August 30, 2018, 10:17 PDT

A majestic glacier on a NASA campaign's return to Greenland

by Carol Rasmussen / KULUSUK, GREENLAND

Apusiaajik Glacier near Kulusuk, Greenland. Credit NASA/JPL-Caltech

Apusiaajik Glacier near Kulusuk, Greenland. Credit NASA/JPL-Caltech

“Incredibly majestic.”

After years of intensive research on Greenland’s glaciers, Josh Willis is standing next to one for the first time in his life. Apusiaajik isn’t one of Greenland’s giants — in fact, its name means “little glacier.” But its marbled blue-and-white wall of ice is tall, long and, as Willis says, majestic.

It’s also melting. From time to time there’s a loud cracking noise, and seconds later, a few refrigerator-sized chunks of ice drop into the ocean. You can’t help wondering when a larger chunk will fall, and how much icy water will hit you when it does. It’s natural for glaciers to lose ice this way, though disconcerting when you’re in the neighborhood. But Apusiaajik is like most of Greenland’s glaciers, it’s out of balance — melting faster than it can be replenished by winter snowfall.

Josh Willis, OMG’s principal investigator, on approach by boat to Apusiaajik glacier in Greenland.
Josh Willis, OMG’s principal investigator, on approach by boat to Apusiaajik glacier in Greenland. Credit NASA/JPL-Caltech

We’re visiting the little glacier on a down day for NASA’s Oceans Melting Greenland (OMG) campaign. It’s close to Kulusuk, a tiny village on Greenland’s east coast that happens to have an airport with a 4,000-foot-long gravel runway. That’s too short for a big jet to take off and land. But for OMG’s converted DC-3, the Kulusuk airport is perfectly located for the mission’s survey flights around southeastern Greenland, studying how ocean water is affecting glaciers like Apusiaajik.

OMG is on its third annual campaign out of a planned five. The goal each year is to blanket Greenland’s continental shelf with probes measuring the seawater’s temperature and salinity. This year, the team has already dropped 89 out of 250 probes, starting at the southern tip of Greenland and working up the east coast. Soon it’ll be time to move north to the next base.

Josh Willis after releasing an ocean probe down the white tube, where it drops from the plane into the ocean.
Josh Willis after releasing an ocean probe down the white tube, where it drops from the plane into the ocean. Credit NASA/JPL-Caltech

Halfway through OMG’s expected lifespan, what have scientists learned, and what do they still hope to find out?

“We’re beginning to see the signs of long-term changes on Greenland’s continental shelf — changes that take years to happen,” Willis says. “We’ve never seen that before.” Daily changes in water temperature come and go, but the OMG scientists are finding that glaciers react more strongly to slow changes in water temperature far below the ocean surface.

Greenland’s continental shelf is shallow, averaging about 1,600 feet (500 meters) deep. But it’s gashed by troughs carved by ancient glaciers, which can be two times deeper than that. These troughs are natural conduits for deep water to get up on the shelf, but it’s not an easy passage. Sills and underwater mountains within the troughs impede the flow and create basins.

Willis gestures at the ice-flecked channel flowing past Apusiaajik. “In a couple of weeks, all this water will be way downstream,” he says. “In the troughs and basins on the shelf, that’s not true. They’re almost like tide pools — the water comes in at high tide and stays there till the tide comes back. In those deep basins, instead of twice per day like the tide, it’s more like once per year and sometimes less. And when warm or cold water gets in, it stays for years.” There’s not always enough variation in the seawater from winter or summer for water to get into the basins each year; it may take a change in a large-scale ocean climate pattern, similar to an El Niño event in the Pacific Ocean, to trigger the change.

For the last two years, the North Atlantic has been moving into a naturally cooler climate phase. Willis is eager to see when and how far the cooler water will move up the West Greenland coast, and how long it will last.

Answering those questions will chip away at the big remaining goal of OMG: quantifying how much glacial ice melt will result from any given change in ocean temperature. If water comes onto the continental shelf that’s a degree Celsius warmer than now, how much will the melt rate increase? What about three degrees?

Ice-filled channel in front of Apusiaajik Glacier. The surface ocean layer is much colder than the deep water below. Credit NASA/JPL-Caltech

“One of the advantages of watching a glacier change year after year after year is that you begin to get an idea of what’s driving the change. If it’s the ocean, I think we’ll be able to quantify that with two more years of OMG data,” Willis says.

“That’s what we set out to do. What I’m really excited about is that it’s beginning to happen.”

August 21, 2018, 07:35 PDT

This twilight zone is dark, watery, and yes, also full of intrigue

by Ken Buesseler / NORTHEASTERN PACIFIC OCEAN

Daily migration of marine life to and from the twilight zone to the ocean surface.

Daily migration of marine life to and from the twilight zone to the ocean surface.

"There is a fifth dimension beyond that which is known to man. It is the middle ground between light and shadow. It is an area, which we call, the Twilight Zone."
- Rod Serling

Like many kids growing up in the 1960s, I eagerly anticipated every episode of a black-and-white TV series by Rod Serling, expecting to be surprised, maybe even a little scared, of the mysteries of that fifth dimension he called “The Twilight Zone.” Little did I know that decades later as an oceanographer, I’d find myself at sea with over 60 like-minded scientists on a program specifically targeting the mysteries of another twilight zone—the one in the ocean that lies just below the sunlit surface.

The WHOI EXPORTS team showed off their glow-in-the-dark ocean twilight zone t-shirts prior to departure from Seattle in August.
The WHOI EXPORTS team showed off their glow-in-the-dark ocean twilight zone t-shirts prior to departure from Seattle in August. Credit: WHOI/Ken Buesseler

What motivates us is the need to learn more about the role of the twilight zone and the animals that live there in regulating Earth’s climate. The story of how they do this actually starts at the surface, where microscopic marine algae, or phytoplankton, turn carbon dioxide in the water into organic matter via photosynthesis, much like plants on land.

This organic matter forms the base of the marine food web, which basically means that these microscopic plants serve as food for tiny marine animals called zooplankton, which are eaten by larger marine organisms and so on up to larger animals, like the fish that humans consume. Many of these animals come up from the twilight zone at night, using the cover of darkness to feed in surface waters and then disappear come daybreak. This is, in fact, the largest animal migration on Earth and happens around the globe every day, and we barely know it happens.

