As I walk up the Alpine Trail in Denali National Park, I can see the vegetation changing before my eyes. Deciduous plants, like willows and smaller shrubs, start huge, as tall as my head and shoulders. But as the trail leads up, and as the altitude grows, the vegetation shrinks.
Over the course of the roughly 1,300-foot elevation gain, the plant life gets shorter and shorter until suddenly it’s almost gone—we’ve reached the tundra. By climbing up the side of this hill, we’ve mimicked traveling north into the colder parts of the Arctic, reaching the tundra much faster.
Tundra is like the Arctic’s desert: an expanse of treeless land with little available water. Most water in the tundra is below the ground in a layer of continuously frozen soil known as permafrost. Between the tundra’s low temperatures and the permafrost, it’s not a hospitable location for much plant life.
On the tundra, Peter Griffith, project manager for the Arctic Boreal Vulnerability Experiment (ABoVE), points out the same shrubs we encountered lower down, although here, instead of towering over our heads, they’re only a few inches above the ground.
But that could be changing. It’s one element of the ABoVE team’s research: understanding how native Arctic vegetation responds to a warming climate.
Griffith describes the shrubs as “ready and waiting to march up the mountain.” They’re opportunistic plants, and all it takes is a little warmth and thawed ground for them to dig in and start growing larger, a process known as “shrubification” and one of the causes of the greening trends seen from long-term satellite records.
As greenhouse gases change Earth’s climate, the Arctic is warming much faster than the rest of the world. And the changes are staggering. Permafrost is thawing, and the shrubs aren’t the only ones taking advantage. Within the soil, bacteria are growing and beginning to metabolize organic matter that’s been frozen in permafrost for thousands of years.
As they feast, bacteria release carbon dioxide and methane, which are released into the air. Plants like shrubs use carbon dioxide to grow even faster. In some ways, it seems like a race.
Will the bacteria respire more carbon dioxide than the growing plants can absorb? At some sites, that already seems to be the case. How this race plays out across the Arctic is another question the ABoVE team is investigating.
Using measurements of carbon dioxide and methane taken from flux towers sitting directly on the tundra, to instruments mounted on airplanes and satellites in low Earth orbit, NASA scientists are finding out how the land ecosystem influences the atmosphere in a greening Arctic, and what the consequences are for not only the Arctic but also the world.
The Arctic Boreal and Vulnerability Experiment (ABoVE) covers 2.5 million square miles of tundra, forests, permafrost and lakes in Alaska and Northwestern Canada. ABoVE scientists are using satellites and aircraft to study this formidable terrain as it changes in a warming climate.
In some ways, NASA’s DC-8 feels like a commercial airplane, with its blue leather seats and tiny bathrooms in the back. But once the plane starts to spiral down over Arctic towns, I remember I’m riding on a flying laboratory studying the amount and distribution of carbon dioxide and methane in the atmosphere.
Over the course of these big, looping spirals, the plane descends from a cruising altitude of about 30,000 feet down to just about 100 feet above the ground. The pilots fly us over the runway, as though we’re about to land, before pulling up at the last minute and returning to the sky, a maneuver known as a “missed approach.”
The whole process of spiraling down is a little scary the first few times we do it, but it’s necessary as an accuracy check for our science instruments, and by the third or fourth spiral down, it’s become a somewhat routine experience for me.
From the windows, I get a good look at the varied Arctic landscapes—twisting, braided rivers, carpets of spruce trees, and broad expanses of flat tundra all spread out underneath us. Each of those landscapes offers interesting scientific insights into how carbon emissions are changing as the climate warms.
The plane is carrying five instruments designed to measure the spatial distribution of carbon dioxide from the air. They’re placed along the plane in place of some the seats and are operated by scientists monitoring screens mounted on their sides.
Someday, a descendent of these instruments will fly on the Active Sensing of Carbon dioxide Emissions over Nights, Days and Seasons, or ASCENDS, satellite, and the spiraling helps the researchers verify their measurements by flying right through the columns of air they’re studying from far above.
Jim Abshire is the project lead for the ASCENDS campaign. He sits near the front of the plane, plugged into the communications system and periodically checking with each instrument’s operators, making sure everything is running smoothly and requesting the occasional altitude change from the plane’s navigators.
