image: File image of muskoxen traveling in the snow in the Arctic. Credit: Lars Holst Hansen/Aarhus University
Credit: File image of muskoxen traveling in the snow in the Arctic. Credit: Lars Holst Hansen/Aarhus University
When rain falls on snow in the Arctic, ice layers can form on top of and within the snowpack.
This increasingly common dynamic can influence the ability of animals, including caribou and muskoxen, to forage and move across the landscape. That, in turn, affects the people who rely on wildlife for subsistence, culture, wellbeing and income.
Given the widespread impacts of rain-on-snow events, Colorado State University researchers are studying and modeling their effects in Arctic systems. The work is especially important considering the rapid rate of climate change across the region, said Stine Højlund Pedersen, who is leading the project.
“There is an almost endless list of implications that come from these ice layers forming. That includes related questions into climate change and the broader physical Earth systems,” Pedersen said. “With these events expected to become more frequent, we need a better understanding of how they change snow’s properties and what that may bring.”
Pedersen and her team recently returned from Alaska as part of a five-year, $2 million project funded by the National Science Foundation.
Their research is conducted through the Cooperative Institute for Research in the Atmosphere, a collaboration between the National Oceanic and Atmospheric Administration and CSU’s Department of Atmospheric Science. The institute is a nexus for multidisciplinary research involving federal scientists and CSU researchers and students.
During an initial field expedition in northwest Alaska, which experiences many rain-on-snow events, the researchers collected data regarding snow and ice – and measured hoofprints reflecting animal movement. Snow measurements included depth, the ice layer’s position, snow grain size and snow grain type, among others. The team also measured hoofprint dimensions and the depth of the depression they made in the snow.
By comparing findings collected from a variety of areas, such as snow in the open, windy tundra and deeper snow in shaded forests, the team hopes to better understand which elements, such as temperature, are key to an ice layer’s formation and persistence in each environment, and what that means for wildlife. The team will use findings to develop and test a snow modeling tool, Pedersen said. Researchers currently lack the ability to quantify and evaluate these ice layers as they form and change over time and therefore are limited in their ability to study their impacts across the system.
“We are building a comprehensive data set that will enable the development of an ice-layer submodel that will be coupled to an existing 3D, physics-based snow modeling system that can estimate the accumulation and re-distribution of snow across landscapes over time,” Pedersen said. “The new data will ensure the model is accurate and useful for showing how an ice layer may melt more on the sunny side of a mountain versus the shaded side. Or how long the ice will persist in the snowpack and support an animal’s weight as they walk across without punching through – forcing them to expend a lot of extra energy to move.”
Adele Reinking, project co-leader and a wildlife research biologist at CIRA, said the team’s approach provides valuable “ground-truthing” that fills a knowledge gap.
“Satellites can provide imagery, and there are weather stations in the area. But those only tell us about single points in space or time and not at all about what is going on within the snowpack,” said Reinking, who is working on her Ph.D. at CSU from the Graduate Degree Program in Ecology. “The goal is to take those existing observations and combine them with the new data set to develop a model that can better predict changes to the environment, help us understand historic conditions, and address some of the more complex and interconnected problems currently at play here.”
The team will conduct similar data collection on another trip to Alaska and during future trips to Greenland and Svalbard, where these events are also becoming more common.
“Our goal is to translate the science into something that matters for everyone and to produce a tool that is useful for the scientific community, no matter their research topic,” Reinking said.