Dust deposits blown onto snow shown to accelerate snowmelt

SALT LAKE CITY — Blowing dust from the dry lakebed of the Great Salt Lake is not only bad for our air quality, but it also threatens Utah’s most precious resource: water. A study published today by University of Utah researchers analyzed the impact of dust on snow during the winter of 2022. It shows that the many, large dust deposits, accelerated the snowmelt.

Last winter, 2022, was one of the driest on record. It was also the dustiest on record. Consequently, the research shows that the snow melted earlier, and there was less runoff for Utah’s reservoirs.

“It was record-breaking. We saw more dust and more dust events,” McKenzie Skiles, a University of Utah assistant professor of geography and water scientist said.

Skiles has studied the melting effects of dust on snow for a decade.

Last winter, there were frequent dust storms.

“Each one of those dust deposition events was depositing a lot of dust,” Skiles said.

Those dust storms left the highest concentrations of dust on the snowpack ever. What difference does that make?

“When we looked at the impact of that dust on snowmelt, we got accelerated snowbelt by 17 days,” Skiles said.

When dust lands on snow, it makes it darker.

“Snow is one of the brightest natural surfaces on earth, it reflects 90% of the incoming sunlight, and when you make it darker, it absorbs more sunlight, and that is actually the main driver of snowmelt,” she said.

When the snow melts faster that impacts the runoff forecast which is critical for understanding how much water will end up in the reservoirs.

“Which means that the water comes out sooner than we expect, and in a low snow year, that’s important,” Skiles said. “We want to be able to use all of the water that we can in efficient way.”

“Where did that dust originate? That’s what we focused on in this study,” Derek Mallia, an atmospheric sciences assistant research professor at the University of Utah said.

He created models to isolate the sources of the dust, and the shrinking Great Salt Lake isn’t the only problem.

“A really large emitter of dust for northern Utah is going to be the west desert.. the Salt Flats. It’s a pretty large, pretty potent emitter of dust,” he said.

This year was also one of the dustiest for the snowpack in spite of record snowfall.

“It just goes to show that even if you’re getting frequent rain and wetting events, those dust source regions are still producing dust, and still have a big impact on melt,” Skiles said.

She said, that could help explain why Utah’s record snowpack this year melted out quicker than it did in previous years with big snowpack. Skiles believes these results are another strong motivator to protect the Great Salt Lake, and keep the lake levels healthy.