He describes the spiral down maneuvers as a check on the lidar measurement systems, specifically ensuring that the instruments are sensitive enough to make precise measurements from space.
As Earth’s climate continues to warm, the Arctic warms much faster, and the subsequent changes in the Arctic regions are resulting in some soils releasing more carbon. More carbon in the atmosphere traps heat, causing more warming, which in turn causes the Arctic soils to release even more carbon, a process called the carbon-climate feedback.
Understanding this vicious cycle is one of the primary goals of the Arctic Boreal Vulnerability Experiment (ABoVE), a NASA campaign that includes the ASCENDS flights, as well as many other experiments, all designed to better understand how the rapid environmental change in the Arctic regions of the world impact ecosystems and society.
Thirty-two undergraduates from across the country had the experience of a lifetime flying on the NASA C-23 Sherpa and UC-12B King Air laboratories as part of the NASA Student Airborne Research Program (SARP) summer internship. One student, Madison Lichak, a biology major from Barnard College in New York, shares her flight experiences.
It is stifling hot inside the aircraft, and I fidget nervously in my seat. A towering metal rack of scientific instruments stands before me, blocking my view toward the front of the plane, close enough that my knees are almost pressed against it. Motion sickness bags, tucked inside their cheerful blue paper wrappers, lie littered across an unused shelf. I try to breathe normally. I have taken many flights in my life, but the flight today is going to be unlike anything I have ever experienced.
The plane I am on, NASA’s C-23 Sherpa, is not your normal commercial aircraft. An old army cargo plane outfitted to carry scientific instruments, the Sherpa reminds me of a bumblebee; with its tiny wings, you have to marvel at the fact that it can even stay up in the air. Loveably ugly and swamp green, the Sherpa is our laboratory for the next two and a half hours. As part of the Student Airborne Research Program (SARP), I, along with 31 other students from across the country, have the unique opportunity to work with NASA scientists to examine Earth from the air.
The previous day, while other students flew in the Sherpa over Los Angeles, I donned a flight suit and flew aboard NASA Langley’s UC-12B with the Geostationary Trace Gas and Aerosol Sensor Optimization (GeoTASO) instrument. It was a thoroughly pleasant, if somewhat cramped, flight at 20,000 feet. Throughout the flight we monitored the instrument as it made measurements of the atmospheric gases below us.
However, on the Sherpa we will be taking physical samples of the air, so we need to fly right through the air we want to collect. This means we will be flying at an average height of 1,000 feet above the ground. As the last flight of the day, the hot air will have had plenty of time to become uneven, making for a very turbulent ride. The previous day’s final flight had been so bumpy that several students became sick, and I stare at the blue motion sickness bags in front of me with a mixture of trepidation and relief.
Luckily, there isn’t much time for me to be nervous, as the Sherpa is only on the ground for a few minutes between flights. It’s almost 100 degrees Fahrenheit outside on the runway at NASA’s Armstrong Flight Research Center in Palmdale, California, and the longer the non-airconditioned plane sits on the ground, the hotter it gets inside and the greater the chance that the instruments will overheat. The turnover between flights has to be quick, so I scurry toward my seat where I begin to sweat nervously as other students and scientists remove used air collection canisters and tubes, affectionately known as “snakes” (due to the way the metal tubing snakes through them), and load new ones onto the plane.
Once the transition is complete, the pilots start the engines, and because the Sherpa isn’t insulated, the noise is deafening. I quickly put my noise-cancelling headset on, just in time to hear the pilots ask if we’re ready for takeoff. I only have time for one more forlorn look at the blue motion sickness bags before we’re up in the air and I begin to relax. The air isn’t as hot and stagnant up here, and the turbulence isn’t that bad. The whole air sampling group gets up to begin taking air samples, and next to me the air quality monitoring research group turns on their instrument to begin collecting data.
I sit back and watch as we fly over the massive redwoods of Sequoia National Park, a wildfire that billows smoke thousands of feet into the air, and oil fields so expansive they seem never-ending. As we spin in endless loops around the landscape, I marvel at all of the ways that scientific research seems to defy boundaries.
