Cloud formation in the atmosphere depends on the presence of tiny particles called aerosols. ACTIVATE scientists are working to understand how variations in these particles from human and natural sources affect low lying clouds over the ocean and how those clouds in turn affect the removal of these particles from the atmosphere.
Despite racing against impending harsh weather conditions, a red and white World War II aircraft flew slowly and steadily over the icy waters surrounding Greenland in August and September. Three weeks delayed by pandemic restrictions, scientists from NASA’s Jet Propulsion Laboratory inside this retrofitted DC-3 plane started dropping hundreds of probes as part of an annual expedition known as the Oceans Melting Greenland (OMG) Project.
Since 2016, the OMG project has conducted numerous flights over the waters near Greenland’s lengthy and jagged coastline. They drop roughly 250 probes each year (though they managed a record 346 during this extraordinary 2020 expedition) which then relay temperature and salinity data. The team uses this information to help determine how much the surrounding ocean is contributing to Greenland’s ice melt.
“The glaciers are reacting very strongly to the ocean and we ignore that at our peril,” said JPL scientist and principal investigator Josh Willis. “The oceans have the potential to melt the ice very quickly and drive the sea level rise even higher than we expected.”
If it all melted, Greenland’s ice could contribute as much as 25 feet of sea level rise—though Willis assures us that this is not expected within the next year, or even the next 100 years. The big question that his team is trying to help answer is rather the speed at which the ice is melting.
Unlike icebergs—which float in water—glaciers sit atop a land mass, seemingly exposed and vulnerable to the warming atmosphere. While the atmosphere is a significant factor, it is not solely responsible for glacial melt. As the glaciers in Greenland start to ooze off the island in massive rivers of ice, they carve fjords into the landscape until they finally connect with the sea. While surface waters are generally frigid, the warmer ocean waters from below can cause the glacier to melt more quickly and speed up the amount of ice that drains off the land into the ocean.
Though the coronavirus pandemic had sweeping impacts across the globe, it didn’t halt environmental processes like Greenland’s glacial ice melt. It also didn’t impede the resolve of the OMG scientists to continue their work.
Starting in March up until the day they landed in Greenland on August 24, Willis says he wasn’t sure they would be able to collect their data this year. But cooperation between the various stakeholders, including NASA, the State Department, and the governments of Canada and Greenland, was key. Willis also gives credit to a huge amount of hard work by OMG’s Project Manager, Ian McCubbin of JPL, for making it possible. “If it wasn’t for McCubbin,” said Willis, “we’d still be sitting on our couches.”
Coordinating the scientists and equipment necessary for any expedition requires a great deal of planning, and the additional pandemic-related precautions made everything just a little bit more complicated.
“It was like a whole new layer, after you go across the border and go through customs and boarder control, now you also go through coronavirus screening,” Willis said.
In addition to getting tested a whopping seven times, two of which took place before even stepping foot in Greenland, Willis and the other members of the OMG team were very cautious. There was an initial isolation period after landing on the island during which they could fortunately work on the plane and equipment preparation, wearing masks when traveling to and from the site and no contact with locals. Greenland has had very few cases of COVID, and doesn’t have enough hospitals to handle any outbreaks, so the team was especially conscious of limiting their interactions with people there.
One exception was communicating with the nurses conducting their COVID-19 tests. “It was quite an experience getting tested this many times,” said Willis, “but the most fun was actually with nurses in Greenland, who were very nice and asked about our mission, so we got to tell them about what OMG was doing—and I suspect they followed along the rest of our journey on social media.”
Though some legs of the scientists’ expedition were delayed or more challenging as a result, Willis says it was well worth the extra effort to ensure everyone’s safety.
The outcome turned out to be a banner year for the project, despite the late start. Instead of heading north at the beginning of the month, it was already well into August when Project Manager Ian McCubbin and the three scientists from JPL—Ian Fenty, Mike Wood, and Willis himself—were able to meet with their flight crew from Kenn Borek Air.
Once they were on the ground in Greenland, their main concern was for the conditions they might encounter once back in the air.
