Observing Biodiversity: One Cell at a Time

A sample mosaic image from the Imaging FlowCytobot, representing material sampled from one bottle of seawater collected by during a CTD cast. Credit: NASA

by Eric Lindstrom / Eastern Tropical Pacific Ocean /

Eric Lindstrom is Physical Oceanography Program Scientist at NASA Headquarters. For the last 20 years, his primary job has been supporting NASA satellite missions related to measuring physical characteristics of the ocean (principally, temperature, salinity, sea level, and winds) and supporting the oceanographers that generate knowledge from such data. He was recently aboard the Research Vessel (R/V) Roger Revelle in the Pacific Ocean as part of the Salinity Processes in the Upper Ocean Regional Study-2 (SPURS-2) field campaign. SPURS is undertaking oceanographic field experiments to further understand the essential role of the ocean in the global water cycle using a plethora of oceanographic equipment and technology, including salinity-sensing satellites, research cruises, floats, drifters, autonomous gliders and moorings.

What lives below us?  This is a question that mariners have wondered for ages.  We no longer think of the darker answers to this question—the sea monsters, the Kraken, the great whales.  For most aboard, the thinking is akin to a fisherman’s—tuna, mahimahi, sharks.  But for SPURS-2, Sophie Clayton is answering this question in terms of microscopic life, namely diverse phytoplankton (plant life) and zooplankton (animal life).

Sophie is an oceanographer interested in understanding how ocean currents at all scales shape the distribution and biodiversity of phytoplankton. She uses a combination of numerical models, large-scale data analysis, and targeted observations made at sea. Her Ph.D. in Physical Oceanography from the Massachusetts Institute of Technology/Woods Hole Oceanographic Institution Joint Program. Now she is a postdoctoral fellow at the University of Washington, working extensively with observations of phytoplankton distributions made using an Imaging FlowCytobot (IFCB) that analyzes discrete samples with video and a hyperspectral optical sensor for recording the continuous optical properties of the water.

Sophie Clayton collects a 4-liter bottle of seawater for filtering. Credit: NASA/Eric Lindstrom

An IFCB is an instrument that is used primarily to count cells, but it also can detect and record information on different properties of the cells that it counts. A water sample is channeled into a thin stream that is passed in front of a laser, and the scatter and fluorescence from each cell that passes along the stream is detected and recorded. In the IFCB, the camera is triggered to take a picture only when fluorescence over a threshold value is detected. This means that the instrument only takes pictures of cells that contain chlorophyll. The images are then stored for analysis back on shore. In addition to the images that are collected, we use the optical properties of the cells (fluorescence and scatter) in the analysis.

Sophie’s work is enabled by surface water collected from the salinity snake while we are underway or from bottle samples taken during Conductivity- Temperature-Depth (CTD) casts. Similar mosaics are made from surface water every 20 minutes. Overall, there will be close to 2,000 mosaics of cellular life to examine.  Samples are also held for later DNA analysis.

There are always meticulous notes to keep about samples. Credit: NASA/Eric Lindstrom

Out here, for the most part, the plankton are actually most abundant below the surface at 40-70 meters depth. Deeper down, below the surface layer mixed by the wind, life has better access to the chemical nutrients of the deep sea while still having enough light for photosynthesis.  Plant life thrives in a layer that best balances the light and nutrient requirements.   Of course, the grazing microscopic animals follow this layer closely.  So Sophie is keen to collect water from this layer during our CTD casts.  She can tell where to sample by optical properties also measured on CTD casts.

Understanding plankton abundance and diversity is a core requirement for ocean climate science.  Phytoplankton are responsible for about half of all photosynthetic production on the planet. (Land plants are also responsible for about half.) It makes them a key part of the carbon cycle on the planet.  Over long periods, phytoplankton can remove carbon from the upper ocean and return it to sediment for long-term sequestration.  Over hundreds of thousands of years, phytoplankton act to reverse the greenhouse effect caused by pulses of carbon dioxide injected into the atmosphere by volcanoes or humans.

Phytoplankton are extremely diverse, varying from photosynthesizing bacteria (cyanobacteria), to plant-like diatoms, to armor-plated coccolithophores (drawings not to scale). (Collage adapted from drawings and micrographs by Sally Bensusen, NASA EOS Project Science Office.)

In a prior blog,  I wondered about the fate of life in the sea. What would become of that abundant life with the continued impacts of ocean acidification, industrial fishing, and plastics pollution?  Science struggles to make any predictions.  Oceanographers particularly, because of our close affinity and observation of the sea, hope that the assaults of society on the sea do not damage its inherent ability to stabilize and heal the rapid changes overtaking the planet.  Our baseline understanding of the complex marine ecosystem is still quite primitive.  The kind of “survey” work that Sophie is undertaking is absolutely necessary to further our understanding of the biogeography of the ocean and how it is changing.  Let’s hope she has a successful career!

A Career in Physical Oceanography

Eric Lindstrom. Credit: David Ho

Eric Lindstrom is Physical Oceanography Program Scientist at NASA Headquarters. For the last 20 years, his primary job has been supporting NASA satellite missions related to measuring physical characteristics of the ocean (principally, temperature, salinity, sea level, and winds) and supporting the oceanographers that generate knowledge from such data. He is currently aboard the Research Vessel (R/V) Roger Revelle in the Pacific Ocean as part of the Salinity Processes in the Upper Ocean Regional Study-2 (SPURS-2) field campaign. SPURS is undertaking oceanographic field experiments to further understand the essential role of the ocean in the global water cycle using a plethora of oceanographic equipment and technology, including salinity-sensing satellites, research cruises, floats, drifters, autonomous gliders and moorings.

You can read more about SPURS field campaign through Eric’s Notes from the Field blogs.

The R/V Roger Revelle in San Diego just before departure. Credit: NASA/Eric Lindstrom

In July 1969 I was watching Neil Armstrong take his first step on the moon at Tranquility Base, like everyone else with a TV at the time.  I was at USC Wrigley Marine Center on Catalina Island as a 13-year-old visiting my brother, who was spending the summer studying there.  If you had asked me then if I would wind up working for NASA, I would have said, “No, I’d rather pursue oceanography!”  Well, since 1997 I have been the Physical Oceanography Program Scientist at NASA Headquarters AND I am a dedicated sea-going oceanographer.  It stills feels kind of crazy what comes around in life.  I write my short career biography here for students who may consider working in oceanography or for NASA or both.

