But no sooner had one problem been solved, another appeared. This time the trouble arose from the failure of a piece of equipment on the ship that is at the heart of our acquisition system – the real time navigation unit (or RTNU, for those in the know). This component gathers satellite and other navigational information from the seismic equipment and delivers it to the navigation software on the ship so that we can determine the positions of all of our equipment in the water, and where and when we need to be shooting. Once again, the dedicated technical staff of the Langseth came to the rescue. Painstaking checking and double-checking of each component in the RTNU began last night and continued into the early hours of the morning. In the wee hours, it’s easy to get a little superstitious. Did all these problems arise because Tim Reston and I each accidentally drew in lines on our chart indicating that we’d completed lines in our 3D box before we actually had? Or was it the curse of Costa da Morte (Coast of Death)? This part of the Galician coast is known for its shipwrecks and nicknamed accordingly. Of course, the real culprit was the non-newness of the gear in question. Once again, the Langseth’s miracle workers saved the day by assembling the working parts of various old RTNU’s into one working unit. Thanks to their efforts, we are up and running again….
RTNU carnage on a table in the main lab.
Poseidon's Zodiak on the way over to exchange supplies.
A few years ago, it was realised that seismic provides a method of directly observing the mixing processes, as the different water layers have sufficiently different seismic velocity and salinity for reflections to be generated at their boundaries: we have already seen reflections in the water column of our data, probably from boundaries between North Atlantic water and warmer, more saline Mediterranean water. However there have been relatively few studies of these processes using traditional oceanographic and seismic techniques, a deficiency being rectified by the deployment of XBTs at regular intervals during our cruise.
A successful exchange on medium-high seas!!
In addition to deploying ocean bottom seismometers to record our seismic shots, the German research vessel F.S. Poseidon has been carrying out oceanographic measurements, mainly using CTD casts (conductivity-temperature-depth), which provide more information than XBTs. As a result they had several XBTs left over. These they transferred to us this morning: Poseidon came within about 1 km of the Langseth and sent the XBTs over in a small boat. A real bumpy ride!
Goodbye, until we meet in Vigo!Tim Reston
University of Birmingham
After days of uneventful and productive data acquisition, a pale fell over the R/V Langseth. Early Sunday morning, one of the streamers began to report communication errors and soon failed to communicate at all. A series of tests over the ensuing hours revealed that the problem was not on the ship but in the equipment out in the water. Recovering and repairing seismic gear is not a quick task. To access this streamer, we had to undo many of the steps required to put it out to begin with: recover the port paravane, shift Streamer 3 starboard and out of the way, and then reel in part of Streamer 4. After hours of troubleshooting, the technical staff of the Langseth brought Streamer 4 back to life. All of the equipment on the Langseth is… not new, and this certainly applies to the seismic streamers. The technical staff on the ship are pros at keeping this equipment alive (and many cases bringing it back from the dead). Twelve hours after the problems with Streamer 4 began, it was back in the water, and we were ready to start collecting data again. But no sooner had one problem been solved, another appeared. This time the trouble arose from the failure of a piece of equipment on the ship that is at the heart of our acquisition system – the real time navigation unit (or RTNU, for those in the know). This component gathers satellite and other navigational information from the seismic equipment and delivers it to the navigation software on the ship so that we can determine the positions of all of our equipment in the water, and where and when we need to be shooting. Once again, the dedicated technical staff of the Langsethcame to the rescue. Painstaking checking and double-checking of each component in the RTNU began last night and continued into the early hours of the morning. In the wee hours, it’s easy to get a little superstitious. Did all these problems arise because Tim Reston and I each accidentally drew in lines on our chart indicating that we’d completed lines in our 3D box before we actually had? Or was it the curse of Costa de Morte (Coast of Death)? This part of the Galician coast is known for its shipwrecks and nicknamed accordingly. Of course, the real culprit was the non-newness of the gear in question. Once again, the Langseth’s miracle workers saved the day by assembling the working parts of various old RTNU’s into one working unit. Thanks to their efforts, we are up and running again….
RTNU carnage on a table in the main labDonna Shillington10th June
Today the Poseidon is recovering eight OBH to download the data they recorded and redeploy them elsewhere within the 3-D box. It will be exciting to see the first OBH data! We won't see the rest of the data until the remaining OBS and OBH are recovered in August and September.
Despite being in the same area, here on the Langseth the science party hasn't seen the Poseidon since our first day passing them on the way out to sea from Vigo. However, this may be because we are all busy below deck in the main lab (with no windows) processing data!