“Weather starts to get pretty rough in September, and very rough in October.” said Willis. Fortunately, they were able wrap up their surveys by mid-September, mostly dodging the snow, sleet and wind that might impede their ability to drop all of the probes. “It was a sprint to the finish line, but we were able to accomplish everything we wanted to do and more.”
In fact, the team encountered unusually good conditions in the north east parts of the island, where ice and fog usually prevent access. As a result, they measured some glaciers that had never been sampled before.
When the project first began in 2016, the scientists also flew a jet with a radar strapped on the bottom to measure big swaths of glaciers from above, but NASA’s ICESat-2, an Earth-observing satellite that measures the mass of ice sheets and glaciers down to the inch that launched in 2018, takes care of that part of the mission now.
More than 45 scientific papers have now been published based on OMG data, with several more in progress. Willis says that every new discovery reminds them that the oceans are more important than they ever thought possible.
This year they noted new observations of Greenland’s largest glacier Jakobshavn, which has been closely monitored since the start of the project in 2016. In the first couple of years, the water near Jakobshavn cooled by 2.7 degrees Fahrenheit (1.5 degrees C)—a whole lot for a block of ice according to Willis. That cooling slowed the melting of the glacier, which then started growing instead. But early this year warm water returned to Jakobshavn and the recent observations suggest it is now thinning once again.
These continued discoveries from the project are very exciting for the scientists and organizations involved. Because of this, the OMG project has gotten approval to continue its research beyond the original end date, meaning that Willis and his crew will again be making their way back to Greenland next August, and this time hopefully without much delay.
Those flights are taking scientists over the western Atlantic Ocean to study how atmospheric aerosols and meteorological processes affect cloud properties. In addition, modelers will use data from these flights to better characterize how the clouds themselves, in turn, affect aerosol particle properties and the amount of time they spend in the atmosphere, as well as the meteorological environment. Coordinated flights between a King Air and an HU-25 Falcon allow researchers to fly above, below and through the clouds with a suite of instruments that can take measurements remotely, or from the air around the aircraft.
“The data have been really good so far,” Armin Sorooshian, ACTIVATE principal investigator and an atmospheric scientist at the University of Arizona, said of the summer flights. “We’ve seen some interesting features, like smoke from the wildfires on the West Coast.”
That smoke can seed clouds over the Atlantic Ocean.
Sorooshian is leading the campaign remotely from his home in Tucson, Arizona, where he and his wife are juggling work and the care of two children — a two-year-old boy and a baby girl who was born in July.
He admits it’s “a little tough.” But in a world where these flights could have been scrubbed from the calendar completely, Sorooshian isn’t interested in dwelling on the negatives.
“They’re good problems,” he said.
The ACTIVATE team began the first of two planned 2020 flight campaigns in February. They completed most of those flights, but had to pull the plug a little early in mid-March when concerns about the spread of COVID-19 began to sweep across the U.S. At that point, the fate of the second set of flights, originally scheduled for May and June, was — pardon the pun — very much up in the air.
As the COVID situation evolved, though, and as Langley leadership began to admit a limited number of research projects back on center with stringent safety protocols in place, it became clear there might be a glimmer of hope for ACTIVATE.
ACTIVATE is uniquely positioned among other current NASA airborne science missions because it’s based out of a NASA center, and the flight crew and many members of the science team are also based out of that center. John Hair, ACTIVATE project scientist with Langley’s Science Directorate, knew that from a purely logistical perspective, the mission could return to flight without the need for anyone to travel in from out of town.
“We had an opportunity because ACTIVATE has a relatively small crew that can operate the instruments in the aircraft, and do that, we felt, safely — albeit with some changes to the initial plans we set out,” he said.
Besides obvious stuff such as wearing masks and being mindful of social distancing, those changes include conducting the various daily flight planning meetings and pre-flight briefings completely via video conference. Researchers are also doing real-time monitoring of flight data from their homes. For researchers who are flying or need to be on center, the project has found ways to streamline some processes.