After graduating from Huntington Beach High School in California in 1973, I took the train across the country to begin my college career at the Massachusetts Institute of Technology.  After only one semester of MIT physics and mathematics problem sets, this boy gravitated to the Department of Earth and Planetary Sciences and asked them how I would train to be an oceanographer.  There were no undergraduate oceanography courses, so I was told to take physics and math (ouch!) and to get my degree in Earth Science I would have to take the required geology and geophysics courses, too.  I did all that, but rocks were not my first love.  Luckily, a Professor of Physical Oceanography at MIT, John Bennett, allowed me to work with him under MIT’s Undergraduate Research Opportunities Program (UROP) and sit in on his graduate level physical oceanography courses.  We worked together on an analysis of the coastal boundary layer in Lake Ontario, and I co-authored a paper with him that appeared in the Journal of Physical Oceanography in the summer of 1977.  UROP and that research paper were a big boost for my applications to graduate school.  I still donate money annually to MIT’s UROP to honor its impact.

For graduate school I sought out a diverse set of schools: UCSD Scripps Institution of Oceanography, University of Washington, Princeton, and University of Miami.  I was told that since I was at MIT, I should NOT apply to the MIT/Woods Hole Oceanographic Institution joint program (that was weird).  In the end I did have choices and settled at University of Washington working with Professor Bruce Taft.  It was the era of Apollo-Soyuz and USA-USSR cooperation in space and oceanography, so I embarked on studying eddies in the North Atlantic with a diverse set of US and USSR scientists.  The project was called POLYMODE.  It was a fun project with time at sea and lots of workshops and meetings, including a month in Moscow doing a data exchange.  The connection to the space program was remote and programmatic and I hardly noticed it at the time.  I received my PhD in September 1983, the day the Australian’s won the America’s Cup sailing race.  I celebrated, since I had signed up to move to Australia to do oceanography (and get married!) the very next month.

Australia was a hoot!  We moved to Hobart in Tasmania where the government was building a new marine science laboratory and eventually a new oceanographic research vessel as well.  It was  a growing field because 200-mile Exclusive Economic Zones had just been declared and Australia wanted to know all about the waters around the continent—good work for a newly minted oceanographer!  The team in Hobart had me focus on the western tropical zone, including the Coral Sea, Solomon Sea, Bismarck Sea, and the circulation around Australia’s neighbor Papua New Guinea.  Hardly anything was known so I worked with some of my buddies back in the USA on developing the Western Equatorial Pacific Ocean Circulation Study (WEPOCS).  It was a great success! We named some new ocean currents and replaced some old stale ideas with some fresh perspective on the role of the western tropical Pacific in climate.

While in Australia in the 1980s I also became involved in the planning of a huge international experiment – the World Ocean Circulation Experiment (WOCE).  My work on WOCE had the Australian government send me back to the USA to work at Texas A&M University, the U.S. WOCE Office.  That certainly began returning my roots to US soil.  After returning to Australia it was not long until headhunters from USA sought my return to work again in the USA at the project office in Boulder, Colorado, of the Coupled Ocean Atmosphere Response Experiment (COARE; an experiment just off the coast of Papua New Guinea).  The family decision was to make a return to the USA permanent.

Boulder only lasted about 18 months and then I returned to WOCE work as U.S. WOCE Program Scientist in Washington, D.C., in 1992 as an employee of Texan A&M University but under the direction of five federal agencies (each providing 20 percent of my support).  Gosh, the world is convoluted sometimes!  That, for me, began “interagency cooperation” in oceanography for which I am still deeply involved.  Broadly, the five agencies that fund global oceanography projects are the same now as they were then: NSF, NOAA, Navy, NASA, and Department of Energy.

Eventually, after five years working on WOCE and the new Global Ocean Observing System, I got a call from Bruce Douglas at NASA Headquarters.  He was serving a stint as Physical Oceanography Program Scientist and asked me to interview as his replacement.  NASA told me they were looking for someone who could integrate their oceanography (from space) into the federal family of oceanography agencies.   Certainly, I had experience for that.  However, I told them I had no particular experience with satellite oceanography.   Their idea, and response at the time, was that they had plenty of satellite oceanographers at NASA but that it might be good for their leader to be someone who had “touched seawater” and was open to learning about the new tools for satellite oceanography.  Wow, I said, you have found the right person!

So, here we are, after 20 years, I have learned my fair share of satellite oceanography and have thoroughly enjoyed NASA.  I have molded NASA Physical Oceanography into a community that fully supports its satellite missions with appropriate science at sea.  I hope I have helped to make satellites an everyday tool for oceanographers.  The positive feedback from the community has been most humbling.  I am very lucky indeed to have landed on my own Tranquility Base.

ACT-America: Settling into the Rhythm of the Field

C-130 pilots Jim Lawson, left, and Paul Pinaud during a flight. Credit: NASA/David C. Bowman

by Hannah Halliday / SHREVEPORT, LOUISIANA /

Fieldwork is my favorite part of my job. I have been working as a postdoc at NASA’s Langley Research Center in Hampton, Virginia, for a few days over a year, and I’m still not over the excitement of arriving somewhere new, ready to take measurements and run our instruments.

My background is in chemistry, but I slid into meteorology because I wanted to apply myself to environmental issues that had global impact. That decision put me on a path into the world of air quality research, and ultimately to NASA to work with airborne science. While I’m still new to flying for science, I love working with instruments and taking measurements. Being on an aircraft turns that feeling up to 11.

Atmospheric Carbon and Transport-America, or ACT-AMERICA, has been an especially cool project to be involved with because I earned my Ph.D. at Penn State, where principal investigator Ken Davis and other members of the ACT-AMERICA planning team are based. Working with ACT-AMERICA is part serious work and part fun reunion, working with people I know well on a totally new subject and project. I got to fly with the mission last spring, and I’ve come back to join them again for two weeks in Shreveport, Louisiana.

The C-130 doesn’t have many windows, but Halliday is lucky to have one beside her seat. Flights often have low-altitude runs, and offer views of the country from unique angles. This is a view of the Mississippi River from the Sunday, Nov. 5, flight. Credit: NASA/Hannah Halliday

On Saturday, Nov. 4, we took a break from flying to do instrument work and maintenance. For my group, which is tasked with the Atmospheric Vertical Observations of CO2 in the Earth’s Troposphere, or AVOCET, in-situ measurements, that meant calibrating our instruments. When we calibrate, we send our instruments gases that have a known concentration and record what our instruments measure. Doing this regularly allows us to keep track and correct for the instrument drifting over time, and to maintain the accuracy and precision of our measurements.