Donna Shillington8th June
Map in the main lab showing planned profiles. The ones we've already completed are in green
*Follow our progress on the "Survey Area" page as we update the sail lines every ~4 days.
Marine reflection seismology involves actively generating soundwaves (rather than waiting for earthquakes as in many other types of seismology). The ideal seismic source is as close to a “spike” as possible. Sound waves from the source travel into the Earth, where they reflect off sedimentary layers as well as hard-rock surfaces. The returning reflections are recorded by over a thousand hydrophones (underwater microphones that gauge pressure changes created by the reflected seismic waves) in the streamers that we have been deploying for the last four days.
The source consists of a series of air guns of varying sizes, which are hung at a depth of 9m (~30 feet) below large inflatable tubes. The tubes are 60m (~200 feet) long and each has 9 active air guns (10 with one to spare). In our case there are two sets of air guns being towed 150m (~500 feet) behind the ship, that alternately fire. To create a strong source that is as spike-like as possible, the guns are carefully arranged and fire almost simultaneously. The air is released from the chamber of the air gun, creating a 3300 cubic inch bubble pulse, which collapses to create the sound waves.
Orientation of the streamer and gun arrays being towed by R/V Langseth.
The red circles indicate the location of the gun arrays.We are making sound in the ocean, where many mammals use sound to communicate and hunt for food. In order to ensure we are operating responsibly and minimizing our impact on mammals, we have five Protected Species Observers (PSO’s) onboard who both watch and listen for (from the observation deck in Donna’s previous post) any marine mammal that comes close to the ship. If any are spotted or heard within a specified radius around the ship, we power down the guns until they leave the area.
The second paravane went in the water at 22:00 this evening, and streamer 2 is currently being uncoiled into the water behind the ship. Despite a few delays, we are making good progress!
Marianne Karplus4th June
Most of the science group has been working in 4 hour shifts thus far - 4 hours of work and then 8 hours of time for other things each 12 hour period. The last day or two, I was using my 8 hour rest periods to eat a couple of saltines, lie down, and attempt to ignore the rocking of the ship, but I must be getting used to the seas (and they are calmer!) because I can now do other things like read papers and look at a computer screen.
We have been collecting data almost since we left port. We are mapping the bathymetry, collecting gravity data, recording ocean current directions, etc. Since we entered our 3-D box area yesterday, it's been exciting to identify fault scarps in the bathymetry.
Donna mentioned in her previous post that once a streamer is in the water, its location is monitored and it can be moved around using winged devices called "birds" that are attached to it. Imagine a number of actual birds holding a cable in their talons at an even spacing while flying. Our mechanical birds are not so different, except they are flying the streamer through the water. We can see where the birds are on a computer screen in the lab, and we can control the depths of the birds by remotely moving their wings. When a streamer goes into the water, it can take some time to get the weighting right and then for the birds to dive the streamer down to the desired depth (generally 8-12 meters below the sea surface).
3rd June (posted late due to internet outage)
Assembing a bird to be attached to the streamer.Birds for streamers 2 and 3 waiting to be deployed.
After steaming for twelve hours out of port, we started the long process of putting out all of the seismic gear needed for this program. The weather worsened as we headed towards the field area, and we have been deploying equipment in 3-4 meter swells for the last 18 hours. This ship can roll by up to 10-15 degrees in these conditions (and more than a couple of people are feeling sea sick as a result). On the deck, ropes and cables connected to equipment towed off the back of the ship lurch and clank rhythmically, and water commonly washes over the lower deck. Down in the main lab, stray items that aren’t properly stowed or strapped down start to roll back and forth, the ship creaks and groans, and office chairs swivel with each swell.
For this program, we will be towing an enormous amount of gear behind the ship to enable us to image faults involved in rifting, the exposure of mantle rocks and continental breakup in 3D. Four 6-km-long seismic ‘streamers’ filled with pressure sensors (which can detect returning sound waves) will be towed 200 m apart, for a full spread of 600 meters. As we deploy the streamers, we add weights to ballast the streamer, acoustic units to determine the locations of the streamers, and ‘birds’ that enable us to control the depth of the streamer remotely. We also swap out broken pieces. The streamers are held apart by two gigantic paravanes, which are like large metal kites that fly out from either side of the ship. Each one weighs an astonishing 7.2 tons and is ~7.5x6 meters in size. There are also myriad floats, cables and ropes to maintain the correct geometry of the entire array. The streamers will record returning sound waves generated by two arrays of air guns, which will be towed 100 m apart and fired separately. We expect that it will take us 3 days to deploy this complicated array of equipment behind the ship. The weather is expected to start improving tomorrow afternoon, which will help us greatly!
