In situ temperature monitoring of the McMurdo Ice Shelf and ice shelf cavity by fiber-optic distributed temperature sensing
AuthorKobs, Scott Blake
AdvisorTyler, Scott W.
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Ice shelf basal melt rates represent an important yet challenging to measure process. Basal melt rate measurements can assist to further understand ice-ocean interactions. In November 2011, two mooring containing fiber-optic cables for distributed temperature sensing (DTS) were installed at Windless Bight, Antarctica. Temperature was measured every meter along the deployed optical fibers over the 14 month test period via Raman backscatter DTS. Over 9 million temperature measurements were recorded from two moorings during the deployment. The data was calibrated into two sets, one representing ice shelf temperature and the other representing ocean temperatures. This study examines temperature observations near the ice-ocean interface in order to understand basal melting at the location of the moorings.Traditional methods for estimating basal melt rates rely on steady state models, however, the smooth thermal profile of ice shelves and high spatial resolution of DTS allow for small changes of the thermal gradient to be monitored over both time and space. The thermal gradient near the ice-ocean interface is extrapolated to the in situ freezing temperature in order to track the interface during the deployment. From the inferred interface locations, daily and annual melt rates are calculated to be 0.008 m∙d<super>-1</super> and 0.99 m∙yr<super>-1</super>, respectively. The application of DTS systems for remote ice shelf measurements represents a new and potentially powerful tool in the study of ice shelf heat transfer.