Hannah Halliday, right, monitors incoming AVOCET measurements during a Nov. 2 science flight. Next to her are Theresa Klausner and Max Eckle, Ph.D. students with the German Aerospace Center, DLR, which has joined the fall flight campaign to test an instrument that measures methane and ethane. Credit: NASA/David C. Bowman
Bianca Baier, a postdoctoral researcher with NOAA’s Earth Systems Research Lab in Boulder, Colorado, and Ken Davis, ACT-America principal investigator from Penn State, talk during a flight. Credit: NASA/David C. Bowman

Our two aircraft, a C-130 and a B-200, are stored in different locations when we’re at our ground sites. The calibration gas tanks are heavy, so for ease of use we’ve built our calibration gas cylinders their own little cart that they live on, which can be towed from one location to another. The cylinders are left on the cart, where we put a regulator on the calibration cylinder we want to use and run a tube into the airplane. It’s a simple solution that lets us easily and quickly use the same calibration gases on two different aircraft.

Calibration gas cylinders on their transportation cart. During a calibration, scientists use three gases with low, middle and high concentrations, and use this information to understand how the instrument will behave when it “sees” gases in the environment. Credit: NASA/Hannah Halliday

One of the reasons I love working in science is that our measurements and our work is built on a heap of clever solutions to small problems. While we also stand on the shoulders of scientific giants who had deep insights into the workings of the universe (for instance, Isaac Newton realizing that the gravity affecting an apple also affects the stars), in our day-to-day work we use the cleverness of the people who worked out the universal swage fittings, or the person who figured out how to set up our inlet system to bring air in from outside the plane when we’re at high altitude.

We’re not all brilliant all the time, but by looking at a problem long enough we can often find a clever solution to a small vexing problem (such as how to quickly transport our calibration cylinders), and that’s where our progress comes from.

On Sunday, Nov. 5, we flew a science mission, measuring the inflow of air from the Gulf of Mexico. It was a busy day for me, because I was both tending my group’s instruments and also taking flask samples for NOAA. NOAA uses glass-lined containers to trap air at specific locations on the flight track. They take these samples back to their lab in Boulder, Colorado, where they measure the greenhouse gases as well as other molecules that help determine whether samples were influenced by other sources, such as traffic or wildfires. My job was to follow their sampling plan, telling their mostly automated system when to collect a sample and coordinating with our in-flight calibrations.

Specialized inlets draw air into the instruments and have different designs based on the needs of the instruments. These inlets are located near the front of the aircraft so they don’t sample the exhaust from the engines. Credit: NASA/David C. Bowman

The flights can be quite busy, and it’s a full day of activity. For the four to five hours that a typical science flight will last, we have an additional three hours of flight prep before we take off, and a debriefing meeting once we land, plus data workup and archiving the preliminary data once we’re back in our hotel rooms.

The C-130 gets a checkup after the Nov. 5 flight. A dedicated flight team keeps the aircraft running and maintained. Credit: NASA/Hannah Halliday

It’s satisfying work, but it’s important that we have non-flight days like Saturday to catch up on our instrument maintenance as well as personal things—exercise, laundry, even sleep. When we’re in the field there’s no set schedule like when we’re in the office, and it’s important to grab that time when we can, because flight days depend on the weather, and a good measurement day waits for no scientist, not even when they have a plane!

ACT-America: Waiting for the Great Big Teaspoon in the Sky

The NASA Langley B200 sits in a hangar at Shreveport Regional Airport. It and the C-130 won’t fly today because the weather pattern is too similar to the one they flew through the day before. Credit: NASA/David C. Bowman

by Joe Atkinson / SHREVEPORT, LOUISIANA /

Brrrr.

I don’t know what I was expecting from Louisiana in late October, but I definitely wasn’t expecting cold and damp.

I’m here for the final leg of the fall 2017 flight campaign for Atmospheric Carbon and Transport-America, or ACT-America, a five-year NASA study looking at the transport of carbon dioxide and methane by weather systems in the eastern United States.

This is the third flight campaign of the study and the team has just arrived in Shreveport—home base for the next two weeks. Flight operations will be based out of Shreveport Regional Airport. Sleep operations are based at a hotel just a few minutes down the road in Bossier City.

ACT America group with the B200 King Air and C130 Hercules in Shreveport Louisiana. Credit: NASA/David C. Bowman

As I’ve already mentioned, the weather so far is pretty meh. There’s a slow-moving front to thank for that. But more on the creeping front later on. First, a little taste of ACT-America’s home for the next couple of weeks.

Shreveport is the largest city in Ark-La-Tex, a region that includes Northwestern Louisiana, Northeastern Texas and South Arkansas. It and Bossier City are divided by the Red River. Shreveport is on the west, Bossier City the east. Casinos dot the riverbank—the Horseshoe, Boomtown, Eldorado, Margaritaville, Diamond Jack’s.

It’s no big surprise that you can’t go far here without finding restaurants that have Cajun and Creole dishes on the menu. The first night in town, a contingent from the ACT-America team visits the Blind Tiger in downtown Shreveport. Steaming plates of crawfish etouffe come out of the kitchen accompanied by crusty homemade croutons and mounds of rice. There’s a dish called Cajun fried corn—breaded, deep-fried corn on the cob. Louisiana beers are on tap. Gumbo is spelled gumbeaux.

The State Fair of Louisiana is taking place in Shreveport. It claims to be the largest livestock show and carnival in the state. Rick Rowe, a reporter with the local ABC affiliate, does a segment on the morning news with a man who sells fried cheese at the fair. Rowe samples a cube that’s just been pulled from the bubbling hot oil and sounds positively ecstatic as he bites through the crispy breading.

The state fair isn’t the only thing going on, though. Another news segment has a meteorologist visiting a Bossier City shop that sells power equipment: lawnmowers, leaf blowers, generators, chainsaws. They have an event coming up called Sawdust Days. Folks who show up for Sawdust Days will be treated to a special demonstration by a man who does wood carvings with a chainsaw.

“He’s carved a lot of pieces right here,” the shop owner says, gesturing to a rustic-looking wooden bear that towers over him and the meteorologist, “so he’s pretty good at it.”

