A Breathtaking View – Literally

Credit: NASA / Jessica Merzdorf
Credit: NASA / Jessica Merzdorf

By Jessica Merzdorf / GRAND MESA LODGE, COLORADO

After visiting with part of the SnowEx 2020 airborne team, we headed up the mountain to rendezvous with the ground team, stationed at Grand Mesa Lodge.

“Does anyone have a headache?” asked Jerry Newlin, SnowEx operations manager, as we left the little town of Delta and the rugged brown foot of the mountain range loomed up in front of us.

“Nope, feeling great” was our answer at the time. We traveled up the winding roads, commenting on the views that became more incredible the higher we went, and arrived at Grand Mesa Lodge in time for dinner and the evening briefing with the team.

But later that evening, at 10,500 feet, both video producer Ryan Fitzgibbons and I started developing symptoms of altitude sickness. Lower oxygen levels at higher elevations can cause headaches, nausea, shortness of breath, dizziness and other symptoms as the body adjusts. Sometimes the symptoms resolve on their own as the body gets used to the conditions; after a long, rough night of intense headaches and nausea, I gratefully accepted an herbal medication from the Grand Mesa Lodge owners. (Severe cases of altitude sickness require quickly moving back down to lower elevations. The ops team kept a close eye on me to make sure I didn’t need medical attention.)

After I took a nap back at my cabin and started to feel better, we checked in with Jerry and were cleared to snowmobile up to the snow pits.

The ground team’s daily “commute” varies depending on where they’re working that day, but it can be as much as 16 miles of hills, curves, bouncy stretches and incredible views of the valley below.

The SnowEx team reached the field sites via daily snowmobile trips. The ride is bumpy and can take 45 minutes to 2 hours, depending on where they’re working on the mesa. They towed their instruments and gear on sleds behind the snowmobiles. Credit: NASA / Jessica Merzdorf
The SnowEx team reached the field sites via daily snowmobile trips. The ride is bumpy and can take 45 minutes to 2 hours, depending on where they’re working on the mesa. They towed their instruments and gear on sleds behind the snowmobiles. Credit: NASA / Jessica Merzdorf

At each of the snow pits in this 3-week phase, the SnowEx ground team digs until they reach the ground, exposing a “wall” of snow where they take their measurements: Depth, density, water content, temperature, reflectance and particle size.

“We can see, and even hear, how the snow’s characteristics change from top to bottom,” said Chris Hiemstra, a researcher with the U.S. Army Corps of Engineers’ Cold Regions Research and Engineering Laboratory (CRREL). “The newest snow at the top is fluffy and loose. Below that, the wind has packed it into dense layers. The snow at the bottom has more water and the particles are sharper. When you dig into it, it sounds different than the other layers at the top.”

When we stopped by deputy project scientist Carrie Vuyovich’s pit, we heard the story of the “strong work mouse,” and saw a snow statue (made from wind-packed snow, incidentally) built in the mouse’s honor.

The SnowEx “mascot” for 2020 was the “strong work mouse,” honoring the small field mice that visited the snow pits during the first two weeks of data collection. Suzanne Craig of the National Snow and Ice Data Center records data next to a snow sculpture of the strong work mouse. Credit: NASA / Jessica Merzdorf
The SnowEx “mascot” for 2020 was the “strong work mouse,” honoring the small field mice that visited the snow pits during the first two weeks of data collection. Suzanne Craig of the National Snow and Ice Data Center records data next to a snow sculpture of the strong work mouse. Credit: NASA / Jessica Merzdorf

“There were these little mice that came to visit us in the first couple of weeks,” she said. “We’d be in pits, and these little mice would come running across the snow – one came down into the pit and hung out with us for a while, another team had a mouse running along beside them, and another member had a mouse come right up next to his boot. So that became our mascot – the ‘strong work mouse.’”

Not all of the research takes place in pits. Team members on skis used snow micro-penetrometers (SMP’s) to measure hardness and microstructure throughout the snow layers with incredibly high precision: The SMP takes 250 measurements every millimeter. Other snowshoe-wearing scientists used MagnaProbes, which have a magnetic probe that goes into the snow and a “basket” that rests on top. The distance between the two parts provides a highly accurate, GPS-tagged measurement of snow depth, and is many times faster than writing depth measurements in a notebook.

