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XBT (a short story)

The ENAM Seismic Experiment - Tue, 09/30/2014 - 00:53
            “Twenty shots until the next XBT.”
            It was nearing time to launch the next expendable bathythermograph probe, or XBT.  The software was readied and two scientists headed out of the lab, radio in hand.  They donned lifejackets that had once been bright orange but were now closer to a dull rust color from long and dirty use on the deck and selected a T-5 probe from the box.
            Out on the deck they were alone, perched partway up the stack of levels in the stern of the ship, the gun deck below them and the paravane deck above.  It seemed that the others working the graveyard shift were all inside, perhaps wrestling with some mechanical puzzle or else simply keeping watch to make sure all was well, sipping strong coffee, playing cards to pass the time.  The scientists snapped the probe into the gun-shaped launcher.  They removed the plastic end cap from the black cylinder that housed the probe and its spool of fine copper wire.
            “We’re in position.”
            There was a pause, then the radio crackled back, “Launch probe.”
            In a moment the probe was sliding down the long tube that extended out and downward from the starboard side.  With a small splash it plunged from the end of the tube into the inky deep.  Now to wait while it made its journey towards the bottom, more than 4000 meters below.  Despite the very late (or very early, depending on your point of view) hour, it was warm.  The air was muggy – not exactly a welcome change from the air-conditioned lab, although the tinge of diesel fumes was less out here in the relative open.  There was little wind and the seas were calm.  Standing on the moving island of light that was the ship the sea quickly disappeared into the surrounding void.  What surface that could be seen appeared to rise disturbingly close up alongside them, like a churning wall of water.  It was only visible at all by the few swirls of foam formed by the ship’s passage and a reflection here and there off the constantly moving face of the black oily-looking water.  They waited for the go ahead to terminate the probe.
            Down in the lab, there was a strange blip on the screen showing the multibeam bathymetry data, but no one noticed as they were too busy entering in location data for the XBT or scrutinizing the movement of the streamer birds that regulated the depth of the hydrophone streamer.  There were, after all, 36 other monitor screens to watch.
            Outside there was a louder than usual splash.  The two scientists peered into the gloom.
            “Dolphin?” one wondered out loud.
            “While we’re shooting?  I hope not,” the other replied, “We’ll end up having to interrupt the line.”
            Was there something just under the water surface?  A pale sinuous shape at the very edge of the ship’s halo of light?  No, it must be a trick of the light and the weird perspective engendered by the lack of any sense of distance.  Perhaps more coffee was in order when they got back inside.
            The radio crackled again, “Terminate probe.”
            The scientists broke the wire that was still spooling out to the probe that was now falling behind them.  “Probe terminated,” they reported.  They were just turning to leave when it emerged.
            At first it looked like a whale back, though pale milky green in color rather than the expected grey.  As it lifted free from the surface it became clear that it was much longer than an orca or even a grey whale, more like an ancient marble column turned soft and rubbery.  It tapered as more of its length was exposed until the tip broke free of the clinging water.  One side of the enormous snake-like shape was covered with round suckers the size of dinner plates in a poisonous green color.  The cyclopean tentacle towered out of the water, waving gently with a sickening sort of grace ten meters or more above the uppermost deck.  Here and there along its length were clots of a coppery tangled substance, almost like seaweed wrapped around it.  “The XBT wire,” one of the scientists realized from the midst of her fascinated horror.
            The tentacle hovered for another movement before swooping down with surprising swiftness.  The two scientists were neatly plucked from the ship in the blink of an eye.  With a clatter, the radio fell to the deck.  They were held above the water for a long moment, crushed together so tightly they couldn’t speak and could barely draw breath.  Then, slowly, the tentacle disappeared beneath the smoothly rolling waves.

            Two hundred and sixty-seven shots until the next XBT.


-by Tanya Blacic aboard the R/V Langseth (with a wink to H. P. Lovecraft)

Life at Sea

The ENAM Seismic Experiment - Sat, 09/27/2014 - 22:34
September 27, 2014

Our small ship is in a state of endless motion with pitch, roll, yaw, and heave. We continuously experience a feeling of fluctuating gravity at sea, as one minute we are several pounds heavier and the next we are several pounds less. We’re tossed about endlessly like riders at the fair. It’s a feeling that can turn the stomach of the saltiest of sailors, but more often disturbs the newbies the most. At sea there is also no such thing as silence. Out here the engines are always running, hydraulic pumps are always droning, and ships operations occur around the clock. From my bunk I can feel us lurch forward and lean into a turn to starboard, or port, and then they reverse the pitch of the propeller as if applying an emergency brake to slow the ships forward motion. This reverse pitch causes a shudder in the hull that shakes us like a cheap hotel vibrating bed and it chatters every moveable thing. From my bunk I can also hear the acoustic pings emanating from the hull-mounted transducers. Speaking to me in code, they tell me if OBS operations are going well.  Based on the ping styles I can also discern the acoustic techniques used by WHOI and Scripps, so that I know which instrument type is being talked to. All of this information creates a movie in my mind that plays out until I fall asleep. Life on a ship is a constant immersion in all that is going on and for 30-days there will be no escape.

-Ernie Aaron

And then there was data…..

The ENAM Seismic Experiment - Fri, 09/26/2014 - 21:10

It’s been a week since we deployed all of our gear and started steaming along our lines, so now we have amassed a lot of data!  Although we can only steam at very low speeds while towing the equipment (~4.5 nautical miles an hour or  ~5 mph), each time we fire the air gun array, the 636 channels on the seismic streamer listen for returning sound waves for 18 seconds and record a total ~25 Mb of data. Repeat that every 30 seconds for 7 days, and it begins to add up!  We now have 400 Gb of seismic data alone, not including all of the other types of data we collect while underway (bathymetry, magnetics, gravity).  We are a data-collecting machine.  

Matt, Jenna and Derek sit  back and watch the data roll in from the Main Lab
Not only are we collecting data, we are also doing some preliminary data analysis to get a first look at the geology hidden below the ocean, which is always exciting.

