Thursday, May 23, 2013

Benefits of a Relatively Dust Free Spring

Over the past few years, we have seen a number of wind-blown dust events, especially in the spring, which have turned our precious Greatest Snow on Earth into the Greatest Snirt on Earth (Snirt=part snow part dirt).  These dust events are typically "recorded" in the snowpack as dirty layers, which collect on the snow surface during the spring melt.  The intensity and frequency of dust events vary from year to year depending on meteorology and land surface conditions.  Below are examples of relatively clean and dirty spring snowpacks in the Wasatch Mountains.

This year has been relatively dust free.  I haven't been up in the Cottonwoods for a while, but reports suggest that the snowpack is relatively clean and that was the case in April when I last made turns.  Yesterday, however, we saw some wind-blown dust over the Salt Lake Valley, with some obscuration of the visibility both in the pre- and post-frontal environment.  

The lack of dust events is good for skiers.  It makes for better spring skiing, but also a longer ski season since it results in a longer duration of snow cover in the mountains.  Dirty snow is darker and absorbs more sun than clean snow, resulting in a faster snowmelt.

Courtesy: Tom Painter, NASA/JPL
It's also good for skiing, and modeling studies suggest that it might be good for runoff too, which should make water managers and users happy given that this otherwise was a below average year.

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