On May 9th, Tom Painter – founder and CEO ofAirborne Snow Observatories, Inc. – gave a presentation on the Sierra snowpack as part of the Sierra Nevada Aquatic Research Laboratory’s Spring Seminar series.
Painter – a snow hydrologist and remote sensing specialist – came on the snowpack scene in 2010, recruited by NASA’s Jet Propulsion Lab to eventually create the NASA Airborne Snow Observatory. 9 years later, he left for the commercial world. His goal: take quantitative snow measurements and accurate snowmelt forecasts global, measuring any range that geopolitics allowed.
He’s been in the game a while.
And, like other scientists in his field, he’s noticed what he calls a “crazed hydroclimate.” Since the 1950s, Painter’s noticed that the variation between annual snowpack sizes started to climb. The average never happens in the Sierra, Painter admits. But, this severe whiplash year to year in the climate system is more than that, and indicates a hydroclimate affected by climate change.
The consequence: forecasting tools for things like runoff become increasingly unreliable. These days, the forecast errors from April through July (i.e. the difference between predicted runoff and actual runoff) are 20% or more, 50% of the time. Water managers – who allocate water based on forecasts – prefer single digit errors.
Much of the problem is that current forecasting tools depend on historic data to calibrate their forecasts for current conditions. But, again, history’s become erratic, and depending on the past creates an unreliable prediction of the present.
Another problem with the old models: they rely on air temperatures to configure a melt factor of a snowpack. Which is far easier than measuring the actually significant factor: sunlight radiation. That’s what causes the snow banks and snowpacks to melt, says Painter. Not air temperature, but how much sunlight is being absorbed by the snow (which depends on the angle of the sun, the amount of dirt and dust in the snow, and the snow’s grain size). The calculation for the forecasted runoff, then, becomes, “How much sunlight can be absorbed by the snow, multiplied by the amount of incoming sunlight.”
That’s where Painter and his airplanes come in. He’s got three of them, and he and his team fly them over winter basins (this year, they added the Shasta basin, the American basin, and the Kern basin) to measure the variables to the calculation above.
To figure out the snow water equivalent (the snow’s depth and density), a laser radar known as Lidar is attached to the plane’s belly.
The plane flies high over the mountains, and Lidar sprays hundreds of thousands of laser pulses that bounce off the snow and back into the instrument’s receiver.
The time it takes for the laser to return to the receiver, after some math, tells Painter and the Airborne Snow Observatories (ASO) team how deep the snowpack is.
The process, once all the calculations are said and done, yields about a 1-2% uncertainty for calculating how much water is tied up in the snowpack.
For the whole basin.
Basically, Painter and the planes have led us into a new era of runoff forecast accuracy.
The average total Sierra snowpack per year is 18.5 cubic kilometers. 4.44 cubic miles for those who don’t mess with metric.
In 2023, Painter’s clocked the snowpack at a hair under 50 cubic kilometers. Nearly 12 cubic miles.
Which is about 60,000,000,000,000,000 liters (picture a Nalgene water bottle).
In some parts of the snowpack – near the Minarets, for example – the snowpack reaches depths of a hundred feet.
On Mammoth, the snow reaches depths of 59 feet in certain places. “Dave’s run will be maintained through the year this year,” said Painter.
Painter, who’s historic data shows that this season’s Northern Sierra snowpack didn’t quite beat out the Northern Sierra record snowpack of ‘82-’83, said that in the Southern and Central Sierra, the snowpack was enormous. And, it hasn’t really dropped yet.
Once snow grain size grows and more dust and dirt accumulates, the sun will start to do damage.
Painter ended the presentation on a sweet note.
Back in February/March during the 395 Lee Vining avalanches, he and the ASO team flew planes along the buried corridor so that snow removal teams could learn what they were dealing with.
This x-ray snow vision, it seems, can come in handy in all sorts of circumstances, and Painter is eager to put his technology on the global stage.