Uncovering the origin of basal features at the Ross Ice Shelf using radar and augmented reality

Measurements of the interior structure of ice shelves give us valuable clues to understand their history, as distinct ice bodies may be traced from the grounding line toward the calving front. On the Ross Ice Shelf, this trajectory from the grounding line to the calving front takes ~1000 years, meaning that the ice shelf holds a 1000-year-long record of processes including snow accumulation, crevassing, basal melting, stretching, and basal freeze-on. Recently acquired radar data from the ROSETTA-Ice project show the internal structure of the ice in unprecedented detail. Two types of radar data, a shallow-ice radar (SIR) and a deep-ice radar (DICE), were acquired through aerogeophysical surveys flown in a grid at 10-km line spacing from 20152017. Radar data analysis entails careful tracking/picking of visible layers within the images. Images are displayed on a 2D screen and manually picked, using in-house MATLAB software. The high-resolution, 10-km line spacing of the Rosetta-Ice survey lends itself to a new method for data visualization, interpretation and analysis using the Microsoft HoloLens, an augmented reality headset that allows users to interact with 3D virtual objects using gestures. We build on previous work using the HoloLens to display ROSETTA-Ice data by creating a new user interface for measuring and comparing ROSETTA-Ice radar data. In this environment, radar images and identified horizons can be dragged in space to facilitate comparison between lines, as well as transformed (e.g., squashed, stretched, and tilted). Through this interface, we can more easily interact with data and determine how the ice changes as it flows downstream. Here we present our analysis of an ice body that appears predominantly in the SIR, and occasionally in the DICE radar data, located between the flow streaks that emanate from the Beardmore glacier. The feature is defined by the basal and near-basal reflections in the image, and can be traced in at least 26 ROSETTA-Ice lines oriented across the feature. This ice feature has a unique arcing shape and is intermittently visible for ~547 km. By comparing radar profiles of this feature, we track its volume and morphological change along flow.