I turn off the TV and head to the airport to catch up with another guy who knows something about meteorology—Ken Davis, principal investigator for ACT-America and a professor of meteorology at Penn State University.

Weather is critical to ACT-America. In fact, it’s the reason that, on its first full day in Shreveport, the campaign is keeping its C-130 and B200 aircraft on the ground. Just the day before, as ACT-America moved from its previous homebase in Lincoln, Nebraska, to Shreveport, the aircraft passed through the very front that’s inching through Louisiana now, bringing the chilly air and rain along with it. Instruments on both aircraft measured carbon dioxide and methane levels during the transit.

“This weather is relatively similar to what we documented yesterday,” Davis says. “If we measured it yesterday, we don’t need to measure it today.”

Although there won’t be a flight today, there’s still work to do. Here, Yonghoon Choi, an instrument investigator from NASA Langley, and Max Eckle, a Ph.D. student with DLR, the German aerospace agency, help unload equipment and supplies that have been trucked to Shreveport from the previous ACT-America homebase in Lincoln, Nebraska. The fall flights are giving the DLR a chance to see how their methane- and ethane-detecting Quantum Cascade Laser Spectrometer operates in the field, while also allowing the ACT-America scientists to better zero in on methane sources. Credit: NASA/David C. Bowman

What the team will want to measure, though, is what happens to the greenhouse gases after the cold front stalls not too far south of Shreveport. There, it’ll get a push from warm, low-level air flowing in from the Gulf of Mexico and then move northeast as a warm front.

It’s a scenario that may take a couple of days to play out, so the next research flights may happen tomorrow, they may happen the day after tomorrow. The atmosphere will do what it wants to do, thank you. Davis likens it to a big cup of coffee.

“Over the timescale of days,” he stretches out days when he says it, “somebody’s stirring it with a great big teaspoon. And you’ve got to wait … every stir takes a couple of days. We want to measure different parts of that.”

Later on, at a planning meeting, they make the final decision—another down day tomorrow, then a flight the next day when the great big teaspoon in the sky has finally mixed things up just so. It’ll be a good day for airborne science.

The meeting breaks up. Folks head back to their hotel rooms.

With a free evening in front of me, I think about taking a chilly walk down the bank of the Red River to get a look at the Shreveport skyline at night. And for some reason, I’m craving a piping hot cup of coffee.

Hannah Halliday, left, a postdoctoral researcher at NASA Langley, and Bianca Baier, a postdoctoral researcher at the NOAA Earth System Research Laboratory in Boulder, Colorado, point out to Ken Davis a region where fires might make for interesting measurements. Credit: NASA/David C. Bowman
At a late-afternoon planning meeting at the hotel, ACT-America prinicipal investigator Ken Davis, left, listens as research scientist Sandip Pal discusses which day might be best to fly next. The weather pattern for the upcoming two days could be favorable for science flights. After much debate, they make the decision to give the pattern an extra day to set up before flying again. C-130 pilot Jim Lawson and mission manager Charles Juenger, far right, listen in. Credit: NASA/David C. Bowman

Searching for the Bluest Blue

by Joaquín E. Chaves-Cedeño / South Pacific Ocean /

It doesn’t take a lot of technology to see that the ocean is blue. And when it comes to the blueness of the ocean, it doesn’t get much more blue than where I am. My current home and office is the research vessel Nathaniel B. Palmer—the largest icebreaker that supports the United States Antarctic Program—which is on an oceanographic expedition across the South Pacific Ocean. On this voyage, however, the Palmer hasn’t broken any ice.

Our Global Ocean Ship-based Hydrographic Investigations Program (GO-SHIP) P06 campaign departed Sydney, Australia, on July 3, and successfully ended the first leg of this journey on August 16 in Papeete, French Polynesia, also known as Tahiti. This is where our team from NASA Goddard Space Flight Center (Scott Freeman, Michael Novak, and I) joined dozens of other scientists, graduate students, marine technicians, officers and crew members for the second and final leg that will end in the port of Valparaiso, Chile, on September 30.

The GO-SHIP program is part of the long history of international programs that have criss-crossed the major ocean basins, gathering fundamental hydrographic data that support our ever growing understanding of the global ocean and its role in regulating Earth’s climate, and of the physical and chemical processes that determine the distribution and abundance of marine life. This latter topic regarding the ecology of the ocean is what brings our Goddard team along for the ride.

The P06 ship track, for the most part, follows along 32.5° of latitude south. That route places our course just south of the center of the South Pacific Gyre—the largest of the five major oceanic gyres, which form part the global system of ocean circulation. The Gyre, on average, holds the clearest, bluest ocean waters of any other ocean basin. This blueness is the macroscopic expression of its dearth of ocean life. We have seen nary a fish or other ship since we departed Tahiti (as this is not a major shipping route). Oceanic gyres are often called the deserts of the sea. On land, desert landscapes are limited in their capacity to support life by the availability of water. Here, lack of water is not the issue. Water, however, is at least the co-conspirator in keeping life from flourishing. Physics, as it turns out, is what holds the key to this barren waterscape.

This map shows MODIS chlorophyll concentrations indicating phytoplankton, with the R/V Nathaniel B. Palmer’s ship track superimposed. The deeper blue the color the less chlorophyll there is. Credit: NASA

Due to the physics of fluids on a rotating sphere such as our planet, the upper ocean currents slowly rotate counterclockwise around the edges of the center of the Gyre—as a proper Southern Hemisphere gyre should—and a fraction of that flow is deflected inward, toward its center. With water flowing toward the center from all directions, literally piling up and bulging the surface of the ocean, albeit, by just a few centimeters across thousands of miles,  gravity pushes down on this pile of water.

This relentless downward push puts a lock on life.

The pioneers of life in the ocean, tiny microscopic organisms known as phytoplankton, drift in the currents and grow on a steady mineral diet of carbon dioxide, nitrogen, and phosphorus, along with a dash of iron. (Meanwhile, they expel oxygen gas as a by-product, to the great benefit of life on Earth). Phytoplankton obtain most of their sustenance from the ocean below. What happens in this Southern Hemisphere gyre is that layers of denser water trap the nitrogen- and phosphorus-rich water to depths that are out of reach to most of the phytoplankton. And phytoplankton that do make it to that depth are too starved of sunlight to spark the engine of photosynthesis that allows them to grow.