Kara and Matt are entranced by velocity analysis
Although we are only a week in, our data collection has already taken us through water depths as shallow as 20 m and as deep as 6000 m.  At the edge of the continental shelf, water depths change rapidly from ~500 to ~3000 m over just 20 km – a slope of 10%.  For perspective, that’s very similar in elevation change and slope to the course for the Pikes Peak marathon.

Perspective view of seafloor depth from MGDS across the continental slope overlain by a higher resolution swath of bathymetric data that we acquired along our transect, which is also shown projected onto the seafloor.
We have also traveled over widely variable geology – from 35-km-thick continental crust to ~7-km-thick oceanic crust, and from sediment thicknesses of 5 m to over 7 km.   Our data are also revealing cool structures in the sediments and crust – faults, sediment waves, and more.  Below is a picture of a salt diapir that we imaged at the edge of the continental margin.  The salt was probably first deposited at least 150 millions years ago in a flat layer, but as more sediments were deposited on top of it, it got squeezed up and out into dramatic diapirs.

Preliminary image of a salt diapir in seismic reflection data near the base of the continental slope. The y-axis shows the time it takes for a sound wave to travel down in the earth and back again. This images shows about ~5 km down into the earth below the seafloor. Donna Shillington aboard the R/V Langseth

First day of land deployment - showing kids how cool seismology is - by Kara Jones

The ENAM Seismic Experiment - Fri, 09/26/2014 - 16:32

(Originally posted on September 12)

Today was the first day of the onshore deployment of the RT130s through southern Virginia and North Carolina. My partner, Yanjun Hao, and I, were just one of five teams working to deploy instruments along the two survey lines. We deployed the first two instruments at West Harnett Middle School and South Hartnett Elementary School, both outside of Lillington, NC. In both case, the fifth and sixth graders were very interested in learning about what we were doing and eager to participate. I explained to them the basic concept of P and S-waves and then asked the children to jump so that we could test that each of the channels on the sensors was working correctly. They very much enjoyed getting to see on the clié exactly what the signal they generated looked like. At both schools, I was surprised how much the children, and the teachers, knew about earthquake seismology and the intelligent questions they asked. A teacher asked whether they would detect the explosives detonated at nearby Fort Bragg, and a sixth grader named Gauge blew me away when he asked if the sensors would be able to record the sound waves generated by the planes or nearby explosions! In total, we probably spoke to 100 kids about the project today. It was a very encouraging to see how excited and interested they all were in the science. When we first arrived and explained that we would be installing a seismometer, a 5th grade teacher looked at us with wide eyed and asked "Are you seismologists?!" I nodded yes and she was so excited she started jumping up and down. Despite some rain and GPS trouble later in the day, the excitement that the elementary and middle schoolers showed about seismology was enough to make it a great start to the deployment.

At South Hartnett Elementary School in Anderson Creek, NC. I am showing one fifth grade class what the seismic signal they just generated looks like on the clié.

The land instruments

The ENAM Seismic Experiment - Fri, 09/26/2014 - 16:26
The insulation was tough but gratifying. The weather in North Carolina is unpredictable. At times it was hot and humid. I was drenched in sweat burying the sensors. Other times we were caught in torrential downpours working under a tarp; terrified by the sound of thunder. The sites were located on mostly private property, hosted by people who were eager to help with the experiment. The interaction with the local people enriched the experience. Many of them showed true southern hospitality. 
 
Station deployed!
From an academic prospective I learned about survey design, instrument deployment and the logistics. This provided a distinctly unique experience that is unavailable in the classroom environment. Beatrice and Dan were tremendously helpful and supportive. I learned a great deal about active seismic from my conversations with them. They’re passionate about nurturing future geophysicist. The GeoPRISMS is an altruistic endeavor for them. I am thankful to them for investing so much of their time and expertise into the project. 

The GeoPRISMS experiment has been an overwhelmingly positive experience. I am grateful to have been given the opportunity to help with the deployment and look forward to my involvement in the recovery of the instruments! A future workshop will be held for processing the data and the inversions. This pre to post educational approach is invaluable to me as a future geophysicist.

Posted by Christopher Novitsky 

The Land Deployment Team!

The ENAM Seismic Experiment - Fri, 09/26/2014 - 15:30
From L-R: Yanjun Hao, David Boyd, Dam Lan, Ana Corbalan, Christopher Novitsky, Pnina Miller, Jason Leiker, Kara Jones, Beatrice Magnani (front), James Farrel (back), Dan Lizarralde.It took us a while, but here we are, the team that deployed the land seismometers on Sept 12-15. The instruments are now continuously recording the Langseth shots and will continue recording for few more weeks. The East Carolina University in Greenville, NC graciously allowed us to use one of the research facilities on their West Campus (a place with a fascinating story - blog on that coming soon!) as the headquarter for operations. We will be back to the field at the end of October to pick up the instruments, download/save the data and demob.

Posted by Beatrice Magnani

The Night Watch in Action!

The ENAM Seismic Experiment - Fri, 09/26/2014 - 12:29
We've captured the process of recovering and deconstructing a Scripps OBS thanks to Harm's nifty GoPro camera attached to the crane. This OBS was a little tricky to hook, but otherwise it was a smooth recovery!



Time series of the recovery after the OBS has been attached to the crane. Photo Credit: Ernie Aaron.



See ya'll later,
Jenny Harding
R/V Endeavor

What are we up to

The ENAM Seismic Experiment - Thu, 09/25/2014 - 16:09
September 25, 2014

        For those of you following at home, it might be a bit confusing on which ship is doing what and where. I've made a little cartoon timeline that will hopefully illuminate our progress so far.
       There are two ships currently in the Atlantic: the OBS deploying R/V Endeavor and the seismic shooting R/V Langseth. The R/V Endeavor has been putting OBS down and picking them back up again on lines 2, 3, and 4 while the R/V Langseth has shot seismic along line 2 and 3, and is going to head over to shoot on line 4 soon.


