Snow science 
in action

Grand Mesa snowpack scrutinized like never before in huge NASA project

NASA scientist Ludovic Brucker discusses the multi-agency, NASA-led snow research project being conducted this month on the Grand Mesa. Behind him is a University of Michigan boom truck equipped with a microwave radiometer, one of numerous instruments used in measuring snowpack. The project’s goal is to help NASA be able to determine what sensors can best be used to measure snowpack from satellites.



NASA weather station on Grand Mesa.



Following the pilots’ preflight examination of the aircraft, the research crew gathers on the tarmac at Grand Junction Regional Airport by the Beechcraft King Air A90 turboprop before the morning flight on Thursday.



Dan Berisford, flight team leader for the NASA Airborne Snow Observatory, looks over the Riegl LiDAR (Light Detection and Ranging) and the black box with the imaging spectrometer to its right in the Beechcrarft King Air A90 turboprop aircraft before taking off.



NASA weather station on the Grand Mesa.



Kelly Elder, a research hydrologist with the U.S. Forest Service,discusses scientific instruments being used in a large-scale snow research project on Grand Mesa. The goal is to help NASA determine what sensors can best be used to measure snowpack from satellites.



Snow to the top of a Stop sign at the Jumbo Campground on the Grand Mesa.



NASA weather station on the Grand Mesa.



You’ve probably skied on Grand Mesa, or snowmobiled, or snowshoed. Or made snow angels or built a snowman.

But you probably haven’t spent that much time taking a close look at the snow. You certainly haven’t looked at snow the way some 100 researchers are this month on Grand Mesa, in a multi-
million-dollar project being led by NASA with the goal of learning how to better measure snowpack.

Using high-tech equipment like infrared sensors and low-tech gear like shovels, they’re trying to determine what remote sensors could best be used on satellites to produce more accurate snowpack measurements around the world.

Coming from federal agencies and universities, and from North America, Europe and Asia, many who work in the global snow science community have been converging on this flat-top mountain. Their hope is to determine how technology can be put to work to better assess snowpack levels so important to forecasting seasonal runoff, water supplies for farms and cities, and the prospects of flooding or fire.

Knowing snowpack levels is of crucial importance to reservoir operators who try to store enough water to meet future needs but leave enough storage space so as not to imperil dams if they overflow. A timely example is provided by the recent threat of the Oroville Dam failing in California, a state hit this winter by heavy rains and snows.

“If we had a better idea what was coming down the pike in terms of either weather and/or snowpack, we could avert things like that,” said Kelly Elder, a research hydrologist for the U.S. Forest Service.

FROM LAND AND AIR

Elder is part of the leadership team carrying out what’s called the NASA SnowEx project on Grand Mesa and on a smaller scale near Red Mountain Pass in southwestern Colorado. The idea is to deploy aerial sensing technologies — such as ones measuring microwaves or using LiDAR, a light-based ground surveying method — and then test their accuracy and effectiveness through on-the-ground measurements. The research also is using high-resolution imagery from satellites.

Researchers hope to find what combination of technologies would work best on a satellite, taking into account the advantages and shortcomings of each approach.

While the aircraft have been staging out of Grand Junction and Colorado Springs, the researchers have been based in the Mesa Lakes Lodge and Grand Mesa Lodge, filling the two facilities for the month. Mike Wenner, who with his wife Rose owns the Grand Mesa Lodge, said his business also has been providing snowmobile outfitters to accompany the researchers to many of the measurement sites spread out on Grand Mesa.

He said the researchers appear to be coping fairly well with the conditions on the mesa.

“Some of these folks were in Antarctica before they came here. They’ve done this type of thing before; they’re snow scientists,” he said.

NASA scientist Ludovic Brucker is one of those veterans of research projects in places like Antarctica and Greenland, perhaps explaining why he was comfortable dressed in only light clothing on a sunny winter afternoon during a media tour this week.