“For example, people are learning how to do their calibrations at the end of the flight after the instruments are already warmed up,” said Hair. “And then it only takes an hour to do.”
Compare that to the three or four hours it can take a researcher to warm up and calibrate an instrument before a flight.
The entire operation has taken a lot of careful planning and coordination between Langley’s Science Directorate, Research Services Directorate and Center Operations Directorate. Sheer determination has certainly played a role as well.
“We all signed up for supporting research as it comes in. ACTIVATE was in the middle of a major campaign and we wanted to get them back to flying as soon as we could,” said Taylor Thorson, ACTIVATE project pilot with Langley’s Research Services Directorate.
Sorooshian believes this experience could be instructive for the next round of flights, which are currently scheduled to kick off in February 2021 when COVID-19 could still be a significant concern.
It’s not just instructive from a safety perspective. Marine clouds are more scattered and difficult to forecast in the summer.
“Flying this summer also allows the team to hone the flight planning strategies, which can build upon heading into the next two years of flight campaigns,” he said.
For now, he and Hair are just happy to see a study they both care deeply about back in action.
“This is exciting that we’re out doing some flights,” said Hair. “People are excited to get the critical science data that we’re collecting on these flights.”
The ACTIVATE science team includes researchers from NASA, the National Institute of Aerospace, universities, Brookhaven National Laboratory, Pacific Northwest National Laboratory, the National Center for Atmospheric Research and the German Aerospace Center. The current flight campaign is the second of two in 2020, with two more to follow in 2021, and another two in 2022.
In the early 1900s, Ernest Shackleton attempted to travel across Antarctica, but as they neared the continent his ship became stuck in an pack of sea ice and was slowly crushed before it reached the landmass. Over 100 years later and on the opposite side of the globe in the Arctic, researchers in the massive, double-hulled icebreaker, Polarstern, are also stuck in a pack of sea ice – but this time on purpose. And this ship isn’t sinking any time soon.
Intentionally trapping itself in the sea ice, Polarstern drifts with the floe, which is a large pack of floating sea ice. Researchers set up “little cities” on the ice where they take measurements using delicate instruments. While it appears that the sea ice they walk on to reach these camps is stationary, everything is actually slowly drifting as wind and ocean currents push the gigantic slabs of ice.
MOSAiC is a multidisciplinary expedition, as researchers from a variety of fields – including marine biology, meteorology, and oceanography – collaboratively study Arctic changes.
“It’s more of a process study,” explained Steven Fons, a Ph.D. candidate at the University of Maryland and NASA’s Goddard Space Flight Center, who studied sea ice from March to May of this year. “The idea, then, is once everybody collects this data, we can compile everything and learn about the sea ice in the ocean, and the atmosphere and the ecology.”
Sea ice is an integral part of the Arctic climate system because it sits directly between the ocean and the atmosphere, moderating the exchange of heat and moisture. An important climate indicator, sea ice research identifies changes in other Arctic climate systems, including the ocean, atmosphere, ecology, and biogeochemical cycles. Basically, studying sea ice can give greater insight into how the entire Arctic is reacting to climate change.
For a small group of MOSAiC researchers, every Monday was a 14-hour workday spent at “Dark Sites,” named so because they are isolated from the bright lights of Polarstern. After traveling over a mile on snow machine, the team used hollow drills to remove cylindric cores from the sea ice floe. In the labs aboard Polarstern, these samples revealed the fascinating characteristics of sea ice.
“As ice forms, it will eject the salt away as it’s freezing,” said Fons. “The longer it stays around, the more salt essentially drains out of it.” Basically, high salt levels tell researchers that this particular ice formed in the most recent winter. This can reveal how the Arctic adjusts to higher temperatures, as the region is warming at a rate more than twice the global average.
In the Arctic, wind chill can reach frigid temperatures as low as minus 70 degrees Fahrenheit. Working in the cold without hand protection was impossible, so Fons wore thin gloves underneath his bulky mittens, which he removed when handling small objects. Even so, frequent warming breaks were necessary, which meant simple, one-minute tasks could take 10 times longer in Arctic conditions.
