Dust Deposition More Influential On Snowmelt Than Warming Temperatures, According to New Study
According to a recent study, increasing temperatures are not the only factors contributing to spring snowmelt.
“So people see temperatures increasing in the spring and summer and then they also see snow starting to melt from the mountain so there’s this assumption that increasing air temperatures forces snowmelt, but there’s actually more energy contained in the sunlight, than there is increasing temperatures," said Dr. Mckenzie Skiles, a snow hydrologist and assistant profession in the geography department at University of Utah.
"So if you make the snow surface darker with something like dust deposition, you absorb more sunlight. And what we have found in this study is that this snow darkening process is actually what’s driving snowmelt in the upper Colorado River Basin,” she said.
During the months of March, April and May, Skiles and her team ski out to study sites where they excavate snow pits and collect snow samples.
“Dust is most important in terms of snowmelt when it’s right at the surface, so we sample at really high resolution about every 3 cm in the top 30 cm of the snowpack,” she said.
Skiles says spring is ideal for this, because the snow is typically still around and 80 percent of the dust deposition takes place during this time. The dust sampling captures large surface disturbances which can tell researchers a lot about water availability.
"The Rocky Mountains where this study took place, they are the headwaters of the Colorado River, which is also known as the lifeblood of the western US. It provides water for seven western US states and Mexico and it’s 80 percent snowmelt fed, so understanding these snowmelt processes is critical to water security,” she said.
The findings of this study have broad implications for water managers in the west who plan for variable climate and hydrologic conditions.