See you later,

Kate Volk aboard the R/V Endeavor

Group photo time

The ENAM Seismic Experiment - Wed, 09/24/2014 - 13:30

September 24, 2014

Well we have finished deploying OBS on line four and are now transiting back to the beginning of line 3 to start picking OBS back up again. At this point, we've all fallen into our jobs and are working like a well oiled machine. Each shift was able to deploy around 9 or 10 OBS in 12 hours time, moving smoothly from one site to the next. To celebrate our progress so far, I've got some group photos to share.

The science party from left to right: Gary, Dylan, Afshin, Harm, Brandon, Pamela, Jenny, and Kate (Photo credit: Dave DuBois, edited by Gary Linkevich)
The WHOI and SIO OBS technicians from left to right: Ernie, Peter, Mark, and Dave (Photo credit: Gary Linkevich)




The whole science group (Photo credit: Ethan, edited by Gary Linkevich)

The science group in the WHOI van with the WHOI OBS (photo credit: Dave DuBois)See you later,

Kate Volk aboard the R/V Endeavor

The Changing Upernavik Waterfront

Arctic Thaw: Measuring Change - Mon, 07/14/2014 - 08:01

Leveraging Local Knowledge to Measure Greenland Fjords: Understanding the Community

GreenlandicLight2Sm

Project location. Currently we are located in Upernavik prior to moving on to Kullorsuaq.

Project location. Currently we are located in Upernavik prior to moving on to Kullorsuaq.

Project Background: Changing conditions in Greenland’s northwest glaciers over the last decade have led to a range of questions about water temperature and circulation patterns in the fjords where ocean water meets the glacial fronts. We can use satellites to measure the loss of elevation, the acceleration of ice flow, or the retreat of ice from a glacier, but we can’t use satellite measurements to collect water column temperature profiles. Water column profiles would allow us to better determine how much melt is possible at the glacier connection to the ocean, and help us pinpoint why neighboring glaciers are behaving differently.

The Leveraging Local Knowledge project will work with members of local Greenlandic communities to collect water measurements in the fjords. This will assist in determining if warming Atlantic Ocean water is circulating up through Baffin Bay where it enters the fjords to lap against the frozen glacier footholds, causing them to loosen their hold on the rock below. Alison Glacier (74.37N and 56.08W) is selected as the project focus. Emptying into Melville Bay to the east of Kullorsuaq Island and has been undergoing dramatic change over the last decade.

Our Journey: Our research trip to the small village of Kullorsuaq is a journey that will start 200 kms to the south in the community of Upernavik, located 800 kms north of the Arctic Circle. Flying in on a small 37 seat Dash 7 airplane we overlook a coastline that is lined with glaciers flowing into a bay that is dotted with islands. Most are uninhabited, but Upernavik is home to a population of 1500 permanent residents. An island community, the main employment is fishing with the waterfront sporting a range of both commercial and smaller independent fishing boats.

Fishing

Fishing is a major occupation in this waterfront community (Photo M. Turrin)

Upernavik town was established by the Danes in the late 1700s but trade and a religious mission in the early 1800s cemented it as a permanent settlement. The southern end of the island is dotted with a cross covered graveyard representing the religion the Danish settlers brought and the practice of the current community. Christmas, Three Kings Day and other religious holidays are all causes for the community to celebrate. This week the priest will visit Upernavik to celebrate three weddings (Friday and Saturday) and the Confirmation (Sunday). With all such events scheduled for when the priest can preside the parties and celebrations will involve the whole community for days. Celebration and gatherings are a large part of this community’s practice.

Upernavik graveyard (Photo M. Turrin)

Upernavik graveyard (Photo M. Turrin)

The Setting: The icebergs being sloughed from the neighboring glaciers dominate the horizon, littering the waterfront with ice ranging from house-sized blocks to looming masses that appear as large as the neighboring islands. Looking around at the open water it is hard to imagine the origin of these large masses of ice. The closest blocks of ice move during the course of the day, shifting back and forth from north to south and back again. With the shifting and changing of the icebergs the sound of the settling and collapsing of ice is drilled into our consciousness – the sharp crack of the ice as if fractures and the larger canon-like rumble as sections break and fall into the water.

Large Iceberg on the waterfront (Photo M. Turrin)

Large Iceberg on the waterfront (Photo M. Turrin)

Our local host, a Dane who has lived in Upernavik for 40 years, has fully blended himself into the community where he and his family are well known and liked by both the Inuit and the Danish population. When he learns of our project he observes that in his time here ice cover has significantly changed. He recalls his early years here when the ice in May was so solid in the bay that visiting boats had to drop dynamite on the ice to open a pathway. He points to the open water and the line of haze that hangs on the horizon offering a cause, ‘global heating’.

The Community of Upernavik (Photo M. Turrin)

The Community of Upernavik (Photo M. Turrin)

Other changes have hit Upernavik. We meet a Danish couple who had spent 4 years living in the community, now returning after 30 years to ‘close out their memories’. They spoke with fondness of this lost time when they raised their small children as they worked as a teacher and a nurse. With a team of 10 dogs ‘Lars’ had hunted Greenlandic seal and still had a sharp eye picking a bobbing seal head out on the horizon. They spoke of the people numbering 900 while the Greenlandic dogs had numbered 3000, many times more than the dogs are now. Dogsleds were an important part of that older Upernavik when individual hunting and fishing were the mainstay of the community. While hunting and fishing are still important today Lars notes that things have changed becoming less rugged for an individual. Whether the changes in ice cover have played a part in this is hard to determine.

Bear Skin

Polar Bearskin hangs off front porch in Upernavik (Photo M. Turrin)

In our few days here in Upernavik we learn that residents are happy to help, they have networks that reach from one island community to another. Names and contacts are offered freely – “try this person for a place to stay”, “this teacher may be interested in helping you”. It is this networking of local people that we will rely on for the project. Their overall interest in what is happening to their community will be an important part of its long term success.