Why are we here and where does NASA come into this story? Since the late 1970s, NASA has pursued, experimentally at first, and now as a sustained program, measuring the color of the oceans from Earth-orbiting satellites as a means to quantify the abundance of microscopic life. It’s microbiology from space, in a way. Formally, though, we call it “ocean color remote sensing.” Bound to polar orbits that allow them to scan the entire surface of the globe every couple of days, satellites whiz by at several hundred miles above the atmosphere carrying meticulously engineered spectra-radiometers, or cameras capable of measuring the quantity and quality, or color, of the light that reaches its sensors. This is where our work aboard the R/V Palmer comes into the story.

The crew prepares to deploy the radiometer from the stern of the R/V Nathaniel Palmer to measure the optical properties of the water from the surface down all the way down to the bottom of the photic zone. Credit: Lena Schulze/FSU

The data the satellites beam down from orbit do not directly measure how much plant life there is in the ocean. Satellite instruments give us digital signals that relate to the amount of light that reaches their sensors. It is up to us to translate, or calibrate, those signals into meaningful and accurate measurements of microscopic life, along with temperature, salinity, sediment load, sea level height, wind and sea surface roughness, or any other of the many environmental and geophysical variables satellite sensors can help us detect at the surface of the ocean. To properly calibrate a satellite sensor and validate its data products, we must obtain field measurements of the highest possible quality. That is what our team from NASA Goddard is here to do.

Scott Freeman of NASA works with an R/V Nathaniel Palmer crew member to prepare an optical instrument for deployment over the side of the ship to collect optical measurements. Credit: FSU/Lena Schulze

Around midday, typically the time an ocean color satellite is flying over our location, we perform our measurements and collect samples. We measure the optical properties of the water with our instruments to compare what we see from the R/V Palmer to what the satellites measure from their orbit. At the same time that we perform our battery of optical measurements, we also collect phytoplankton samples to estimate their abundance and species composition as well as the concentration of chlorophyll-a, the green pigment common to most photosynthesizing organisms, such as plants. By simultaneously collecting these two types of measurements—light and microscopic plant abundance—we are able to build the mathematical relationships that make the validation of satellite data products possible.

Mike Novack of NASA studies the optical and biological characteristics of sea water samples in the ship’s laboratory.
Credit: NASA/Joaquin Chavez

The waters of the South Pacific Gyre are an ideal location for gathering validation quality data, perhaps one of the most desirable, because there are few complicating factors and sources of uncertainty that blur the connection we want to establish between the color of the water and phytoplankton life abundance. Our measurements will extend NASA’s ocean chlorophyll-a dataset to some of the lowest such values on Earth.  The water here is blue; in fact, it’s the bluest ocean water on Earth.

Making It Work in the Field with ORACLES

Visible haze layer above and around some small cumulus clouds, as seen from the window of NASA’s Orion P-3 aircraft. Credit: NASA/Kristina Pistone

by Kristina Pistone / NASA Ames Research Center /

I’m not gonna lie: field work is probably my favorite part of the job as a scientist. Aside from my personal interest in visiting new places and cultures, having firsthand experience in data collection is valuable for when we return home and start doing the hard work of interpreting our observations to understand new things about Earth’s climate. While it’s often physically and mentally exhausting, being in the field provides a context that is difficult to get even from the most thorough notes by colleagues.

Thus, I was very excited to be able to participate in the ORACLES-2017 deployment in São Tomé, a tiny island in the crook of Africa’s arm, where we flew NASA’s Orion P-3 aircraft to understand how pollution affects clouds in this region. My colleagues Kirk Knobelspiesse and Michael Diamond have already posted a couple of great pieces, which include an overview of ORACLES, the general science questions we are studying, and how we go about doing that in the middle of the Atlantic Ocean.

I work primarily with 4STAR, the Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research, a pretty cool instrument which we use to learn about pollution in the atmosphere. (See a more detailed post about the instrument here.) For 4STAR, deployment involves not only having an operator on every flight to make sure the instrument is in the right mode at the right time, but also cleaning and calibrating it before and after each flight to make sure everything is going as expected and that we’re able to process and interpret the data when we get home.

The Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research, or 4STAR, down inside the plane, with its lamp attached during a post-flight cleaning and calibration. During flight, only the black spherical part is outside of the aircraft. Credit: NASA/Kristina Pistone
4STAR installed in the roof of the plane. Yes, it goes through a hole in the plane, but the hole (or lack thereof) is inspected and secured by the crew before each flight. Credit: NASA/Kristina Pistone
4STAR tracking the sun pre-flight, on a rare sunny morning! (Most days were overcast in São Tomé). 4STAR is able to find the location of the sun and adjust itself in real time to always stare at it, which allows us to get measurements even as the plane does complicated maneuvers. Credit: NASA/Kristina Pistone

Of course, despite months and even years of planning and organization, sometimes field work doesn’t go quite as expected. It’s a huge feat to pull off a massive, international, multi-institutional observing campaign, especially when it’s happening on the other side of the world and in a country where the infrastructure, where it even exists, is less well-maintained than we’re used to in the United States. Even with an excellent logistics team (which we had) things can still go wrong: shipments are delayed, the weather doesn’t cooperate, hardware suddenly fails for no apparent reason and then, right as you’ve fixed it, something different breaks. Part of the job is to make things work in the face of unexpected challenges. ORACLES-2017 was no exception. While we’ll be processing and analyzing the data we collected for months to come, there were some notable ordeals.

When I arrived in the second half to relieve my colleagues, the team had already had to deal with several mechanical issues that, while minor, meant that in the name of safety we couldn’t fly on the schedule that was initially planned. The team had to develop a new flight schedule on the fly, so to speak, while still taking into account how the atmospheric conditions changed from day to day so that each flight maximized the amount of data toward our science goals.

Daily morning forecast briefing at the airport. This may have been the day when the power went out for about three hours, but our logistics crew was able to use a backup generator to get us back on the internet so we were still able to communicate with the scientists who were out on the day’s science flight. Credit: NASA/Kristina Pistone

Instruments break. When the aerosol mass spectrometer’s (AMS) instrument power supply died with three flights still remaining, we were able to get the system working again by opening 4STAR’s spare computer and donating its power supply to the other instrument team (known as HiGEAR, since they’re from the University of Hawaii and scientists love acronyms). It ended up being functional if inelegant, due to the slightly different sizes of the two computers.

