Abstract Semantic segmentation is a critical part of observation-driven research in glaciology. Using remote sensing to quantify how features change (e.g. glacier termini, supraglacial lakes, icebergs, crevasses) is particularly important in polar regions, where features of interest may be spatially small but reflect important shifts in boundary conditions. In this study we assess the utility of the Segment Anything Model (SAM), released by Meta AI Research, for cryosphere research. SAM is a foundational AI model that generates segmentation masks without additional training data. This is highly beneficial in polar science because pre-existing training data rarely exist. Widely used conventional deep learning models such as UNet require tens of thousands of training labels to perform effectively. We show that the Segment Anything Model performs well for different features (icebergs, glacier termini, supra-glacial lakes, crevasses), in different environmental settings (open water, mélange, and sea ice), with different sensors (Sentinel-1, Sentinel-2, Planet, time-lapse photographs) and different spatial resolutions. Due to the performance, versatility, and cross-platform adaptability of SAM, we conclude that it is a powerful and robust model for cryosphere research.
We present a compilation of radio-echo sounding (RES) measurements of five radar systems (AWI, BAS, CReSIS, INGV and UTIG) around the EPICA Dome C (EDC) drill site, East Antarctica. The aim of our study is to investigate the differences of the various systems in their resolution of internal reflection horizons (IRHs) and bed topography, penetration depth and capacity of imaging the basal layer. We address the questions of the compatibility of existing radar data for common interpretation and the suitability of the individual systems for reconnaissance surveys. We find that the most distinct IRHs and IRH patterns can be identified and transferred between most data sets. Considerable differences between the RES systems exist in range resolution and depiction of the bottom-most region. Considering both aspects, which we judge as crucial factors in the search for old ice, the CReSIS and the UTIG systems are the most suitable ones. In addition to the RES data set comparison we calculate a synthetic radar trace from EDC density and conductivity profiles. We identify 10 common IRHs in the measured RES data and the synthetic trace. We then conduct a sensitivity study for which we remove certain peaks from the input conductivity profile. As a result the respective reflections disappear from the modeled radar trace. In this way, we establish a depth conversion of the measured travel times of the IRHs. Furthermore, we use these sensitivity studies to investigate the cause of observed reflections. The identified IRHs are assigned ages from the EDC's timescale. Due tothe isochronous character of these conductivity-caused IRHs, they are a means to extend the Dome C age structure by tracing the IRHs along the RES profiles.
Significant progress has been made in the development of next-generation ice-sheet models to simulate the response of large ice sheets in a warming climate and to determine their contribution to sea level rise over the next century. Good progress has also been made in characterizing the bed topography of a few key outlet glaciers in Greenland and Antarctica. These new models and data have been used to generate sea level rise projections of between 26 and 98 cm by the end of this century. However, there is still a need to better understand both ice-stream dynamics near the grounding lines and ice-shelf-ocean interactions, as well as to incorporate this understanding into improved models to reduce the large uncertainly in sea level rise predictions. We developed an ultra-wideband radar that operates over a frequency range of 150-450 MHz for fine-resolution measurements over the ice sheets in Antarctica and Greenland. This radar was developed specifically to obtain measurements over ice shelves and fast-flowing glaciers. The current antenna-array, which consists of eight elements, is housed in a certified antenna structure for a Basler aircraft. It will be soon expanded to 24 elements to cover a wider frequency range (150-600 MHz). During December 2013 and January 2014, we collected data over a few ice streams and glaciers in Antarctica. This paper will provide an overview of the radar, antenna array and results from the 2013-2014 deployment in Antarctica, as well as our plans for a larger array and wider bandwidth system.
The evaluation of ice sheet models is one of the pressing problems in the study of ice sheet dynamics. Here we examine the question of how much isochronous information is contained within the publicly available Center for Remote Sensing of Ice Sheets (CReSIS) Greenland airborne radio echo soundings data set. We identify regions containing isochronous reflectors using automatic radio echo sounding processing (ARESP) algorithms. We find that isochronous reflectors are present within 36% of the CReSIS radio echo sounding englacial data by location and 41% by total number of data. Between 1000 and 3000 m in depth, isochronous reflectors are present along more than 50% of the data set flight path. Lower volumes of cold glacial period ice also correspond with more isochronous reflectors. We find good agreement between ARESP and continuity index results, providing confidence in these findings. Ice structure data sets, based on data identified here, will be of use in evaluating ice sheet simulations and the assessment of past rates of snow accumulation.