Also a leader on the project, he said every research project is different, and the one on Grand Mesa is notable in its large size and involvement of so many organizations and universities. The project — which the researchers call a campaign — entails anywhere from 38 to 43 people working on weekly shifts, with some of them rotating out each week and others here for the duration of the effort. Each week begins with training in safety and other matters on Monday, followed by work through Saturday and a transition day on Sunday.

H.P. Marshall, an associate professor of geophysics at Boise State University, said this year’s research project is the largest of its kind since another that was conducted in the Fraser and Steamboat Springs areas in Colorado about 15 years ago. That was just a two-year project, with the current one scheduled to continue for four more years at research sites that haven’t yet been determined.

 

TRAINING THE NEXT GENERATION

Marshall participated in the 2002-03 project as a student and is now one of the current project’s leaders, working with colleagues he had interacted with as faculty or fellow students during that prior project.

He said the current project could be executed by hiring perhaps 15 or 20 experts. But instead it was opened to anyone willing to commit to a full week of work, again including students and others.

“It’s a big community-building project within the snow science community. … A big part of this effort is training and development collaborations,” Marshall said.

Elder said one of the goals of the project is to try to train the next generation of snow scientists. He cited as an example Mohammad Mousavi, a doctoral candidate in electrical engineering at the University of Michigan. Mousavi is working on Grand Mesa with a University of Michigan boom truck parked at the Jumbo Campground by Mesa Lakes and outfitted with a microwave radiometer, one type of snowpack measurement device.

Mousavi said being part of such a big campaign has exposed him to a wide variety of measurement devices.

“There are a lot of other instruments. You can compare your results with other people to see if your results make sense,” he said.

Volunteers also are part of the project, including Marshall’s wife, Amaya Odiaga. She is involved with logistics, having helped develop a system for checking out winter gear to researchers, and working to ensure the gear is dry and in good working order at the start of each day. While Marshall and Odiaga both get to spend the month on Grand Mesa, they’re pretty busy doing their own jobs, but Odiaga is glad to at least get to spend a lot of time outdoors.

“I got to spend Valentine’s Day on a snowmobile measuring radar,” Odiaga said with a laugh. “It was pretty fun.”

 

‘FUNDAMENTAL SCIENCE’

While the project comes at the beginning of a new presidential administration that has called some science into question, Elder said he’s not aware of any such questions being raised about the NASA project.

“This is pretty fundamental science. We’re trying to measure water on the planet,” he said. “We’re focusing on the snowpack and the water that comes out of it.”

With so much being integrally linked to snowpack in the West, “everybody’s got a stake in this game,” Elder said.

The hope of the project is to boost certainty in assessing water content in snow and to be able to better assess that snowpack globally through satellite use. While there are some 800 automated, ground-based measurement sites across the West, scientists are left to try to estimate snowpack between those sites.

Marshall said the problem is that snowpack “varies over really short distances, like on the scale of a football field, and so we’re not able to take those (800) sites and estimate what’s going on in between them very accurately.”

Snowpack also can vary in density from top to bottom, meaning that water content isn’t consistent from layer to layer of snow between the surface layer and the ground.

Another huge complication comes from trees. Chris Hiemstra, a scientist based out of Alaska for the U.S. Army Corps of Engineers, specializes in studying interactions between vegetation and snow. Also a leader on the Grand Mesa project, he noted that the boreal forest is the largest terrestrial land cover type in the world. Yet a lot of remote sensing techniques can be thwarted by plants, and snow that’s hard to remotely measure can linger below tree canopies.

One big reason Grand Mesa was chosen for this year’s research is that it offers a spectrum from open areas to thick forests. That will enable researchers to compare how sensors work in areas of varying vegetation.

Meanwhile, Grand Mesa’s topography is fairly uniform, meaning it won’t act as much of a variable that could affect the research being conducted. The concurrent work near Red Mountain Pass, which Marshall also is leading, is in a different type of topography, in a mountain basin, to allow for different kinds of research than on Grand Mesa.

Hiemstra said the Grand Mesa work involves gathering hundreds of thousands of data points about where things like leaves, stems and trunks are, and will help facilitate basic research because there’s so little known about how things such as snow, trees, sun and wind interact.

