Webinar: The missing mountain water -- Slower westerlies decrease orographic enhancement in the Pacific Northwest

Event Type: 
Other Webinar
Date and Time: 
Jan 28, 2014 (All day)

Time: 11am-12pm Mountain / 10-11am Pacific

Hosts: This webinar is brought to you by the Pacific Northwest Climate Change Collaboration, C3

Presenter: Charlie Luce, U.S. Forest Service Research and Development, Boise

Description: Trends in streamflow timing and volume in the Pacific Northwest United States have been attributed to increased temperatures because trends in precipitation at lower elevation stations were negligible.  However, researchers now suggest that the lack of long-term precipitation data from mountains severely limits our understanding of historical trends and the empirical framework needed for understanding impacts of climate variability and change.

Charlie will present new research (citation, below) demonstrating that observed streamflow declines likely are also associated with declines in mountain precipitation, revealing previously unexplored differential trends. Lower-troposphere winter (November-March) westerlies are strongly correlated to high elevation precipitation but weakly correlated with low elevation precipitation. Decreases in lower-tropospheric winter westerlies across the region from 1950-2012 are hypothesized to have reduced orographic precipitation enhancement, yielding differential trends in precipitation across elevations and contributing to the decline in annual streamflow. Climate projections show weakened lower troposphere zonal flow across the region under enhanced greenhouse forcing, highlighting an additional stressor relevant for climate change impacts on hydrology.

Charlie Luce is Research Hydrologist at the Boise Aquatic Sciences Laboratory. Charlie’s research interests include hydrology, watershed processes, sediment and erosion and climate change.  He has led and contributed to a long list of publications which can be viewed and obtained at: http://www.fs.fed.us/rm/boise/AWAE/scientists/profiles/AWALuce.shtml

Citation: C. H. Luce, J. T. Abatzoglou, and Z. A. Holden, Science Xpress, publication ahead of print, published online 29 November 2013 [DOI:10.1126/science.1242335] at http://www.sciencemag.org/content/early/recent

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