Glaciers in Upernavik Waterfront (Photo M. Turrin)

Icebergs in Upernavik Waterfront (Photo M. Turrin)

 

Leveraging Local Knowledge to Measure Greenland Fjords:
Dave Porter and Margie Turrin are in northwest Greenland working with local community members to collect water column temperature profiles. The project is funded by a Lamont Climate Center grant with support from the NASA Interdisciplinary Program and logistical support from NSF.

http://www.ldeo.columbia.edu/~dporter/Kullorsuaq/

 

 

Herbie’s Great Adventure: NUM Dendroecological Fieldweek

Kristen de Graauw and Cari Leland

Cari and Kristen here, checking in from Mongolia. This year we were invited to be instructors for the Third National Dendroecological Fieldweek, May 23-29 in Udleg, Mongolia. We arrived to Ulaanbaatar on May 20th so we were fortunate enough to have a few days to recover from some pretty terrible jetlag before beginning the fieldweek marathon. Anyone who has ever attended a fieldweek anywhere in the world knows how challenging (and rewarding!) these events can be. Our first few days of the fieldweek were spent at the NUM (National University of Mongolia) research station near Udleg, a few hours north of UB. We were so happy to see the beautiful countryside for a few days. We got to ride there in this awesome Russian vehicle, which Cari nicknamed Herbie.

 

The roads were rough but Herbie was a trooper and we arrived at the research station safely.

The roads were rough but Herbie was a trooper and we arrived at the research station safely.

We took a break at Teacher’s Pass for a nice panoramic view of the mountains before continuing on to the research station.

We took a break at Teacher’s Pass for a nice panoramic view of the mountains before continuing on to the research station.

The research station was a complex of buildings for housing, a kitchen, and lecture rooms. We shared a cozy room for two and enjoyed beautiful views of the valley and mountains surrounding us.

The NUM Forestry research station

The NUM Forestry research station

Our room from the outside...

Our room from the outside…

..and the inside.

…and the inside (Hi Cari!).

After everyone settled in, we met for the opening ceremony. Baatar gave a nice introduction of the project and the history of the CEME collaboration. There were 8 students in total, and 7 of them were female (girl power!). There was a good mix of participants; from first year undergraduates to PhD students.

Baatar giving the opening ceremony speech.

Baatar giving the opening ceremony speech.

After the opening ceremony we went out to the field. Baatar gave us a guided tour of all the current research projects at the station (there were many!) and the potential sites for the fieldweek. Then we gave a quick lecture on the basics of dendrochronology and headed back towards the research station to discuss potential fieldweek projects.

The flux tower on the research station property. It was pretty impressive.

The flux tower on the research station property. It was pretty impressive.

We noticed Gypsy moth larvae emerging from their cocoons on the ground near the forest.

We noticed Gypsy moth larvae emerging from their cocoons on the ground near the forest.

More gypsy moth larvae after emerging from their cocoons.

More gypsy moth larvae after emerging from their cocoons.

We headed back after a nice hike through the forest.

We headed back after a nice hike through the forest.

Day 2 at the research station was field sampling day. Unfortunately we woke up to a cold and rainy day but that didn’t stop our groups from heading out into the forest. After a long discussion we decided Cari would teach the Climate group and Kristen would teach the Ecology group. Cari’s group headed up the mountain in search of old larch and pine trees to core while Kristen’s group went to a portion of the forest that had been logged. The goal for the climate group was to find moisture-stressed trees and look at the relationship between tree rings and climate. The ecology group’s goal was to determine logging dates and the effects on surviving trees.

Cari’s group preparing to core a large pine near the mountain ridge.

Cari’s group preparing to core a large pine near the mountain ridge.

Kristen’s group coring a living larch near the stump graveyard.

Sundermaa coring a living larch near the stump graveyard for Kristen’s ecology group.

After one of the coldest and rainiest field days we’ve ever experienced we headed back to the field station to thaw and dry ourselves and the cores.

Cari’s group heading back from the ridge.

Cari’s group heading back from the ridge.

While we waited for the cores to dry, the students practiced skeleton plotting.

The students mounting wet cores with tape to help them dry straight.

Margad, Togii, and Badra mounting wet cores with tape to help them dry straight.

Byamba teaching Oyunna a skeleton plotting exercise.

Byambaa teaching Oyunna a skeleton plotting exercise.

The students are working hard on their skeleton plot exercises, while Kristen and Cari check their work.

The students are working hard on their skeleton plot exercises!

Everyone was very anxious to see if their skeleton plots matched!

Everyone was very anxious to see if their skeleton plots matched!

After a rainy day, we were treated with a beautiful sunset.

After a rainy day, we were treated with a beautiful sunset.

The next day we mounted the cores with glue and taught the students how to sand. They quickly learned that a well sanded core took time, patience, and persistence. At the end of the day we headed back to UB to begin laboratory methods.

Sainaa sanding her first core.

Sainaa sanding her first core.

Kristen telling the students they need to sand more! “Sand more!!”

Kristen telling the students they need to sand more…“Sand more!!”

The view from our sanding “room”. Not bad!

The view from our sanding “room”. Not bad!

Back at the university we had to hit the ground running with lab methods. The students skeleton plotted the samples from the research station one day, learned how to do the list method and measure the next day, and finally on the last day they learned how to run COFECHA and read the output files. It was challenging but everyone worked their hardest. The final day was very busy. The students were working on their presentations until the very last minute. The groups did an outstanding job presenting their projects, which made us feel so grateful for being able to teach such a bright and dedicated group of students. During the closing ceremony Baatar gave us both a really nice Mongolian tree and shrub guide book and then presented each student with a certificate of achievement. The students then gave us the most thoughtful gifts of Mongolian art and script.

Oyunna discussing the correlations between climate and pine during the climate group presentation.

Oyunna discussing the correlations between climate and pine tree growth during the climate group presentation.

Baatar presenting Margad with her certificate of achievement.