Phytoplankton in the form of a diatom chain.
Phytoplankton in the form of a diatom chain. Credit: University of Rhode Island/Stephanie Anderson

But I am getting ahead of myself, because despite how appropriate Rod Serling’s description of the mysteries of “the middle ground between light and shadow” fits with what we are doing out here, peering with our instruments into the dimly lit depths, his TV show is not the origin of the name of a twilight zone in ocean sciences. In fact, at least as far back as 1915, textbooks included discussion of the “decrease in the abundance of life from the sunlit surface layers, through the twilight zone, to the zone of darkness,” as was written in College Physiography.

Getting back to this cruise, most of the carbon either sinks out of the surface ocean directly or is carried by animals back down to the twilight zone in their guts and gets excreted. All of this sinking carbon becomes food for other twilight zone animals, with less and less remaining as you go deeper. This constant rain of organic carbon is known as “marine snow,” which drifts through the twilight zone and into the deep ocean.

Who cares how much organic matter or carbon goes through the twilight zone? Well, if you are an animal living in the twilight zone, that’s your main food supply. As a human concerned with the potential for rising carbon dioxide levels in the atmosphere to disrupt our climate, it’s the quickest way you can get organic carbon to the deep ocean, effectively removing it from contact with the surface ocean and atmosphere for hundreds or thousands of years.

Simply put, without the ocean storing carbon in the deep sea, the levels of carbon dioxide in the atmosphere would be much higher than they are today. And the last time they were this high, Earth was a much different place.

The open top of a neutral-buoyancy sediment trap (NBST) showing the opening through which marine snow drifts and is then collected.
The open top of a neutral-buoyancy sediment trap (NBST) showing the opening through which marine snow drifts and is then collected. Credit: UCSB/David Siegel
WHOI marine chemist Ken Buesseler (right) helps deploy a sediment trap from the research vessel Roger Revelle as part of the EXPORTS program.
WHOI marine chemist Ken Buesseler (right) helps deploy a sediment trap from the research vessel Roger Revelle as part of the EXPORTS program. Credit: UCSB/Alyson Santoro

The tools I used to measure this cascade of particles carrying organic carbon to depth on this voyage include sediment traps—something like a rain gauge that captures in a tube the sinking particles that are slowly settling through the water. A second method my group uses to measure sinking particles takes advantage of a naturally occurring element called thorium-234, which is slightly radioactive and decays with a precise 24.1-day half-life. This clock allows me to calculate very precisely how much carbon is being carried from the surface through the twilight zone.

It’s far too early to share my results from this cruise, but the importance and complexity of these links between twilight zone organisms and climate should not be underestimated. Like snowfall on land, organic carbon transport to the depths varies with the seasons and locations in the oceans, but in ways we cannot predict. And it is important for us in our efforts to better understand how quickly climate will change as we keep adding more carbon dioxide to the atmosphere. This job is so complex that it takes a village out here aboard two research ships, with autonomous vehicles in the water and support teams on land and satellites above. We work together to study these carbon flows and the living organisms in the twilight zone that create what marine biologist and conservationist Rachel Carson called the “most stupendous snowfall on earth.”

I don’t know if there are any episodes of The Twilight Zone to watch out here, but I do know there are many deeper mysteries we hope to unravel about the ocean’s twilight zone.

Ken Buesseler is a senior scientist at the Woods Hole Oceanographic Institution. He has been working for decades on the ocean twilight zone and its impact on Earth’s carbon cycle. He is currently on the R/V Roger Revelle as part of the Export Processes in the Ocean from Remote Sensing (EXPORTS) field campaign.

This piece was originally published on the NASA Earth Expeditions blog.

August 15, 2018, 11:40 PDT

Just sit right back and you'll hear a tale, a tale of a plankton trip

by Dave Siegel / SEATTLE, WASHINGTON

A mixed phytoplankton community. Credit: University of Rhode Island/Stephanie Anderson

A mixed phytoplankton community. Credit: University of Rhode Island/Stephanie Anderson

I am Dave Siegel, a professor of marine science at the University of California, Santa Barbara. I have been working for many years to implement the Export Processes in the Ocean from Remote Sensing (EXPORTS) oceanographic campaign: a coordinated field effort to understand the interactions between life in the sea and Earth’s carbon cycle.

Last Thursday night, I watched “my baby” of a campaign sail away, as the Research Vessel Sally Ride left Pier 91 in Seattle for the northeastern Pacific Ocean.

While I am the science lead for EXPORTS, it’s not just my baby—it is truly a group effort. Two teams of scientists created the EXPORTS science and implementation plans, with a lot of input from the greater oceanographic community. The result is a campaign comprising more than 50 funded NASA and NSF investigators from nearly 30 institutions and many graduate students, postdocs and technicians, all excellently supported by the masters and crews of two Scripps Institution of Oceanography’s research vessels: the R/V Roger Revelle and the R/V Sally Ride.

The R/V Sally Ride, operated by the Scripps Institution of Oceanography, anchored at Pier 91 in Seattle before departing for the northeastern Pacific Ocean on Thursday, Aug. 9.
The R/V Sally Ride, operated by the Scripps Institution of Oceanography, anchored at Pier 91 in Seattle before departing for the northeastern Pacific Ocean on Thursday, Aug. 9. Credit: NASA/Katy Mersmann

EXPORTS aims to develop a predictive understanding of the interactions of life in the sea and Earth’s carbon cycle, which is critical for quantifying the carbon storage capacity of the global ocean. The oceans are Earth’s largest active reservoir, or storage, of carbon and carbon dioxide concentrations in the atmosphere and thus helps regulate our planet’s climate. This predictive understanding of the interactions of ocean life and the carbon cycle is especially important as we are seeing that our ocean ecosystems are changing in response to changes in Earth’s physical climate. To do this we need data to test and validate these satellite-based assessments and numerical model predictions.

