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The mystery behind the brownish-red dust that's covering our hills has been the primary topic of conversation on the lift, in the shuttle, at local watering holes and even at school functions for the past few weeks.
Questions swirl wildly, like the winds of late, about the dirt's source: Did it come from Mexico or Moab or even Mongolia? Will it affect our run-off and are the other ski areas in the state feeling the same impact?
The answers to the latter two questions are “yes and yes.” And the dirt's actual path and place of origin are less of a mystery than recent discussions would indicate.
Last week's dust event, which was augmented by another wind event on April 12, most likely emanated from the Four Corners area, said Jeffrey Deems, research scientist at the NOAA Western Water Assessment and the National Snow and Ice Data Center at the University of Colorado.
“We can see the plumes on satellites and can run weather models backwards to look at the path of the air mass. Let's choose Aspen and Snowmass and calculate where the air mass came from. Based upon that evidence (the mass came from) generally southeast Utah, northeast Arizona and northwest New Mexico,” he said.
Deems, who just returned from examining the recent dust deposition at the Center for Snow and Avalanche Studies field site near Silverton, did not completely discount the theory that some of the dirt that arrived late last month came from halfway around the globe.
“We do get dust occasionally from Asia. It's not out of the realm of possibility. But by the time those events arrive here, they don't have a lot of mass in them,” he said.
Asian dust events in the past have added haze to the skies, but “have little impact on the snow's energy balance.”
Nature-made or man-made?
Travel past Vail or Copper Mountain, Loveland or the now shuttered-for-the-season Telluride ski resort and you'll see that the dust decorating the areas isn't isolated to just a single section of the state.
“This last event was pretty strong and blanketed the whole state pretty evenly,” Deems added.
Indeed, Deems said it's also present on the Continental Divide, outside of Boulder, location of his main office.
The gradations within the layers – Garrett Peak (as visible from Sneaky's run) looks like a soft-serve ice cream cone, with distinct stripes of white and brown. On other mountain aspects, the dirt layer is more solid or divided by elevation. The difference is in part due to how to how much snow was deposited or drifted onto the dust layer, Deems suggested.
The more deeply the dust is buried, either by new or drifted snow, the longer it takes for the dust to emerge on the surface.
Why has it come so late in the season? One reason may be because of the storm track that seemed to shift in late February, bringing this region some much-needed moisture while drying the soils in the desert.
Is it worse this year than last? Not yet, said the scientist, who characterized last year's occurrence as “super intense.”
“I can't say there's a trend but there's definitely been a couple of big years in a row,” Deems added. In fact, while long-timers of Aspen/Snowmass remember the winds kicking up dust in years gone by, the phenomena has only been intensively studied since 2003.
One reason is because researchers have determined that the dust is rough on our snowpack and our run-off. Think of a dark-colored car seat (and how it absorbs heat) as compared to one that is light in hue. The darker surface absorbs more sun and therefore, hastens the meltdown.
“The dust has a dramatic impact,” he emphasized, adding, “We think this is going to advance this year's snowmelt timing.” Recent work by Tom Painter at the University of Utah suggests that dust causes the snowpack to disappear about a month early in Colorado, compared with a clean snowpack.
Humans are certainly having an impact on the dust storms.
Research has been completed by Jason Neff of the University of Colorado that looks at dust emissions from areas where grazing has taken place, areas where grazing has been curtailed and areas where no grazing has ever occurred.
The good news is: “The land has some capability to recover its crust if the soil-disturbing mechanism is removed,” Deems said, paraphrasing some of the study's findings. In other words, changing some land management practices could have a positive impact on future conditions.
By removing a particular disturbance, the soil and vegetation are allowed to recover, the study seems to conclude.
Do your own experiment: Just look at the contrast between the Buttermilk half-pipe, which has been groomed recently, with the non-groomed and dark adjacent slopes. In the coming days and weeks, see what difference the brown layer makes on the snowmelt. While it's impractical to think humans can clear the layer of dust off snow in order to prolong its lifespan, certainly the stark contrast is a reminder as to how man-made disturbance may wreak havoc upon different facets of nature.
mosberger@snowmasssun.com
Questions swirl wildly, like the winds of late, about the dirt's source: Did it come from Mexico or Moab or even Mongolia? Will it affect our run-off and are the other ski areas in the state feeling the same impact?
