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R. Wilson, A. Bartsch, K. Joly, J. Reynolds, A. Orlando, W. Loya:
"Frequency, timing, extent, and size of winter thaw-refreeze events in Alaska 2001-2008 detected by remotely sensed microwave backscatter data";
Polar Biology, 36 (2013), 3; 419 - 426.

Creation of ice layers in snow due to thaw-refreeze events can lock away winter forage, preventing access by large mammals and causing population declines. Data are limited, however, on the frequency, timing, extent, and size of thaw-refreeze events in northern latitudes given the area´s remoteness and paucity of weather stations. We used a remote sensing approach to detect thaw-refreeze events in Alaska during winter between 2001 and 2008. We also compared these results to a regional climate reanalysis dataset that identified rain events (freezing and non-freezing rain). All areas of the state, except high elevation sites, had ≥1 thaw-refreeze event during the study period. Southwestern Alaska had the highest frequency of thaw-refreeze events with an average of >4 events each winter, whereas northern Alaska had the lowest frequency with an average of <2 events. We observed substantial inter-annual variation in the distribution and frequency of thaw-refreeze events. For most of the state, thaw-refreeze occurred at similar rates each winter month, except in northern Alaska where thaw-refreeze events were most frequent in early and later winter. The median extent of individual thaw-refreeze events was 469 km2, however, events in the interior of the state tended to be larger. Remotely sensed thaw-refreeze detections generally had low correspondence with observations from the climate reanalysis dataset. Our results support the use of remotely sensed data to identify thaw-refreeze events.

Alaska, Freezing rain, Ice, QuikSCAT, Rain-on-snow, Remote sensing, ROS, Scatterometer, Snow characteristics

http://dx.doi.org/10.1007/s00300-012-1272-6