Tidal influence on ice shelf flow dynamics on the Dotson-Crosson Ice Shelf, Antarctica

Abstract:

We analyze the ice shelf flow direction using repeat ice flow mappings from the GoLIVE data set, looking for changes in ice dynamics at short and long time scales. GoLIVE ice velocity maps are based on feature correlation tracking in Landsat 8 image pairs, separated by 16 to 400 days with 300 m spatial resolution.

We have found periodic changes in ice flow direction of the Dotson Ice Shelf, in a confined zone buttressing the Kohler Glacier. The range of flow direction variation is greater than 90° in azimuth. We obtained a good correlation (r=-0.48 and p-value= 0.029) between direction changes and tides using the CATS2008 Circum-Antarctic Inverse Tidal Model. Previous studies have found connections between tide and ice flow speed mainly through three different mechanisms: changes in the basal friction of the grounded ice, changes in hydrostatic pressure and changes in the buttressing of pinning points. Our results provide new evidence of how tides influence ice shelf dynamics not only in speed but also in flow direction. This link will become more important with continued ice shelf thinning and associated destabilization in the near future.