Before I know it we are touching down at Armstrong. As the Sherpa makes its way toward the hangar, I revel in the fact that we just did science on an airplane, and I am so grateful to the scientists, pilots and staff that made this wonderful opportunity possible. We gather up our things and shut down the instruments, opening the Sherpa’s rear door to the jubilant cries of our fellow scientists and students waiting on the ground, and see that they are holding up their hands above their heads to create a human tunnel. Running underneath their arms, I smile and yell, too, laughing and sharing in their joy.
Many people are familiar with—or have at least heard of—the Mariana Trench. Located in the western Pacific Ocean, this crescent-shaped feature on Earth’s crust is the deepest part of the world’s ocean, reaching a maximum depth of 10,994 meters (36,070 feet) in an area known as “Challenger Deep.”
Fewer people, however, are familiar with the Mariana Islands—a chain of 15 islands that include ten uninhabited volcanic islands to the north and five limestone islands to the south. The Marianas are divided into two political regions: the Commonwealth of the Northern Mariana Islands (a Commonwealth of the United States comprising Saipan, Tinian, and Rota) and Guam (a US territory). Fringing the coasts of each of these islands are lush coral reefs that support indigenous fishing and a large tourism economy, including many ecotourism opportunities.
For six weeks in April and May, the coral reefs of the Mariana Islands also supported a cadre of scientists deploying instruments and collecting data as part of NASA’s COral Reef Airborne Laboratory (CORAL) mission. Using a state-of-the-art sensor—the Portable Remote Imaging Spectrometer (or PRISM)—housed in a Gulfstream-IV airplane, CORAL will provide a new perspective on the function and future of coral reef ecosystems.
The data collected by PRISM, and validated through extensive in-situ (or in-water) measurements in the field, will form a series of maps that indicate the relative densities of coral, sand, and algae in each study area, as well as rates of primary productivity (the creation of new organic material) and calcification (the process by which reefs produce calcium carbonate, an important determinant of reef health). With these maps, the CORAL team can build models to help scientists, resource managers, and politicians better predict how reefs are impacted by both natural and human processes.
From April 7-18, the CORAL field validation teams surveyed locations in Guam and from May 1-16 they conducted similar validation activities in Palau, an island nation southwest of Guam and the Northern Mariana Islands whose coral reefs have been named one of the “Seven Underwater Wonders of the World” by the Council for Educational Development and Research. (The Great Barrier Reef and the Galapagos Islands are two other famous examples on this list.)
While in Guam, the three in-water validation teams surveyed 65 benthic cover sites (from which high-resolution photo-mosaics will be produced, allowing for detailed analysis of the various types of seafloor, or benthic, habitats), 6 metabolism gradient flux sites (which reveal information about reef productivity), 1 metabolism Lagrangian site (with instruments that measure reef productivity and calcification in a set mass of water, over a specific amount of time, along a set transect across the reef), and 42 water optical property sites (which yield information on how light travels through the water column, from the surface to the seafloor and back).
Having spent a significant amount of time doing underwater surveys in Guam during the mid-2000s, Eric Hochberg, an associate scientist at the Bermuda Institute of Ocean Sciences and the CORAL principal investigator, was pleased to see the reefs looking much the same as they did a decade ago.
“The conditions in Guam were great, with the water ridiculously clear just a few hundred meters offshore,” said Hochberg. “Honestly, the biggest challenge in Guam was the fact that we didn’t have access to a working field lab and had to create a makeshift lab in a conference room at the Hilton!”
Brandon Russell, a postdoctoral fellow at the University of Connecticut and part of the CORAL optics team, echoed Hochberg’s sentiments about the challenges in Guam. “Working in remote locations is incredibly challenging,” Russell said. “It forces you to be flexible in planning and implementation to successfully collect good data but, if you can overcome these challenges, there’s a great opportunity to collect a huge, unique, and varied data set.”
In Palau, the field teams surveyed 74 benthic cover sites, 10 metabolism gradient flux sites, 2 metabolism Lagrangian sites, and 52 water optical property sites. In addition, 23 sites were studied with an underwater spectrometer to collect measurements of benthic reflectance, or the amount of light that is reflected from the seafloor back to the ocean surface. Each benthic community—in this case coral, sand, and algae—has a different spectral “signature” (how much light is reflected as a function of wavelength), which means that measurements of benthic reflectance can be used to identify the composition of the seafloor.
