Frequency, timing, extent, and size of winter thaw-refreeze events in Alaska 2001–2008 detected by remotely sensed microwave backscatter data
Wilson R, Bartsch A, Joly K, Reynolds J, Orlando A, Loya WM. 2013. Frequency, timing, extent, and size of winter thaw-refreeze events in Alaska 2001–2008 detected by remotely sensed microwave backscatter data. Polar Biology. 36(3):419–426
Creation of ice layers in snow due to thawrefreeze events can lock away winter forage, preventingaccess 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 weatherstations. We used a remote sensing approach to detectthaw-refreeze events in Alaska during winter between 2001and 2008. We also compared these results to a regionalclimate reanalysis dataset that identified rain events(freezing and non-freezing rain). All areas of the state,except high elevation sites, had C1 thaw-refreeze eventduring the study period. Southwestern Alaska had thehighest frequency of thaw-refreeze events with an averageof[4 events each winter, whereas northern Alaska had thelowest frequency with an average of \2 events. Weobserved substantial inter-annual variation in the distribution and frequency of thaw-refreeze events. For most of thestate, thaw-refreeze occurred at similar rates each wintermonth, except in northern Alaska where thaw-refreezeevents were most frequent in early and later winter. Themedian extent of individual thaw-refreeze events was469 km2, however, events in the interior of the state tendedto be larger. Remotely sensed thaw-refreeze detectionsgenerally had low correspondence with observations fromthe climate reanalysis dataset. Our results support the useof remotely sensed data to identify thaw-refreeze events.
- Type
- Journal Article
- Authors
- Wilson, Ryan; Bartsch, Annette; Joly, Kyle; Reynolds, Joel; Orlando, Anne; Loya, Wendy
- Units
- AKR
- Keywords
- Alaska, Climate, Forage, freeze, Freezing rain, Ice, Mammal, microwave, QuikSCAT, Rain-on-snow, refreeze, Remote Sensing, ROS, Scatterometer, Snow characteristics, thaw, timing
- Subjects
- Ecological Framework: Air and Climate | Weather and Climate | Weather and Climate