Assessing River Ice Breakup Date, Coastal Tundra Vegetation And Climate Divisions In The Context Of Alaska Climate Variability

• Main Author: Bieniek, Peter A.
• Other Authors: Bhatt, Uma
• Format: Doctoral or Postdoctoral Thesis
• Language: unknown
• Published: 2012
• Subjects: Atmospheric sciences; Climate change; Arctic; Bering Sea; Fairbanks; Gulf of Alaska; Yukon; Sea ice; Tundra; Alaska
• Online Access: http://hdl.handle.net/11122/9147

Dissertation (Ph.D.) University of Alaska Fairbanks, 2012 In Alaska, there exists a substantial knowledge gap of key climate drivers and filling these gaps is vital since life and the economy are inexorably linked with climate in the state. This thesis identifies and investigates three topics that advance the understanding of Alaska climate variability: the role of large-scale climate in Interior river ice breakup, the link between climate and arctic tundra vegetation, and climate divisions based on objective methods. River ice breakup in the Yukon-Kuskoswim watershed is occurring earlier by 1.3 days decade-1 1948-2008 and displays large year-to-year variability. April-May Interior Alaska air temperatures are the best predictor of river ice breakup and were linked to El Nino Southern Oscillation (ENSO). During the warm phase of ENSO, fewer storms track into the Gulf of Alaska during Boreal Spring, resulting in reduced April-May cloudiness over Alaska, increased solar insolation at the land surface, warmer air temperatures and consequently earlier breakup. Northern Alaska tundra vegetation productivity has increased 1982-2011, based on the Normalized Difference Vegetation Index (NDVI), a satellite measure of vegetation correlated with above ground biomass. Vegetation productivity was linked to the Beaufort High circulation as well as snowfall, in addition to land surface temperatures and coastal sea ice extent. NDVI has decreased from 1982-2011 over the coastal tundra along the Bering Sea and was correlated with delayed springtime warming due to enhanced coastal sea ice and a delayed snowmelt. Cluster analysis was applied to 2-meter air temperature data 1977-2010 at meteorological stations to construct climate divisions for Alaska. Stations were grouped together objectively based on similar homogeneous seasonal and annual climate variability and were refined using local expert knowledge to ultimately identify 13 divisions. Correlation analysis using gridded downscaled temperature and precipitation data ...