Not the clearest photo of the AMS, but as you can imagine, the blue tape is not usually present. You can just see how the replacement power supply sticks out the top, too. But it worked! Credit: NASA/Kristina Pistone

On one of our non-flying days we walked to the equator, which ran south of where we were staying (a change from flight days, when we would fly over it on our way to sample clouds). A couple of locals ended up walking along with us and between their limited English and my broken Spanish-inspired Portuguese and a lot of gesturing towards the ORACLES logo on other team members’ t-shirts, I tried to explain what exactly we were doing in their country: why we’re measuring pollution and clouds, why particularly São Tomé is the place we chose to come to measure these conditions, and how understanding the conditions of ORACLES is important to our broader understanding of Earth’s climate.

I’m not sure I got all the way through those points, but I hope it was at least partially intelligible, as part of our job as scientists is to convey to non-scientists why what we do is important. And having conversations with people who otherwise might not be exposed to Earth science is particularly important to me since we all live on the same planet, and as recent events have sadly reminded us, what goes on in Earth’s climate system often has very immediate impacts on people’s lives.

At the equator marker, with one foot in either hemisphere. Credit: NASA

One final note: a lot of us scientists, despite being Earth scientists, were super bummed to miss out on the North American eclipse last month. I think it led to a couple hours of computer screens looking like this:

Credit: NASA

But did you know that São Tomé and Príncipe played a role in another scientific eclipse event? It was one of the locations to which scientists traveled in 1919 to make observations during a different total solar eclipse that would then be used to verify Einstein’s theory of general relativity. It’s amazing to think that a hundred years ago there were scientists who probably had to overcome their own field work challenges very near to the places we were staying. Just another reminder of how global an endeavor this thing we call science is.

Up in Smoke (and Clouds) over the Southeast Atlantic

Smoke from small-scale burning on the northern side of São Tomé island. Although burning was prevalent across São Tomé, the vast majority of the smoke in our study area originated from the south-central African continent, in countries like Angola and the Democratic Republic of the Congo. Credit: Michael Diamond

by Michael Diamond / SÃO TOMÉ & PRÍNCIPE /

In August, dozens of scientists from across the United States descended on the small island nation of São Tomé and Príncipe. Nestled on the equator off the coast of western central Africa, São Tomé was an ideal location to study the phenomenon we had all gathered to observe: a seasonal plume of smoke from agricultural and forest fires that gets lofted by the prevailing winds from the African continent to over the southeast Atlantic Ocean. As part of the NASA field campaign Observations of Aerosols above Clouds and their Interactions, or ORACLES, our aim was to better understand how all that smoke over the ocean affects the amount of sunlight that gets absorbed in the atmosphere and at Earth’s surface.

Aerosols—small airborne particles, like smoke, desert dust, and sulfates from power plants—affect the amount of energy the southeastern Atlantic Ocean gets from the sun, not only by absorbing and reflecting sunlight directly, but also through its effects on clouds. A large expanse of very bright low clouds covers much of the southeastern Atlantic, very similar to the clouds off the coast of California that create San Francisco’s characteristic fog. Smoke can change the properties of these clouds in various ways, including brightening the clouds by creating lots of small droplets, which, interestingly, make the clouds less likely to drizzle and thus stick around for a longer time. Both of those changes allow the clouds to reflect more sunlight, creating a cooling effect.

As anyone who’s been outside on an overcast day knows, clouds play a major role in regulating the amount of the sun’s energy that gets to Earth’s surface, so any changes in the clouds over the southeast Atlantic and those like them across the globe can have big implications for Earth’s energy balance. It is well-known that the heat-trapping effect of man-made greenhouse gas emissions have led to a net warming over the 20th and early 21st centuries. However, unresolved scientific questions about the potential cooling effects of aerosol-cloud interactions over the past century represent a large fraction of the uncertainty in estimates of how much humans have affected the present-day climate.

Snapshot of the smoke-cloud system over the southeast Atlantic Ocean, taken from the window of the P-3 during the August 24th routine flight. A thick plume of milky-gray smoke overlies a blue ocean surface dotted with puffy white low clouds. Credit: Michael Diamond

For ORACLES, NASA’s P-3 Orion aircraft was our primary transport for measuring the smoke-cloud system. On the P-3 we have a set of instruments that can be broadly separated into two categories: in-situ and remote sensing.

In-situ instruments, like those in the picture collage below, measure things in place through air inlets. For example, we have particle counters that can measure the number and size of smoke particles in a plume, and cloud probes that can measure how much liquid water is in a cloud.

In contrast, remote sensing instruments sense things remotely; that is, they tell us about the properties of clouds and smoke from far away, like how we use a telescope to observe stars. In our case, we use instruments like a radar to look at precipitation and a lidar (a laser that provides information about a what’s between the plane and the ground) to look at the smoke plume’s structure.

Top-left: Mary Kacarab and Amie Dobracki operate in-situ instruments studying the chemical properties and cloud-forming ability of aerosol particles. Top-right: One of the P-3 propellers visible outside an aircraft window. Bottom-right: Cody Winchester and Nikolai Smirnow operate a suite of in-situ instruments to study a variety of smoke properties. Bottom-left: The P-3 post-landing in São Tomé after the August 24 flight. Credit: Michael Diamond

Of course, the in-situ instruments that measure clouds aren’t much use when flying through smoke above the clouds, and when we fly high to get good lidar profiles, we can’t get in-situ smoke measurements. In addition, some of the remote sensing instruments don’t work well when high clouds are present, and the smoke and low clouds aren’t always in the same place from one day to the next. How do we balance all these competing objectives to produce a flight that collects high-quality, usable data? That’s where the forecasting and flight-planning team comes in.

As a graduate student at the University of Washington in Seattle, my role in ORACLES is to look at model forecasts from computer simulations and satellite imagery and then use flight-planning software to create flight plans that will meet our scientific objectives. On what we call routine flights, that mostly means picking altitudes and aircraft maneuvers rather than locations, because for these flights we always stick to the same north-south track to build up statistics that can be used to compare our observations with various computer models.

One example of the choices that have to be made here is whether to do stacked legs, in which we fly over the same location at different heights, or sequential legs, which let us cover more ground because we don’t need to backtrack and instead gives us observations at slightly different locations that might be harder to interpret. A similar choice has to be made when we switch between altitudes: we can ramp down and cover a lot of ground, or do a square spiral and get a vertical profile over the same location.

Time-lapse video of a square spiral maneuver over a relatively uniform field of low clouds during the August 24th routine flight. About 10 minutes elapse in the span of this video. Video credit: Michael Diamond.

