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Detection of rain-on-snow (ROS) events and ice layer formation using passive microwave radiometry: A context for Peary caribou habitat in the Canadian Arctic

Langlois, A., Johnson, C.-A., Montpetit, B., Royer, A., Blukacz-Richards, E.A., Neave, E., Dolant, C., Roy, A., Arhonditsis, G., Kim, D.-K., Kaluskar, S., Brucker, L.
Remote sensing of environment 2016
Rangifer tarandus, algorithms, freezing, glaciers, grazing, habitats, ice, islands, melting, population dynamics, radiometry, remote sensing, snow, temperature, winter, Arctic region, Canada, Greenland
Over the past four decades, amplified warming in the Arctic has led to numerous consequences. Of particular relevance, negative anomalies of snow and sea ice cover, glacier retreat, and the extended melt of Greenland combined with increasing temperature at double the rate of the rest of the planet have been observed in the Arctic. Several studies have suggested that another response to the current arctic warming could be an increase in rain-on-snow (ROS) events followed by subsequent freezing and the creation of ice layers. We use recently developed detection algorithms of ROS and ice events using passive microwave retrieval approaches to examine the spatial and temporal trends in rain-on-snow and ice layer creation for 18 islands across the Canadian Arctic Archipelago (CAA) over the last two decades. Results show that both icing and ROS event occurrence tripled between the periods of 1979–1995 and 1996–2011, with very active years in winters 1993–1994, 1998–1999 and 2002–2003. The areas with the most combined occurrences are the Boothia Peninsula and Axel Heiberg, Cornwallis, Banks and Victoria Islands. We then compare the rain-on-snow and icing events to Peary caribou estimates to test whether the algorithms can detect weather events associated with population declines. There has been an important reduction in population numbers of Peary caribou, the northernmost caribou population in Canada, over the last three generations. The major hypothesis for the decline is that severe weather events lead to more difficult winter grazing conditions. The comparison with the Peary caribou population estimates suggest that caribou numbers decrease with increased occurrence of ROS and icing events, where 3–4 ROS events and 1–2 icing events in one winter season are sufficient to have a negative impact on Peary caribou.