This is an excerpt from a NASA FINESST grant proposal. Full proposal text available upon request.
Plain Language Summary
Subglacial hydrology (how water moves beneath glaciers) influences the speed of ice sheets, so knowing how water flows beneath these glaciers can help improve future ice sheet models and sea level rise forecasts, both of which are urgent topics with significant societal impact. Adjoining Thwaites and Pine Island glaciers are two critical areas to watch over the coming decades, but uncertainties remain about how water flows beneath these massive West Antarctic Ice Sheet glaciers. Specifically, previous hydrological models rely on unrealistically smooth subglacial topography, which biases our perception of how subglacial water flows. Our research will use geostatistical simulation methods to generate realistically rough topography and assimilate ice-penetrating radar observations and models in order to improve our understanding of subglacial hydrology on Earth, and apply these techniques in the search for liquid water on Mars.
Our first research objective will combine realistically rough topography with a complex water flow model for the first time beneath Thwaites and Pine Island glaciers, allowing us to better understand how water moves under these critical glaciers. We will compare these results to existing radar data, to look for distinct radar signatures related to flow dynamics beneath the glaciers. Our second research objective aims to use a certain type of radar signal called off-nadir reflections, or clutter, to help us understand the material conditions of the subglacial environment (such as wet versus frozen). The noise from radar clutter can make it difficult to interpret reflectivity data, which is one way we can identify liquid water beneath glaciers. For example, several materials can return signals that can be misinterpreted as liquid water. We will use a unique geostatistical simulation method to identify all of the bed topographies and materials that could result in the observations that radar analyses have uncovered so far, and use that information to better distinguish bed material conditions. Finally, with our third research objective we will bridge the gap between terrestrial and planetary glaciology by using similar methods from our research in Objective 2 to explore a potential subglacial lake on Mars. We will use geostatistical simulations of subglacial topography to determine the statistical likelihood of the presence of a lake.
Relevance to NASA
This research is only possible with the use of NASA’s data and software. We will use the Glacier Drainage System model, part of NASA’s Ice Sheet System Model software, to study subglacial water routing. We will use NASA datasets from Operation IceBridge, Airborne Geophysical Survey of the Amundsen Sea Embayment Antarctica, the Mars Orbiter Laser Altimeter on NASA’s Mars Global Surveyor spacecraft, and Mars Advanced Radar for Subsurface and Ionosphere Sounding.
Objectives one and two address the FINESST Earth Science Research Program mission by seeking to advance our scientific knowledge of our changing planet in response to a warming climate. Improving our understanding of subglacial topographic and hydrological conditions beneath two critically important Antarctic glaciers can inform future ice sheet models and sea level rise forecasts, a topic of urgency with significant societal benefit. Objective three addresses the FINESST Planetary Science Research Program strategic objectives to advance our scientific knowledge for the potential for life elsewhere, and hazards and resources present as humans explore space. With implications for both astrobiology and planetary glaciology, this research will help to bridge the gap between terrestrial and planetary subglacial hydrology by applying rigorous geostatistical models tested on Earth, to a scientific question that has far-reaching implications in the planetary sciences.