Decoding the Mysteries of the Ross Ice Shelf

Antarctica’s Ross Ice Shelf covers an area the size of France and measures a few hundred meters thick above the water. It plays a critical role in stabilizing the West Antarctic Ice Sheet, and scientists are concerned about its future in a warming world. In the field, a team of scientists from Lamont-Doherty Earth Observatory, Scripps Institution of Oceanography and the U.S. Geological Survey is flying over the Ross Ice Sheet, using the IcePod—an assemblage of radars and other instruments bolted to the fuselage of a C-130—to study how the ice, ocean and underlying land interact. They call it the Rosetta project, named after the enigmatic stone containing a script in three languages that led to the decoding of an ancient language. Back at home, they are joined by geologists from Colorado College and oceanographers from ESR to work through the data.

 

Posted By: Guest Blogger on November 16, 2017
By Julian Spergel
Antarctic Ice showing crevassing along the edges of flow. photo J. Spergle

Antarctic Ice showing crevassing along the edges of flow. photo J. Spergel

As we prepare for our sixth flight of the season, I wanted to offer a glimpse of one of the types of glacial features that we are observing and studying as we map the Ross Ice Shelf: Crevasses. The word sends shivers down the spine of anyone whose job involves working on a glacier. These cracks through the glacier can be hundreds of feet deep and hidden beneath a thin layer of snow. They are incredibly treacherous and have claimed the lives of many polar explorers and scientists. They also appear quite frequently in our sensor data as we fly our survey flights for Rosetta-Ice.

The Icepod instrument, with the radar blades shown along the front edge, is being used by the Rosetta project to view through the ice to understand the features and thickness. Photo S. Howard

The Icepod instrument, with the radar blades shown along the front edge, is being used by the Rosetta project to view through the ice to understand the features and thickness. Photo S. Howard

Crevasses are fractures in a glacier caused by the stresses of movement. They are like the cracks in the surface of clay as one pulls it apart past the limits of elasticity. They most often occur where the flow of a glacier increases, like in a steep deepening valley, and are thus oriented perpendicular to direction of flow. Crevasses that lie in a cross direction are called ‘transverse crevasses.’ There are also longitudinal crevasses that form parallel to ice flow and at an angle to the valley walls. These form as the glacier widens and the ice is pulled apart. These cracks in the surface of the ice shelf are an easily identifiable marker of areas of high stress within the ice flow. Mapping where crevasses appear is equivalent to mapping where the ice tensional stresses are highest.

Several different types of crevassing are visible in this image including transverse crevasses, as ice flow from different areas collides. photo M. Wearing

Several different types of crevassing are visible in this image including transverse crevasses, as ice flow from different areas collides. photo M. Wearing

On an otherwise featureless ice shelf, crevasses show where the different ice flows merge as they flow towards the open sea. Fahnestock et al. (2000) mapped crevasses, rifts, and glacial stretch marks they call “flow lines” on the Ross Ice Shelf in order to study the flow of ice from different glacial source areas to the Ross Sea and how these patterns may have changed in the past thousand years. From their study of the surface features, they were able to draw lines across the Ross Ice Shelf and identify whether a region of ice shelf was flowing in over the Trans-Antarctic Mountains from East Antarctica, or from the rapidly flowing ice streams from West Antarctica, named from southwest to northeast Ice Streams A, B, C, D, and E. A piece of ice takes about one thousand years to travel from the back of the Ross Ice Shelf to the front, and from its surrounding area we can tell where the piece of ice originated.

Ice streams A, B, C, D and E flowing in from West Antarctica. Image from Rignot et al, 2011

Ice streams A, B, C, D and E flowing in from West Antarctica. Image from Rignot et al, 2011

The Rosetta ice-penetrating radar shows us crevasses deep with in the ice. These cracks formed on the surface and were carried along and buried by centuries of snow and glacial flow. In the radar image, buried crevasses appear as thin arches. As the radar beam penetrates through the snow and ice like ripples in a pond, bouncing off of surfaces of changing density, the sharp corner of a crevasse scatters the ripples. When the radar image is processed from the echoes of the broadcasted signal, this sharp point of scattering becomes an arch descending down from an otherwise flat surface.

Radar images of crevassing in the ice shelf showing the characteristic arch descending down from the flattened surface. Photo J. Spergle

Radar images of crevassing in the ice shelf showing the characteristic arch descending down from the flattened surface. Photo J. Spergle

What do these buried crevasses tell us? Like digging to the bottom of a stack of papers on a desk, these ancient crevasses tell us of past glacial events. Their burial depth divided by the local snow accumulation rates gives an estimate for the period of stagnation required to stop flow, fill and bury the crevasses to the observed depth. They indicate past flow conditions, or even the locations of abandoned shear margins, where there used to be a boundary between ice streams moving at differing speeds.

Close up view showing the strain in the ice as it is pulled by changes in flow speed. photo S. Howard

Close up view showing the strain in the ice as it is pulled by changes in flow speed. photo S. Howard

Lastly, crevasses are interesting because sometimes fascinating things fall into them. A few studies have shown that wind-blown meteorites get caught in snow-filled crevasses. Knowing where to look for rare meteorites is a huge help to our friends in the astro-geology community. Crevasses are also the places where meltwater drains down to the base of the ice. This affects the slipperiness of the glacier’s bed, and can speed up it flow. Meltwater flowing through crevasses also widens the crack, called hydrofracturing. This can further weaken the structural stability around the crevasse, priming the area for a later break. While Rosetta-Ice is not specifically looking for extraterrestrial rocks or draining water, we are on the lookout in our radar data for anything that can tell us about the history or current flow conditions of the Ross Ice Shelf.

Answers to a few of the questions asked by students at East Harlem School:

Is it possible for plants to grow in Antarctica?