We are trying to tackle a super hard problem—one I believe to be a true grand challenge in Earth System Science. Our approach is simply to follow the money. For ocean ecosystems, that currency is the energy stored in phytoplankton carbon from photosynthesis. The production of phytoplankton carbon is nearly balanced by its consumption by animals called zooplankton, which in turn provide the energy for the higher trophic levels of the sea, such as fisheries and charismatic megafauna (whales, seals, sharks, and the like).

A mixed phytoplankton community.
A mixed phytoplankton community. Credit: University of Rhode Island/Stephanie Anderson

The slight imbalance—roughly 10 percent of phytoplankton production globally—drives an export of organic carbon from the well-lit surface ocean into the dimly-lit twilight zone beneath. Within the twilight zone, microbes and animals of all description consume this exported organic carbon, utilizing their energy for metabolism. This export of organic carbon from the upper ocean and their consumption within the twilight zone, along with ocean circulation, shape the carbon storage capacity of the global ocean and frame the two major research questions for EXPORTS.

Constructing a field campaign to identify and quantify the flows of organic carbon through the ocean is, of course, a major challenge. Phytoplankton physiologists need to assess phytoplankton growth rates and responses to perturbations in their required nutrients (nitrogen, phosphate, silica & iron). Zooplankton grazing and the carbon cycle impacts of their daily vertical migration to the sunlit layer of the ocean from the twilight zone need to be assessed.

In the hydro lab aboard the R/V Roger Revelle, sampling tubes will collect water samples at varying ocean depths for analysis.
In the hydro lab aboard the R/V Roger Revelle, sampling tubes will collect water samples at varying ocean depths for analysis. Credit: NASA/Katy Mersmann

Sediment traps that catch the rain of sinking particles measure the flux of sinking carbon as well as make detailed geochemical measurements that test how well our measurements of the individual pathways reflect the large-scale mass budgets needed to build and test satellite and computational models. Optical oceanographers make ocean color measurements that link the EXPORTS datasets to NASA satellite data products. And I feel bad that I left out so many other individual research activities going on, but mentioning each of them would take up another two paragraphs!

For EXPORTS, scientists are deploying robotic explorers, like these from the Applied Physics Lab at the University of Washington. They are traveling with the ships, taking measurements at various depths.
For EXPORTS, scientists are deploying robotic explorers, like these from the Applied Physics Lab at the University of Washington. They are traveling with the ships, taking measurements at various depths. Credit: NASA

The measurements needed to constrain the various food web and export pathways as well as adequately sample the highly variable ocean environment requires technologists that can overcome these challenges. For example, the EXPORTS team includes robotics experts who build, deploy, and analyze data from an array of autonomous underwater vehicles (AUV) that sample ocean properties on time scales ranging from minute to years.

EXPORTS has also taken advantage of recent technological advances such as novel high-throughput microscopes and in situ imaging devices that take individual images of billions of phytoplankton cells as well as zooplankton and other various organic matter. These images are then analyzed using advanced machine learning techniques to provide unique views of the structure of plankton communities.

Advancements are also available from the biomolecular sciences where metagenomic and bioinformatics approaches provide complementary ways to characterize plankton communities and their metabolism. Lastly, several projects include numerical modelers who will use computational approaches to help answer EXPORTS science questions.

The first EXPORTS field deployment will be to Station P (50N 145W) in the Northeast Subarctic Pacific Ocean. Station P (or PAPA) has been sampled and resampled over many decades—from as far back as 1949, when it served as an ocean weather station. Presently, Station P is the terminus of the Canadian Line P transect ocean research program and is an area of focus for the National Science Foundation’s Ocean Observatories Initiative project.

Last week, the R/V Roger Revelle and the R/V Sally Ride sailed to Station P. Both are floating laboratories that enable our research, but they will have different missions. The R/V Roger Revelle will make detailed rate measurements and conduct a wide variety of experiments while the R/V Sally Ridewill make spatial surveys around its partner ship to assess the three-dimensionality of these processes. These ship-based measurements will be supplemented by the array of AUVs. Both ships and robots will make ocean optical measurements linking the EXPORTS field data to present and future NASA ocean color satellite missions.

Graphic representation of the Northeastern Pacific Ocean deployment for EXPORTS.
Graphic representation of the Northeastern Pacific Ocean deployment for EXPORTS.

EXPORTS is also planning a second field deployment in the North Atlantic Ocean in the spring of 2020 to provide contrasting data. Furthermore, NASA has supported a group of Pre-EXPORTS projects aimed at mining available, relevant data sources for use in EXPORTS synthesis analyses and to conduct modeling experiments to help plan this and the North Atlantic expeditions.

So I’m the science lead but I’m not sailing. Seems weird, but early in our planning we were worried about the coordination between all of the things going on. My job back home now is to help coordinate activities on the two ships and assist the four co-chief scientists in fouling off whatever curveballs that may come. I’m sure they will provide blog posts soon introducing themselves.

It is been a long time coming and I realized that as the R/V Sally Ride was sailing away. I have been there from the start pushing this along, so I suppose it is “my baby.” I do want to thank all involved in the planning and implementation, including the program officers at NASA and NSF.

Further information about EXPORTS can be found at the NASA EXPORTS expedition team blog and the EXPORTS website.

This piece was originally published on the NASA Earth Expeditions blog.

August 8, 2018, 07:08 PDT

Students study Earth systems on NASA's DC-8 flying laboratory

by Arie Feltman-Frank / NASA ARMSTRONG FLIGHT RESEARCH CENTER, PALMDALE, CALIFORNIA

Student Airborne Research Program (SARP) participant Arie Feltman-Frank aboard the DC-8 monitoring air pollution on June 25, 2018. Credit: NASA/Megan Schill

Student Airborne Research Program (SARP) participant Arie Feltman-Frank aboard the DC-8 monitoring air pollution on June 25, 2018. Credit: NASA/Megan Schill

My name is Arie and I am a 21-year-old student at the University of Denver studying environmental science. I am one of 28 students selected to participate in NASA’s Student Airborne Research Program, or SARP, an eight-week summer internship program that exposes undergraduate students to all aspects of airborne science campaigns, including data collection techniques and data analysis. Students from diverse STEM backgrounds were placed into four research groups—atmospheric chemistry, ocean remote sensing, land remote sensing, and whole air sampling—and they must complete and present a research project by the end of the summer.