SnowEx 2020 project scientist Hans-Peter (HP) Marshall drives his snowmobile in a tight clockwise circle called a “radar Hiemstra spiral”, taking active radar measurements of the snow. The Twin Otter aircraft carrying SWESARR will later fly over this circle and take similar measurements. Credit: NASA / Jessica Merzdorf
SnowEx 2020 project scientist Hans-Peter (HP) Marshall drives his snowmobile in a tight clockwise circle called a “radar Hiemstra spiral”, taking active radar measurements of the snow. The Twin Otter aircraft carrying SWESARR will later fly over this circle and take similar measurements. Credit: NASA / Jessica Merzdorf

SnowEx project scientist Hans-Peter (HP) Marshall and Mike Durand, an associate professor at Ohio State University, used snowmobiles to create tight clockwise circles of radar measurements. This spiral sampling strategy is called a “Hiemstra spiral” after Chris Hiemstra, who developed them using the MagnaProbe, Marshall said. His snowmobile carried an active radar instrument, which generates pulses that bounce off the snow and the layers.  These pulses are timed to nanosecond accuracy, allowing estimates of snow depth, water equivalent and thickness of major layers, 100 times per second. Durand’s had a passive instrument that measured the radiation naturally generated by earth and scattered by snow.

If these measurements sound familiar, that’s because they’re the same types, frequencies, and polarizations as the airborne instrument SWESARR, Marshall said. The Twin Otter aircraft flies over these spirals and takes the same measurements in the same location. Later, the two teams can compare the data and see how well they align with each other and the standard snow pit and depth observations.  Data from both the active radar and passive microwave sensors on SWESARR will be combined to estimate snow properties such as snow water equivalent.

On the last day of data collection, Vuyovich revealed that the team had successfully collected data from 153 snow pits and 6 SWESARR flights in just three weeks — even more than originally planned.

SnowEx 2020 operations manager Jerry Newlin (ATA Aerospace) caught Chris Hiemstra (U.S. Army Corps of Engineers’ Cold Regions Research and Engineering Laboratory) in the reflection of his goggles during one of their daily snowmobile commutes. "It looks like Chris is collecting data on the Moon," Newlin said. Credit: NASA / Jerry Newlin
SnowEx 2020 operations manager Jerry Newlin (ATA Aerospace) caught Chris Hiemstra (U.S. Army Corps of Engineers’ Cold Regions Research and Engineering Laboratory) in the reflection of his goggles during one of their daily snowmobile commutes. “It looks like Chris is collecting data on the Moon,” Newlin said. Credit: NASA / Jerry Newlin

But SnowEx is off to a great start, not wrapping up. SnowEx 2020 has another phase: The time series. Smaller, local ground teams are currently performing weekly snow measurements at sites in Colorado, Utah, Idaho, New Mexico and California through March, and bi-weekly in April and May, at the same time as UAVSAR overflights. UAVSAR is an L-band InSAR (radar) instrument developed by NASA’s Jet Propulsion Laboratory. The time series will give the researchers data on how snow changes over time, especially as it melts in the spring.

When asked about the best memories they will take home from the mesa, each team member’s answer was the same: The team.

“The best part has been the team,” Vuyovich said. “The people that have been out here have been working super hard, and it’s been a lot of fun.”

“These kinds of intensive field campaigns form bonds that last a career,” said Marshall. “Chris Hiemstra and I met during the last big series of field experiments 17 years ago, and we have been working together ever since.  The younger generation in particular really stepped up this campaign – it will be exciting to see where their careers take them.”

Snow Science Two Miles in the Sky

Grand Mesa, Colorado has an elevation of 10,500 feet, and from the Land’s End Observatory, you can see across the valley to Utah. The large, flat surface of the mesa is perfect for SnowEx 2020’s instrument testing and validation activities. Credit: NASA / Jessica Merzdorf
Grand Mesa, Colorado has an elevation of 10,500 feet, and from the Land’s End Observatory, you can see across the valley to Utah. The large, flat surface of the mesa is perfect for SnowEx 2020’s instrument testing and validation activities. Credit: NASA / Jessica Merzdorf

By Jessica Merzdorf / GRAND MESA LODGE, COLORADO

What is it like to do science nearly 2 miles above sea level?

