A Few of My Favorite (Frozen) Things

Sastrugi, crevasses, sea ice, and bergy bits—a few of my ever-changing favorite things. Credits: NASA/Kate Ramsayer

by Kate Ramsayer / ANTARCTICA /

I knew they were my favorite as soon as I saw them. Sastrugi, the ice dunes of the polar desert, covered the landscape when I first flew low over Antarctica with Operation IceBridge. They were amazing—winds had shaped them into repeating patterns, appearing as diamonds or fish scales or branching tree roots. They were the only texture in the vast ice sheet that stretched as far as the eye could see.

The next day, however, crevasses took the top spot. Gigantic cracks that bent around mountains as the mass of ice crept toward the ocean—those were definitely my new favorite ice formations. As our IceBridge team took measurements down a path that ICESat-2 would trace from its orbit in space, I wondered how the height profile from these instruments could reflect these seemingly bottomless and terrifying cracks in the ice.

Then sea ice made an appearance. Icebergs were trapped at awkward angles in the frozen floes, and new ice spreading across open waters in translucent blues and whites—those had to be the most artistic formations, right? Maybe so—in my mind—until the next flight, which measured a newly created gigantic iceberg, and I glimpsed the jumble of bergy bits and sea ice in the rift between it and the glacier.

A glacier on the Antarctic Peninsula flows into the Bellingshausen Sea. Credits: NASA/Kate Ramsayer

At least I would be safe from a new favorite ice formation on my last flight, I thought. A survey farther inland of a region we had flown before, it should be old hat. But no. As we flew toward the site, the skies cleared over the Antarctic Peninsula, revealing glacier after glacier after glacier, all textbook examples of how spectacular glaciers can be.

Every day flying over Antarctica with the Operation IceBridge campaign brought a new incredible stretch of ice that left me, a new visitor to the continent, awestruck. Many members of the team have been surveying the continent for years, using a suite of instruments to map the ice and bedrock and monitor change. I couldn’t pick a favorite view, and can’t imagine they could either, so instead I just asked some of the IceBridge crew for an example of one of the neatest things they’ve seen flying over Antarctica.

Actually seeing Pine Island and Thwaites glaciers, which she has studied for more than a decade, is a highlight for Brooke Medley, IceBridge’s deputy project scientist. Her research showed that enough ice flows out of each glacier to contribute 1 millimeter to global sea level rise per decade. They’re massive glaciers, and flying over them puts into perspective just how massive they are. Credits: NASA/Kate Ramsayer 
The vastness of the Antarctic ice sheet can leave Eugenia DeMarco, IceBridge’s project manager, speechless. It’s just raw nature, she said, and provides a glimpse of what early explorers might have felt when they first ventured to this distant part of the world. Credits: NASA/Kate Ramsayer
In massive ice streams that appear solid and unmoving, it’s the crevasses that remind you the ice is in motion, said Thorsten Markus, ICESat-2 project scientist. These giant breaks form as the faster ice downstream pulls away from the slower ice upstream. Credits: NASA/Brooke Medley 
From above, crevasses can appear as wrinkles on fabric. Credits: NASA/Kate Ramsayer
The ice may seem desolate, but there’s life in Antarctica, and Lyn Lohberger, an aircraft mechanic and safety technician, points to seals visible on the ice floes. They provide a contrast as well, he said—the black seals on the white ice, with blue seas and sky. Credits: NASA/Jeremy Harbeck
Icebergs that have broken off of glaciers and ice shelves create different three-dimensional shapes in the flat sea ice, noted Victor Berger, with the CReSIS snow radar team. And Tim Moes, DC-8 project manager, pointed out the blue color of the older ice visible in the bergs. Credits: NASA/Kate Ramsayer
Operation IceBridge has surveyed Arctic and Antarctic ice for a decade, collecting scientific data on the changing ice. It’s the best office window view, said Jim Yungel, Airborne Topographic Mapper team lead—and it never gets old. Credits: NASA/Kate Ramsayer

Iceberg Ahead!

The NASA DC-8 aircraft’s shadow is dwarfed in scale by the B-46 iceberg. Credits: NASA/Brooke Medley

by Kate Ramsayer / THE SKIES ABOVE ANTARCTICA /

The crack that would become B-46 was first noticed in September 2018 – and the berg broke the next month.

