Earth scientists are using space lasers to observe a water system of 130 lakes in Antarctica. They used the latest data combined with historical observations to discover two new lakes and improve their maps of the frozen continent. The lakes periodically fill and drain into the ocean on cycles that are still not fully understood.
Studying these mysterious subglacial lake systems can help scientists understand more about ocean circulation, the speed and direction of Antarctica’s ice sheet flow, and Earth’s water system as a whole.
Let’s take a closer look at this discovery and what it can teach us about the world at large.
As Space.com reports, the newly discovered lakes are called the Lower Conway Subglacial Lake and the Lower Mercer Subglacial Lake. They are part of a larger system of lakes hidden below 1.2 to 2.5 miles of ice. The lakes and others like them are dynamic. They can change the currents in the Southern Ocean and can potentially affect worldwide ocean circulation.
“It’s not just the ice sheet we’re talking about,” researcher Matthew Siegfried said in a NASA statement. “We’re really talking about a water system that is connected to the whole Earth system.”
Siegfried and co-author Helen Amanda Fricker studied data from several Earth-observing satellites and reported their findings in the journal Geophysical Research Letters. In the paper, they explain that below the glaciers, several factors lead to small amounts of melting ice: insulation, pressure, the heat of the Earth and friction. These drops of melted ice add up to produce “large volumes of subglacial water,” which is stored in lakes and aquifers hidden below the surface of the ice.
Subglacial Lake Studies
Naturally, these water systems have been difficult for researchers to observe and access, since they are cloaked in miles of ice. Recent technology upgrades have made satellite observation possible. According to Space.com, as the lakes drain and fill on their natural cycles, the ice above them rises and falls. By measuring changes in the height of the glaciers, scientists can see evidence of what’s happening below the surface.
Satellites have observed these glaciers since 2007, with a NASA satellite called ICESat and then later with the Cryo-Sat2, a European Space Agency (ESA) satellite. The data collected from NASA and ESA satellites covered a broad area and gave scientists baseline measurements that kicked off a new era of understanding Antarctica.
When the first generation of satellite data became available, Fricker discovered that subglacial lakes were much more dynamic than scientists previously suspected. While scientists thought the lakes in Antarctica were fairly still, the data revealed otherwise. Instead of being static reservoirs, they fill and drain on a cycle. The volume of water that flows from Antarctica’s lakes is significant. One study found that a single Antarctic lake dumped 21 billion to 26 billion cubic feet into the ocean in 2019, as Live Science reports.
Technology That Enabled the Discovery
Earlier data was not precise enough to allow researchers to fully understand the water systems below the surface.
“Satellite measurements have been limited by how often they collect the data and their coverage,” the researchers explain in the paper. “Using new data from NASA’s ICESat-2 mission, we show that ICESat-2 provides unprecedented detail over lakes, both in time and space. The ICESat-2 data will lead to a steep change in our understanding of how Antarctica’s hidden subglacial water system operates, which is a crucial ingredient for how an ice sheet behaves and evolves.”
Northrop Grumman built the ICESat-2 satellite, which uses 10,000 laser pulses per second to measure the ice sheets in unprecedented detail. The satellite is equipped with a sensing technology called Light Detection and Ranging, or LIDAR, which is similar to RADAR but uses light instead of radio waves. A laser altimeter sends laser pulses down to Earth and analyzes the reflected light, measuring how long it takes the light to return to determine the distance.
“The discovery of these interconnected systems of lakes at the ice-bed interface that are moving water around, with all these impacts on glaciology, microbiology and oceanography — that was a big discovery from the ICESat mission,” said Siegfried. He added, “ICESat-2 is like putting on your glasses after using ICESat. The data are such high precision that we can really start to map out the lake boundaries on the surface.”
The discovery of two new lakes highlights the fact that there is still a significant portion of our planet we do not understand. Earth-observing satellites can provide clues about what’s happening below the surface and how those lakes and their draining cycles affect ocean circulation. This type of information can help to reveal details about what happens when glaciers melt — a topic that is becoming increasingly urgent as global temperatures rise.
“There are processes that are going on under Antarctica that we wouldn’t have a clue about if we didn’t have satellite data,” said Fricker. “We’ve been struggling with getting good predictions about the future of Antarctica, and instruments like ICESat-2 are helping us observe the process scale.”
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