Month**} & \multirow{2}{*}{**May**} & \multirow{2}{*}{**June**} & \multirow{2}{*}{**July**} & \multirow{2}{*}{**August**} & \multirow{2}{*}{**September**} & \multirow{2}{*}{**October**} \\ \cline{3-3} \cline{6-9}  & & T, \({}^{\circ}\)C & & & & & & \\ \hline \multirow{4}{*}{Northeast} & SEM, K & \(\pm\)0.2 & \(\pm\)0.3 & \(\pm\)0.3 & \(\pm\)0.4 & \(\pm\)0.3 & \(\pm\)0.1 \\ \cline{2-9}  & \(\overline{\pi}\) & 17 & 23 & 24 & 23 & 19 & 20 \\ \hline \multirow{4}{*}{Lena} & T, \({}^{\circ}\)C & 1.9 & 11.5 & 15.8 & 13.6 & 6.5 & 0.6 \\ \cline{2-9}  & SEM, K & \(\pm\)0.2 & \(\pm\)0.4 & \(\pm\)0.4 & \(\pm\)0.3 & \(\pm\)0.3 & \(\pm\)0.1 \\ \cline{2-9}  & \(\overline{\pi}\) & 16 & 20 & 23 & 24 & 18 & 19 \\ \hline \multirow{4}{*}{Yenisei} & T, \({}^{\circ}\)C & 1.9 & 9.8 & 15.6 & 14.1 & 8.1 & 1.9 \\ \cline{2-9}  & SEM, K & \(\pm\)0.3 & \(\pm\)0.5 & \(\pm\)0.4 & \(\pm\)0.5 & \(\pm\)0.4 & \(\pm\)0.3 \\ \cline{2-9}  & \(\overline{\pi}\) & 16 & 18 & 21 & 16 & 16 & 18 \\ \hline \multirow{4}{*}{North of the West Siberia} & T, \({}^{\circ}\)C & 2.6 & 11.5 & 16.9 & 14.5 & 8.3 & 1.9 \\ \cline{2-9}  & SEM, K & \(\pm\)0.4 & \(\pm\)0.6 & \(\pm\)0.4 & \(\pm\)0.4 & \(\pm\)0.4 & \(\pm\)0.2 \\ \cline{2-9}  & \(\overline{\pi}\) & 20 & 23 & 23 & 21 & 17 & 18 \\ \hline \end{tabular}
\end{table} 
Table 7: Average water temperature in non-frozen rivers of the Russian Arctic (based on data from 286 gauging stations) and standard error of the mean (SEM) calculation in separate months of the year in the period from the change point year to 2021. The spatial distribution of river water temperature in June and September is shown in Figure 6.  
The length of the water temperature series has little influence on the reliability of the estimates after the change point year. In 0.8% of cases (for 286 hydrological gauging stations), the value of the error in the calculation of the mean value reached 1 K or more. This situation is observed in the summer period (calendar summer) in the mountainous sections of small and medium rivers. The inter-annual variation of water temperature of individual months can reach 15 K in some river sections, but, in most cases, the water temperature of individual months \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Region**} & \multicolumn{2}{c}{**Month**} & \multirow{2}{*}{**Jave**} & \multirow{2}{*}{**July**} & \multirow{2}{*}{**August**} & \multirow{2}{*}{**September**} & \multirow{2}{*}{**October**} \\ \cline{3-3} \cline{5-8}  & T, \({}^{\circ}\)C & 5 & 12.8 & 17.4 & 14.5 & 9 & 3.3 \\ \cline{2-8} \multirow{2}{*}{North of the European part of Russia} & SEM, K & \(\pm\)0.4 & \(\pm\)0.4 & \(\pm\)0.5 & \(\pm\)0.4 & \(\pm\)0.3 & \(\pm\)0.3 \\ \cline{2-8}  & \(\overline{\pi}\) & 18 & 28 & 21 & 18 & 19 & 19 \\ \hline \multirow{4}{*}{Karelia} & T, \({}^{\circ}\)C & 6.8 & 14.7 & 18.1 & 15.7 & 10.8 & 4.7 \\ \cline{2-8}  & SEM, K & \(\pm\)0.5 & \(\pm\)0.4 & \(\pm\)0.5 & \(\pm\)0.4 & \(\pm\)0.3 & \(\pm\)0.3 \\ \cline{2-8}  & \(\overline{\pi}\) & 15 & 19 & 19 & 16 & 16 & 16 \\ \hline \multirow{4}{*}{Kola Peninsula} & T, \({}^{\circ}\)C & 3.8 & 10.9 & 15.6 & 14 & 9.2 & 3.3 \\ \cline{2-8}  & SEM, K & \(\pm\)0.3 & \(\pm\)0.4 & \(\pm\)0.5 & \(\pm\)0.3 & \(\pm\)0.3 & \(\pm\)0.3 \\ \cline{2-8}  & \(\overline{\pi}\) & 21 & 27 & 19 & 20 & 17 & 20 \\ \hline \hline \end{tabular}
\end{table}