The reefs in Palau lived up to their billing, providing a stunning natural backdrop for the CORAL survey work being conducted. Stacy Peltier, a research technician in Hochberg’s lab at BIOS and part of the CORAL benthic team, said the reefs there were a completely new experience for her.
“While in Palau we discovered a gap in our underwater communication,” Peltier said. “We had no way of conveying how awesome something was, so we had to invent a new diver signal: the head explosion. The scenery was so overwhelming you could barely decide what to look at.”
And, unlike in Guam, the CORAL team had access to dedicated facilities and research vessels in Palau courtesy of the Coral Reef Research Foundation and the dynamic husband-and-wife team of Pat and Lori Colin, the foundation’s director and laboratory manager/research biologist, respectively.
“It’s not an exaggeration to say that we wouldn’t have been able to complete this portion of the CORAL mission without the support of Pat and Lori,” Hochberg said. Agreeing, Peltier said, “Pat and Lori were eager to share their knowledge of Palau’s reefs and actively guided us through so many field aspects that could have easily turned into serious problems.”
The airplane carrying the PRISM instrument shuttled between bases of operation on Guam, Yap (part of the Federated States of Micronesia), and Palau, allowing the flight team to take advantage of shifting weather windows in each region. Over the six-week campaign a total of 75 flight lines were collected, representing at least partial coverage of reef areas in Guam, Rota, Tinian, Saipan, Farallon de Medinilla, Anatahan, Guguan, Alamagan, Pagan, Asuncion, Maug, Farallon de Pajaros, and Palau.
With the campaign in the western Pacific complete, and with flight hours remaining, the CORAL investigation ended on a high note by flying PRISM over reef tracts in the Florida Keys. This “bonus reef” is the first CORAL data set from the Atlantic Ocean and will serve as another representative reef area in terms of reef type, physical forcings, human threats, and biodiversity.
“As we ended the campaign with a number of planned flight hours ‘in the bank,’ we were able to quickly formulate a plan to image the coral reefs around Florida,” said William Mateer, CORAL project manager with NASA’s Jet Propulsion Laboratory. “This reef was the initial location for the CORAL operational readiness test. Weather cooperated and we had two days of great collections (22 lines) to add to the data available for science analysis.”
The field and airborne teams have returned to their respective home institutions and the CORAL project is now moving into the data processing and analysis phase, which will extend into 2018. CORAL datasets and data products are publicly available. For more information, please visit www.coral.bios.edu/data, which will be updated as data become available, and www.coral.jpl.nasa.gov.
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.”
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.
“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.”
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.”
Do you remember that dreaded math problem in high school, the one where two trains left different stations traveling at different speeds toward each other and you had to calculate when and where they would meet? Now try solving a variation of this problem where the two trains are substituted with three very different aircraft—two leaving from the Canadian Arctic, one from northwestern Greenland—plus a satellite flying overhead. This was the logistical puzzle that Operation IceBridge, NASA’s airborne survey of changing polar ice, had to crack on Friday, March 24, during its ninth Arctic campaign.
The original plan had involved four planes: IceBridge’s P-3, the G-III from NASA’s Oceans Melting Greenland (OMG) campaign and two aircraft from the European Space Agency (ESA)—a Twin Otter and a Basler dubbed Polar 5, both carrying laser scanners and radars, among other instruments. The goal was for all of the planes to fly the same path over sea ice, right beneath one of ESA’s CryoSat-2 satellite tracks, while simultaneously collecting measurements so that scientists could later compare the data gathered by the different instruments on the three planes and the spacecraft’s radar altimeter.
“The primary reason for the whole exercise was to cross-calibrate the CryoSat-2 radar with all of our radars and lasers,” said John Sonntag, IceBridge mission scientist. “This will allow us all to better understand the performance of our instruments and how well we perform our surveys”.
Early in the morning of Thursday, March 24, IceBridge’s P-3 and OMG’s G-III took off from Thule Air Base in northwest Greenland and headed to the Lincoln Sea, north of Canada. They were planning to rendezvous there with the two ESA planes, which were based in Alert Station, a Canadian base in Ellesmere Island, in the Canadian Arctic. Since the Twin Otter and Polar 5 were located closer to the target site, the Europeans would depart Alert four hours after the NASA planes had left Thule. But before they could take off, an unexpected fog bank rolled over Alert, shutting the airport down.
