Ice Shelf Roughness: Its Fractal Nature and Relationship to Basal Melt

Stability of the Antarctic Ice Sheet is linked to ice shelves and ice shelf collapse could trigger widespread drawdown and retreat of marine based portions of the ice sheet. However, little is known about the processes that control the stability of ice shelves. Recent observations show that the bottom of ice shelves have extensive topography across a spectrum of magnitudes and wavelengths. Current literature speculates that these features are the direct result of basal crevasse formation and melt channels. Here, we use ground penetrating radar from Operation IceBridge and the ROSETTA project to quantify the magnitude of roughness beneath Pine Island, Thwaites, Larsen C, Ross, Dotson, Getz, and Filchner Ice Shelves. Despite the presence of basal melt channels, crevasses and rifts in some ice shelves, we find that spectrum of basal roughness follows a power-law (fractal) distribution with nearly constant fractal dimension between ice shelves. However, we find that the amplitude of the roughness—how large the bumps are—shows a statistically significant trend where increased basal melt strongly correlates with increased roughness. We speculate that increased roughness is due to the complex interplay between localized basal channels melts, increased crevasses and loss of buttressing. Moreover, these results suggest that roughness could be a key indicator of ice shelf stability