NASA’s Operation IceBridge flew over a new iceberg that is three times the size of Manhattan on Wednesday – the first known time anyone has laid eyes on the giant berg, dubbed B-46, that broke off from Pine Island Glacier in late October.

The flight over one of the fastest-retreating glaciers in Antarctica was part of IceBridge’s campaign to collect measurements of Earth’s changing polar regions. Surveys of Pine Island are one of the highest priority missions for IceBridge, in part because of the glacier’s significant impact on sea level rise.

On Wednesday, IceBridge’s approach to the iceberg began far above the glacier’s outlet, in the upper reaches of ice that will eventually flow into the glacier’s trunk. There, as far as the eye can see, it was flat and it was white.

As the aircraft headed toward the glacier’s outlet in the Amundsen Sea, snow-covered crevasses became visible when sunlight struck at just the right angle. Every once in a while, a dark hole appeared in the crevasses where the snow had fallen through, providing a glimpse into the depths of the ice sheet. Then the holes got bigger.

The crevasses and dunes became a jumbled mess of ice, as Pine Island Glacier picks up speed as it flows to the sea. The crevasses got deeper and wider, swirling around each other. Striated snow layers in white and pale blue were visible down the crevasse walls, like an icy version of the slot canyons in the American West.

Crevasses in Pine Island Glacier indicate how fast the ice is moving. Credits: NASA/Kate Ramsayer
Crevasses in Pine Island Glacier get larger as the ice moves faster toward the Amundsen Sea. Credits: NASA/Kate Ramsayer

Then finally – the berg. Satellite imagery had revealed a massive calving event from Pine Island in late October, and the IceBridge crew was the first to lay eyes on the newly created iceberg.

The glacier ends in a sheer 60-meter cliff, dropping off into an ocean channel filled with a mix of bergy bits, snow, and newly forming sea ice. On the other side, a matching jagged cliff marked the beginning of B-46, as it stretched across the horizon.

The rift between Pine Island Glacier and a new giant iceberg, dubbed B-46, in Antarctica. Credits: NASA/Kate Ramsayer

“From this perspective at 1,500 feet, it’s actually really difficult to grasp the entire scale of what we just looked at,” said Brooke Medley, Operation IceBridge’s deputy project scientist who has studied Pine Island Glacier for 12 years. “It was absolutely stunning. It was spectacular and inspiring and humbling at the same time.”

Even though it had calved just over a week ago, the berg was already showing signs of wear and tear. Cracks wove through B-46, and upturned bergy bits floated in wide rifts. The iceberg will probably break down into smaller icebergs within a month or two, Medley said.

Iceberg calving is normal for glaciers – snow falls within the glacier’s catchment and slowly flows down into the main trunk, where the ice starts to flow faster. Eventually it encounters the ocean, is lifted afloat, and over time travels to the edge of the shelf. There, ice breaks off in the form of an iceberg. When the amount of snowfall and ice loss (from iceberg calving and melt) are the same, a glacier’s in balance. So it’s hard to link a particular iceberg like B-46 to the increasing ice loss from Pine Island Glacier.

A sheer wall of the new iceberg B-46 looms over a mix of sea ice, bergy bits, and snow at the base of Pine Island Glacier, as seen from a NASA Operation IceBridge flight on Nov. 7, 2018. Credits: NASA/Kate Ramsayer

But the frequency, speed, and size of the calving is something to keep an eye on, Medley said. In 2016, IceBridge saw a crack beginning across the base of Pine Island; it took a year for an actual rift to form and the iceberg to float away.

The crack that would become B-46 was first noticed in September 2018 – and the berg broke the next month.

They’re not the biggest glaciers on the planet, but Pine Island and its neighbor, Thwaites, have an oversized impact on sea level rise. Enough ice flows from each of these West Antarctic glaciers to raise sea levels by more than 1 millimeter per decade, according to a study led by Medley. And by the end of this century, that number is projected to at least triple.