I grew up in Lincolnshire, Illinois, and since a young age I have been fascinated by the scientific processes that influence our planet. I believe that every human has the right to live a meaningful and purposeful life predicated on the existence of certain universal guarantees, such as clean air to breathe, safe food and water to eat and drink, and preserved natural areas. Those values align with SARP and almost all other NASA Earth Science campaigns, as their main objective is to collect accurate and high-quality data about the land, ocean, and atmospheric properties of Earth to understand how our world is changing.

SARP participants, pilots, and flight specialists after their third and longest flight on the DC-8 on June 26, 2018. Credit: NASA/Megan Schill
SARP participants, pilots, and flight specialists after their third and longest flight on the DC-8 on June 26, 2018. Credit: NASA/Megan Schill

For this campaign, we were seated in NASA’s DC-8 flying laboratory, a unique plane with scientific instruments protruding from the windows. NASA’s DC-8 is not like any traditional commercial airline flight. It was once a commercial airliner but was repurposed by NASA’s Earth Science Division and is now one of the best research aircraft in the world for conducting airborne science. Prior to my flight, the aircraft completed flights for NASA’s Atmospheric Tomography Mission (ATom), an around-the-world airborne science campaign dedicated to studying the impact of human-produced air pollution on greenhouse gases and on chemically reactive gases in the atmosphere.

On this particular flight, we had instruments that measured the presence and relative concentrations of important atmospheric gases over regions in southern and central California, including the San Joaquin Valley. I could hear the faint crescendo of the aircraft’s engine and full-blast air conditioning system through my noise-canceling headphones. The scientists, flight engineers, and pilot talked over the on-board communication system. I listened intently to the scientists as they updated the crew on their instruments.

SARP participants Sujay Rajkumar and Kiersten Johnson on board the DC-8 operating Whole Air Sampling instrumentduring a science flight on June 26, 2018. Credit: NASA/Megan Schill
SARP participants Sujay Rajkumar and Kiersten Johnson on board the DC-8 operating Whole Air Sampling instrumentduring a science flight on June 26, 2018. Credit: NASA/Megan Schill

The aircraft flight path and maneuvers depend on the goals of a particular scientific mission. On this six-hour flight, we undertook spirals, loops, and Meteorological Measurement System (MMS) maneuvers, which are important for understanding the aerodynamics of the aircraft and its effects on measurements such as pressure, winds, and air flow. We also flew in turbulent conditions at various elevations and over diverse environmental gradients.

Student Airborne Research Program (SARP) participant Dallas McKinney, a meteorology major at Western Kentucky University, aboard the DC-8 experiencing the cockpit during a June 26, 2018 science flight. Credit: NASA/Megan Schill
Student Airborne Research Program (SARP) participant Dallas McKinney, a meteorology major at Western Kentucky University, aboard the DC-8 experiencing the cockpit during a June 26, 2018 science flight. Credit: NASA/Megan Schill

That being said, it may come as no surprise that my DC-8 flight was as turbulent as it was long; I actually ended up getting pretty motion sick on the mission. Getting sick is a sacrifice some make to collect the necessary data. Despite not feeling well, I was surrounded by passionate students, scientists, engineers, and flight specialists all cumulatively working to advance one of NASA’s core missions: to understand and protect our home planet.

I am excited to see all of the diverse and interesting projects that SARP 2018 will embark and present on at the end of the summer. I couldn’t ask to be in a better place or time here at NASA working with and be mentored by some of the best minds in the field.

This piece was originally published on NASA's Earth Expeditions blog.

July 11, 2018, 12:18 PDT

Glory of the pilot

By Kathryn Hansen,
NASA's Earth Observatory

Glory of the pilot

Earlier this month, we showed a space-based view of a glory—a colorful, circular optical phenomenon caused by water droplets scattering light. The Moderate Resolution Imaging Spectroradiometer on the Terra and Aqua satellites can see only a cross section of the glory, making it appear in satellite imagery as two elongated bands parallel to the path of the satellite.

To the Earth-bound observer, however, glories take on a circular shape. You might have seen one while on an aircraft. From this perspective, passengers on the side of the plane directly opposite the Sun can sometimes see the plane’s shadow on the clouds below. This position is also where glories can be observed as the cloud’s water droplets scatter sunlight back toward a source of light.

Before aviation, the phenomenon was often seen by mountain climbers; the glory encircling the climber’s shadow on the clouds below. Today, pilots and passengers have a good chance of seeing them, earning the phenomenon the name “glory of the pilot” or “pilot’s halo.”

But you still have to be flying close enough to the cloud deck for the phenomenon to be visible, which is one of the reasons why they are frequently spotted by scientists and crew with NASA’s Operation IceBridge mission. The mission makes annual flights over Earth’s poles to map the ice; flights are relatively low, long, and frequent. Glories are not part of the mission’s science goals—in fact, clouds can interfere with the collection of science data. But they are on the list of natural wonders that IceBridge scientists witness in the field.

Jeremy Harbeck, a sea ice scientist at NASA’s Goddard Space Flight Center, snapped the top photograph of a glory on April 18, 2018, during an IceBridge science flight over the Chukchi Sea. (See the full image and other photographs shot by Harbeck during the Arctic 2018 IceBridge campaign here.)

“I remember having taken more images of glories, especially down over Antarctica, as we see them quite often down there,” Harbeck said. “From what I remember, they’re not outside the window all the time, but you can catch them here and there on flights when conditions are right.”

An Antarctic glory as seen from an Operation IceBridge flight

One such Antarctic glory is visible in the image above, snapped by Michael Studinger during an IceBridge flight on October 26, 2010. Read more about that image here.

This piece was originally published on the NASA Earth Observatory Earth Matters blog.

May 17, 2018, 07:29 PDT

Making a map of water and ice

By Ellen Gray,
NASA's Earth Science News Team

Hydrologist Matt Rodell at NASA's Goddard Spaceflight Center has been living with first-of-its-kind data from the Gravity Recovery and Climate Experiment (GRACE) for 16 years. That data shows big changes of mass in specific spots on Earth, primarily the result of the movement of water and ice, but it doesn’t tell them what causes those changes. That's where Matt and the GRACE team come in, painstakingly connecting these observed changes to the loss of ice sheets, depleting aquifers, and climate change. It's a problem they're still working on, getting closer every day. Matt explains the years-long process in his own words.