“Some of the really cold days, you can only last 30 seconds at a time taking off your big mittens,” he recounted. “You just have to put five zip ties on this cable, perfect. It should take one minute to do, but it would take 20 minutes because you have to keep warming your hands and [the zip ties] keep breaking in the cold.”
Native to Wisconsin, Fons is no stranger to subzero winters. Nonetheless, during this expedition he witnessed temperatures unlike anything he had ever experienced before. Icy winds bit into any exposed skin. His only relief: a thick, bushy beard and about ten layers of clothing.
In an ever-changing environment, researchers’ locations can be difficult to determine on the ice cover, which can literally shift beneath their feet. For MOSAiC, every measurement is paired with a GPS coordinate. However, the ice drifts, and so the latitude and longitude change every day. Instead, the immense icebreaker Polarstern is used as a point of reference, a sort of ground zero for field navigation.
“You’re given a position away from the ship, so a certain distance of x and y, and that will theoretically never change,” Fons explained. But even this system has its obstacles. “If the ice broke up and the ship moves a little bit, then you can lose your x-y positions, so it didn’t always work.”
Helicopters and planes accompany Polarstern, getting a birds-eye view of the stark white landscape. Flying high above the floe, planes take airborne measurements in a similar way to Operation IceBridge. Fons does research using data from NASA’s ICESat-2 – the satellite that surveys glaciers and sea ice around the globe – and he was lucky enough to validate some of the satellite’s measurements while researching with MOSAiC.
“On the ship, since we’re constantly drifting with the ice, we don’t exactly know where we’re going to be on any given day,” he said. “We got lucky that we happened to be drifting one day over a spot that ICESat-2 was going to fly over. We were able to jump on that opportunity and schedule a helicopter flight.”
Seasonal changes near the poles are unlike anywhere else on Earth. Summer and winter are really the only seasons these regions experience, characterized by a dramatic transition between complete darkness during winter days to total sunlight during the summer. Ten days after reaching Polarstern, Fons witnessed his first Arctic sunrise. As summer came, the Sun sailed over the horizon for longer and longer each day until it refused to set, resulting in the phenomenon of the “midnight sun.”
Ice dynamics, or the movement of ice slabs in the floe that changes the terrain, were a trademark of Fons’ three months on Polarstern. Sometimes, the researchers would wake up to massive leads, or ice fractures, blocking their usual routes. Other days, research tents would be buried in ice piles from leads that closed to form towering ridges. Sea ice dynamics had a wide appeal for study among MOSAiC teams. Below the floe, marine biologists and ecologists studied microorganisms. Within the ice itself, sea ice researchers examined crystallization patterns.
“With MOSAiC, what people are able to do is look at the ice at so many different scales and through many different lenses,” Fons summarized.
Leaving from Nassau on a Tuesday night in August 1975, Jacques Cousteau and his team set out on the Calypso for a three-week expedition designed to help NASA determine if the young Landsat satellite mission could measure the depth of shallow ocean waters.
For days, the Calypso played leapfrog with the Landsat 1 and 2 satellites in the waters between the Bahamas and Florida. Each night, it sailed 90 nautical miles to be in position for the morning overpass of the satellite.
Ultimately, research done on the trip determined that in clear waters, with a bright seafloor, depths up to 22 meters (72 feet) could be measured by Landsat.
This revelation gave birth to the field of satellite-derived bathymetry and enabled charts in clear water areas around the world to be revised, helping sailing vessels and deep-drafted supertankers avoid running aground on hazardous shoals or seamounts.
“It was a tremendous example of how modern tools of scientists can be put together to get a better understanding of this globe we live on,” the Deputy NASA Administrator, George Low, said of the joint Cousteau-NASA expedition in a 1976 interview.
But it couldn’t have happened without the world’s most famous aquanaut, his team of expert divers, and the Calypso.
Astronauts and Aquanauts Together
The ocean’s vastness made Cousteau an early supporter of satellite remote sensing.