Baatar presenting Margad with her certificate of achievement.

 Cari, Margad, Togii, Sundermaa, Oyunna, Sainaa, Gerelee, Baatar, Sanaa, Kristen, M?, Byambaa, and Badra.
The whole group after an amazing fieldweek! From the left: Cari Leland*, Margad Ovgonkhuu, Togtokhbayar Erdene-Ochir, Sundermaa Sergelen, Oyunmunkh Byambaa, Sainbayar Gombo, Oyungerel Sereenen, Baatarbileg Nachin*, Oyunsanaa Byambasuren*, Kristen de Graauw*, Myagmarsuren Batdorj, Byambagerel Suran*, and Badar-Uugan Khasbaatar. ( *Instructors)

 

 


Categories: TRL

Clock Is Ticking in West Antarctic

Melting Glaciers-Tracking Their Path - Fri, 05/23/2014 - 12:54
Pine Island Glacier, Antarctica

The leading edge of the floating ice tongue of the Pine Island Glacier, Antarctica. Photo: M. Wolovick

Reports that a portion of the West Antarctic Ice Sheet has begun to irretrievably collapse, threatening a 4-foot rise in sea levels over the next couple of centuries, surged through the news media last week. But many are asking if even this dramatic news will alter the policy conversation over what to do about climate change.

Glaciers like the ones that were the focus of two new studies move at, well, a glacial pace. Researchers are used to contemplating changes that happen over many thousands of years.

This time, however, we’re talking hundreds of years, perhaps — something that can be understood in comparison to recent history, a timescale of several human generations. In that time, the papers’ authors suggest, melting ice could raise sea levels enough to inundate or at least threaten the shorelines where tens of millions of people live.

“The high-resolution records that we’re getting and the high-resolution models we’re able to make now are sort of moving the questions a little bit closer into human, understandable time frames,” said Kirsty Tinto, a researcher from Lamont-Doherty Earth Observatory who has spent a decade studying the Antarctic.

“We’re still not saying things are going to happen this year or next year. But it’s easier to grasp [a couple of hundred years] than the time scales we’re used to looking at.”

The authors of two papers published last week looked at a set of glaciers that slide down into the Amundsen Sea from a huge ice sheet in West Antarctica, which researchers for years have suspected may be nearing an “unstable” state that would lead to its collapse. The West Antarctic Ice Sheet is mostly grounded on land that is below sea level (the much larger ice sheet covering East Antarctica sits mostly on land above sea level).

Advances in radar and other scanning technologies have allowed researchers to build a detailed picture of the topography underlying these glaciers, and to better understand the dynamics of how the ice behaves. Where the forward, bottom edge of the ice meets the land is called the grounding line. Friction between the ice and the land holds back the glacier, slowing its progress to the ocean. Beyond that line, however, the ice floats on the sea surface, where it is exposed to warmer ocean water that melts and thins these shelves of ice. As the ice shelves thin and lose mass, they have less ability to hold back the glacier.

What researchers are finding now is that some of these enormous glaciers have become unhinged from the land – ice has melted back from earlier grounding lines and into deeper basins, losing its anchor on the bottom, exposing more ice to the warmer ocean water and accelerating the melting.

In their paper published in Geophysical Research Letters, Eric Rignot and colleagues from the University of California, Irvine, and NASA’s Jet Propulsion Laboratory in Pasadena, Calif., described the “rapid retreat” of several major glaciers over the past two decades, including the Pine Island, Thwaites, Haynes, Smith and Kohler glaciers.

“We find no major bed obstacle upstream of the 2011 grounding lines that would prevent further retreat of the grounding lines farther south,” they write. “We conclude that this sector of West Antarctica is undergoing a marine ice sheet instability that will significantly contribute to sea level rise in decades to come.”

The region studied holds enough ice to raise sea levels by about 4 feet (Pine Island Glacier alone covers about 62,000 square miles, larger than Florida). If the whole West Antarctic Ice Sheet were to melt, it could raise the oceans about 16 feet.

 Eric Rignot

The glaciers studied by Rignot’s research team. Red indicates areas where flow speeds have increased over the past 40 years. The darker the color, the greater the increase. The increases in flow speeds extend hundreds of miles inland. Image: Eric Rignot

In the second paper, Ian Joughlin and colleagues from the University of Washington used models to investigate whether the Thwaites and Haynes glaciers, which together are a major contributor to sea level change, were indeed on their way to collapsing. “The simulations indicate that early-stage collapse has begun,” they said. How long that would take varies with different simulations – from 200 to 900 years.

“All of our simulations show it will retreat at less than a millimeter of sea level rise per year for a couple of hundred years, and then, boom, it just starts to really go,” Joughin said in a news release from the University of Washington.

Many scientists who’ve been studying the region were already braced for the storm.

“It’s gone over the tipping point, and there’s no coming back,” said Jim Cochran, another Lamont researcher with experience in the Antarctic. “This … confirms what we’ve been thinking for quite a while.”

Cochran is principal lead investigator for Columbia University in Ice Bridge, the NASA-directed program that sends scientists to Antarctica and Greenland to study ice sheets, ice shelves and sea ice using airborne surveys. Much of the data used in the new papers came from the Ice Bridge project.

Tinto, also an Ice Bridge veteran, agreed. “I thought it was pretty exciting, because we’ve all been working on this area for a long time, and that potential for the West Antarctic Ice Sheet to behave in this way, we’ve been aware of it for a long time,” she said. “[It] made me want to get in there and look at the rest of the area, what else is going on.”

And there are still many questions about what’s going on: How fast the ocean that swirls around Antarctica is warming, how those ocean currents shift, and to what extent that is influenced by global warming.

“I have a problem with the widespread implication (in the popular press) that the West Antarctic collapse can be attributed to anthropogenic climate change,” said Mike Wolovik, a graduate researcher at Lamont-Doherty who studies ice sheet dynamics. “The marine ice sheet instability is an inherent part of ice sheet dynamics that doesn’t require any human forcing to operate. When the papers say that collapse is underway, and likely to last for several hundred years, that’s a reasonable and plausible conclusion.”