Matt Rodell
Matt Rodell is Chief of the Hydrological Sciences lab at NASA’s Goddard Space Flight Center in Greenbelt Maryland. Credit: Matt Rodell

Ominous beginning: Garbage data from a new satellite

Six months after GRACE launched in March 2002, we got our first look at the data fields. They had these big vertical, pole-to-pole stripes that obscured everything. We’re like, holy cow this is garbage. All this work and it’s going to be useless. But it didn’t take the science team long to realize that they could use some pretty common data filters to remove the noise, and after that they were able to clean up the fields and we could see quite a bit more of the signal. We definitely breathed a sigh of relief. Steadily over the course of the mission, the science team became better and better at processing the data, removing errors, and some of the features came into focus. Then it became clear that we could do useful things with it.

Steenstrup Glacier
In 2016, NASA’s Operation IceBridge took this picture of Greenland's Steenstrup Glacier. Credit: NASA/John Sonntag

And then trends emerged

It only took a couple of years. By 2004, 2005, the science team working on mass changes in the Arctic and Antarctic could see the ice sheet depletion of Greenland and Antarctica. We’d never been able before to get the total mass change of ice being lost. It was always the elevation changes – there’s this much ice, we guess – but this was like wow, this is the real number.

Not long after that we started to see, maybe, that there were some trends on the land, although it’s a little harder on the land because with terrestrial water storage — the groundwater, soil moisture, snow and everything – there’s inter-annual variability, so if you go from a drought one year to wet a couple years later, it will look like you’re gaining all this water, but really, it’s just natural variability.

But by around 2006, there was a pretty clear trend over Northern India. At the GRACE science team meeting, it turned out another group had noticed that as well. We were friendly with them, so we decided to work on it separately. Our research ended up being published in 2009, a couple years after the trends had started to become apparent. By the time we looked at India, we knew that there were other trends around the world. Slowly not just our team but all sorts of teams, all different scientists around the world, were looking at different apparent trends and diagnosing them and trying to decide if they were real and what was causing them.

Global freshwater map from 14 years of GRACE data
This map depicts a time series of data collected by NASA's Gravity Recovery and Climate Experiment (GRACE) mission from 2002 to 2016, showing where freshwater storage was higher (blue) or lower (red) than the average for the 14-year study period. Credit: NASA

A world of big blobs of red and blue

I think the map, the global trends map, is the key. By 2010 we were getting the broad-brush outline, and I wanted to tell a story about what is happening in that map. For me the easiest way was to just look at the data around the continents and talk about the major blobs of red or blue that you see and explain each one of them and not worry about what country it’s in or placing it in a climate region or whatever. We can just draw an outline around these big blobs. Water is being gained or lost. The possible explanations are not that difficult to understand. It’s just trying to figure out which one is right.

Not everywhere you see as red or blue on the map is a real trend. It could be natural variability in part of the cycle where freshwater is increasing or decreasing. But some of the blobs were real trends. If it’s lined up in a place where we know that there’s a lot of agriculture, that they’re using a lot of water for irrigation, there’s a good chance it’s a decreasing trend that’s caused by human-induced groundwater depletion.

And then, there's the question: are any of the changes related to climate change? There have been predictions of precipitation changes, that they’re going to get more precipitation in the high latitudes and more precipitation as rain as opposed to snow. Sometimes people say that the wet get wetter and the dry get dryer. That’s not always the case, but we’ve been looking for that sort of thing. These are large-scale features that are observed by a relatively new satellite system and we’re lucky enough to be some of the first to try and explain them.

Matt Rodell
Credit: NASA

What kept me up at night

The past couple years when I’d been working the most intensely on the map, the best parts of my time in the office were when I was working on it. Because I’m a lab chief, I spend about half my time on managerial and administrative things. But I love being able to do the science, and in particular this, looking at the GRACE data, trying to diagnose what’s happening, has been very enjoyable and fulfilling. We've been scrutinizing this map going on eight, nine years now, and I really do have a strong connection to it.

What kept me up at night was finding the right explanations and the evidence to support our hypotheses – or evidence to say that this hypothesis is wrong and we need to consider something else. In some cases, you have a strong feeling you know what’s happening but there’s no published paper or data that supports it. Or maybe there is anecdotal evidence or a map that corroborates what you think but is not enough to quantify it. So being able to come up with defendable explanations is what kept me up at night. I knew the reviewers, rightly, couldn’t let us just go and be completely speculative. We have to back up everything we say.

A view of California taken in 2014, showing impacts of drought season on the state.
A view of California taken in 2014, showing impacts of drought season on the state. Credit: NASA Earth Observatory

A tangled mix of answers

The world is a complicated place. I think it helped, in the end, that we categorized these changes as natural variability or as a direct human impact or a climate change related impact. But then there can be a mix of those – any of those three can be combined, and when they’re combined, that’s when it’s more difficult to disentangle them and say this one is dominant or whatever. It’s often not obvious. Because these are moving parts and particularly with the natural variability, you know it’s going to take another 15 years, probably the length of the GRACE Follow-On mission, before we become completely confident about some of these. So it’ll be interesting to return to this in 15 years and see which ones we got right and which ones we got wrong.

You can read about Matt’s research here: https://go.nasa.gov/2L7LXoP.

May 9, 2018, 17:38 PDT

Cloudy with a chance of chemistry

By Ellen Gray

The Atmospheric Tomography, or ATom, mission is investigating the atmosphere above the remote oceans. Above the Atlantic ocean near Ascension Island, the research team saw haze from African fires during ATom’s February, 2017, flight. Credit: NASA

The Atmospheric Tomography, or ATom, mission is investigating the atmosphere above the remote oceans. Above the Atlantic ocean near Ascension Island, the research team saw haze from African fires during ATom’s February, 2017, flight. Credit: NASA

The most important question at the daily briefing for NASA’s Atmospheric Tomography, or ATom, mission is: What are we flying through next?