At a majestic 10,500 feet elevation, Grand Mesa is the world’s tallest mesa, or flat-topped mountain. It’s also the site of an intense month of data collection by NASA’s SnowEx 2020, a ground and airborne campaign testing a variety of instruments that measure the water contained in winter snowpack.

Snow is vital for Earth’s ecosystems and humans, from its temperature-regulating reflection of sunlight and insulating properties, to its life-sustaining water as it melts in the springtime. SnowEx is taking coordinated measurements on the ground and in the air to compare how well different instruments work in different conditions. Not only does this help them improve measurement techniques in the future, but eventually, NASA can use this information in developing a future snow satellite mission.

The “golden” measurement they’re after is snow water equivalent, or SWE (pronounced “swee”).

“SWE is our measure of the volume of water held in the snowpack,” said Carrie Vuyovich, a research scientist at NASA’s Goddard Space Flight Center and SnowEx 2020’s deputy project scientist. “It’s such a crucial measurement because the winter snow is a natural reservoir – when it melts in the spring, it feeds the groundwater, lakes and streams.”

To understand SWE, imagine taking a cubic foot of snow, and measuring how much water is left in the container after you melt it. The amount of water depends on how densely packed the snow is and how big its particles are. Measuring these properties for small amounts of snow and calculating SWE is fairly simple – but measuring it spatially for an entire snowpack over a large mountain range? That requires instruments on planes or satellites that can sense snow properties from a distance in bigger swaths.

We met up with SnowEx operations manager Jerry Newlin of ATA Aerospace on Monday. We were invited to stay with the team during their final week of data collection for this phase of the project. Our first stop was with the airborne team, at Montrose Regional Airport in Montrose, Colorado.

When we arrived, the DHC-6 Twin Otter aircraft was grounded due to high winds over the mesa. The Twin Otter carries SWESARR – the Snow Water Equivalent Synthetic Aperture Radar and Radiometer. Developed at NASA Goddard, SWESARR uses active and passive microwave instruments to calculate SWE. Its precise measurements require precise flying, and the 50-knot winds were too strong for the plane to collect good data.

“SWESARR’s active instrument transmits a pulse, which penetrates the snowpack, hitting and interacting with all these little snow particles, and bouncing back to the instrument,” said Batu Osmanoglu, a research scientist at NASA Goddard and the principal investigator of the SWESARR team. “The passive side is more like a thermal camera, collecting the natural radiation coming from the snowpack. These two pieces of information are what we use to infer the SWE for a given area.”

The plane also carries CASIE, the Compact Airborne System for Imaging the Environment. CASIE was developed at the University of Washington and collects data on snow surface temperature, which is important for both validating satellite data and improving models of snow’s surface energy balance – the exchange of energy between the snow, the atmosphere and the ground beneath.

Shortly after we arrived, the team convened for a new weather report: The winds had calmed in time for a late afternoon flight. The airport team prepped the plane for flight while the instrument team got SWESARR ready to go.

The DHC-6 Twin Otter carrying the SWESARR and CASIE instruments was grounded in the morning due to high winds, but took off late in the afternoon for one flight over the mesa. Credit: NASA / Jessica Merzdorf
The DHC-6 Twin Otter carrying the SWESARR and CASIE instruments was grounded in the morning due to high winds, but took off late in the afternoon for one flight over the mesa. The team completed all 6 planned SWESARR flights. Credit: NASA / Jessica Merzdorf

After takeoff, it was time for us to take off too: The trip from Montrose to Grand Mesa is just under two hours, and we wanted to reach the lodge before dark. We were hoping for a good night’s rest – after catching up with the airborne team, our next stop was traveling by snowmobile to spend time with the ground team on the mesa.

Puzzles Within Puzzles

The SnowEx aircraft fly in "lines" above field sites set up on Grand Mesa, Colorado. Here, a satellite image of Grand Mesa in summer shows the topography with the flight lines superimposed on top. Credit: NASA/ Joy Ng
The SnowEx aircraft fly in “lines” above field sites set up on Grand Mesa, Colorado. Here, a satellite image of Grand Mesa in summer shows the topography with the flight lines superimposed on top.
Credit: NASA/ Joy Ng

by Ellen Gray / WESTERN COLORADO /

Eugenia De Marco loves puzzles. Her face lit up and she grinned broadly when asked what it was like to figure out how to get NASA instruments that measure snow on the ground attached and running on a Naval Research Lab P-3 plane.