Still, IceBridge and OMG proceeded with their flight, sampling the thick multi-year ice near the Ellesmere coast and the gradient to thinner ice closer to the North Pole with their instruments: OMG’s radar mapper and IceBridge’s suite of instruments, encompassing a scanning laser altimeter that measures ice surface elevation, three types of radar systems to study ice layers and the bedrock underneath the ice sheet, a high-resolution camera to create color maps of polar ice, and infrared cameras to measure surface temperatures of sea and land ice.
The following day, the IceBridge team decided to give it another go but OMG had already exhausted its allotted flight hours and had to stay on the ground. To increase their confidence that their European collaborators would be able to fly that day, the P-3 took off one and a half hours later than it normally would have. This time, it was a success: the three aircraft flew over the CryoSat-2 track line (one a few dozen miles east of the one IceBridge and OMG had flown the day before) within 42 minutes of each other. The satellite overflew the same line just two minutes after IceBridge had completed it.
“Ideally, all three aircraft and the satellite would be over the same point at exactly the same time, but that’s almost impossible to do with three airplanes operating at different speeds and altitudes,” Sonntag said. “Still, we had some flexibility because the sea ice moves slowly—as long as we all flew over it within two hours, we could be sure we were all measuring the same ice.”
It will take scientists from the different teams about six months to process all the measurements before they’re able to compare them, but NASA and ESA are already calling the collaboration a success.
“This collaboration took a lot of careful coordination,” Sonntag said. “It demonstrates the commitment of ESA and NASA to work cooperatively to better understand the cryosphere.”
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.
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.
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.
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.
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.
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.
I managed to capture some great footage and discovered that, for me, the mountaintop views were a good remedy for any motion-induced mishaps.
Atmospheric Carbon and Transport-America, or ACT-America, wrapped up its winter field campaign Friday, March 10, with a final set of flights out of coastal Virginia.
The campaign, which is looking at how weather systems and other atmospheric phenomena affect the movement of carbon dioxide and methane in the atmosphere around the eastern half of the United States, began Feb. 1 with two weeks of flights out of Shreveport, Louisiana. The base of operations moved twice: to Lincoln, Nebraska, then to Virginia.
ACT-America employs two aircraft outfitted with several science instruments—a C-130 based at NASA’s Wallops Flight Facility on Virginia’s Eastern Shore and a B-200 based at NASA’s Langley Research Center in Hampton, Virginia.
Principal Investigator Ken Davis of Penn State took lots of photos during the six-week field excursion. Here are a few of the sights he and a couple of the other team members captured. All photos courtesy of Davis except where noted.
Fire in the Southeast
During a flight out of Shreveport, Davis took this picture of smoke rising from a fire somewhere in Alabama or Mississippi. According to Davis, there were a few fires in Gulf Coast forests in early February. Some of the most noteworthy ones were in Arkansas. “We did encounter elevated CO2 over Arkansas,” he said, “probably caused in part by the biomass burning we passed over.”
Gulf Coast Flow
Along the Gulf Coast, Davis took this photo of what he believed to be an offshore oil facility. Facilities like this one could be sources of methane, but ACT-America wasn’t specifically attempting to detect emissions from offshore oil. Of greater interest was air flowing from the Gulf of Mexico onto the continent. “There is often onshore flow from the Gulf across the midwestern and southeastern U.S.,” he said. “That was what we wanted to measure this day.”
Squares of White
The campaign moved to Lincoln, Nebraska, in mid-February. During that midwest leg, a storm system brought a blanket of snow to the region, making for serene scenes like this one, photographed by Project Scientist Bing Lin.
Davis took this photo over the midwest during a flight to validate remote sensing data from the Orbiting Carbon Observatory-2 (OCO-2) satellite. OCO-2 uses near infrared reflection to make its measurements of carbon dioxide. Snow is dark in the near infrared, though, meaning it’s not reflective, so satellite validation flights like this one can help researchers see how well OCO-2 is working as it collects measurements while orbiting over snow-covered land.
Down and Outlaws?