The Grand Mesa project involves some 100 measuring sites where researchers walk transects, measure depths and dig snow pits to analyze layers and other aspects of snowpack. Remote cameras installed across Grand Mesa take time-lapse photos of poles to document changes in depth.

Other instruments monitor an endless range of things. One measures radiation from sunlight. Another can shoot 380 frames per second during snowfall and rainfall, which Brucker said can allow for determination of things such as a particle’s size and falling speed. But Elder — standing in a snow pit and pointing to one device with a price tag of $80,000 — said one of the most essential tools in snow science remains the $40 shovel. It’s what a researcher can use to build a snow cave in an emergency and is central to the job of excavation of snow pits that yield so many scientific secrets. The act of digging itself reveals some of those secrets, he said.

“You can tell a lot about the snowpack by what your feet are doing (in the pit). Your ears will tell you stuff. The way your shovel’s behaving, you can feel (things) in your shovel,” he said.

Even the taste of snow can reveal things about it, Elder said.

 

IMPORTANCE OF 
GROUND-TRUTHING

It’s for such reasons that Elder believes basic tools such as shovels and skis will remain essential to snowpack assessment even if satellites eventually are well-armed to do the job remotely.

“It’s really an important part,” he said. “If you lose the focus of what’s happening in the field you quickly find that your errors (from remote sensors) are increasing. You don’t have a way of grounding those and all of a sudden you’re caught in a bad situation. I think there will always be a ground-truth component to this.”

Marshall agrees, seeing field trips as crucial to calibrating and validating remote sensor data.

“The only way we can tell how accurate it is is with a field measurement, so I don’t think (field measurements) will ever go away,” he said.

It’s such ground-truthing that will let researchers ferret out which combination of sensors might work best in space. Marshall said LiDAR, for example, has proven successful as an aircraft-borne means of measuring snow depth. But he said it can’t see through clouds and could prove to be an engineering challenge from a cost and resolution standpoint if used in space.

In addition, it doesn’t measure snow density, which must be known along with depth to calculate water content, so some other form of measurement would be needed along with it.

 

RETURN TO MESA POSSIBLE

As researchers pursue answers to their questions about remote sensors, they also are reveling in the camaraderie of colleagues sharing the same interest.

Said Hiemstra, “It’s been an interesting project and a good opportunity to work with a lot of different people in the same place. That’s the fastest way to exchange ideas and see what everybody else is doing and what works and what doesn’t and think about new ways to do things, which is really important,” he said.

It’s not out of the question that researchers could return to Grand Mesa for another winter at some point in the five-year project. Scientists will spend the next year evaluating data from this year’s work before returning to the field in year three. Marshall said that while new locations would offer advantages such as different kinds of snowpack and vegetation to study, there also would be advantages to coming back to Grand Mesa for a year.

Past smaller-scale projects previously done on Grand Mesa by Marshall and some of the others involved in this year’s work helped convince them of its value as a site for the NASA project.

“It’s not straightforward to run a campaign of this size,” Marshall said.

He pointed to the partnerships scientists have developed with lodges, local Forest Service officials, National Weather Service employees in Grand Junction who provide crucial daily forecasts, and others in preparing for this winter’s work.

“All these things sort of had to be developed and would have to start over if we moved to a new place,” he said.

Factors such as Grand Mesa’s extensive snowmobile trail system and plowed road access also were important to researchers. And there also would be value in being able to compare data from this year to any gathered on Grand Mesa in a future year.

Either way, researchers say the trove of data being collected this year will serve as a lasting legacy, providing for further scientific analysis for decades to come. Marshall said papers continue to be published based on the data from the Colorado project 15 years ago.

For now, the researchers’ work this month goes on, from the high-tech observations conducted from aircraft and via expensive ground-based technology, to the equally important analysis accomplished using such simple tools as a magnifying lens to analyze individual snow crystals. The latter is something Elder excitedly encourages any snow-country visitor to try.

He promises, “You’ll see a world that you cannot believe.”


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