Yes, a few. There’s a dozen native species that live on the Antarctic Peninsula, the thin peninsula of land that stretches north into relatively warmer parts of this continent. Everywhere else, only a few lichens, the crinkly stuff that grows on rocks and trees, survive.

How do you survive in the cold? What’s the hardest part about living/being in Antarctica?

With the right warm clothing and the right behavior, Antarctica’s conditions are very survivable. It’s very important to wear the right layers of clothes because you need to both stay warm, but also not let your sweat stay wet against your skin. I wear a thermal underwear layer that is warm and wicks sweat away. On top of that I’ll either wear a warm shirt or a thin sweater. On top of that, I wear a fleece or wool jacket, and then I wear my big red parka. Everyone has one and we call them our “Big Reds.” On my legs, I wear fleece pants and snowpants. I wear two layers of socks usually, and either my boots or the rubber boots that they gave us, called “Bunny Boots.” When I get too cold, I go inside, out of the wind, to warm up.

For me, the hardest part of living in Antarctica is the isolation. I personally use the internet a lot to connect to friends and family, but the combination of the slow internet connection and the time difference makes it difficult.

How has global warming affected how much ice will be there in 5 years?

We’re certain that the warming of ocean water is melting from underneath the floating ice shelves around Antarctica, and we predict that the warming atmosphere will lead to more melting and calving, but how much global warming-caused ice loss might there be within the next five years? There’s no way to know. What we still don’t know about how Antarctica’s climate works could fill a library. Weather over Antarctica is incredibly unpredictable, and we still cannot tell for sure how the multi-year climate cycles affect melting continent-wide. That question, how will global warming effect ice mass loss in Antarctica, is quite literally a multi-million dollar question. Thousands of scientists are studying every aspect of the Antarctic glacial system to get a sense of what is “natural” — what amounts of ice loss and gain are within the normal range of decades- or century-long cycles — and what can be interpreted as a result of human-caused climate change. Hopefully, Rosetta-Ice will yield a small piece of the puzzle.

For more information about Rosetta-Ice, check out our website and the archive of this blog. Have questions about Rosetta-Ice or about living and working in Antarctica? Feel free to email your question to juliansantarctica@gmail.com, and I will try to answer it in the next blog entry!

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery.

Posted By: Guest Blogger on November 07, 2017
By Julian Spergel

As of my writing, we have completed three survey flights.  It feels good to finally be collecting data. The night shift, myself included, has spent the past two days checking the collected data for signs of any instrument breakage or recording errors.

 Susan HowardFlying past the Trans-Antarctic Mountains that line the East side of the Ross Shelf. Photo credit: Susan Howard

Although Peter Pan suggested ‘happy thoughts’ would get us airborne, in Antarctica we are still very much at the will of the weather. Yesterday evening’s flight was cancelled because of fog, and so this morning we wanted to get as much flying in as possible before the late afternoon fog rolled in. Although the morning shift had to wait a bit for the IcePod instruments and the plane to warm up before departing, they were able to complete two full survey lines before their afternoon return. It is early in the season and I haven’t been able to fly a mission yet myself, but I am eagerly waiting for my first opportunity.

 Alec LockettView out of the LC-130 during Monday afternoon’s flight. The aircraft wing is visible in the top left of the photo and the tiny grey spot in the snow is the shadow of the plane. Photo Credit: Alec Lockett

Our daily schedule is not the easiest when we fly. This is especially true for those who need to make decisions about our daily activities. Every day, from 4 to 4:30 AM, Kirsty Tinto, our chief scientist, checks to see if that morning’s flight is going ahead, next she checks in with the team ending their night shift for updates on instrument functioning. At 5 am, she and the day’s flight engineer meet with the weather operations and flight operations team to go over the day’s flight plan considering the weather forecast. The team has to be flexible when building a daily mission that works with the daily weather constraints.

 Susan Howard

Flight Engineer Chris Bertinato monitoring the airborne instruments inside the LC—130 cargo hold. Photo Credit: Susan Howard

Meanwhile, the gravity instrument operators, affectionately called the “graviteers,” go down to the airfield with the aircraft load-masters to oversee the loading of the gravimeter into the plane. Collecting data on minuscule changes to gravity requires that we know exactly where in the plane the instruments sit to calculate accelerations. Although it is tempting to leave the sensitive instruments on the plane overnight, the gravimeters must be kept warm at all times for peak functionality, as a result the gravimeters must be loaded and surveyed at the beginning of every day and unloaded at the end of the day. The plane is readied for take-off with a systems check and the flight crew and our project’s flight engineers prepare for flying.

The non-flight members of our team arrive to Williams Airfield soon after from our base at McMurdo camp. Every shift has an archivist, someone who copies the data from the various digital storage units carried in flight and then carefully transports them back to the tent. The data is transferred to the central computer, as well as to two backup hard drives for redundancy. At the end of the shift, there are nine hard drives and two USB sticks filled with data. The archivist also selects three to four five-minute segments of data for quality control, which we call “QCing”. The other QCers and I look through the segments from every data set for breaks in the data, for anomalies, and for particularly good or interesting segments. Arguably, the most important data set to check is our positioning-navigation-timing system. None of our data is useful if we cannot precisely place where in the world we were when we collected the data. Some of our instruments must also know precisely the angle and velocity of the plane in order to yield useful data. Once that is checked, we look at the data readouts.