“These aircraft have deliberate holes where things kind of hang off of or look out of so we can get data. But all the holes are different sizes, or in different locations in the aircraft,” she said as she described fitting aboard five unique instruments that have been designed to fit on several different types of aircraft. “These are all little puzzle pieces that you need to keep in mind when you design something.”

Eugenia De Marco is Snow Ex's lead integration engineer for the P-3 aircraft, responsible for each instrument aboard getting the data they need. Credit: NASA/ Joy Ng
Eugenia De Marco is Snow Ex’s lead integration engineer for the P-3 aircraft, responsible for each instrument aboard getting the data they need. Credit: NASA/ Joy Ng

As a mechanical engineer at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, De Marco is part of a team that designs science instruments for airborne missions that study Earth. Many of these instruments are early versions of what may one day fly on satellites. For the past year, she has been working with a program called SnowEx, a five-year airborne campaign that is trying to figure out one of the most challenging puzzles in Earth observation: how do you measure from the air the amount of water in snow that’s on the ground?

Snow on the ground is easy to observe from space or the air, but not so easy to measure how wet or dense it is, and thus how much water may flow downstream into reservoirs and agricultural fields when it melts in the spring. One instrument is unlikely to be able to give scientists the observations they need, especially on rugged mountain slopes whose steep angels can complicate things. But many instruments, whose observations fit together like puzzle pieces to illuminate the bigger picture, just might.

Five of those instruments were De Marco’s responsibility aboard the Naval Research Lab’s P-3 aircraft this February during SnowEx’s first trip to their testbed, the snow-covered Grand Mesa and Senator Beck Basin outside Colorado Springs, Colorado. As the lead integration engineer for the aircraft, her job during the flights was to coordinate with the pilots and the instrument scientists to make sure that each instrument collects the data it needs.

Engineer Eugneia De Marco consults with instrument scientists Alex Coccia during a SnowEx research flight aboard the Naval Research Laboratories P-3 aircraft. Feb. 16 2017. Credit: NASA/ Joy Ng
Engineer Eugneia De Marco consults with instrument scientists Alex Coccia during a SnowEx research flight aboard the Naval Research Laboratories P-3 aircraft. Feb. 16 2017.
Credit: NASA/ Joy Ng

“The pilots will call down to me and usually, in general, to everyone, ‘We’re this close to our target,’ and then I make sure everybody’s ready to go and then science starts happening. In the meantime, I keep track of every time we hit the line and start and stop [data collection],” she said.

The “line” she mentions refers to the pre-determined path the airplane flies along so that it will fly above ground stations set up by scientists below to measure snow directly. Dozens of researchers from a variety of universities and government agencies were camped out on Grand Mesa and in Senator Beck Basin, going out each day on snowmobiles, skis or snow shoes to dig snow pits or set up other sensors directly on the snow in the mountains.

“They’re doing that to compare what we’re seeing with our instruments,” De Marco said.” Our instruments will say, ‘Hey, we just saw ten feet of snow,’ and the ground will say, ‘Yep that was ten feet of snow.’ It’s a data comparison-type deal.”

Grand Mesa in the Colorado Rockies is NASA and its partners' testbed for figuring out how much water content is in snow. Credit: NASA/ Joy Ng
Grand Mesa in the Colorado Rockies is NASA and its partners’ testbed for figuring out how much water content is in snow. Credit: NASA/ Joy Ng

On a given flight, the P-3 aircraft flies 12 lines that lasts from three to ten minutes each. One instrument that looks at how light scatters after bouncing off snow on the ground actually needs to fly in a circle around a ground station so it can capture all the angles. Sometimes problems with the instruments crop up, usually small glitches that can be fixed on board, and De Marco will rejigger the flight pattern so when the instrument is ready to go again, they can still fly over that instrument’s line.

