Western Fires Have Far Greater Impact On Snowpack, Melt Rates Than Previously Thought

[hatrack]

EDIT

The research looked not only at how wildfires contribute to the depletion of snowpack, it looked at how widespread the phenomenon is across 11 Western states. Researchers used satellite data to study the rate of snowmelt in burn zones left behind by about 850 fires since 2000. The data showed snow melted, on average, five days sooner within burn zones than in places that hadn’t burned. The shift was in addition to other factors, such as human-caused climate change, that also contribute to an earlier melt. The satellite data also showed the phenomenon was widespread across 11 states, meaning it’s likely happening just about anywhere there are forest fires and snow.

The results showed the main contributors to earlier snowmelt in burn areas was the loss of tree canopy which exposed the snow to more sun and the increased presence of black carbon and other debris that made the snow absorb more heat instead of reflecting it back to the sky. The tree loss effect was expected. The widespread persistence of the debris effect was more surprising.

“Snow is typically very reflective, which is why it appears white, but just a small change in the albedo or reflectivity of the snow surface can have a profound impact on the amount of solar energy absorbed by the snowpack,” McConnell said. “This solar energy is a key factor driving snowmelt.” Although a difference of five days seems minor, spread across hundreds of burn areas across the West, it’s significant, Gleason said. Snowpack acts as a reservoir for about 50 to 70 percent of the water across the Intermountain West. In some areas, depending on seasonal variation, it can be even greater.

During this past winter, the Central Sierra Snow Laboratory in Truckee, Calif., showed that more than 80 percent of precipitation came in the form of snow.

EDIT

https://www.rgj.com/story/news/2019/05/08/research-finds-link-between-wildfire-accelerated-snowmelt-across-west/1133438001/

[FirstLight]

1. wow...really interesting

I would expect the tree thing too, but yeah...just a little less than pure snow will absorb the heat. Isn't this also some of whats being seen in the Arctic with the different reflectiveness of thinner ice?

[hatrack]

2. Oh, yeah - and along those lines, there's a great project to check out

https://www.darksnow.org/

Jason Box is the best-known of the scientific team, and they've been working for the better part of a decade on learning how snow albedo, dust and soot work to change Greenland.