Timelapse video of a few hours of night shift “QCing” Credit: Julian Spergel

If there’s anything surprising within the Ross Ice Shelf, we QCers might be the first ones to know…while it is fun to wonder what we could find, what do we actually see? In the radar data, we can see the surface and bed of the ice shelf and often we can see areas of buried crevasses. In the shallow ice radar, we can often see where different ice masses from geographically disparate glacial sources merge as they flow towards the ocean. From LiDar (Light Detection and Ranging), we can see very high detailed maps of the surface of the ice shelf, which can give us information about the flow of the ice and the changing surface climate conditions, i.e. wind and temperature. From gravity and magnetics readings, we can glean information about the size of the cavity under the ice shelf and the ocean bed beneath the water.

An aerial photo from our onboard camera of the edge between the ice and McMurdo Station. Photo by Susan Howard.

An aerial photo from our onboard camera of the edge between the ice and McMurdo Station. At the lower right you can see the circlar shape of a tank. Photo by Susan Howard.

Though we’ve just begun our survey flying, we’re excited to see what our instruments will show us about the Ross Ice Shelf. Weather permitting we will fly day and night this week pushing through being tired. Yes we are tired, and I know I am guilty of getting a little snippy, but we are down at the edge of the world for valuable scientific work. When I see the sun kiss the horizon, and watch the shadows lengthen for a moment and the snow become golden, I know that this experience will end up being incredible.

The mother crab-eater seal nursing her newborn pup. In the background, a skua hungrily eyes the afterbirth. South polar skua are aggressive seabirds,  scavengers and carrion eaters, readily scavenging any food source.

The mother crab-eater seal nursing her newborn pup. In the background, a skua hungrily eyes the afterbirth. South polar skua are aggressive seabirds, scavengers and carrion eaters, readily scavenging any food source. One of our ‘tough’ Alamo floats is named after a south polar skua. 

In non-science news, we saw the birth of a baby crabeater seal on Sunday. Everyone else on the team has named the newborn seal “Rosetta,” but in my mind, the seal’s name is “Boopy.”

For more information about Rosetta-Ice, check out our website and the archive of this blog. Have questions about Rosetta-Ice or about living and working in Antarctica? Feel free to email your question to juliansantarctica@gmail.com, and I will try to answer it in the next blog entry!

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery.

Posted By: Guest Blogger on November 02, 2017

The Rosetta team has been in Antarctica for a week now and we’re almost done with unpacking and testing all of our equipment. Our first survey flight of the season is scheduled for the end of the week.

An official 'proof'! My photo by the McMurdo sign is proof that we have really made it here after a lot of anticipation!!

An official ‘proof’! My photo by the McMurdo sign is proof that we have really made it here after a lot of anticipation!!

The first few days of our time in Antarctica was spent on safety training and ‘waiting on the weather’. Each step of our set-up process, like receiving cargo, installing electricity in our tent, unpacking our boxes, and building disassembled instruments, needs to wait for safe weather conditions, which in Antarctica is by no means guaranteed. Our workstation is a yellow Jamesway tent on the airfield named Williams Field. It is about a thirty minute drive from McMurdo Station, on a nearby section of the Ross Ice Shelf.

The landscape seems endless with ice shelf merging into white cloudy skies. The airplanes on the ice are close to the only relief.

The landscape seems endless with ice shelf merging into white cloudy skies. The airplanes on the ice are close to the only relief.

Even though we are within a short drive of McMurdo station, a small town with most of the safety and logistical equipment on the entire continent, we still need to prepare ourselves for sudden, extreme weather. Every time we leave the relative safety of McMurdo, we carry our Extreme Cold Weather equipment and our tent has emergency food and sleeping equipment. Driving onto the ice shelf is a surreal experience: the landscape is a nearly featureless white, flat expanse, with only tiny buildings and the black, slug-like shapes of lounging seals to break up the uniform whiteness. When there are low-lying clouds, the ice and the sky seem to meld into a single white area.

Unpacking our workspace in the Jamesway that will be our 'command center' during our work here.

Unpacking our workspace in the Jamesway that will be our ‘command center’ during our work here.

After two days of unpacking, our little tent is becoming very cozy. We have a line of tables for our computers and printer, a coffee machine and two gas heaters, a number of powerful external hard drive units called a Field Data Management System. Our scientific instruments are coming together, as well. To keep both ourselves and our electronics warm, we keep two heat-stoves running all the time. In preparation for our flights, we’ve split into two shifts, one in the day and one at night. Myself and six other people spent last weekend transitioning our daily schedules to sleeping during the day and being awake to work over the night. Due to the polar latitude, the sun never goes down, so the two shifts experience nearly identical levels of light. Yet my sense of time is very confused and I often forget what day of the week I am currently in.

Setting up our basestations to support our flight data.

Setting up our basestations to support our flight data.

Before we start recording and processing data from our first survey flights, we need to rebuild the instruments that were deconstructed for shipping, and calibrate them to make sure the data recorded is accurate. With round-the-clock activity, we have set up everything in only a few days. One of the needed activities was hanging the gravimeter onto a freely-suspended gimbal with bungee cords so that it is stabilized against the movement of the plane. Many of the components of our sensors are very delicate, but a large number of the external components are larger, easily adjusted, and could be found in a hardware store. Unlike other fields of science, polar fieldwork operates best when adjustments can be made while wearing heavy gloves.

Helping Tej to calibrate the IcePod on the C130 aircraft.

Helping Tej to calibrate the IcePod on the C130 aircraft.

Additional set up involves installing “base stations” to record a background level of magnetics and GPS information. A five minute walk across the ice from our tent, we have erected two yellow tripods and partially buried a small box of sensors. The instruments are powered by a small solar panel that we set up nearby. Each tripod needed to be secured against wind by tying the legs to bamboo poles we buried in the snow, a snow anchor. The snow on the ice shelf is incredibly dry and compact, so digging into it feels like digging through styrofoam. Filling in the holes with snow, stamping on it, and waiting only a few minutes allows the snow to harden to a strength similar to concrete.

Checking on the data output inside the plane and hoping for good weather for a flight!