2nd June Looking forward on the Langseth as she takes a roll in the swell.A streamer with a 'bird' being deployed off the Langseth's stern into the waves.
The R/V Marcus G. Langseth pushed away from the docks of Vigo at 8 am local time. The sun was shining, and the views of the rugged cliffs, forests and Galician towns along the coastline were spectacular. We will only be able to see land at the very beginning and very end of this 45-day cruise. We steamed out of the protected waters around Vigo and out into the open Atlantic Ocean a few hours later, and happily were met by relatively calm seas (1-2 meter swells), although its quite brisk compared to summer weather back home. We actually saw the F.S. Poseidon in the distance as she headed back to Vigo at the end of the first OBS cruise of this program. We only have a relatively short transit of ~10 hours before we begin to deploy the extensive suite of scientific equipment behind the ship needed to image the structures beneath the seafloor in 3D. Putting out the seismic streamers and associated gear will take 3 days!
1st June The science party on deck as the ship departs Vigo.
I returned to New York on Monday, but Lamont-Doherty Earth Observatory scientists Andy Juhl and Craig Aumack remain working in Barrow, Alaska for another week. They’ll continue to collect data and samples in a race against deteriorating Arctic sea ice conditions as the onset of summer causes the ice to thin and break up. Even in the two weeks I stayed in Barrow the ice changed dramatically, shifting from a snow-covered ice pack to a nearly snow-free ice pack, covered in cracks and increasingly large melt ponds. An animation from the May 23 Barrow sea ice radar reveals just how quickly shorefast sea ice can change. Soon the ice will be deemed unsafe for travel by snow machine and spring fieldwork conducted on the ice will end.
Our team’s research in Barrow is just one part in the long process of studying and answering questions about algae growing in and under Arctic sea ice and its role in the marine ecosystem. And, it’s a process that does not necessarily have a defined end — investigating the natural world always leads to more questions. From fieldwork, where observations are made and data gathered, new questions arise, new hypotheses are put forward and new ways of collecting data are developed. This work leads to further experiments where new data and samples are collected, observations are made, analyses performed and results interpreted. Some of the findings will challenge existing hypotheses, leading to their modification, which starts the research process over again.
Fieldwork gives scientists the opportunity to observe systems in a holistic way, leading to new insight and further research questions; each piece of data causes a rethinking of ideas and expectations for future results. “Fieldwork is inspiring and it’s critical to the creative process for environmental science because you often see things that you don’t necessarily see in your data,” said Andy. “There are subtleties and patterns that you can pick on if you pay attention to observe the natural world. You can’t do that in the lab or by looking at numbers.”
Some people may be disappointed to learn that we don’t have many immediate answers about sea ice algae and the Arctic ecosystem based on our month of Barrow fieldwork. But, scientists don’t set out to study things that are already understood or to answer questions that already have answers, and it takes time to unravel Earth’s mysteries. On this trip, project scientists discovered and collected lots of algae, observed novel behavior by marine organisms in the water column and on the seafloor, and gathered lots of data. The next steps in this project are to analyze the samples and data collected in Barrow, interpret these, write up findings and report these in journals and at scientific meetings. And, in 2014, Andy and Craig will return to Barrow to continue their study of sea ice algae, armed with new understanding of the algae, as well as new research questions to explore.
The goal of our project is to understand how ice algae functions and its role in the marine ecosystem, but we’ve received many questions about how ice algae, the residents of Barrow and the rest of life in the Arctic will be affected by a climate that is undoubtedly and irrevocably changing. The answer is that we don’t know, but our research may contribute to future understanding of these issues. Though the Arctic is changing faster than anywhere else on the planet, with temperature increasing and ice volume decreasing, it is still one of the least explored places on Earth. In order to know how climate change will impact this region, the basic oceanographic and ecological processes must first be understood.
As our project progresses, we’ll continue to provide updates and look forward to sharing a video of our time in Barrow that’s being produced by our friends at Climate Science TV. For more information on this research project, visit http://lifeintheice.wordpress.com. Our colleagues at Lamont-Doherty Earth Observatory also travel the world exploring our planet; to keep up with more interesting Earth science research and reports from the field, follow Lamont-Doherty on Twitter and Facebook.
And thanks to everyone who followed our expedition, we enjoyed sharing it with you!