But, he said, the link between CO2 levels and the loss of ice in West Antarctica “is pretty tenuous.” The upwelling of warmer waters that melt the ice has been tied to stronger westerly winds around Antarctica, which have been linked to a stronger air pressure difference between the polar latitudes and the mid-latitudes, which have in turn been linked to global warming.

“I’m not an atmospheric scientist, so I can’t evaluate the strength of all of those linkages,” Wolovik said. “However, it’s a lot of linkages.” And that leaves a lot of room for uncertainty about what’s actually causing the collapse of the glaciers, he said.

Researchers have been discussing the theory of how marine ice sheets become unstable for many years, said Stan Jacobs, an oceanographer at Lamont-Doherty who has studied ocean currents and their impact on ice shelves for several decades.

“Some of us are a bit wary of indications that substantial new ground has been broken” by the two new papers, Jacobs said. While ocean temperatures seem to be the main cause of the West Antarctic ice retreat, there’s a lot of variability in how heat is transported around the ocean in the region, and it’s unclear what’s driving that, he said. And, he’s skeptical that modeling the system at this point can accurately predict the timing of the ice’s retreat.

But, he added, “this is one more message indicating that a substantial sea level rise from continued melting of the West Antarctic Ice Sheet could occur in the foreseeable future. In the absence of serious near-term greenhouse gas mitigation efforts, such as an escalating tax on carbon, they may well be right.”

“It starts bringing it a little closer to home,” said Tinto. “It’s a significant amount of change, but something we can start planning for. Hopefully [this will] make people stop procrastinating and start planning for it.”

Cochran agreed: The papers’ message is “that … over the next couple hundred years, there’s going to be a significant rise in sea level, and at this point we can’t stop it.” But, he added, “it doesn’t say give up on trying to cut emissions. … [Just] don’t buy land in Florida.”

____________________________________________

For further details on what’s going on in West Antarctica, check out these resources:

The two papers in question:

Widespread, rapid grounding line retreat of Pine Island, Thwaites, Smith and Kohler glaciers, West Antarctica from 1992 to 2011, E. Rignot, J. Mouginot, M. Morlighem, H. Seroussi, B. Scheuchl, Geophysical Research Letters (2014)

Marine Ice Sheet Collapse Potentially Underway for the Thwaites Glacier Basin, West Antarctica, Ian Joughin, Benjamin E. Smith, Brooke Medley, Science (2014)

Armin Van Buuren, Ancient Wood, and Ghengis Khan: This is not your father’s field research in Mongolia

We never expected this. Enkhbat had us hovering at warp speed along the Millennium Road in the northern shadows of the Khangai Mountains. Armin Van Buuren’s A State of Trance filling our rig. We were starting a new project to study the interaction between climate, fire, and forest history in the land of Chinggis Khaan and a silky voice was lifting us higher, “and if you only knew, just how much the Sun needs you, to help him light the sky, you’d be surprised. Do…do…do.do”. We were exhilarated. The Sun was shining. This was not exactly Chinggis’ steppe. But little did we know, we would eventually be chasing his ghost.

 

Image

Byarbaatar & Amy in front of Khorgo, unknowingly about to meet Chinggis’s ghost. Photo credit: Enkhbat.

After about a day’s travel we started passing the Khorgo lava field. Amy asked, “What’s that?” Neil had forgotten about this landmark despite having walked upon it 10 years prior. It is a ~30 km2 lava field with old trees on it. Gordon Jacoby, Nicole Davi, Baatarbileg Nachin, and others had sampled in the early aughts and put together a ca 700 yr long drought record from Siberian larch. Neil relayed this information to Amy and she said that we should sample on it knowing that a 2,000 yr long record in the American Southwest had been produced on a similar landscape feature. We had a tight schedule, but as we drove out to the western edge of the Khangai’s, sampled sites, witnessed a sheep in the dying throes of a brain worm infection, got snowed on, and then sweated in much warmer temperatures, we decided it was worth the time to see what was out there. Little did we know.

By the time we arrived to start sampling, Neil was getting sick (we learned days later that Neil was coming down with tonsillitis) and we were on fumes from some bone-challenging swings in the weather. Amy pushed on during the first day with Byarbaatar and Balginnyam. The found a pile of dead horse bones and couldn’t get the chainsaw running stopping them from acquiring samples from downed, dead trees. It felt almost hopeless.

We summoned our strength the next day and explored a new section of the lava field. Soon after getting out there we starting seeing Siberian pine, a tree Neil hadn’t seen on his first visit and hadn’t been sampled previously at this site. We decided that after our fire history collection we would sample some pine trees just to see what They might have to say.

 

Image

The Logo Tree: The Siberian pine that clued us into the possibility that there might be something extraordinary on the Khorgo lava field. Photo credit: Amy Hessl

As this collection wasn’t priority, these samples sat until late January of the following year. Here is the first email of the discovery (partially redacted for some sensitive language).

 

The sample “locked in and said the inner ring i measured was 1235…whoa! that was cool b/c i started a good bit from the pith…. i race back to me scope and measuring stage…..make mistakes. going too fast. fix the mistakes…..the PITH is 1142!!!!

yes, i can see the yr Chinggis was born. i can see the yr he died. i can see the yrs Mongolia rose to rule Asia!

this has been our Holy Chinggis during the entire Mongolian project.

this is totally hot censored.

neil

ps – i guess we are going back to Khorgo, huh?”

 

Image

KLP0010a – the first sample of Siberian pine from the 2010 Khorgo lava collection to break the 1200s. The pith is 1142 CE (Common Era). Photo credit: Neil Pederson

We secured funding and we went back to Khorgo in 2012 with a bigger crew and one goal in mind – collect more wood.

We cannot believe what we have found.

