SALT LAKE CITY — In a recent study, University of Utah researchers found that dust accelerates snowmelt in the Colorado River Basin.
They analyzed 23 years of satellite imaging, noting patterns of dust deposition and snow melt between April and May in 2001 to 2023. Their work revealed that dust quickened snowmelt every spring, regardless of dust levels.
According to McKenzie Skiles, the study’s co-lead author and an associate professor at the U of U School of Environment, yearly dust-related melting rates can vary, but Colorado River Basin snowmelt is impacted by dust every year to some degree.
However, Skiles noted that recent years have seen a decline in dust-related melting.
“If we look over the whole record, we actually see a slight decline in impacts. It's slight, but it's statistically significant,” Skiles said. “We don’t actually understand what’s causing the decline yet.”
When dust enters a snowpack, it impacts the snow’s albedo, or reflectivity.
Dust accumulation leads to faster melting
“Snow is actually the brightest natural surface on Earth,” Skiles said. “It reflects up to 90% of incoming sunlight … basically anything that you put at the snow surface is going to make it darker.”
When snow is darkened, it absorbs more sunlight, leading to faster melting. Skiles said the region’s iron-rich, dark-hued dust also impacts snowmelt rates.
Researchers found that when the sun is at its highest, dust deposition can increase snowmelt rates by up to 1 millimeter of water-equivalent per hour. During higher dust years, that can equal as much as 10 mm of dust-related melting per day.
“The impacts are most intense in the central to southern rockies. That makes sense because that’s closest to the dust source regions, which [are] the four corners, southern Colorado plateau area,” Skiles said.
Colorado River Basin dust storm causes
Although researchers don’t know the cause of variation in dust events yet, Skiles explained that dust is deposited into the snow by wind.
“But not every dust event contains the same amount of dust and not every year has the same number of dust events,” Skiles said.
She said satellite records are useful in understanding events in real-time. More research is needed to understand contributors to dust storm activity.
“We can observe it when it’s happening but we don’t quite understand all the processes that come together to determine the magnitude of those dust events.”
Snowmelt is essential to the area
The Colorado River Basin is fed primarily by seasonal snowmelt. During the winter, it accumulates, then, as temperatures warm in the spring, it gradually melts.
According to Skiles, snowmelt timing is essential to the area’s needs. Early melting can prompt earlier greening of plants, allowing less water to flow downstream for human use.
“Usually, if the snowmelt is slow enough, it sort of sustains those water resources through the summer. But if the snow melts really quickly, then we’re left with less water later in summer,” Skiles said.
By understanding what controls the timing and amount of snowmelt, Skiles said snowmelt forecasts could be improved. Currently, they don’t account for dust-related melting.
“Our goal is to help water managers make better decisions about when to store water [or] when to let it run off downstream,” Skiles said.
