Streamflow Response to Seasonal Snowcover Change over the Large Northern Rivers

Snowcover is one of the critical land memory processes that significantly affect atmosphere, hydrology and ecosystems in the high latitude regions. Snowcover melt and associated floods are the most important hydrologic event of the year in the northern river basins. Snowmelt has started earlier over the recent decades in the northern regions due to warming in winter and spring seasons. Our current knowledge of large-scale snowmelt processes and their interaction with climatic change and variation is incomplete; this limits our ability of understanding past changes and predicting future changes in the arctic hydrology system. This study explores the potential of using remotely sensed snowcover extent (SCE) and snow water equivalent (SWE) information to improve our understanding of snowmelt and runoff generation over the largest northern river basins - the Ob, Yenisei, Lena, Mackenzie, and Yukon rivers. We use the NOAA weekly-mean snowcover extent, SSM/I SWE, and discharge data to examine the basin-scale snowcover and snowmelt runoff regimes in these large watersheds. Preliminary results show reasonable relationships among basin mean SCE-SWE, SCE-discharge, and SWE-discharge. This presentation will discuss basin snowcover seasonal cycles (including both snowcover extent and SWE), and the compatibility of remotely sensed snowcover data/products with winter snowfall and river streamflow records. The emphasis is on snowmelt processes and associated peak flows. We find strong linkages between important hydrologic events, such as the correspondence between maximum SWE and peak discharge. These results are useful to better understand large-scale streamflow variations and changes in the Arctic regions.