The answers to the latter two questions are “yes and yes.” And the dirt's actual path and place of origin are less of a mystery than recent discussions would indicate.
Last week's dust event, which was augmented by another wind event on April 12, most likely emanated from the Four Corners area, said Jeffrey Deems, research scientist at the NOAA Western Water Assessment and the National Snow and Ice Data Center at the University of Colorado.
“We can see the plumes on satellites and can run weather models backwards to look at the path of the air mass. Let's choose Aspen and Snowmass and calculate where the air mass came from. Based upon that evidence (the mass came from) generally southeast Utah, northeast Arizona and northwest New Mexico,” he said.
Deems, who just returned from examining the recent dust deposition at the Center for Snow and Avalanche Studies field site near Silverton, did not completely discount the theory that some of the dirt that arrived late last month came from halfway around the globe.
“We do get dust occasionally from Asia. It's not out of the realm of possibility. But by the time those events arrive here, they don't have a lot of mass in them,” he said.
Asian dust events in the past have added haze to the skies, but “have little impact on the snow's energy balance.”
Nature-made or man-made?
Travel past Vail or Copper Mountain, Loveland or the now shuttered-for-the-season Telluride ski resort and you'll see that the dust decorating the areas isn't isolated to just a single section of the state.
“This last event was pretty strong and blanketed the whole state pretty evenly,” Deems added.
Indeed, Deems said it's also present on the Continental Divide, outside of Boulder, location of his main office.
The gradations within the layers – Garrett Peak (as visible from Sneaky's run) looks like a soft-serve ice cream cone, with distinct stripes of white and brown. On other mountain aspects, the dirt layer is more solid or divided by elevation. The difference is in part due to how to how much snow was deposited or drifted onto the dust layer, Deems suggested.
The more deeply the dust is buried, either by new or drifted snow, the longer it takes for the dust to emerge on the surface.
Why has it come so late in the season? One reason may be because of the storm track that seemed to shift in late February, bringing this region some much-needed moisture while drying the soils in the desert.
Is it worse this year than last? Not yet, said the scientist, who characterized last year's occurrence as “super intense.”
“I can't say there's a trend but there's definitely been a couple of big years in a row,” Deems added. In fact, while long-timers of Aspen/Snowmass remember the winds kicking up dust in years gone by, the phenomena has only been intensively studied since 2003.
One reason is because researchers have determined that the dust is rough on our snowpack and our run-off. Think of a dark-colored car seat (and how it absorbs heat) as compared to one that is light in hue. The darker surface absorbs more sun and therefore, hastens the meltdown.
“The dust has a dramatic impact,” he emphasized, adding, “We think this is going to advance this year's snowmelt timing.” Recent work by Tom Painter at the University of Utah suggests that dust causes the snowpack to disappear about a month early in Colorado, compared with a clean snowpack.
Humans are certainly having an impact on the dust storms.
Research has been completed by Jason Neff of the University of Colorado that looks at dust emissions from areas where grazing has taken place, areas where grazing has been curtailed and areas where no grazing has ever occurred.
The good news is: “The land has some capability to recover its crust if the soil-disturbing mechanism is removed,” Deems said, paraphrasing some of the study's findings. In other words, changing some land management practices could have a positive impact on future conditions.
By removing a particular disturbance, the soil and vegetation are allowed to recover, the study seems to conclude.
Do your own experiment: Just look at the contrast between the Buttermilk half-pipe, which has been groomed recently, with the non-groomed and dark adjacent slopes. In the coming days and weeks, see what difference the brown layer makes on the snowmelt. While it's impractical to think humans can clear the layer of dust off snow in order to prolong its lifespan, certainly the stark contrast is a reminder as to how man-made disturbance may wreak havoc upon different facets of nature.
mosberger@snowmasssun.com