Weather, however, is the biggest thing that can impact a flight, said De Marco. Clouds get in the way of some instruments’ observations, so the plane may try to fly above or below them depending on the instrument. Choppy air can complicate flying over the lines. When planning flights, De Marco and the science team try to fly in good conditions, but with weather over the mountains difficult to predict, they often go out in less than ideal weather and adjust their flight plan as they go.

“I think the most exciting thing is when we land and we know that we hit those lines and everything was working well and the sky looked great and the weather was great,” De Marco said. “I mean that just feels really good and makes all that hard work totally worth it.”

A ‘Dizzying Dance in the Air’ for Science

by Joy Ng / WESTERN COLORADO /

As I walked down the aisle of a plane with a camera clasped between my two sweaty palms, I had two thoughts on my mind: First, my footsteps feel very heavy; second, I hope I can film without vomiting. As you might guess, this was no ordinary flight.

Scientists Alex Coccia (left) and Albert Wu during a SnowEx science flight over Colorado. Credit: NASA/Joy Ng
Scientists Alex Coccia (left) and Albert Wu during a SnowEx science flight over Colorado. Credit: NASA/Joy Ng

Why did this flight feel like a nauseating roller coaster ride? The Navy’s P-3 Orion aircraft was outfitted with a variety of instruments that required various flying maneuvers to collect data. The plane flew back and forth in a straight line and around in tight circles. It was literally a dizzying dance in the air.

The P-3 Orion aircraft in the Peterson Air Force Base in Colorado Springs just before take-off. Credit: NASA/Joy Ng
The P-3 Orion aircraft at Peterson Air Force Base in Colorado Springs just before take-off. Credit: NASA/Joy Ng

This science flight was carried out as part of a new NASA-led campaign called SnowEx. At the moment, we have satellites that can see snow cover but no instruments in space that can accurately measure how much water they hold. Such a measurement is important, considering that roughly one-sixth of the world’s population relies on snow for their water resources. The campaign is exploring instruments and technologies for measuring snow that may eventually result in a snow-observing satellite.

One of the biggest land areas where snow falls is boreal forest, so SnowEx chose its first flights over the forests of Grand Mesa and Senator Beck Basin in western Colorado. Because leaves and branches can act like obstacles for some snow-measuring instruments, scientists are using these forests to investigate what combination of instruments can successfully measure snow over this kind of terrain.

The Grand Mesa in Colorado is one of the sites for this year’s SnowEx campaign. Credit: Ryan Cook
Grand Mesa in Colorado is one of the sites for this year’s SnowEx campaign. Credit: Ryan Cook

At the same time, scientists are working on ‘ground-truthing’ the airborne measurements. This involves more than 100 scientists measuring snow depth and density on the ground to get accurate snow measurements that can validate the measurements taken by the airborne instruments.

Travis Roth, Oregon State University looks at snow consistency at various depths as Jinmei Pan, Ohio State University logs data. Credit: Ryan Cook
Travis Roth, Oregon State University, looks at snow consistency at various depths as Jinmei Pan, Ohio State University, logs data. Credit: Ryan Cook

Collecting these in-flight measurements is tricky. Each instrument works at specific altitudes, over specific types of snow, and only in certain types of weather. This means that the aircrew and scientists have to work together to come up with a detailed flight plan—one that can change day to day—that allows all instruments to collect data successfully.

Lt. Denise Miller from the U.S. Navy speaks with Principle Investigator Edward Kim during a science flight. Credit: NASA/Joy Ng
Lt. Denise Miller from the U.S. Navy speaks with Principle Investigator Edward Kim during a science flight. Credit: NASA/Joy Ng

While I was on the plane, most of the scientists were in seats next to their instruments. I, on the other hand, was swerving side to side as I did my own little dance to capture my shots. It’s not the ideal film set. The light is constantly changing. Every surface of the plane is vibrating and it’s very loud. In these conditions, I had one priority in mind: stabilization. Luckily, I used a handheld gimbal—an electronic device that counteracts any minor movements—that allowed me to film smooth shots while my feet were to the contrary.

The view outside of the P-3 Orion aircraft during a science flight. Credit: NASA/Joy Ng
The view outside of the P-3 Orion aircraft during a science flight. Credit: NASA/Joy Ng

I managed to capture some great footage and discovered that, for me, the mountaintop views were a good remedy for any motion-induced mishaps.