Cousteau, by then a decades-long oceanographer, was keenly aware that ocean monitoring from above would be necessary to understand the ocean as part of the interconnected Earth system and to raise the awareness requisite for protecting the sea. There was a growing recognition in the 1970s that helping the planet required understanding the planet.
“Everything that happens is demonstrating the need for space technology applied to the ocean,” Cousteau said during a 1976 interview at NASA Headquarters.
George Low, the Deputy NASA Administrator, himself a recreational diver, connected Jacques Cousteau with former Apollo 9 and Skylab astronaut Russell Schweickart. Schweickart was heading up NASA’s User Services division and both he and Cousteau were looking for ways to advance Earth science.
At the time, it was theorized that the new Landsat satellites might be useful for measuring shallow ocean waters. New deep-drafted supertankers were carrying crude oil around the globe, and to avoid environmental catastrophes it had become important to know where waters in shipping lanes were less than 65 feet (20 meters).
To establish if Landsat could accurately measure ocean depth from space, simultaneous measurements from ships, divers and the satellite were needed.
Schweickart knew a coordinated bathymetry expedition was an essential step. He had honed his diving expertise while training for his Skylab mission in NASA’s water immersion facility and was enthusiastic about scuba work. Teaming with Cousteau was a natural fit.
An elaborate experiment was designed to determine definitively if multispectral data from the Landsat satellites could be used to calculate water depth. The clear waters of the Bahamas and coastal Florida were selected as the test site.
The experiment design involved two research vessels, the Calypso and Johns Hopkins University Applied Physics Lab’s Beadonyan, being in position, or “on station,” when the Landsat 1 and 2 satellites went overhead on eight different days (four consecutive days on each of two weeks).
The overall concept was simple: the research ships would use their fathometers to measure water depth at the exact same time that the satellite flew overhead and then those measurements would be compared (the simultaneous measurements eliminated any environmental or atmospheric differences that could have complicated comparisons). But realizing that plan took extraordinary coordination.
As the Landsat satellite flew overhead, Cousteau and his team of divers made a series of carefully timed measurements of water clarity, light transmission through the water column, and bottom reflectivity. This was done both near the Calypso and at two sites 60 meters from the Calypso using small motorized Zodiac rigid inflatable boats.
To make the light transmission measurements, two teams of divers had to use a submarine photometer to measure light at the water’s surface, one meter under the water and in 5-meter increments to the bottom (down to 20 meters).
The divers had to hold the photometer in a fixed position looking up and cycle through four different measurements. They also used specially filtered underwater cameras to measure bottom reflectivity (assisted by gray cards for reference). Everything was carefully timed. Schweickart and President Gerald Ford’s son Jack helped with these underwater measurements.
To make the precision measurements, the skill of these divers – including Cousteau’s chief diver, Bernard Delemotte – was essential.
“I was in charge of the divers,” Delemotte explained in a recent interview. “We were very convinced that we could do serious work together [with NASA].”
Before the satellite overpass, the Calypso and Beayondan were in position, anchored side-by-side, and ready to make all specified measurements.
“Two small Zodiacs left from the Calypso just before the satellite passage,” Delemotte recalls.
The Zodiacs stationed themselves 200 feet (60 meters) from the Calypso, and at the moment that the satellite was overhead someone on the Calypso would call to the divers through the portable VHF radio: “Go now!”
The divers would then start the series of prescribed measurements.
Using these measurements, scientists developed mathematical models describing the relationship between the satellite data and water depth, accounting for how far the light could travel through water, and how reflective the ocean floor was.
“Particular thanks” was given to Cousteau’s team of divers in the experiment’s final report “for their dedication and expertise in the underwater phases of the experiment, without which, measurements of key experimental parameters could not have been made.”
The diving prowess of Cousteau, Delemotte, and the Calypso crew added inextricably to the realm of satellite-derived bathymetry. Because of data collected during the NASA-Cousteau expedition, charts in clear water areas around the world were updated, making sea navigation safer. It was the precision measurements made by Delemotte and Cousteau’s team of divers that made bathymetry calculations for those chart updates possible.