The other type of flight we call a flight of opportunity, in which we have more latitude in choosing our flight location to sample interesting features, or to avoid pitfalls like high clouds, that are identified by the models.

We were also able to combine flight plans so that the flights of opportunity could resample air that we observed a day or two earlier. Ideally, to study how the smoke evolves during the course of its journey over the Atlantic, we would be able to follow it as the winds push it westward and downward over a period of days. Unfortunately, this is not at all practical in an aircraft with nine hours’ worth of fuel. Instead, we can run a weather forecast model to predict where the air we sampled during a routine flight will end up in a few days. Then, like an advanced game of connect-the-dots, we can design our next target of opportunity flight to hit the right location and altitude to resample that air to see how it’s evolved.

Example of a resampling flight plan conducted on the August 15th routine flight (dark blue line) and August 17th flight of opportunity (cyan line). The blue gradient lines represent the motion of air parcels first sampled on the 15th (dark blue) and then resampled 2 days later on the 17th (light blue). Black dots represent the location of the air parcels after 1 day. Credit: NOAA Air Resources Laboratory/Michael Diamond

Our August 17 flight of opportunity was a bit special because, rather than return to São Tomé, the P-3 landed on Ascension Island in the middle of the South Atlantic Ocean so we could do some joint flights with a British team studying similar science questions. On the way to Ascension, we planned our track to intersect the new (forecasted) locations of a few different smoke plume air parcels that we sampled on August 15.

Now that the 2017 ORACLES deployment is over, the task ahead of us will be to analyze the data we collected in flights like the August 15-17 resampling mission to produce new scientific insights into this unique smoke-cloud system. Within a year, all of our data will become public at https://espoarchive.nasa.gov/archive/browse/oracles so that other researchers across the country and around the world will be able to contribute their own research and generate new ideas and solutions. The data from last year’s deployment, which took place in September and was based out of Walvis Bay, Namibia, is already available. However, we’re not done with data collection just yet: We’ll be heading back into the southeast Atlantic next year for one last deployment, this time in October to characterize the end of the southern African fire season.

Over the Cloudbow with ORACLES in the South Atlantic

A view from the window of the P-3. A layer of smoke is visible over patchy clouds. This is somewhere over the Atlantic Ocean, quite possibly near the [0˚, 0˚] point, where the Prime Meridian crosses the Equator. Credit: NASA/Kirk Knobelspiesse

by Kirk D. Knobelspiesse / SÃO TOMÉ & PRÍNCIPE /

We can’t build a scale model of planet Earth to study in a laboratory, but we can on a computer. But how do we know a computer model we’ve built is right—or even how to build it in the first place? For atmospheric scientists like myself, the answer is measurements: from satellites, from instruments on the ground, and from airplanes.

This is how I find myself on the small African island of São Tomé, curled up inside the ‘bomb bay’ of a NASA P-3 aircraft pouring liquid nitrogen into a specialized camera called the Research Scanning Polarimeter (RSP). This is a long way from home: I work at the NASA Goddard Space flight center in Greenbelt, Maryland.

The NASA P-3 aircraft on the ground in São Tomé. The Research Scanning Polarimeter (RSP) is located in the “bomb bay,” in the fuselage just forward of the engines. It has a small amount of space for somebody to crawl in and perform instrument maintenance. Credit: NASA/ Kirk Knobelspiesse

So, why São Tomé? We’re pretty close to a phenomenon that beguiles climate models and is difficult to observe by satellites – so we need to fly there instead. It all starts with ocean currents, which bring cold, deep ocean water to the surface (known as upwelling). There’s a strong current off the southwest coast of Africa called the Benguela current. The upwelled water, in turn, causes a low, semi-permanent cloud deck to form at certain times of the year – much like June Gloom in Southern California, for example. From a climate perspective, these clouds can be cooling because they reflect the sun’s energy back to space. What’s unique about where we are is that there is a tremendous amount of biomass burning nearby in sub-Saharan Africa, from both agricultural fires and natural forest fires. The smoke from these fires gets blown west, out over the clouds.

A map of our study area off the western coast of Africa. The image, from the NASA’s Moderate Resolution Imaging Spectroradiometer, or MODIS, instrument on the Terra satellite, shows the persistent marine stratocumulus cloud deck created by cold water from the Benguela current (the black stripes being unobserved segments between orbits). Smoke is visible as a haze over the African continent. São Tomé, Walvis Bay, Namibia (where we were last year) and Ascension Island (where we have flown for overnight stays) roughly bound our region of interest. Credit: NASA

Atmospheric scientists call suspended particulate matter “aerosols”—and smoke is a type of aerosol. When suspended above clouds, aerosols can do a couple of things that impact climate. Most directly, smoke aerosols make the clouds look darker, meaning that less of the sun’s energy is reflected back to space. But the aerosols can also modify cloud properties by serving as seeds for cloud droplet formation, for example, or modifying the temperature of the atmosphere, changing how clouds form.

We know all of these things happen, and we include them in our climate models. The uncertainty boils down to how often they occur, and to what magnitude. The root of the problem is that we don’t have all the measurements we need. Satellites provide a nice snapshot, and many of our colleagues at NASA and elsewhere develop instruments especially devoted to the measurement of clouds and aerosols. They don’t, however, simultaneously measure all of the things we need to know, such as the optical and chemical properties of smoke and its exact location, or smoke in the act of modifying cloud properties.

This is why field campaigns, which make targeted observations to resolve specific scientific questions, are so important. I’m here as part of the ObseRvations of Aerosols above CLouds and their intEractionS (ORACLES) field campaign. (Yes, we love our tortured acronyms.). Last year, we sent two airplanes stuffed to the gills with instruments to Walvis Bay, Namibia, and we flew northwest to our area of interest. This year, we’re flying south and west from São Tomé. We’ll return again next year.

This year we’re working with one aircraft: the NASA P-3. The P-3 is a four-engine turboprop designed as a maritime surveillance aircraft for the US Navy. It is ideal for our purposes because of its endurance, size and ability to fly at very low altitudes. We have a wide variety of instruments on the P-3. Some are in situ, meaning they sample the air as the P-3 flies through a cloud or the aerosols, and they tell us size, chemical composition, and other information specific to the aircraft location. Others are remote sensing instruments, meaning they observe the scene from a distance (usually above). Examples include a downward looking precipitation radar, or a lidar, similar to a radar but using a pulsed laser beam instead of radio waves.