For the 30 scientists plus aircraft crew loaded up on NASA’s DC-8 flying research laboratory on a 10-flight journey around the world to survey the gases and particles in the atmosphere, knowing what’s ahead isn’t just about avoiding turbulence. It’s also about collecting the best data they can as they travel from the Arctic to the tropics then to the Antarctic and back again.

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ATom’s flight path over the oceans. Credit: NASA

“ATom is all about the up and downs,” said Paul Newman, lead of the ATom science team and chief scientist for Earth Sciences at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The ups and downs he’s referring to are slow descents from 40,000 feet to 500 feet above the ocean so the researchers aboard can sample the atmosphere at all altitudes in between. That’s not a maneuver the pilots will do if they can’t see what’s below or ahead of them, but the measurements are why the team is out there.

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The DC-8 makes a series of dips to the surface during each leg of the flight to sample air at all altitudes. Credit: NASA

Which is why to find out what they might encounter and safely plan their flight path, it takes a team back home in their offices supporting them with freshly downloaded satellite data, updating forecasting models, an internet connection and phone. The pre-flight briefing takes place at 9 a.m. where the plane is, so for the forecasters calling in from Colorado, Virginia, and Maryland, it often means working late or early to brief the mission scientists and pilots at their hotel. And then when the flight takes off, one of them is in the plane’s private satellite chat room giving them live updates while the plane is in the air.

Weather is of course the big concern. The pilots of the DC-8, which in another life was a mid-sized passenger plane, need to know where the fair and foul weather is.

“Just cutting across the equator, what do you do?” Newman said. “You just fly through those thunderstorms? Or is it better to go west or east around a particular convective cell? You don’t want to get trapped. We don’t want to spend a lot of time flying through a thick cloud. It screws up your measurements, clogs up your air intakes. So with real-time meteorological support, it creates a level of comfort for the team and pilots to know that there won’t be any surprises.”

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View from the DC-8 above the Pacific Ocean, Feb. 2017. Credit: NASA/Róisín Commane

Weather isn’t the only forecast the team gets before and during the flight. They also get a forecast of the atmospheric chemistry. From supercomputers at Goddard, a computer simulation of Earth projects the paths of carbon monoxide plumes. Carbon monoxide is one of over 400 gases being measured aboard the DC-8, but since it’s the result of incomplete combustion, whether from cars, power plants, wild fires or agricultural fires, it’s one of the simplest for the computer to track. Like a weather forecast, the chemical forecast takes current satellite data of carbon monoxide and then uses winds and temperature to project where it will go into the future – and where the DC-8 aircraft might encounter it on flight day.

“It’s fun to see during the flight whether or not some of these forecasts are realized,” said Julie Nicely of the chemical forecast team. “The person who measures carbon monoxide, for instance, might get on the chat and say, ‘Oh, we just saw CO [carbon monoxide] rise right where you said it would!'” Where turns out to be the easier question to answer. How much of it there is and what other gases occur with and react with it to turn into other gases are much more difficult questions and are among the reasons ATom’s science team is flying through these plumes of pollution.

Carbon monoxide isn’t the only gas whose intermingling with other atmospheric chemistry is being studied. When Nicely’s not supporting ATom she’s researching the hydroxyl radical, a chemical that lasts for a fraction of a second before reacting with other gases in the constantly churning chemistry of the atmosphere. It’s impossible to simulate in the model at the moment, and ATom’s flights are the first time its concentration, along with hundreds of other gases, is being measured on a global scale.

What the science team learns from these flights will go toward not only understanding the chemistry along the strip of the ocean their plane flew over but also improving the atmospheric chemistry models that are a tool for looking at what’s happening across the entire globe.

This piece was originally published on the NASA Earth Expeditions blog.

May 7, 2018, 13:26 PDT

Spring has sprung in the Arctic Ocean

By Kathryn Hansen,
NASA's Earth Observatory

Spring has sprung in the Arctic Ocean

With springtime comes sunlight and warmth that advance the melting and breakup of Arctic sea ice. Varied patterns and textures appear across the icescape, and many are visible in this image, which was our Image of the Day on April 30. This satellite image includes the area photographed a day earlier by Operation IceBridge—the same photograph that sparked discussion on our blog and on news and social media about what might have caused the holes in the ice.

The holes were not a research focus of the mission; scientists were flying that day to measure the thickness of sea ice. Rather, as some scientists explain below, the holes were simply a sign of spring, and just one of the many interesting and photogenic sights seen from the aircraft in 10 years of research flights over the Arctic.

Nathan Kurtz, IceBridge project scientist

“The main purpose of these IceBridge flights is to measure the thickness of the sea ice. Ice thickness is an important factor which allows us to assess the health of the pack and its ability to survive the summer melt. It is also an important regulator in the exchange of energy and moisture between the ocean and the atmosphere.

“While on the flights, I’ll stare out the windows for hours looking at the surface. The movement of the ice leads to huge variability over small scales, with many interesting scenes and patterns visible and a variety of color shades. But there’s only so much that can be discerned with human eyes. That is why we have the sensitive instrument suite on the plane: to map the intricacies of the ice cover which may otherwise be invisible to us and to quantify parameters for scientific interpretation.”

Chris Shuman, UMBC glaciologist based at NASA’s Goddard Space Flight Center

“Well back into March, satellites show a whole series of relatively clear images over Mackenzie Bay, indicating lots of sunshine coming in. The ‘holes’ in the sea ice are just a sign of spring, augmented by some particular process—’submarine groundwater discharge,’ large mammals, algae growth, brine pockets draining, or something else entirely. Attributing any particular area of open water to a particular process is speculation. There is always a lot going on in the spring sea ice pack of the Beaufort Sea.”

John Sonntag, IceBridge mission scientist

“As scientists, we have the privilege of witnessing the beauty and mystery of the cryosphere firsthand, even as we work to collect that data. The Beaufort 'ice circles' were among those. We have heard a number of plausible explanations for those fascinating features. In a more personal sense, I have been genuinely gratified to see the high level of interest from the public in the ice circles. The public’s clear enthusiasm for the puzzles of nature matches my own. It’s why I like my job!”

This piece was originally published on the NASA Earth Observatory Earth Matters blog.

May 1, 2018, 13:28 PDT

Team Sea Ice or Team Land Ice?