Checking on the data output inside the plane and hoping for good weather for a flight!

Our first test flight is scheduled for the end of the week. We will fly one of our survey lines and make sure that the instruments’ readings are accurate so that on future flights we will know that the instruments are working properly. In addition we will be ensuring that each of the instruments functions by checking sections of the data after every flight. My assigned role once flights are running regularly is to analyze the ice-penetrating radar during the night shift.

For more information about Rosetta-Ice, check out our website and the archive of this blog. Have questions about Rosetta-Ice or about living and working in Antarctica? Feel free to email your question to juliansantarctica@gmail.com, and I will try to answer it in the next blog entry!

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Professor Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery.

Posted By: Guest Blogger on October 24, 2017

The Rosetta team has been delayed in Christchurch, NZ since October 20th, and today, the 24th, we are all hoping very hard that today will be the day, that the weather will cooperate and the plane will have no issues so that we can get to McMurdo and start preparing to work. Morale is still high, we have all enjoyed exploring the local sights in Christchurch in the spare time we suddenly have. But it would be a huge inconvenience if we stay in Christchurch too long.

The Dumont d'Urville base where winds have been recorded at 199 mph. (photo credit Samuel Blanc)

The Dumont d’Urville base where winds have been recorded at 199 mph. (photo credit Samuel Blanc)

The dangers of Antarctic air travel cannot be emphasized enough. The weather is notoriously temperamental: winds as fast as 199 mph (327km/h) have been recorded at Dumont D’Urville station. Wind gets funneled down mountains and through fjord valleys, picking up speed. Blowing snow can limit visibility in a matter of seconds. Even crossing the Antarctic Circle is dangerous. Because there are no large landmasses to break the 40th line of latitude, ocean and wind currents can spin unimpeded around the continent. This is called the Antarctic Circumpolar Current. Sailors called the latitudes between New Zealand and Antarctica in order of southernness the Roaring Forties, the Furious Fifties, and the Shrieking Sixties.

Yet this inaccessibility is two-sided. The spinning wall of wind and water acts as a thermal insulator and keeps Antarctica chilly. The extreme environment, the massive ice sheet, and the unique ecosystems that attract the scientific community are all due to this forbidding climate system.

Antarctica is an isolated massive block of land primarily covered in ice. (photo M. Turrin)

Antarctica is an isolated massive block of land primarily covered in ice. (photo M. Turrin)

Was Antarctica always so inhospitably cold? Surprisingly, no. The development of the Antarctic ice sheets are relatively recent compared to the 4.5 billion year old history of the Earth. The precise mechanism that triggered Antarctic glaciation is still debated, but there is significant evidence that continental scale glaciation began around 33 million years ago, at the boundary of the Eocene and Oligocene. A combination of lowering CO2 levels and the formation of the Circumpolar Current when South American and Antarctica detached led to mountain glaciers in the Trans-Antarctic mountains to expand until the continent was covered [10.1038/nature01290]. Prior to this point, Antarctica is believed to have been forested, and dinosaur and early mammal fossils have been found around the continent.

We theorize that the crustal depression that has become the embayment holding the Ross Ice Shelf developed during the break-up of Gondwana.

We theorize that the crustal depression that has become the embayment holding the Ross Ice Shelf developed during the break-up of Gondwana.

The glacial and geological history of the Ross Embayment, the bay in which the Ross Ice Shelf sits, is one of Rosetta-Ice’s leading research questions. By making measurements of the seafloor, we hope to improve our understanding of the timing and distribution of sea-floor extension in the geological past. The tectonics of the region are still not well understood. We theorize that the crustal depression that has become the embayment developed during the break-up of Gondwana, the Mesozoic supercontinent composed of modern-day South America, Africa, Australia, Antarctica, India, and Arabia around 200 million years ago. As it pulled apart over millions of years, it stretched the crust in the region of the Ross Sea, thinning and depressing it. Over the past 33 million years, glacial ice has carved out landforms that now lie under the ice. During our work, we will use our instruments to look through the ice shelf and map those present day landforms. We would like to improve our knowledge of the history of the region, both of the geology and of the ice shelf. Why is this important? In addition to increasing our knowledge of the world’s geological history, the past of the Ross Sea can give us clues to its future. If we see evidence that the Ross Ice Shelf has broken up or disappeared in the past, we can say that the present-day ice shelf has the capacity to disappear in the future.

Stay tuned for updates on our Antarctic arrival and our scientific work. We’re standing by in Christchurch, parkas on, bags in hand, excited and ready to start another season of Antarctic science.

Julian Spergel is a graduate student at the Department of Earth and Environmental Science at Lamont-Doherty Earth Observatory and will be blogging from Antarctica. He works with Prof. Jonathan Kingslake on analyzing spatial and temporal trends of supraglacial lakes on the Antarctic Ice Sheet using satellite imagery. He graduated with a BS in Geophysical Sciences with General Honors from the University of Chicago in 2016. He has been involved with a number of diverse projects and has been interested in polar studies since early in his career. His fieldwork has brought him north to the Svalbard Archipelago and south to McMurdo Station, Antarctica.

Learn more about previous years’ research, here.

For more on this project, please visit the project website: http://www.ldeo.columbia.edu/rosetta

Posted By: Guest Blogger on October 20, 2017

We have embarked! Our third Antarctic field season is underway putting us only 18 flights away from completing our mission to investigate the Ross Ice Shelf, the largest ice shelf in Antarctica. The Rosetta Ice Project is focused on developing a more complete understanding of the Ross Ice Shelf, the history of how it formed, what are the factors driving its current condition and what might control its future stability.

