It is uncertain how much glaciers and ice sheets will influence rising seas because scientists are not quite sure how they behave, contributing to wide predictions of future sea levels.
To better understand this, an international team of researchers are studying the North East Greenland Ice Stream, and engineering researchers at The University of Alabama will develop a radar that will be able to provide an accurate image of what occurs at the base of the ice. The radar will be the first of its kind, advancing the use of a type of radar known as ultra-wide band surface-based radar for scanning the interior of ice.
According to Dr. Prasad Gogineni, the Cudworth Professor of Engineering at UA - There is no radar capable of imaging ice layers within the bottom 10 percent of the ice with the resolution and precision required for this project. What they are developing, will be a state-of-the-art radar specifically for this purpose.
The project will be funded through a $1 million grant from a Denmark-based foundation, Villum Fonden, which is funding the larger project led by Professor Dorthe Dahl-Jensen at the University of Copenhagen.
This is the first project for the newly established UA Remote Sensing Center, which plans to develop technologies that enable high-resolution measurements of soil moisture, snow and ice. Gogineni, an internationally recognized expert in the field of remote sensing, leads the center.
At the outset of the project, Gogineni is joined by Dr. Charles O’Neill, assistant professor of aerospace engineering and mechanics, and Dr. Stephen J. Yan, assistant professor of electrical and computer engineering.
Like a slow moving river, the North East Greenland Ice Stream carries water into the ocean by dumping icebergs and melting on its edges. Its speed has been increasing, but changes in the ice stream are not well understood, making it difficult to predict through modeling. Researchers need to better understand what is happening at the very base of these ice streams and glaciers to be able to incorporate them into better models that predict what an ice sheet’s contribution will be to sea level rise in the future.
The ice stream has been studied heavily through drilling ice core samples and airborne radar, and Gogineni has been involved in several such projects at his previous position at the University of Kansas.
However, this project aims to understand how the structure of the ice crystals and the interaction within the ice, particularly at the bottom, has influenced flow over time. To help with that, researchers need a detailed image of the ice stream that will come from the radar built by the UA engineers. The radar will be used to expand knowledge from a site where a core sample will be removed.
The proposed ultra-wideband radar operates over a wide bandwidth in the Very High Frequency and Ultra High Frequency bands to penetrate deep into ice, as opposed to commercial radios or satellites that use microwave frequencies with large antennas to transmit over longer distances.
The UA-developed radar will operate at a higher power and have a bigger antenna than similar radars for ice sounding. The UA radar will be pulled over the ice surface by a vehicle at about 10 mph, moving much slower than existing airborne radars and thus allowing measurements that are more sensitive. The result should mean a radar 100 times more sensitive than the current state-of-the-art radar used to image glaciers.
Yan and his students are working to build the antenna and radar technology, while O’Neill and his students are working on the sled and mechanical design of the radar that must operate in a frigid environment while traveling over a rough surface.
The 16 antennas on the radar should also be able to send signals in different directions rather than just straight down, which should give a 3-D image of the structure of the ice, helping scientists better understand how it formed over time. The plan is to test the radar in Greenland in 2019 and collect data for up to six weeks in 2020. In all, the team plans to image nearly 20 square miles.
After collecting the data, the UA team will process it to generate images and 3-D topography maps of the bottom of the ice stream. The information will go to improve the models, and the models will be used to predict what will be the contributions of these large ice sheets to sea level rising in 50 to 100 years time.