By Linette Boisvert, Kangerlussuaq, Greenland 

Above Greenland, where land ice meets sea ice and some open water. Credit: NASA/Linette Boisvert

Above Greenland, where land ice meets sea ice and some open water. Credit: NASA/Linette Boisvert

Linette Boisvert is a sea ice scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland, and researcher with Operation IceBridge. The mission of Operation IceBridge, NASA’s longest-running airborne mission to monitor polar ice, is to collect data on changing polar land and sea ice and maintain continuity of measurements between ICESat missions.

For more about Operation IceBridge and to follow future campaigns, visit http://www.nasa.gov/icebridge.

I am lucky enough to get to travel to Kangerlussuaq—a small town on the southwestern coast of Greenland that means “big fjord” in the Kalaallisut language—to join NASA’s Operation IceBridge for the remainder of their Arctic spring campaign.

I landed in Kanger on the morning of Friday, April 20, after leaving Washington, D.C., Wednesday evening, flying and overnighting in Copenhagen, Denmark, and then taking an Air Greenland flight, crossing the Atlantic Ocean twice in less than 36 hours. (Fun Fact: Greenland is owned by Denmark, so flying through Copenhagen is the only way to get to Greenland commercially.) The flight was on an Airbus, which had a surprisingly large number of passengers aboard.

After landing I thought, hmm, why do all of these people want to go to Kanger? Kanger is a small, roughly 500-person town comprising buildings surrounding the airport. There is a grocery store, a coffee/ice cream shop that never appears to be open, a youth “jail” for all of Greenland, and a Thai restaurant that is known for its pizza. Odd.

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View of the town of Kanger from across the river. Credit: NASA/Linette Boisvert

Regardless, Kanger is pretty, being situated in the fjord valley with a river running through it, although currently it is frozen solid. It is also warmer here than I would have expected for Greenland, with highs in the upper 20’s to low 30’s. For the rest of the campaign, until May 4, I will be in Kanger, with the rest of my “OIB family,” as I call them, living in dorm-style housing and cooking family-style dinners together just about each night.

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Build your own pizza for dinner in our dorm-style housing in Kanger. Credit: NASA/Linette Boisvert

April 21 was our first science flight out of Kanger, and as with the rest of the flights from here, it was a land ice flight. Sidebar: I am a sea ice scientist and have never been on a land ice flight before. There is a friendly rivalry between the land ice and sea ice scientist community (go Team Sea Ice!), and it is clear here that I am the only sea ice fanatic aboard, so I get picked on a bit. For those of you who don’t know, sea ice is frozen seawater that floats around on the ocean, and land ice is snow that is compacted over many, many years and turns into ice and is located on the bedrock of Greenland. Sea ice = salty (good in a margarita), while land ice = fresh (good in a smoothie).

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NASA P-3 aircraft propellers outside the hangar in Kangerlussuaq, Greenland. Credit: NASA/Linette Boisvert
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Photo showing land ice (bottom left corner) flowing down through the channel in the (center), and sea ice (bottom right corner). Credit: NASA/Linette Boisvert

It is not surprising to say that they really wanted to convert me to Team Land Ice, and they couldn’t have chosen a more scenic flight for this attempt. The flight is named Geikie 02 and highlights eight glaciers on the Geikie Peninsula on the eastern coast of Greenland.

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Screen shot of the “Geikie 02” flight line mid-flight. Credit: NASA/Linette Boisvert

Glaciers are slow-moving rivers of ice, where land ice from the Greenland Ice Sheet is transported into the oceans or sea ice pack depending on location and time of year. As the ice gets forced into these channels and around bends, it cracks, making crevasses, similar looking to crocodile skin (or the skin on your elbow) at times.

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Crevassed land ice in the foreground and Greenland mountains behind. Photo credit: NASA/Linette Boisvert

These glaciers have carved out deep channels and fjords in the bedrock over time, making for awe-inspiring views and terrain, especially when you are flying in the P-3 plane at just 1500 feet. There were many times where I would look out the window and see mountains reaching high above us as we flew over the glaciers deep in the fjord valleys and other times where it felt as it we were just skimming the tops of the mountains. This is not something that normally happens on commercial airline flights and is not for the faint of heart, but it is spectacular to behold, and I felt truly lucky to be able to witness this magnificent place.

As we flew out of the fjord to where both land ice and land meets sea, I instantly became overjoyed to view the sea ice (go Team Sea Ice!): all thicknesses, broken up, ridged, consolidated and flooded along with numerous leads and icebergs, which are land ice deposited into the ocean from the glaciers. Sea ice on a land ice flight? I think I could get used to this.

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An iceberg surrounded by sea ice. Credit: NASA/Linette Boisvert
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Sea ice floes, openings, and leads. Photo credit: NASA/Linette Boisvert
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Where sea ice meets Greenland’s cliffs and mountains. Credit: NASA/Linette Boisvert

As we crossed the fjords and the sea ice, we noticed multiple polar bear tracks in the snow (likened to a “polar bear highway”), and multiple holes in the sea ice where seals will come out for air and rest. A few people even claimed they saw a polar bear running on the sea ice after being startled by our plane flying over, but I didn’t see it and I am skeptical. Another highlight of this flight was flying past Greenland’s tallest mountain, Gunnbjorn, which rises 12,000 feet, and the “Grand Canyon of Greenland” – the one not covered by kilometers of ice in the center of the ice sheet that data from a previous IceBridge campaign had recently discovered. Needless to say, I was glued to my window for the majority of this flight. These pictures just don’t do them justice.

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Flying in a fjord valley with the mountains above us. Credit: NASA/Linette Boisvert

Although this flight did not convert me to Team Land Ice, it did reiterate to me that all ice types matter, especially in the broader context of climate change, and it is the main reason for the IceBridge field campaign: to repeatedly gather data of both land and sea ice to determine where, how, and why both ice types are changing. Specifically, melting land ice flows into the ocean and contributes to global sea level rise, whereas the loss of sea ice affects ocean and atmospheric circulation patterns both locally and globally, reminding us that what happens in the Arctic doesn’t stay in the Arctic.

This piece was originally published on the NASA Earth Expeditions blog.