Drawing of the author Julian Spergel (by Freddy Bendekgey)

Drawing of the author Julian Spergel (by Freddy Bendekgey)

It is this writer’s first Antarctic field season, although traveling to Antarctica has been a life dream of mine since high school. I came to my obsession in an unusual way. In the summer of 2011, a heat wave knocked out the air conditioning units in my town. Sweltering, I took what little refuge there could be had in the public library. I had read somewhere that reading about cold places could cool you down, so for the next few weeks I pored over every account of polar exploration I could get my hands on. I was hooked, and especially hooked on Antarctica. It represented to me a place that remained mysterious and extreme, and whose challenging exploration by scientists represented the pinnacle of human ingenuity and international collaboration. I feel honored to be included in this field season, and to be documenting our findings and experiences for readers to learn from and enjoy. It is exhilarating to be on my way to achieving a personal goal of mine, though when I pictured myself as an Antarctic explorer as a teenager, I thought I would be taller!

An annotated version of the front of the Ross Ice Shelf from radar collected in this project. Note the shelf sits with most of the ice below the waterline.

An annotated radar image collected in the project showing the front of the Ross Ice Shelf. Note the shelf sits with most of the ice below the waterline.

To more thoroughly introduce the Rosetta-Ice project, it is a National Science Foundation funded multi-year collaboration between Lamont-Doherty Earth Observatory, Scripps Institute of Oceanography, Colorado College, and Earth & Space Research with critical support from the New York Air National Guard. Out goal is to complete a high-resolution survey of the Ross Ice Shelf in West Antarctica. The Ross Ice Shelf is a floating ice shelf roughly the size of Texas or of France that extends from the Trans-Antarctic Mountains into the Ross Sea, the portion of the Southern Ocean that faces New Zealand. Part of the ice shelf’s perimeter is grounded, at term that means frozen all the way down and connected at the base to the seafloor below. The rest of the shelf extends out floating as a thick apron of ice with about 10% of it visible above the ocean’s surface, the rest floating below the waterline. The ice shelf is up to 4000 thousand feet thick in its interior, and its margin with the sea is nine hundred feet thick in places. A large percentage of the surrounding ice streams in the Trans-Antarctic Mountains and West Antarctic Ice Sheet flow into the Ross Ice Shelf. As a result, the friction of the grounded portions affects the rate at which the ‘upstream’ ice flows and loses its mass through iceberg calving.

Lamont-Doherty Earth Observatory / Photo: Winnie Chu. The Rosetta project is focused on the Ross Ice Shelf in Antarctica. This shelf plays a critical role in stabilizing the Antarctic ice sheet, buttressing the ice that is constantly moving over the land surface. Studying how the ice, ocean and underlying land interact will inform us of potential change in the ice shelf from projected climate change. IcePod, shown along the front of the shelf, is a critical instrument in completing this project.

The IcePod flying over the the Ross Ice Shelf in Antarctica as part of the Rosetta project. The pod is lowered from an LC130 aircraft and holds a series of instruments that are critical to completing this project. (photo: Winnie Chu)

Rosetta-Ice is a detailed aerogeophysical survey, a series of survey flights collected using LC130s, rugged military cargo planes that fly equipment and support in the polar regions. The planes carries a variety of remote-sensing instrumentation inside an attached structure called IcePod, and flies a tight grid of observation tracts collecting data. The ultimate result will be a map of the Ross Ice Shelf with a spatial resolution of 10km (6mi). This will give us a comprehensive look into the ice shelf’s surface elevation, its internal glacial stratigraphy, its thickness, the ocean circulation beneath it, and the morphology of the bed beneath.

The research questions that the project seeks to answer concerns the ice shelf’s past and future. We want to understand how the ice shelf formed, and we are thus studying the internal structures within the ice and the bathymetry and geology of the bed underneath. Looking from the past to the future, we are interested in the stability of the floating ice. For this question, we are studying the circulation of ocean water underneath the ice, how the ocean interacts with the ice through melting, and where the ice shelf may be resting on the underlying bed. Each one of our instruments’ data gives us a piece of the answers. The Rosetta Stone, our project’s namesake, was inscribed with a message in multiple languages that could only be completely understood by comparing the three translations and interpreting them together. Likewise, we are interpreting our data from ice-penetrating radar, visual and infrared imagery, magnetic readings, and gravimeter information together to produce a complete picture of the Ross Ice Shelf’s dynamics.

McMurdo Base, Antarctica imaged with LiDAR. (processed by S. Starke)

McMurdo Base, Antarctica imaged with LiDAR. (processed by S. Starke)

In this coming week, we will be settling into McMurdo Station, the largest of Antarctica’s research stations, and setting up and calibrating our instruments so that we can begin this year’s flights as soon as we can. For more information about previous years’ work, please take a look at previous blog entries in the archives of this blog.

Author: Julian Spergel.  Julian will be blogging this season from Antarctica for the project.

For more on this project please go to the project website: http://www.ldeo.columbia.edu/res/pi/rosetta/

Posted By: Margie Turrin on December 04, 2015

The pod preparing to be mounted onto the LC130 aircraft for another day of work. (photo S. Pascaud)

The pod preparing to be mounted onto the LC130 aircraft for another day of work. (photo S. Pascaud)

As we closed out November the project team had completed 18 survey lines and 4 tie lines from a total of 9 flights, producing over 16,000 line km of data. The IcePod and team have been a working hard! The closing email for the month of November included these beautiful LiDAR images.

What is LiDAR?

LiDar (Light Detection and Ranging) is a remote sensing technique that uses light to develop an image of the surface of the Earth, and is an important part of our geophysical suite of measurements in ROSETTA. In the IcePod the instrument is located on the pod bottom behind a protected window. In flight, when the pod is lowered to collect data, the window cover slides open and a series of light pulses are sent to illuminate the area below. The time is then measured for the reflected light to return. Because we know the speed of light. and that speed is a constant (0.3 meters per nanosecond…or a very fast 186,000 miles per second!), we can use light to calculate distance with a high degree of accuracy. The equation is simple:

Distance = (speed of light X time of flight)/2 in order to account for the distance down and back from the aircraft. The result is the ability to create these 3 dimensional images of the land surface.

