Let it snow, inside for science

CSU scientist studies snow processes at unique lab

story by Jayme DeLoss
photos and video courtesy of Steven Fassnacht
published Nov. 29, 2022

In the headwaters state of Colorado, snowpack is king. Colorado State University snow hydrologist Steven Fassnacht recently traveled to one of the most advanced snow laboratories in the world to study this important resource and how snow influences water management and climate forecasting.

To allocate water wisely, water managers need to know how much is available, but estimates based on snowpack are not precise, in part because some snow processes are not well understood. The data from Fassnacht’s experiments will inform models to improve water forecasting and management.

“We’re trying to use better tools to estimate how much water is going to come out of the mountains,” Fassnacht said of snow hydrologists’ comprehensive approach combining lab results with remote-sensing, or satellite, data and observations in nature. 

man looks up as snow falls inside lab
Steven Fassnacht examines the fresh snow generated at the Cryospheric Environment Simulator.

Fassnacht, a professor of ecosystem science and sustainability in the Warner College of Natural Resources, traveled to Japan on a fellowship sponsored by the Japanese Society for the Promotion of Science. He spent a month conducting research with the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) in Yokohama and one week at a unique snow-simulating facility at the National Research Institute for Earth Science and Disaster Prevention in Shinjo. 

The Shinjo Cryospheric Environment Simulator’s cold room keeps the temperature constant at 14 degrees Fahrenheit, or -10 Celsius, and its snow generator makes snow crystals that are as close to the real thing as you can create in a lab – much closer structurally to fresh powder than ski resorts are able to produce. 

“I felt like a kid at Christmas because they were able to create this snow on demand,” Fassnacht said. “My understanding is that there’s no such facility elsewhere. This is the only place of its kind in the world.” 

Snow surface is not that simple

Fassnacht is studying snow surface and how it influences water availability and climate. Hydrologic, weather and climate models assume snowpack is a uniform, flat surface, but in reality, wind and sun unevenly transform the surface. Conversely, the surface also affects whether snow will be picked up and blown around by the wind.  

In the snow lab, Fassnacht and his colleagues used a wind tunnel to simulate consistent conditions. They were able to dial in specific wind speeds and see how that affected different snow surfaces.   

One process they examined was how much snow is lost to the atmosphere through sublimation, when a solid becomes a vapor. Wind increases sublimation, but water forecasts often don’t account for it.  

The researchers want to figure out how much snow will melt or be lost to sublimation and how long the snow will stick around – information that’s essential for water planning. In most places that have a seasonal snowpack, the snow is relatively shallow, Fassnacht said, but it’s still very important to the water cycle.   

“Having snow on the ground versus having grass or bare ground is a big deal in the energy balance,” he said. Bare ground absorbs more energy than snowpack, which reflects sunlight – an important factor for climate prediction.  

closeup of snowflakes on a mitten
The Cryospheric Environment Simulator’s snow generator makes snow crystals that are structurally similar to fresh powder and as close to the real thing as you can create in a lab.

Due for an update  

Fassnacht said scientists are using basically the same approaches to forecast water based on snowpack that have been used since 1905.  

“It’s a very simple approach, and it works relatively well, except in extreme years – and that’s when we need it most,” Fassnacht said. “In dry years, it often doesn’t work well.”  

Accurate water estimates will require improved modeling combined with on-the-ground and remote-sensing data collection, he said.  

Fassnacht met his fellowship host, Kazuyoshi Suzuki, a researcher with JAMSTEC, in 2010 while Suzuki was on sabbatical at CSU. The study originally was scheduled for March 2020 but was postponed due to the pandemic. Japan closed its borders as Fassnacht was on his way to the airport.   

Fassnacht hopes to return to the lab for future studies, and he would like to bring students along next time, so they can experience the research and cultural exchange firsthand.