The RSP instrument station inside the P-3 aircraft. Our job in flight is relatively simple: only three switches, a keyboard, and a tiny display to manage. Credit: NASA/Kirk Knobelspiesse

The Research Scanning Polarimeter (RSP) also falls in the remote sensing category. It is a passive scanner, meaning it makes a measurement of light reflected from a location under the aircraft at many different angles. One thing we’re looking at is the cloud bow, which is similar to a rainbow, but involves refraction of light from cloud—not rain—droplets. Precise measurements of the cloudbow can tell us the size of the cloud droplets at the top of a cloud, which in turn indicates the cloud meteorological state, whether or not the aerosols are interacting with the cloud, and so forth. We can also determine optical properties of aerosols above the cloud, but analysis of the data requires lots of computing power and can’t be performed easily in the field. My primary role in ORACLES is to improve this analysis, and along with my colleague, Michal Segal Rozenhaimer, we’re looking into using a type of artificial intelligence to “train” a computer to analyze our data.

This is largely done at home, so here in the field my job is to be one of the team members that ensures the RSP is working properly. This means operating the instrument in flight, participating in creating flight plans, and, yes, periodically pouring liquid nitrogen inside. (The instrument sensors work best when they’re very cold.) So even if the “bomb bay” is cramped and noisy, and I’m quite literally thousands of miles from home, I feel very fortunate to be here and a part of this field campaign.

Drifters that Float and Floats that Sink

A snapshot of scientific floats in the North Atlantic Ocean. Credit: Biogeochemical Argo.

by Denise Lineberry / WOODS HOLE, MASSACHUSETTS /

Each year the world’s largest phytoplankton bloom in the North Atlantic goes through distinct phases. In Fall, the plankton are declining after the summer climax. And there are many factors, such as sunlight, water depth, available nutrients and carbon, that control it. Understanding those processes enables more accurate forecasting of this bloom, and others, for ocean management and assessing ecosystem change.

With those goals in mind, for the third time NASA’s North Atlantic Aerosols and Marine Ecosystems Study, or NAAMES, has set sail.

On August 29, about 60 people—half NAAMES scientists and half crew—boarded the R/V Atlantis to test and strap down instruments before settling into their home away from home for the next month. On August 30, despite the possibility of stormy seas, they departed from Woods Hole, Massachusetts, for the wide open North Atlantic.

Sunset from the R/V Atlantis. Credit: NASA/Aimee Amin

With it being the third deployment, the ship crew has some clear expectations on what they want to find out, some really cool instruments to get the data, and an undeniable sense of humor and comradery that has grown from doing life and science on a ship.

“James can be a bit cranky sometimes,” said Cleo Davie-Martin, a postdoctoral scholar at Oregon State University’s Department of Microbiology. But James isn’t a person, it’s a mass spectrometer that measures, or essentially sniffs out, volatile compounds from plankton that can move into the air.  

Some of the crew jokingly refers to the ship’s main lab as the ‘meat locker’ due to the low temperatures needed to maintain the integrity of samples collected and stored by several groups who study the microbial food web. Scenes there include bundled up scientists among rows of tables with latched down filtration systems, microscopes, imagers, monitors and countless other scientific tools.

Water filters in the main lab of the R/V Atlantis. Credit: NASA/Aimee Amin

The floats used for NAAMES are definitely not your average float. In fact, they sink. But depending on the type of float used and depth they sink to, they return to the surface within two to six hours with data on the vertical structure of the ocean, salinity, pressure, light, chlorophyll, oxygen and more. These important bits of data are key to understanding phytoplankton growth and decline.

Using an Iridium Antenna, the floats can be powered and tracked.

“It’s basically like AT&T for satellites,” said Nils Haëntjens, an oceanography student from the University of Maine, as he began testing and calibrating the floats prior to departure.

Atlantis researchers test and calibrate floats aboard the R/V Atlantis prior to NAAMES deployment. Credit: NASA/Aimee Amin

The Atlantis has planned stations that serve as research pit stops for the crew. Just before and while at each stop, they toss about three drifters out to sea. The drifters do float, but more importantly, they drift.

“Drifters help us to do research, because while we stay in one spot at a station, they can move about 20 miles within four days,” said Peter Gaube, research scientist from the University of Washington’s Applied Physics Laboratory.

Baskets filled with 60 drifters sit on the deck of the R/V Atlantis, waiting to be named, painted and tossed to sea by NAAMES researchers. Credit: NASA/Aimee Amin

While at sea, the Gulf Stream current carries the drifters through eddies like a skier going through moguls. There are 60 drifters aboard Atlantis and the crew will sign up for slots to toss a drifter. But first, they get to name and decorate them with paint.

The drifters track changes in the physics of the water over time, providing a snapshot of water properties back to the ship. And often times, they continue to provide this data long after the ship has returned to port.

The sensors on the drifters serve as tiny breadcrumbs for NASA’s C-130 as it flies over the North Atlantic to eventually fly over the Atlantis. The drifters report current positions that allow the aircraft to measure the same locations as the ship.

From space, satellites play an integral role in measuring what’s over the plane. From 20,000 to 30,000 feet in the air, the aircraft validates down-looking measurements from space. And the Atlantis and its full suite of measurements provide ground, or ocean, truth to aircraft and space measurements.

Other instruments aboard Atlantis study ocean optics, atmospheric aerosols, cloud condensation, dissolved organic carbon, cell characterization, growth rates, species composition and predation, grazing and mortality of plankton.

The combined ship-airborne measurement strategy used by NAAMES makes a critical contribution to the ocean ecosystem scientific record by capturing the full range of scales of the plankton ecosystem.

Stay tuned, as NASA’s C-130 is in St. John’s, Newfoundland, preparing to follow the drifting breadcrumbs for its first of many science flights during the fall 2017 campaign.

In Arctic Tundra, It’s Getting Easy Being Green

A view of tundra and native spruce trees in the valley. Credit: NASA/Katy Mersmann

by Katy Mersmann / DENALI NATIONAL PARK, ALASKA /

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.

In some places, the trail bisects the hill, with large deciduous plant life on one side and tundra on the other. Credit: NASA/Katy Mersmann

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.

Shrubs that grow as tall as a person further down the hill carpet parts of the tundra, waiting to take advantage of slightly warmer temperatures and more available water. Credit: NASA/Katy Mersmann

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.