Enjoy these wonderful LiDAR images collected by the project team!

McMurdo Base, Antarctica imaged with LiDAR.  (processed by S. Starke)

McMurdo Base, Antarctica imaged with LiDAR. (processed by S. Starke)

The first image is from a standard pass over McMurdo Base in order to calibrate and confirm that the LiDAR system is working accurately. You can clearly see every building, fuel tank, road/pathway and the very systematic way that the base is laid out. The scale bar showing meters of elevation (or height) listed with elevation noted by ‘Ellipsoidal Height’ in meters, not a unit we see every day.

What is ellipsoid height?

We describe the Earth’s shape as an ellipsoid, rather than round or spherical, as the radius at the polar regions is slightly shorter than the radius at the equator. In reality the Earth’s surface is not smooth like an ellipsoid, instead we have mountains, deep valleys, ocean trenches and other surface features with elevation. However, GPS receivers used to locate placement follow a map of sea level using a reference ellipsoid to calculate elevation. To view these images the best approach might be to look at them as relative measures, for example the image of McMurdo shows a 185 m elevation difference between the the surface at 166°42’E and the surface at 166°39’E.

White Island in the Ross Ice Shelf of McMurdo (processed by S. Starke)

White Island in the Ross Ice Shelf of McMurdo (processed by S. Starke)

Located close to McMurdo on the Ross Ice Shelf is a small island ~28 km or 15 miles long called White Island. Protruding up through the ice shelf it is named for its covering of snow, and is a sister to Black Island, named, not surprisingly for its lack of snow cover. Both were discovered on the same expedition in the early 1900s. Using the scale for this image you will see the elevation contours for the island peaking out at 40 m Ellipsoid Elevation, approximately 80 m higher than the ice at the ice shelf.

Crary Ice Rise, Ross Ice Shelf, Antarctica (processed by S. Starke)

Crary Ice Rise, Ross Ice Shelf, Antarctica (processed by S. Starke)

The third image is of crevassing near Crary Ice Rise.

What is an ice rise?

An ice rise is a region of increase in elevation in the relatively flat expanse of the ice shelf caused by floating ice in the shelf physically ‘grounding’ or touching the seafloor below. It differs from an island as the land in an island sits above sea levels. Here the ice is touching land that is still below sea level; it is a section of sea floor raised so that it causes the flowing ice in the deep ice shelf to hit it and drag. This tension of the ice dragging over the contact area, combined with the faster flowing ice around the edges, causes the ice to crevasse as seen in the image.

Yes those are seals! Weddell seals lying on the  ice and imaged by the LiDAR. (Processed by S. Starke)

Yes those are seals! Weddell seals lying on the ice and imaged by the LiDAR. (Processed by S. Starke)

Our fourth image is of seals laying out on the ice. The Weddell seal is well represented in the area of McMurdo, although they are also found distributed around the circumpolar Antarctica. Weddells are well studied by the science community, as they are very accessible, abundant in numbers, and are easily approached by humans. Perhaps they have been imaged in LiDAR previously, but we are happy to have captured them resting on the ice! To provide some context we have included a video of a Weddell seal collected by our project GPS specialist, Sarah Starke.

Be sure to check our GIS flight tracker for the most up to date flights!

For more about this NSF and Moore Foundation funded project, check our project website: ROSSETTA.

Margie Turrin is blogging for the IcePod team while they are in the field.

Posted By: Margie Turrin on November 25, 2015

Moving across the ice with IcePod in the front and active Volcano Mt. Erebus in the distance.

Moving across the ice with IcePod in the front and active Volcano Mt. Erebus in the distance. (Photo Sarah Starke)

The project is several weeks in and with each new line of data we celebrate the collection and then dig into it to see what we can learn. The map is growing, filling in with the 20 km flights designed to provide a framework for the 10 km flights that would fill in the gaps during our next field season. However, already in some instances the team has tightened their grid lines to 10 kms, taking advantage of opportunities in the weather or the inability to collect a line over another part of the shelf.

(Above is a video of the retraction of the IcePod arm as the plane flies over the Ross Sea Polynya (open water set in the middle of the sea ice). During data collection the pod is lowered and then retracted upon completion. Video by Dave Porter.)

The latest team celebration is around the magnetometer data. Magnetics is used to understand the make up of Earth’s crust. The end goal is to calculate the anomaly or unique magnetic signal from the geology in an area after separating out all the other magnetic ‘interference’ to better understand the formation of this area of Antarctica. The Earth’s magnetic signature varies by location so a base station is set up in order to collect a background magnetic level for the area. During data collection the base station will be used to determine anticipated magnetic levels for the region.

Map of Rosetta flights with the magnetic compensation flight noted in the lower right corner.

Map of Rosetta flights with the magnetic compensation flight noted in the lower right corner.

In data processing the local signal is corrected for and small spikes from the aircraft that the instrument is mounted to will be removed. This means that each magnetic survey includes a magnetic compensation flight at high elevation so that the magnetic signature of the plane can be identified. A  model is then developed to separate the signal of the plane from that of the geology. The magnetic compensation flight includes flying in all four cardinal directions – check the annotated flight track image above to see a recording of these flight lines.

The compensation flight also includes 3 repeat pitch-roll-yaw moves. Pitch includes tipping the wings side to side, roll is moving the nose and tail down and then up and yaw is a rotating or twisting of the plane left and then right. Thanks to New York Air National Guard loadmaster Nick O’Neil we have a video of the pitch and roll pieces of this compensation flight. Note the video is sped up to show 2 minutes of filming in 17 seconds so hold onto your seats! Be sure to note how the vapor contrail of the plane tracks the serpentine movement of the flight pattern during the rolls!