For centuries, common wisdom held that the Mongols were driven to conquest because of harsh conditions – drought. Our new record, dating back with confidence to 900 CE (Common Era), indicates the opposite. After the unification of the Mongols, Chinggis Khan, you know him as Ghengis Khan, led his army from Northern China in 1211 to the Caspian Sea in 1224 CE. Our new record in PNAS indicates that it was consistently wet from 1211-1225, a period we are calling the Mongol Pluvial (look for an open access version of this paper here or contact Amy or me). No years during this period were below the long-term average, which is a singular rare run of moisture conditions in our 1,100 year long record. Independent tree-ring records over extra tropical Asia also indicate that this period was warm.

On the cool semi-arid steppe of Central Asia, water is life and in those days, water was energy. The Mongol diet is heavily based on the meat of grazers. Their mode of transportation was the short, but Pheidippidic horse. So, for food and for travel, grass is life. Grass is energy. An abundance of moisture would seem to provide the horsepower for the rapidly growing Mongol Empire. The Mongol soldier had five steed at their disposal. With a large army, that quickly translates into a huge herd and a huge need for grass.

Our tree-ring record suggests that the grasslands of central Mongolia were likely productive. They strongly agree with satellite estimates of grassland productivity. Going back in time, then, the trees would suggest the Mongol Empire during its rapid expansion was sitting in a sea of grass, a sea of energy, a potential abundance of life.

That is our hypothesis, anyhow, and something we will test in the coming years with historical documents, environmental records from lake sediments, more tree rings, and ecological modeling experiments.

While this record speaks to a rapid transformation of Eurasian culture during the 13th century, it also speaks about an abrupt transformation in Mongol culture today. Towards the end of our tree-ring record we see a prolonged drought from the end of the 20th century into the beginning of the 21st century. This drought followed the wettest century of the last 11 and occurred during the warmest period of the last 1,100 years in Asia. The abrupt transition in the environmental conditions, a transition that saw hundreds of lakes and wetlands disappear from the landscape, occurs during the transition from a more agriculturally-based economy to a more urban-based economy. These severe conditions, in combination with some harsh winters, killed millions of livestock and are thought to be one trigger of a mass migration of Mongols from the countryside into the capital of Ulaanbaatar.

 

Image

Ulaanbaatar in 2006. The homes on the far hills likely reflect climatic and economic refugees moving from the countryside into the city. Photo credit: N. Pederson

Though we cannot connect this heat drought to climate change (though maybe we kind of can), warming temperatures have stacked the deck towards higher evaporative demand, so even if the amount of precipitation remains the same, high temperatures will generate a more intense drought. That’s what we observed in the early 21st century and based on past moisture variation in Mongolia and future predictions of warming, we would expect to see similar events in the future.

From Armin Van Buuren to Chinggis Khaan to Armin Van Buuren again. We had no clue of how Summer 2010 would light the sky.*

 

_____________

 

* this post was requested by a media outlet so they could have the ‘author’s voice’ on this discovery. That version was ultimately sanitized for your protection. Here it is unadultered.

 

 


Categories: TRL

Long lines and lots of instruments

Sugar - Tue, 03/25/2014 - 11:38
If you want to image the Earth’s crust and upper mantle with seismic data, you need to record the arrival of seismic waves that have propagated down to, in our case, depths of up to ~30 km.  These deep-diving phases travel quickly through the denser, higher velocity rocks of the lower crust and upper mantle, and they arrive back at the surface ahead of shallower phases at long source-receiver offsets (see video below).  




To record these lower-crustal and upper-mantle phases as “first arrivals”, where they are not obscured by the arrival of energy from shallow paths, we use long lines.  Long lines mean lots of receivers and lots of driving to deploy and recover these instruments.  We could have used lots of sources instead, but the blasts we used to get seismic energy into the lower crust and upper mantle in this experiment take a lot of time and money to setup.  Receivers are much cheaper, so we used a lot of them.  (For similar wide-angle/long-offset work at sea, airgun sources are cheaper than putting seismometers on the seafloor, so we use many shots and a smaller number of receivers out there.)


This time-lapse video shows Team 13 of 14 recovering 89 of the 1200 total short-period seismograph stations from where our line crossed Fort Benning, near the northwestern end of the line.



Nathan Miller, LDEO


Deploy in the rain, recover in the sunshine…

Sugar - Tue, 03/25/2014 - 00:32


Weather map during deployment.
When the time came to install our 1200 small seismographs across Georgia at the flagged positions, the rains came….   A lot of rain.  During our first deployment day, we received 1-2 inches of rain, and another wave of rain clouds came through on Day 2 (check out map). Roads that used to be easily passable became mudholes or were flooded with water. All-wheel-drive vehicles and drill rigs alike got stuck, and a few station locations could only be reached on foot. Our hard-working field crew labored in the rain digging holes and deploying seismometers.  Vehicles, equipment and people were covered in the famous Georgia red clay (and other muds and sands of Georgia and northernmost Florida). Adding insult to injury, problems with the programming of some of the instruments meant that we actually had to pick up and redeploy many of them. It was a mudbath.  Nonetheless, our field crew managed to deploy 1200 seismometers across Georgia by Tuesday at sundown. It was an impressive show of endurance, and an inspiring display of positivity given the number of people that were still smiling and upbeat at the end of it all. 
A couple of days later, after our seismic shots, it was already time to pick up the instruments, and the weather changed completely.  The sun shined on SW Georgia, and we picked up almost every last seismometer in just one day under blue skies….  
Donna Shillington, LDEO

Random Pictures from the Road (and otherwise)

Sugar - Wed, 03/19/2014 - 13:43
As a follow follow up to Chastity's post, I thought a few random pictures from the road would be entertaining. I have been part of group 5 and as such responsible for the part of the line that spans from Hahira in the south to just north of Adel.

 South-central part of the seismic line. The yellow line is team 5's section.  We have been in a relatively rural part of Georgia and as a result have not encountered many locals save a few who have stopped to ask if we are ok. However, we have seen quite a few interesting things that are quite out of the ordinary (to me at least).