During a down day in Lincoln, a few folks from the team toured a brewery that sits above a 5,000-square-foot cave. Pictured, from left to right, are Bill Ziegelbauer, Nathan Blume, Dirk Richter, Rebecca Pauly, Matthew Elder, Cate Easmunt, Mike Wusk and Greg Slover. According to a local legend, outlaw Jesse James may have used the cave as a hideout after a heist in Minnesota. No outlaws on the ACT-America team, though. They all left the cave after the tour was over. We think. Photo courtesy of Cate Easmunt.
Reunited and … You Know the Rest
During the Mid-Atlantic leg of the campaign, Davis posed for this photo at Wallops with Hannah Halliday of NASA Langley and Bianca Baier of the National Oceanic and Atmospheric Administration. Halliday and Baier, who had both been taught by Davis at Penn State, operated instruments on the flights. “I didn’t know we’d all be in the field together,” said Davis, “and I was smart enough to get a couple of photos.”
Flights over the Appalachian Mountains in southwest Pennsylvania and eastern West Virginia allowed ACT-America researchers to measure carbon emissions upwind and downwind of coal and gas extraction activities in the region.
ACT-America Project Manager Mike Obland of NASA Langley wears long sleeves to keep warm on one of the flights over the Mid-Atlantic. Even on relatively warm days, temperatures on the C-130 can get chilly, particularly at higher altitudes.
That’s a Wrap
As the winter field campaign came to a close in Virginia, team members posed for this group photo by the C-130. Photo courtesy of Cate Easmunt.
ACT-America will return for a second 2017 field campaign in the fall.
Understanding our planet and how it functions, as well as the impacts that human activities have on it, requires frequent and extended forays into the field to yield valuable data and observations. The COral Reef Airborne Laboratory (CORAL) investigation is a prime example. The three-year mission, funded by the NASA Earth Venture Suborbital-2 program, is conducting airborne remote sensing campaigns, along with in-water field validation activities, across four coral reef regions in the western and central Pacific Ocean.
“The objective is to conduct coral reef science at the ecosystem scale to find out the relationship between reef condition and the biogeophysical factors we think impact reefs,” said Eric Hochberg, CORAL principal investigator from the Bermuda Institute of Ocean Sciences, St. George’s, Bermuda. “With that understanding, we can build models to help scientists, resource managers and politicians gain a new perspective on reef function and better predict how natural and human processes will shape the future of reefs.”
When CORAL traveled to Hawai‘i last month for its second field campaign, it already had nearly a year of the mission under its belt. The Operational Readiness Test (ORT) took place in Hawai‘i last summer and the team completed a successful first field campaign in Australia’s Great Barrier Reef last fall. During both, communications between the airborne and field teams were streamlined, field operations and equipment deployments were tested and refined, and team members gained valuable experience working with both equipment and each other.
Even with years of planning and preparation, however, such ventures are always undertaken with the knowledge that some variables are out of the researchers’ control. For the CORAL team, there was one thing they couldn’t prepare for in Hawai‘i: the weather.
While the in-water field teams can—and do—work in what are often considered adverse conditions, the weather can still take a toll on the instruments left in the water to collect data.
“Our metabolism work on the fore reef of Kāneʻohe Bay was going well until a large north swell wrapped around to the windward side and toppled one of our gradient flux instrument stands,” said Robert Carpenter, CORAL co-investigator from California State University Northridge and leader of the reef metabolism team. “Luckily, it happened during the night before we were going to pick the instruments up, so we did not lose any data and the instruments were not damaged. Because of the swell, we continued the remainder of our data collection in the back reef and lagoon. So much for a calm time of the year!”
Unlike the in-water teams, the airborne operations for CORAL require substantially fairer conditions. The PRISM (Portable Remote Imaging Spectrometer) instrument that forms the backbone of the CORAL science is housed in the belly of a Gulfstream-IV airplane that flies over survey areas at an altitude of 28,000 feet. In order to obtain the most accurate spectral data possible from the seafloor, the airplane must fly in relatively cloudless skies with low surface winds over clear waters.