For the magnetics the flight line selected was one that has been flown previously by the NASA IceBridge program. Duplicating flights between different projects provides an opportunity to test and validate equipment. From the onset collecting magnetics data from the LC130 with the IcePod system was considered challenging. The compact nature of the instruments and all the metal surrounding them made this a real test, however, the resulting first unprocessed flight line (below) shows that the shape of the two lines agree! The alignment will only improve with processing against the base station. This is a significant achievement given the very compact environment of the instruments in IcePod – cause for celebration!

Magnetics line from the ROSETTA project. Right is the volcanic signature of Marie Byrd Land volcanism.

Magnetics line from the ROSETTA project set against the Ice Bridge line. Right is the volcanic signature of Marie Byrd Land volcanism.

The magnetic image shows the signature of this area of Antarctic geology in clear detail. Flying away from McMurdo the Transantarctic Mountains are on the left side of the dataset. The flight moves towards the highly magnetized volcanic environment of Marie Byrd Land in West Antarctica on the far right. Note the elevated magnetics on the right form the volcanic rock. A magnetic high is also visible in the center, yet on the left side the Transantarctic Mountains show no sign of high magnetism. This is not surprising as this mountain range that stretches mainly north to south across Antarctica, was formed from uplift beginning about 65 million years ago, and is composed of sedimentary layers of rock overlying granites and gneisses.

Magnets mounted on the tips of the wings during the 2008 AGAP project. (photo R. Bell)

Magnetics mounted on the tips of the wings during the 2008 AGAP project. (photo R. Bell)

Magnetics has evolved quite a bit over the years of geophysical sampling. Lamont scientist Robin Bell recalls when in the 1990s when she worked on a project mapping a active subglacial volcanism in West Antarctica that the magnetometer was towed on a winch ~100 meters behind the aircraft. If the wiring got caught up in the tail section it was cut lose and the instrument was lost. More recent work has located the instrument in the tail of the plane (as in the P3 bombers of World War II) and on the tips of the wings of the plane as was the case during the 2008 AGAP work in East Antarctica mapping the subglacial Gamburtsev Mountains. The IcePod model of placing the magnetics so close to the radar has not been done before.

Check out the newest lines on the GIS map and stop back for more.

For more about this NSF- and Moore Foundation-funded project, check our project website: ROSSETTA.

Margie Turrin is blogging for the IcePod team while they are in the field.

 

Posted By: Margie Turrin on November 19, 2015

Annotated radar image from project flight over the Ross Ice Shelf (credit ROSETTA)

Annotated radar image from project flight over the Ross Ice Shelf (credit ROSETTA)

The lines of data are slowly creeping across our Ross Ice Shelf GIS map and with each new line comes an improved understanding of Ross Ice Shelf. What can you learn from a ‘snapshot’ of data? The radar image above contains a nice story. You can see the ice thickness in the Y-axis of the annotated radar image. The ice shelf is approximately 300 meters thick. For scale this means you could stand 3 statues of liberty one on top of another and still have 21 meters of ice layered above them. The top layer on the ice shelf is snow that has accumulated on the surface of the shelf, layered almost flat as it fell on a level ice surface. Below you can see the ice that has flowed in from the Antarctic ice sheet with rumpling and roughness collected as it moved over the rougher terrain of the bed topography. Below that you can see the faint outline of the bottom of the ice shelf. This is where the radar stops, unable to image through the ocean water.

 Matt Siegfried)

Gravity data collected on the bed below the ice shelf.  (Credit: Matt Siegfried)

Air National Guard, complete with IcePod patch on his uniform, reviewing safety breathing apparatus with Sylvain Pascaud, filmmaker  LCL production interested in technology and airborne science.

Air National Guard, complete with IcePod patch on his uniform, reviewing safety breathing apparatus with Sylvain Pascaud, filmmaker LCL production interested in technology and airborne science. (credit: Matt Siegfried)

The radar and gravity work together to create a complete image of the Ross Ice Shelf and the bed below. Radar provides information on the ice layers but stops where the gravity excels, at the ice/ocean interface. With two gravimeters strapped down side by side in the LC130 and humming away as they collect data, the dual instrumentation has the project well covered.

A schedule of flying two flights a day can be exhausting.  However, the limited time in an Antarctic field season led to the plan to fly with two crews so data can be collected day and night; after all radar, gravity and magnetics don’t need the light to collect images. The personnel have been broken into teams so there is a constant rotation of working, sleeping and data review. The small cohort in the science team has been training each other on the various instrument operations to provide more flexibility in the flight planning.

Being on the ice can be an intense and compressed time…but it can also be filled with unexpected problems and delays. Weather has cancelled several flights, as have priority needs of the guard to handle emergencies and support missions.  The cold, dry static environment can be hard on equipment and a couple of the laptops used to manage the data have stopped working adding stress to the workload, as has illness. Although the team has been challenged by the cold and the weather they have managed 6 flights with more on the upcoming docket.

Scott Base, Ross Island, Antarctica, New Zealand research base.

Scott Base, Ross Island, Antarctica, New Zealand research base.

The team has taken advantage of down days to share presentations about the ROSETTA project with the other residents of McMurdo and Scott Bases. McMurdo and Scott are both located on Ross Island just at the edge of the Ross Ice Shelf. McMurdo is home to the U.S. research teams housing about 1000 residents during the austral summer season. Scott Base is home to the New Zealand teams, with close to 100 during the austral summer season. Sharing science is one of the perks of polar fieldwork.