April 26, 2018, 07:49 PDT

See fifteen years of change in the Arctic

By Adam Voiland,
NASA's Earth Observatory

Remember the year 2000? Bill Clinton was president of the United States, Faith Hill and Santana topped Billboard music charts, and the world’s computers had just “survived” the Y2K bug. It also was the year that NASA’s Terra satellite began collecting images of Earth.

Eighteen years later, the versatile satellite — with five scientific sensors —is still operating. For all of that time, the satellite’s Moderate Resolution Imaging Spectroradiometer (MODIS) has been collecting daily data and imagery of the Arctic — and the rest of the planet, too.

If you knew where to look and were willing to wait patiently for file downloads, the images have always been available on specialized websites used by scientists. But there was no quick-and-easy way for the public to browse the imagery. With the recent addition of the full record of MODIS data into NASA’s Worldview browser, checking on what was happening anywhere in the world on any day since 2000 has gotten much easier.

Say you want to check on the weather in your hometown on the day you or your child was born. Just navigate to the date on Worldview, and make sure that the MODIS data layer is turned on. (In the image below, you can tell the Terra MODIS data layer is on because it is light gray.)

Worldview screenshot of first day Terra MODIS data were collected
This Worldview screenshot shows the first day that Terra MODIS collected data — February 24, 2000. The very first Terra scene showed northern Argentina and Chile. Credit: EOSDIS.

One of the things I love about having all this MODIS data at my fingertips is that it makes it possible to see the passage of relatively long periods of time in just a few minutes. Look, for instance, at the animation at the top of this page, generated by Delft University of Technology ice scientist Stef Lhermitte using Worldview.

Lhermitte summoned every natural-color MODIS image of the Arctic that Terra and Aqua (which also has a MODIS instrument) have collected since April 2003. The result — a product of 71,000 satellite overpasses — is a remarkable six-minute time capsule of swirling clouds, bursts of wildfire smoke, the comings and goings of snow, and the ebb and flow of sea ice.

Though beautiful, Lhermitte’s animation also has a troubling side to it. If you look carefully, you can see the downward trend in sea ice extent. Look, for instance, at mid-August and September 2012 — the period when Arctic sea ice extent hit a record-low minimum of 3.4 million square kilometers (1.3 million square miles). Between the heavy cloud cover, you will see lots of dark open water. Compare that to the same period in 2003, when the minimum extent was 6.2 million square kilometers (2.4 million square miles). Scientists attribute the loss of sea ice to global warming.

Arctic sea ice extent
NASA Earth Observatory chart by Joshua Stevens, using data from the National Snow and Ice Data Center.

Earth Matters had a conversation with Lhermitte to find why he made the clip and what stands out about it. MODIS images of notable events that Lhermitte mentioned are interspersed throughout the interview. All of the images come from the archives of NASA Earth Observatory, a website that was founded in 1999 in conjunction with the launch of Terra.

What prompted you to create this animation?

The extension of the MODIS record back to the beginning of the mission in the Worldview website triggered me to make the animation. As a remote sensing scientist, I often use Worldview to put things into context (e.g. for studying changes over ice sheets and glaciers). Previously, Worldview only had data until 2010.

What do you think are the most interesting events or patterns visible in the clip?

I think the strength of the video is that it contains so many of them, and it allows you to see them all in one video. The ones that are most striking to me are:

Barents Sea algal bloom
An Aqua MODIS image of an algal bloom in the Barents Sea on August 14, 2011. Image by Jeff Schmaltz, MODIS Rapid Response Team at NASA's Goddard Space Flight Center.
  • algal blooms in the Barents Sea
  • declining sea ice extent. You can see this both annually and over the longer term.
  • changing snow extent. You can see this each summer, especially over Canada and Siberia.
  • summer wildfire smoke in Canada (2004, 2005, 2009, 2014, 2017) and Russia (2006, 2011, 2012, 2013, 2014, 2016)
  • albedo reductions (reduction in brightness) over the Greenland Ice Sheet in 2010 and 2012 related to strong melt years.
  • overall eastward atmospheric circulation
  • the Grímsvötn ash plume (21 May 2011)

How did you make it? Was it difficult from a technical standpoint?

It was simple. I just downloaded the MODIS quicklook data from the Worldview archive using an automated script. Afterwards, I slightly modified the images for visualization purposes (e.g., overlaying country borders, clipping to a circular area). and stitched everything together in a video.

When you sit back and watch the whole video, how does it make you feel?

On the one hand, I am fascinated by the beauty and complexity of our planet. On the other hand, as a scientist, it makes me want to understand its processes even better. The video shows so many different processes at different scales, from natural processes (annual changes in snow cover and the Vatnajökull ash plume) to climate change related changes (e.g. the long term decrease in sea ice).

Grímsvötn Volcano eruption
Terra MODIS image of the eruption of Grímsvötn Volcano in Iceland on May 22, 2011. NASA image by Jeff Schmaltz, MODIS Rapid Response Team.

There are some gaps during the winter where the extent of the sea ice abruptly changes. Can you explain why?

I used the standard reflectance products, which show the reflected sunlight. I decided to leave all dates out where part of the Arctic is without sunlight during satellite overpasses (approximately 10:30 a.m. and 1:30 p.m. local time). The missing data due to the polar night are very prominent if you compile the complete record including winter months, and I did not want it to distract the viewer from the more subtle changes in the video.

Siberia smoke and fires
A Terra MODIS image of smoke and fires in Siberia on June 29, 2012. NASA image by Jeff Schmaltz, LANCE MODIS Rapid Response.

In the course of your day job as a scientist, do you use MODIS imagery? For what purpose?

Yes, as a polar remote sensing scientist, I tend to work with a range of satellite data sets. MODIS is a unique data product, given its global daily coverage and its long record. Besides the fact that I use MODIS frequently to monitor ice shelves and outlet glaciers, my colleagues and I use it to study snow and ice-albedo processes, snow cover in mountainous areas, vegetation recovery after wildfires, and ecosystem processes. One MODIS animation of ice calving from a glacier in Antarctica actually made it into the Washington Post recently.

This piece was originally published on the NASA Earth Observatory Earth Matters blog.