“One of the biggest operational challenges that the CORAL Hawai‘i campaign faces is the weather,” said CORAL project engineer Ernesto Diaz from NASA’s Jet Propulsion Laboratory, Pasadena, California. “For optimal data, a clear line of sight between the sun and the coral reefs is necessary, making clouds CORAL’s biggest enemy. Hawai‘i’s tropical location, the drastic topography differences within each island, and the trade winds, are some of the factors that make forecasting clear weather days particularly tricky. A clear day over an entire island is uncommon so we usually plan for collections over portions of the islands that have the best clear sky forecast, i.e. windward, or leeward sides. All of these factors make a successful data collection flight very rewarding.”
CORAL scientists also had to contend with a significant rain event over the region in late February as a slow-moving storm system dumped rain on the islands for two straight days and caused urban flooding in many areas. These floodwaters, originating on land and emptying into the surrounding ocean, led to a significant amount of soil runoff in areas. The additional sediment in the waters reduced water clarity and, as a result, impacted the ability of the PRISM instrument to “see through” the water to the seafloor.
Despite these challenges, the CORAL team was able to complete in-water validation activities in Kāneʻohe Bay and collect flight lines over the Big Island (the island of Hawai‘i), Maui, O‘ahu, Kaua‘i, Ni‘ihau, Moloka‘i, Lana‘i, and Kaho‘olawe. The benthic team also visited Maui and the Big Island to gather data for various benthic communities not represented in Kāneʻohe Bay.
“It was nerve-racking checking the weather forecasts each day and following the progress of the airplane, hoping for clear skies and calm waters over the different islands where we needed PRISM data,” said Hochberg. “We got some good breaks, though, and the Hawai‘i campaign was successful. Next month we get to start it all over again in Guam and Palau. I’m looking forward to it!”
The Atmospheric Tomography, or ATom, mission’s world survey of the atmosphere can’t fly the order of its locations in reverse.
Its flight plan begins with traveling from California to Alaska and the North Pole before flying south down the center of the Pacific Ocean by way of Hawaii to New Zealand. From New Zealand, they cross east to Chile before ascending north up the Atlantic to Greenland.
It’s this southernmost crossing from Christchurch, New Zealand, to Punta Arenas, Chile, that’s a one-way street.
“The plane can’t make it from Punta Arenas to New Zealand because the winds are too strong,” said Róisín Commane, an atmospheric scientist at Harvard University who is part of the ATom mission.
The winds that travel from west to east above the Southern Ocean around Antarctica are among the strongest in the world. With few land masses to slow them down, they blow unimpeded.
Those strong winds led to complications for the ATom team as they were preparing for their Feb. 10 flight from Christchurch to Punta Arenas. In a small hotel conference room around a cell phone and computers sharing a screen from weather forecasters back at NASA’s Goddard Space Flight Center, Steve Wofsy, ATom’s project scientist, peered at a circular weather system at the end of their flight path. The system created an eddy in the prevailing west-east wind that coincided with their arrival in Punta Arenas. The concern around the table was that strong winds would be blowing perpendicular to the runway when the plane was trying to land, potentially pushing it sideways.
The DC-8 can handle this kind of crosswind up to about 25 knots, or 28 miles per hour. Above that, for safety the pilots would have to divert to a back-up landing site. The closest in Chile was in the range of the same weather system—and likely to have the same crosswinds. The other was in Argentina two hours away, which would require fuel reserves that would take away from the number of profiles of the atmosphere they could do on the crossing, one of the main reasons for this mission. It would also require a second flight to get the team back to Punta Arenas the day after the system passed.
It was a disruption that Wofsy didn’t want to take on after an already difficult 10-hour flight with an 8-hour time change. From their experience on ATom’s first deployment in 2016, they knew from experience that the jet lag on this leg of the trip was brutal.
After three mornings watching the updated forecasts and NASA ground personnel talking with local weather forecasters in Punta Arenas, the morning of their scheduled departure from New Zealand arrived. The forecast hadn’t changed much. There was a 20-25 percent chance that the winds would be too strong and the plane would have to divert, said Wofsy. After a last early morning meeting with the pilots and forecasters, they made the decision to scrub the flight and wait a day for the storm to pass.
By the next day the system had indeed moved on, and the runway in Chile was safe for landing. The ATom team departed after their extra day in Christchurch and with. an adjusted schedule that would give them one less day in Punta Arenas. But on a mission dependent on good weather, that’s the way the wind blows.