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Interaction between snow phenology and streamflow timing in the Yukon River Basin

Authors: Caleb G Pan*, Geospatial Technology and Applications Center, Salt Lake City, UT., Peter B Kirchner, Southwest Alaska Network Inventory and Monitoring Program, National Park Service, Anchorage, AK, John S Kimball, Numerical Terradynamic Simulation Group, University of Montana, Missoula, MT, Jinyang Du, Numerical Terradynamic Simulation Group, University of Montana, Missoula, MT
Topics: Remote Sensing, Cryosphere, Climatology and Meteorology
Keywords: snowcover, streamflow, remote sensing, Alaska, Arctic, climate change
Session Type: Paper
Presentation File: No File Uploaded

The snowoff date (SO) is an important governor of seasonal hydrologic and ecologic processes
in the boreal-Arctic. Greater variability and uncertainty in the timing of SO occurs in
anomalously warm years, while four of the warmest years of record in Alaska have occurred
since 2003. In this study, we examine the hydrologic implications of SO variability from 1988-
2016 in the Yukon River Basin (YRB) to better understand how earlier SO will influence
streamflow. A satellite-based annual SO record was derived from MEaSUREs Calibrated
Enhanced-Resolution Passive Microwave (PMW) Daily EASE-Grid Brightness Temperatures (19
GHz, 37 GHz) and provides enhanced temporal fidelity and favorable accuracy (SO within ±6
days) relative to in situ observations. In the YRB, we characterized when 20%, 50%, and 80% of
the total area experienced SO according to the satellite record, which was compared with the
same quantiles (Q20, Q50, Q80) of cumulative annual streamflow within the basin. Our results
reveal a strong correlation between the SO Q20 and streamflow Q20 in the YRB headwaters at
Eagle, AK (r=0.61, p<0.001). In the middle sub-basin at Stevens, AK, we found a strong
relationship between SO Q50 and the peak discharge (r = 0.68, p<0.001). We found strong SO
and temperature correlations of -0.68, -0.71, and -0.72 at Eagle, Stevens Village, and Pilot
stream gage locations, respectively. Our results suggest that as temperatures across Alaska
continue to warm, peak river discharge and the spring flood pulse will shift in tandem with SO
towards an earlier onset in the YRB.

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