“It’s deeply concerning,” Medley said. The geography of these glaciers make them highly susceptible to ice loss: relatively warm waters cut under the ice shelf, weakening it from below. This shock to the system has the capability to initiate an unstoppable retreat of these glaciers. There’s a reason Pine Island and Thwaites are dubbed the “weak underbelly” of Antarctica.

NASA has been monitoring Pine Island Glacier from aircraft since 2002, and IceBridge started taking extensive measurements of the fast-moving ice in 2009.

“Both Pine Island and Thwaites are ready to go and to take their neighboring glaciers with them,” Medley said. “Ice is getting sucked out into the ocean – and it’s hard to stop it.”

Send Me a Postcard From Station P, Will You?

Satellite image of ocean color showing variations in phytoplankton biomass in the Northeast Pacific Ocean (cyan colored swirls). Station P is at the bottom of the image, hidden under the clouds. Credits: NASA

Adrian  Marchetti is an associate professor in the department of Marine Sciences at the University of North Carolina at Chapel Hill and was aboard the R/V Roger Revelle for the EXPORTS field campaign this August and September.

So perhaps you read about the EXPORTS cruise and have heard about this place called Station P. You are now probably wondering why NASA would fund a mission that includes two research vessels spending over three weeks at this place?  Well, to some, Station P (also known as Ocean Station Papa or P26) is simply a point on a map in the middle of the North Pacific Ocean – latitude 50 degrees north, longitude 145 degrees west.  But to others it is much more than that.

Historically, in the 1950’s the Canadian weather service established a program to position ships off the west coast of Canada to forecast the incoming weather and sea state conditions. Station P was occupied for six weeks at a time by one of two alternating weather ships. Spending that much time at sea at one location can get, well, boring.  To help pass the time, the crew collected samples and obtained measurements of the ocean. In the early days, these included bathythermograph casts that measured ocean temperatures at various depths.  As more sophisticated approaches were developed to measure additional ocean properties, they started collecting samples for analysis of seawater chemistry (salinity, nutrient concentrations, etc.), chlorophyll concentrations (used as a proxy for phytoplankton biomass) and performed the occasional plankton haul to discover what critters called Station P their home.

A few decades later, with the development of new satellite technologies that enabled the monitoring of weather conditions from space (thanks NASA!), the weather ships became obsolete, and so the program was discontinued in the early 1980s. But as a result of the decades-long time series, what became apparent was the critical need for long-term monitoring of the ocean.  So the Department of Fisheries and Oceans Canada established the Line P program made up of a transect where Station P is the endpoint.  Today the Line P program is one of the longest ongoing oceanographic time series.

Map of the Line P transect, ending at Station P (also known as Ocean Station Papa or P26) in the Northeast Pacific Ocean. Credits: Karina Giesbrect.

So what’s so special about Station P?  Well, this mostly depends on who you ask. For one, the North Pacific is one of the largest ocean basins.  It undergoes periodic oscillations on approximately decadal timescales that can influence global climate. The North Pacific also represents the finish line of a long conveyer belt that transports deep waters from far-off regions of the planet to the surface.

From a biologist’s perspective (yes, I am a biological oceanographer), Station P also happens to reside in a so-called High Nutrient, Low Chlorophyll (HNLC) region where the growth of phytoplankton is limited by the availability of the micronutrient iron. This is a relatively new discovery, and although evidence for iron limitation in this region dates back to the early 1980s, the most compelling data was obtained in 2002 when Canadian scientists performed a large-scale iron fertilization experiment at Station P. The experiment was named the Subarctic Ecosystem Response to Iron Enrichment Study, or SERIES.

I participated in SERIES as a graduate student while completing my Ph.D at the University of British Columbia.  My Ph.D. research focused on pennate diatoms (a type of phytoplankton) of the genus Pseudo-nitzschiathat that dominate iron-induced blooms in many HNLC regions across the globe .

Microscope image of the pennate diatom Pseudo-nitzschia granii. Diatoms like this one are common responders to iron enrichment in many iron-limited regions of the ocean, including Station P. Credits: Adrian Marchetti.

These particular diatoms can achieve rapid growth rates at iron concentrations that would leave their coastal counterparts fully anemic and left for dead. These oceanic diatoms have many adaptations to survive in