Hydro-climatic drivers of mid-winter break-up of river ice in western Canada and Alaska

作者：Newton B W^*; Prowse T D; de Rham L P

来源：Hydrology Research: An International Journal , 2017, 48(4): 945-956.

DOI：10.2166/nh.2016.358

• mid-winter
• rain on snow
• river ice break-up
• warm spells

The mid-winter break-up of a competent river ice cover can cause ice jamming and flooding, which can have profound impacts on the structure and strength of the ice cover. This research identifies 52 mid-winter break-up events in western Canada (1950-2008) and Alaska (1950-2014) and evaluates the hydro-climatic drivers including temperature and precipitation. The identified mid-winter break-up events are primarily located in the temperate zone, defined as the region between 400 and 1,000 winter (December-February) freezing degree-days. Further delineation by terrestrial biome revealed considerable variability in hydro-climatic triggers, particularly the role of freeze-thaw days (T-max > 0 degrees C and T-min < 0 degrees C) in Tundra and Boreal Forest/Taiga biomes and short-term (3-day) warming events in Temperate Coniferous Forests and Temperate Grasslands, Savannas, and Shrublands. The classification of 5-day sequences of mid-tropospheric circulation indicates that a persistent trough of low-pressure over Alaska and the North Pacific is the dominant pattern preceding mid-winter break-ups. Furthermore, the trough is stronger for events in British Columbia and Alberta compared with Alaska and the Yukon. The results of this research improve our understanding of the hydro-climatic conditions that generate mid-winter break-up events in western Canada and Alaska and will aid in the prediction and risk management of such events.

• 出版日期2017-8