By Katie Stern, IMPACTS’ Deputy Project Manager / HUNTER ARMY AIRFIELD, SAVANNAH, GEORGIA/
“Get in there and check it out!”
I was encouraged by “Corky” Cortes from the NASA ER-2 Life Support Team to see how the pilots prepare for their flight. This was my first NASA field campaign with the ER-2, a high altitude aircraft requiring a Life Support Team to help maintain the health and safety of the pilots. This aircraft is highly specialized and has been modified by NASA for conducting airborne science research.
As the Deputy Project Manager for the NASA IMPACTS project (Investigation of Microphysics and Precipitation for Atlantic Coast-Threatening Snowstorms), I spent January and February at Hunter Army Airfield in Savannah, Georgia, managing the deployment site for the ER-2 and the mission scientists. Our project is specifically focused on studying snowbands across the Eastern seaboard. The ER-2 plays a critical role in capturing remote sensing data to better predict the severity of storms.
As a new member to the team, I was unfamiliar with what the Life Support crew and pilot needed to do before each flight. Determined to find out, I peered into the tiny office and saw Joey Barr from Life Support setting up the dressing area for pilot Cory Bartholomew. The full pressure suit was completely unzipped, its green lining visible. It was laid out on the floor to make the dressing process easier. Shiny black boots with metal stirrups used for the ejection seat were placed neatly on both sides of the vinyl chair. Behind Cory were two bright yellow gloves and a space helmet carefully placed on a donut shaped pillow. Everything was ready to go. All we needed was the pilot.
The actual suiting-up process looked a bit cumbersome. I could see why it would be easy to overheat if you tried dressing yourself. One foot, after another, Cory stepped into the matte yellow and green suit and then poked his head through a metal collar, which was used to secure his space helmet.
The two men worked silently, adjusting the suit, putting on the torso harness, tightening straps, and going over the checklist in their heads. They’ve both been through this routine hundreds of times, but for me it was fascinating to see the thought and care going into each movement.
After a few adjustments to the velcro reading glasses that went inside the helmet, Cory snapped the visor shut, and Joey put on his headset to begin the suit pressure checks. A small yellow box filled with liquid oxygen was then connected to the front of the suit with a hose. These pressurized suits along with the liquid oxygen (LOX) allow pilots to fly at an altitude of 65,000 feet, so high the pilots can see the curvature of the Earth.
A few moments later the suit began to inflate and Cory motioned for me to tap on his knee to feel the outward force from the pressure check. A few more checks were conducted and within 15 minutes Cory was ready to be escorted to the van that would take him out to the aircraft.
“If the pilot has an 8 hour mission, how does he eat or drink once he’s in his suit?” I asked Joey, knowing that it was probably a common question.
“See this small hole at the bottom of the helmet? We have a whole selection of food that we can give the pilots and they drink it through a straw that goes into that hole. They can have applesauce, beef stew, key lime pie, peaches, chocolate pudding, you name it!” Joey was excited to share the menu with me and I couldn’t help thinking that the key lime pie sounded pretty good. And after actually trying it, I can confirm it does taste exactly like key lime pie, just put through a blender.
After answering a few other questions of mine, Joey escorted Cory out to the jet. Witnessing the amount of preparation to get ready for the flight only made me want to learn more about the ER-2 and its history. It also gave me a huge appreciation for all of the expertise that goes into ensuring the success of the IMPACTS mission and other NASA missions.
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.
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.
“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 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.
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.”
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.
“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.
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.
By Ellen Gray /NASA’S WALLOPS FLIGHT FACILITY, VIRGINIA/
After a cloudy and rainy morning, by 1:50 pm the sun had come out and the skies were clear for take-off at NASA’s Wallops Flight Facility in Virginia. The P-3 Orion research aircraft outfitted with eleven instruments to measure conditions inside snow clouds was heading north to a storm system over New York and Vermont for the second science flight of the Investigation of Microphysics and Precipitation for Atlantic Coast Threatening Snowstorms, or IMPACTS field campaign.