McMurdo Base, Ross Island, Antarctica U.S. research base.

McMurdo Base, Ross Island, Antarctica U.S. research base.

Check out the newest lines on the GIS map and stop back for more. As we write the team is gearing up for another flight….and more lines of data with more stories.

For more about this NSF and Moore Foundation funded project, check our project website: ROSSETTA.

Margie Turrin is blogging for the IcePod team while they are in the field.

Posted By: Margie Turrin on November 13, 2015

As the project sets out to explore the Ross Ice Shelf it seems appropriate to include a photo of Minna Bluff,  a prominent volcanic promontory that sticks out close to McMurdo. The bluff was first identified by Capt. Scott in 1902 and is mentioned often in Antarctic exploration history. (Photo Nigel Brady)

As the ROSETTA project sets out to explore the Ross Ice Shelf it seems appropriate to include a photo of Minna Bluff, a prominent volcanic promontory that sticks out close to McMurdo. The bluff was first identified by Capt. Scott in 1902 and is mentioned often in Antarctic exploration history. (Photo N. Brady)

The Ross Ice Shelf is much like the Rosetta Stone. The historic stone was inscribed in three different scripts; each telling the same story but in a different tongue. When matched together the information was enough to allow scholars to decode an ancient language. The Rosetta Project in Antarctica also brings together three different ‘scripts’, but in this case they  written by three Earth systems; the ice, the ocean and the underlying bed each have a story to tell. Mapped together these three systems can be used to unlock the mysteries of Antarctic ice history in this region and help us to develop models for predicting future changes in Antarctic ice.

Two gravimeters, one was used last year in test flights in Antarctica with GNS Science from New Zealand, and the second is from Dynamic Gravity Systems purchased through funding by the Moore Foundation. (Photo K. Tinto)

The team moves two gravimeters from the tent where they have been stabilizing for two days after arriving in Antarctica.  One instrument was used last year in test flights in Antarctica with GNS Science from New Zealand, and the second is from Dynamic Gravity Systems purchased through funding by the Moore Foundation. (Photo K. Tinto)

The  multi-institutional project is multi-disciplinary in nature and takes advantage of the recently commissioned IcePod integrated ice imaging system as the main science platform. IcePod is package of geophysical instruments packed into a 9 ft. container and loaded onto the large LC130 transport planes supporting science in the polar regions. Flown by the US Air National Guard these planes are the workhorses of the science program.  A unique ‘arm’ that fits into the rear side-door of the plane is used to attach the IcePod outside the aircraft, allowing it to be used on both dedicated missions and flights of opportunity.

IcePod’s instruments include two radar to image through the ice, lidar to measure to the ice surface, cameras for surface images, and a magnetometer to better understand the tectonics and origin of the bed below the ice shelf. Together with the IcePod instruments the project will  use two separate gravimeters in order to develop a bathymetric map of the seafloor under the ice shelf. Gravity is a critical data piece in this project as the radar is unable to image through the water under the ice shelf.

Crossing the Transantarctic Mountains on the flight to South Pole. (Photo N. Brady)

Flying up from the Ross Ice Shelf to cross the Transantarctic Mountains on the flight to South Pole. The Transantarctic Mountains are a stunning contrast to the flat surface of the Ross Ice Shelf. With peaks that reach upwards of 4000m they act like a zipper stretching  across the continent for over 3500 kms connecting two very different sections of the Antarctic continent. (Photo N. Brady)

The Ross Ice Shelf is a thick slab of ice that serves to slow and collect ice as it flows off the Antarctic peninsula. Ross is the largest of the Antarctic ice shelves moving ice at rates of 1.5 to 3 meters/day. Somewhat triangular in shape, it is bounded by the West Antarctic ice sheet on the west, the East Antarctic ice sheet on the east, and the Ross sea along the front.

//pgg.ldeo.columbia.edu/projects/rosetta/

Our interactive Rosetta flight tracking instrument. Go to the page to follow the flights as they are added. http://pgg.ldeo.columbia.edu/projects/rosetta/

This three year project involves 36 separate flights in a two season field campaign. The first field season is underway now, and will focus on building the larger framework for the dense 10 km spaced grid of flights that is planned for the following season. As each day’s flights are logged they are being posted on our interactive website. You can follow our campaign by linking directly to this data portal to watch the grid develop. You can select the project proposed flight plan (v9) on the Data Map to get a complete look at the project plan. The end product will be a dense grid of flightlines evenly spaced and crossing with regular tie points.

On the flight to the South Pole the LC130 hercules aircraft is the rear right parked at the edge of the skiway. The ice pod is on the far side the South Pole station. Team members Kirsty, Tej and Fabio are heading towards the South Pole passenger terminal waiting to reboard. (Photo N. Brady)

On the flight to the South Pole the LC130 hercules aircraft is the rear right parked at the edge of the skiway. The icePod is on the far side the South Pole station. Team members Kirsty, Tej and Fabio are heading towards the South Pole passenger terminal waiting to reboard. (Photo N. Brady)

First flights included two survey lines across the ice shelf. The most southern of the two lines was flown by IcePod in 2014 during commissioning flights, and by the NASA IceBridge project in 2013. These two flights provide a calibration line for the system. The northern line is the first new line for the project. The map also shows a small test flight for the equipment and a line up to South Pole that was a piggy back flight with another mission of the plane.

You will note that flights originate from McMurdo so there is a dense radiating line from the base. Minna Bluff is a prominent volcanic promontory that sticks out close to MCM. The bluff was first identified by Capt. Scott in 1902 and is mentioned often in Antarctic exploration history.

Check the flight tracker daily for updated flight lines.

For more about this NSF and Moore Foundation funded project please check our project website: ROSSETTA

Margie Turrin is blogging for the IcePod team while they are in the field.