UMass Amherst Receives nearly $6 Million NASA Grant to Understand the Fate of River Water in the Arctic Ocean

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This story was first published by the UMass News Office.

The world’s smallest ocean—the Arctic—is also the most mysterious. The Arctic’s sub-zero temperatures, extreme weather and large amounts of thick sea ice present challenges for studying the interaction between the frigid saltwater ocean and the freshwater rivers that empty into it. Under a $5.89 million NASA grant, UMass Amherst’s Colin Gleason will lead a multi-institutional team, combining field work in Alaska, icebreaking ships in the Arctic Ocean and specialized satellite data to do just that. 

Studying the influx of fresh water into salt water is particularly important for the Arctic. Elsewhere on Earth, water creates currents in the ocean due to temperature: cold water sinks, warm water rises. However, because it’s so cold in the Arctic, this process is controlled by salinity, which is directly influenced by freshwater flowing in from land where it sits atop the salty water. These currents modulate heat flux at the ocean surface and impact seasonal evolution of sea ice. 

“The Arctic Ocean is the least studied and it’s the coldest—and we don’t know how it’s changing,” says Gleason, associate professor of civil and environmental engineering in the Riccio College of Engineering at UMass Amherst. “Now, the Arctic Ocean is vastly free of sea ice in ways it never was before, so you take a sea-ice-free Arctic Ocean, you take rivers that are bumping water and especially sediment out as permafrost thaws in a way they’ve never done before, and we just do not know what going to happen.”

Weather and climate are defined by the circulation of water, salt and heat. (“Consider El Niño,” says Gleason as an example. “Small changes in ocean temperature off the coast of South America induce a cascade of anomalous weather around the world.” This kind of circulation is precisely what the researchers seek to understand in the Arctic, where there is a dearth of data. 

This research will include a three-month field campaign in the Colville River Delta and Beaufort Sea. When paired with global satellite data from SWOT (Surface Water and Ocean Topography) —used to calculate river discharge, or how much water flows through a particular point in a river at a specific time—this campaign data will be extrapolated to other Arctic basins, allowing the fate of fresh water in the Arctic to be remotely monitored.

This multi-institute effort includes hydrologists, oceanographers and delta specialists from the University of Washington, Williams College, University of Cincinnati, Pennsylvania State University, and the United States Geological Survey.

“We came up with this idea of integrating the hydrology of the Arctic with the ocean to ask the question: What happens to fresh water when it leaves the continent and flows into the Arctic?” says Peter Gaube, senior principal oceanographer in the Applied Physics Laboratory at the University of Washington.

“We’re usually very siloed,” says Taylor Rowley, a visiting assistant professor at Williams College, who previously conducted field research for the SWOT satellite mission as part of Gleason’s lab. “This project really integrates all three things—rivers, deltas and oceans—which is pretty unique.”

The ultimate goal is to create predictive Earth, ocean and atmosphere models that serve several purposes and can be scaled, locally to globally. For instance, Gaube highlights that native communities in the North Slope Borough of Alaska need to be able to predict ice thickness in order to support their subsistence hunting and fishing of marine mammals. 

Also, modern shipping needs sea ice prediction in order to determine when it is safe to allow merchant ships that aren’t icebreakers to traverse the Northwest Passage. “If you can’t predict when it’s going to freeze up, and you have a series of merchant vessels up there in the fall that get stuck, all of a sudden, you have a huge catastrophe,” Gaube says.

Globally, accurate models will inform how people around the world can prepare for future conditions. “The Arctic is one of the regions that is warming the fastest,” adds Rowley. “It also has huge implications for the rest of the globe, because it’s losing its ability to cool everything. The whole world is just heating up more and more because of the Arctic.”

“This work boils down to: What is the fate and transport of this river water?” asks Gleason. “Where does it go? What does it do? If it’s full of nutrients, how are those nutrients consumed, or do they just settle on the seafloor? How long does the water stay fresh as a plume before it’s mixed and how does this change ice formation?”