Climate and year‐to‐year variability of atmospheric and terrestrial water cycles in the three great Siberian rivers

Abstract Among all the rivers that flow into the Arctic Ocean, the Lena, Yenisei, and Ob are the three largest in terms of water discharge ( R ), and they are a large source of freshwater. We analyzed the R observed at the river mouths and precipitation minus evapotranspiration ( P  −  E ) estimated from atmospheric reanalyses. P is a key player in the water cycles of the Siberian rivers, but regional differences of E also affect the long‐term means of R and P  −  E . Climate fields and terrestrial conditions play some roles for the regional differences of P and E . A decomposition analysis of the moisture flux revealed that moisture transport associated with cyclone activity dominates the climatological features of P  −  E over the Lena, whereas moisture transport associated with seasonal mean winds dominates the features of P  −  E over the Ob. Both transport processes affect over the Yenisei. Whereas the moisture transports related to the climatological P  −  E differs among the rivers, P  −  E variations are mainly affected by the stationary component of moisture transport for all three Siberian rivers. Although previous studies have shown considerable deviations between P  −  E and R variations, the year to year variations agree very well with each other when appropriate seasonal time lags are taken into account. Comparison with the results of six atmospheric reanalyses indicated that estimations of P  −  E with the reanalyses produce values comparable to observed R s and are therefore an effective way to examine the water cycles of the Siberian rivers.