Today they are reloading the ship with 18 more OBS to deploy on Leg 2. The personnel on board will also exchange two Ocean Bottom Instrument Consortium personnel for two GEOMAR personnel.
What is an OBS?
An OBS is an autonomous instrument that sits on the ocean floor and records waves (sound waves as well as other types) traveling through the earth and/or ocean water. All of our Galicia instruments have ocean bottom hydrophones (OBH) to record waves traveling through the ocean (including some types of whale calls!), and a subset of fifty also have geophones to record waves traveling through the sediments and rocks beneath the sea floor.
The OBS record waves by measuring tiny motions of the earth and sea water, converting it into electrical signals, which are stored digitally. The geophones, data logger, and batteries are stored in a water tight, floating sphere, and the hydrophone is attached to the outside of the sphere. A heavy anchor attached to the sphere enables it to sink to the bottom when it is deployed (sent off into the ocean).
To pick up the OBS, the ship goes to the location where it was deployed, and a sound signal with a particular frequency is sent out. The OBS replies acoustically, cuts its anchor, and resurfaces. Scientists can then download the data and begin to piece together a picture of the local Earth structure!
It’s near midnight and Lamont-Doherty Earth Observatory researchers Andy Juhl and Craig Aumack, and Arizona State’s Kyle Kinzler are gathered around a table in their lab at the Barrow Arctic Research Consortium discussing the best way to catch an isopod. When scientists do fieldwork, they enter into it with specific questions and science goals in mind, but one of the joys of exploring the world through scientific research is solving challenges and devising new ways to collect data.
Meet Brinson. He’s a remotely operated vehicle (ROV) along on our Arctic expedition and named in honor of a foundation that provided Andy funding to build him. Brinson, originally designed and built by engineer Bob Martin, and modified by Andy, is the result of an idea that evolved over several years of Arctic fieldwork.
“We were deploying just this ice fishing camera, but were frustrated by the fact that there was always something just beyond our range that we wanted to see,” said Andy. “So we wanted mobility and once we got that we were frustrated by the fact that we didn’t know how big things were, and that’s when we decided we needed the laser pointers to provide scale. So Brinson has been a multi-step evolution into a simple, but well-equipped ROV.”
Brinson now consists of a GoPro camera and a standard ice fishing camera attached to a frame made of PVC pipe that can be lowered into a hole in the ice. On the ice surface, the ice fishing camera’s live video feed shows what Brinson sees as he travels through the water. Brinson is equipped with small bilge pumps that act as motors, which enable him to be maneuvered forward, up, down and side to side via his tethered remote control. When Brinson is below the ice, Craig monitors the video feed and describes to Andy what he sees on the screen. When something of interest appears, Craig tells Andy which way to maneuver Brinson, so they can continue to get footage of the organism.
Brinson recently saw small crustaceans called isopods roaming around the ocean floor. Andy and Craig were excited about this find and very curious to learn more about what isopods might eat and their role may be in Arctic the marine food web. Once Brinson, and Andy and Craig, saw the isopods, it was decided that our team should catch some, but we had no trap or means of doing so.
Scientists need to bring absolutely everything they need, and think they might need, with them on research expeditions, especially those to remote areas like Alaska’s North Slope. So, when, for example, you decide you must build an isopod trap late at night in Barrow, you’re pretty much limited to what you have on hand: a plastic buckets, plastic window screening, electrical tape, rocks, string.
With these materials, a little ingenuity and their limited knowledge of isopod behavior, Craig and Kyle constructed isopod traps. The guys hypothesized that isopods might like chicken, so baited their traps with chicken bones saved from our dinner. The traps were attached to eight meters of string and dropped to the sea floor. Kyle’s trap sat overnight and caught two isopods; Craig’s trap sat on the ocean bottom for several days and contained at least 20 isopods when it was pulled up.
The beauty of the isopod traps is that they worked and project scientists will get valuable data about the Arctic marine food web as a result. “From the underwater videos shot by Brinson, it looks like the activity of the isopods increases after the ice algae exports,” Andy explained. “We think there’s a plausible connection there: the ice algae could be a food source for isopods. We never would have posed that as a hypothesis unless we had the opportunity to observe them and make these connections.”
Fieldwork is, in part, a pattern of observing and questioning, and responding to these with new theories, methods and experiments. It’s also part of a larger creative process that involves improvisation and unconventional thinking. Said Andy, “In the field, we make a lot of stuff out of duct tape and epoxy.”