NASA’s high-flying ER-2 was already in the air. Based out of Hunter Army Air Field in Savannah, Georgia, it had an extra hour to fly so that the two planes—the ER-2 at 60,000 feet and the P-3 starting at 18,000 feet—would arrive at the same time and fly along the same path to make simultaneous measurements.
Since we were flying into bad weather, I was worried about a bumpy ride—and we got it. Our flight path led us out over the ocean first to approach Long Island from the south. At thirty minutes after take-off Claire Robinson from NASA’s Langley Research Center prepped the first of two dropsondes to drop from a tube at the back of the plane into the storm over the ocean. A dropsonde is a small instrument package in what looks like a paper-towel roll. It has a parachute and a radio transmitter that sends data on temperature, humidity and wind speed as it falls, giving a vertical profile of the atmosphere from the plane to the ground.
While Claire was watching her monitor for the plane to be over the right spot, we hit turbulence that made it feel like we were going over bumps on a roller-coaster. It got bad enough we needed to return to our seats in the ten minutes between the first and second dropsondes. The turbulence evened out fairly quickly though, especially once we were back over land where the upward movement of air was less severe. Bumps returned periodically throughout the flight, but it ended up being smoother overall than expected.
After the dropsondes were away we continued north over Connecticut and western Massachusetts where we turned left to start the first of three bowtie flight patterns, two over southeastern New York and one over Vermont. Bowties are these large triangular patterns that approach the storm from many different angles.
“The atmosphere is not a layer cake,” said atmospheric scientist Sandra Yuter from North Carolina State University, when I spoke with her before the flight. She’s in charge of plotting the flight paths to maximize the science measurements based on the forecasts two-days ahead of time, which she then sends to the pilots and aircraft coordinators who will iterate on it to make the final flight plan.
The atmosphere is instead more like a cake with a marbled interior—swirls and wiggly lines sliced one way, large patches and different swirls when sliced another. “We’re not expecting the same cross-sections in different parts of the storm,” Sandra said. “Bowties give you those multiple angles.”
At the top of the first bowtie over New York, we started out at 18,000 feet, high above the freezing level (0°C). (About half-way through we descended to 16,000 feet at the request of Air Traffic Control.) Mike Poellot of the University of North Dakota and today’s Flight Scientist, sitting in the cockpit to coordinate between the science team and the pilots, asked over the headset, “Cloud probes what are you seeing?”
In the main cabin, Greg Sova, a grad student at the University of North Dakota and Starboard Wing Instrument Operator, answered the first of many such check-ins. On his monitor, streams of tiny pictures from his instrument scrolled by. The tiny pictures were of cloud, ice, and snow particles, most less than a millimeter big, that had just been imaged at ~300 mph.
On that first pass of the bowtie, he was seeing from the cloud probes, “Columns and dendrites but a lot of shattering.”
Columns and dendrites are types of snow crystals and were also common in later check-ins as we continued on. So were aggregates, a bunch of snowflakes stuck together in a mass, thin needles, and at lower altitude, spheres that were probably water droplets as we did the second bowtie at lower altitude where the air temperature was warmer. Sometimes it was mix of all three. At times it would switch back and forth as we passed through air with different characteristics—remember that marble cake analogy?
At one point on the northern bowtie over Vermont, Greg reported that we’d passed from seeing more liquid droplet spheres to being back in crystals of snowflake plates, dendrites, with a column or two. Then he added, “And as soon as I said that we’re back into small spheres.”
While the P-3 flew through the clouds, the ER-2 paced us from high above with its suite of remote sensing instruments. The two planes were in sync, for the most part passing over the same legs of the bowties less than 5 minutes apart. Each bowtie took about an hour, and a little after 6:00 pm we dropped to 12,000 feet for the flight home, while the storm system continued east.
“I think was good mission,” Mike said when we got back. “The instruments seem to work well, aircraft coordination seemed to go well, and we definitely got into some weather. A lot of precipitation down low that was occurring, and I think it was more along the lines of what we’re looking to do in this project.”