Friendly Muscovy duck.Rocks in a stream bed with associated pink spongy material (?)
Spanish moss.Linguoid (current) ripples on a washed out road. We have also seen quite a few old abandoned farm houses in various stages of aging...



At least 10-15 dogs were standing guard at this house, including about 8 puppies.

Caroline making some new friends.
All said we have dug 122 holes in team 5's stretch. We have also helped deploy instruments in other sections as well and while doing so have seen others hard at work.

Meghan and Nate getting it done!Along the way the cars have taken quite a beating and have actually held up pretty well. Although there have been a few instances where people got stuck, I think that the people with the toughest job will be the guys that have to detail the cars upon their return...



A more appropriate vehicle (?)And lastly here's a couple more random pictures that I thought were interesting.

The large disparity in fuel grade gas prices.
A ~perfectly leveled geophone (it's harder than you'd think).Hopefully this random selection of pictures was entertaining. Up next we will post about last night's "shots." In the meantime, I can say that they were all successful with varying degrees of excitement. The most important thing is that all of our hard work is being realized as the instruments are recording refractions from buried geology that will help us unravel some of the mystery that surrounds events that happened in this area long ago.

James Gibson, LDEO

Rain, geophones, and animals … Oh my!

Sugar - Tue, 03/18/2014 - 17:15

Chastity Aiken
Georgia Institute of Technology

Flags, Flags, and More Flags - Locating the sites for 1200 instruments

Sugar - Sat, 03/15/2014 - 23:14
Many of the SUGAR field team arrived in Americus, GA on Wednesday to start helping with the massive charge of deploying 1200 seismic instruments along the SUGAR seismic line.  The seismic line spans 200 miles from northwest Georgia to just past the Georgia-Florida border; a 4+ hour car drive from end to end!  Everyone gathered early Thursday morning on the idyllic Georgia Southwestern State campus to meet with the chief scientists and learn about the proper techniques for identifying installation sites for the seismographs (just the first step in installing the instruments).  With neon orange safety jackets, numerous maps, GPS devices, packets of official permitting documents, and heads full of safety precautions the field team split into seven two-person pairs each equipped with their own squeaky clean rental car (though they didn’t stay clean for very long!).  
The fleet of SUGAR rental cars looking clean and shiny before being driven
into the field where they undoubtedly got a little mud on their tires.
Each pair of field assistants was given a segment of the seismic line to drive and flag locations for instrument installation deemed safe both from the seismograph (i.e. dry, firm soil) and the install team (i.e. a safe distance from the road).  Given the shear distance of the seismic line, teams found themselves amid diverse backdrops from rolling farmland with overly friendly cows to buzzing residential neighborhoods to sandy stretches flanked by towering groves of Ponderosa Pine trees. 
Antonio placing a flag and using a GPS device to note the location where a
seismograph will be installed amid the sandy surroundings of a Ponderosa Pine farm.
Every team was able to flag all their sites within just two days leaving us the luxury of a sunny Saturday morning free for exploring more of our beautiful Georgia surroundings.  Next up is the actual task of installing the 1200 seismographs which will involve twice the people, six more (temporarily clean) vehicles, and of course countless exciting adventures from the field.  Happy (almost) St. Patrick’s Day from Americus!
A picturesque county road near Jasper, FL along which instruments will be deployed.
-- Natalie Accardo, LDEO





A day with the seismic source team in photos

Sugar - Fri, 03/14/2014 - 23:43
The source of sound waves for the SUGAR experiment will be a series of controlled blasts along the profile.  For each of these, we drill a 60-100 ft deep hole, place emulsion explosives with boosters and caps at the base of the hole, and fill in the rest of the hole with dirt and gravel.  Each seismic source location requires a substantial amount of work by drillers and the UTEP seismic source team.  Below, Adrian Gutierrez shows a day in the life of the source team with pictures (Donna Shillington, 13 March 2014)

Adrian Gutierrez, 13 March 14
7:30 am: Leave Georgia Southwestern State University, where we are staying, and head to the site8:20 am: Arrive at site 8:30 am: Start drilling and take geological samples every 5 ft.

9:00 am: Dyno Nobel truck arrives; load emulsion into cut PVC pipe sections that serve as a holders for emulsion.
9:30 am: Surprise visit from other scientists on the project9.50 am: Setting up the booster in the emulsion.11.20 am: Loading the explosives into the drill hole12.00 pm: Drill crew starts removing their equipment12.45 pm: Tagging the charges and plugging the hole3.15 pm: Move onto the next drill site.Nighttime: Finally back to the dorm.



Arrival of the seismic equipment!

Sugar - Tue, 03/11/2014 - 19:57
Boxes with seismographs and other equipment
During this project, we will deploy 1200 small seismographs along a 200-mile-long (300-km-long) profile across Georgia.  All of these seismographs were shipped to Georgia from Socorro, New Mexico. This is the headquarters of the Incorporated Research Institutions for Seismology (IRIS) Program for Array Seismic Studies of the Continental Lithosphere (PASSCAL), a facility that provides seismic instrumentation to US researchers.  It takes a lot of boxes to hold all 1200 seismographs and the associated equipment and tools.  There are 15 seismographs per box, so that's 80 boxes alone without counting boxes for geophones, etc. 

Fortunately, we have a lot of space! Our field headquarters is located in a historic gym on the campus of Georgia Southwestern State University in Americus, GA.  Faculty and staff at GSW have been extraordinarily generous with their time and expertise. They are allowing us to use the Florrie Chappel gym as our base of operations, and they have helped us enormously with Georgia geology and logistics coordination, handling our huge shipment of equipment and supplies, housing on the campus (many of us are staying in one of the dorms!), setting up the gym with internet access, power, and tables, and much, much more. Today, they moved all of the boxes with our seismic equipment from the shipping warehouse to our field headquarters in the gym. I can sense that all of our seismic instruments are itching to be deployed....
Pallets waiting outside the Florrie Chappell gym
Donna Shillington
11 March 2014

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