In the days that follow, the instrument teams will begin processing the data they collected, while the forecasters look out for the next storm on the horizon.
By Ellen Gray /NASA’S WALLOPS FLIGHT FACILITY, VIRGINIA/
The IMPACTS team is what makes the field campaign happen. Over 200 people are contributing to the project from aircraft crews and managers, to support and logistics staff, to the scientists running the instruments and asking the big questions. They include veteran pilots and mission managers, university and NASA researchers who’ve done field campaigns before, and graduate students on their first campaign.
Field campaigns provide valuable training and perspective in researchers’ early careers. We caught up with three students who are on the rotating roster for the IMPACTS forecasting team. Their responses have been edited for clarity.
My name is Sebastian Harkema. I’m a first year PhD candidate at the University of Alabama in Huntsville. This is my first field campaign in general so I’m super excited about this. I’m actually studying snowfall so I’m going to be using the IMPACTS data as part of my PhD for the next three years. Specifically, I’m looking at thundersnow, so I’m hoping to use some of the instrumentation to look at that and to understand how lightning and snowfall can be used in nowcasting—predicting heavy snowfall, where the models really have trouble in that near-term period where forecasters really need that information.
Being a forecaster is different. Going from research to being an actual forecaster is kind of challenging. Because when you’re a researcher you’re staring at a TV screen or a monitor all day. For forecasting you’re doing that but it’s in a completely different environment. As for my schedule, showing up at 5:45 am in the morning, having to put a presentation together by 8:45 am and presenting at 9 am, that’s a challenge unto itself, let alone trying to understand what is going on in the atmosphere. So I definitely give a lot of credit to all the forecasters throughout the United States, and the world—Props to you guys! It’s a lot of hard work and I definitely appreciate it a lot more than I did in the past.
I’m Ben Kiel and I’m a Masters student at Stonybrook University in New York. With IMPACTS, I’m helping out with storm forecasts, if there are storms to forecast for. It’s been quite a bit of challenge I would have to say. We were hoping for more storms than what we’ve had so far. It’s kind of funny, most people want good weather, we want bad weather.
This one that we’re looking going after Saturday is one where, if the pattern was more active it’s one we wouldn’t prefer to chase because it’s a messy system. There’s a lot of dry air getting into it. It’s a very warm system. There’s going to be a lot of rain. At least there will be snow aloft. There’s certainly things we can learn from snow aloft, because that’s how this rain is forming as it’s staring out as snow and then falling down and then turning into rain. So we’ll take it.
My main focus will not actually be directly related to IMPACTS. I’m actually working with IMPACTS mission scientist Brian Colle, I’ll be doing a project related to machine learning. It’s a different sort of problem, trying to figure out or explain why our weather models are so variable. We’re trying to find better explanations so that we can pinpoint and improve them. So that’s not necessarily directly related to the IMPACTS project but the data that comes from here will probably certainly get ingested into my work as time goes on. All of these projects end up connected in some way that one acts as a validation for the other. We’ll see what happens there. I’m looking forward to it.
My name is Phillip Yeh and I grew up in Parsippany, New Jersey, and I’m currently at Stonybrook University as a PhD student. My focus for my PhD project will likely be using the data that we gather from the IMPACTS project to understand these snow bands associated with these snow storms here in the North East.
I am helping with forecasting for the IMPACTS project. So forecasting involves many things. A lot of it involves looking at the weather models and trying to figure out where the storm is going to be, especially in regard to the timing of the storm, in regard to where the rain/snow line is going to set up, and in regard to where we should be flying the plane. This is my first field campaign. I think the biggest thing I’m looking forward to is the opportunity to fly on the P-3 and the second biggest thing is being able to launch weather balloons, which I’ll do when I leave Wallops and go back to Stonybrook where we’re doing that.
I’ve always loved snow ever since I was young, and often times watched as a snow storm runs too far to the south or to the north and just misses us, or occasionally when the snow hits us perfectly, and also seeing how the forecast models may struggle with getting the location of a storm right.