Seven days and eleven flights after we arrived in Alaska, we finished deploying our seismic stations onshore. Our final constellation of stations differs a little from our original plan (as always happens with field work), but achieves our main goal of instrumenting the part of the Alaska Peninsula that is nearest to our planned offshore work on the R/V Langseth. We installed our final seismic station yesterday in aptly named Cold Bay. This town sits next to a large bay with the same name and is famous for its wind. The most common damages sustained by cars and trucks here are jack-knifed doors from the wind (as I learned the hard way!).
As luck would have it, we finished deploying our seismometers just in time to catch a large earthquake (magnitude 7.2) that occurred farther west in the Aleutians around the Fox Islands. Of course we would love to immediately look at the recordings of this event on our stations, but we must wait patiently until August when we return to recover them. Many permanent seismic stations are telemetered, so data are transmitted back to scientists in near real time. But for temporary deployments like ours, the data are just written to a local disk and thus must be downloaded in person at the station.
We did have the chance to take a sneak peak at some of the data recorded at our station in Nelson Lagoon during the first few days of our deployment. Reassuringly, we saw evidence for several local earthquakes in these data, including a magnitude 3.1 near Sand Point.
Now that the onshore deployment is finished, Katie and Guy departed for home, and I soaked in some sunshine in Anchorage and started looking ahead to our upcoming research cruise. Tonight I fly to Kodiak to await the arrival of the R/V Langseth and our shipboard science party…
June 20, 2011
This morning we left Arequipa and the comforts of the tourist trail, driving east across the puna towards the Andes proper. Our route took us along the newly constructed Caraterra Interoceanica – a highway linking the Pacific coast of Peru to ports in Brazil – and up to elevations of 4700 m. Along the way we passed the smoking Volcan Ubinas, Peru’s most active volcano, and the enormous inland sea of Lake Titicaca. As we approached the Cordillera Carabaya, which bounds the puna to the east, the clouds increased and the landscape changed dramatically, from desert to grassland.
In recent weeks, social unrest related to the opening of a gold mine near the city of Puno has resulted in violent protests. Though we were able to avoid Puno as we travelled east, this sort of anti-mining sentiment underlines the importance of obtaining the blessing of locals to carry out our research on their land.
By mid afternoon we arrived in the small town of Crucero, located at 4100 m beneath Laguna Aricoma – our first site. This town is, frankly, a bit grim, consisting of grey concrete houses and rubble streets, and located on a windswept plain below the mountains. Nonetheless, we’ll spend the night here in order to meet with the governor tomorrow. Fingers crossed that he will remember us and grant us permission once again to roam around. To end on a light note, the Cordillera Carabaya happens to be the alpaca centre of the universe, and so there is a high chance that one of these cute fluffy camelids will end up on our dinner plates tonight.
19th June 2011
What a difference a day makes! We’ve said goodbye to the sprawling metropolis of Lima and now are happily settled in Arequipa – the White City. This name refers to the white sillar rock used in the construction of the old colonial city and which is in fact a pyroclastic deposit from the volcanoes towering above us. From our hotel room I can see the massive bell-shaped peak of El Misti (5800 m), the only active volcano of the group, and it’s looking particularly snowy this year. In fact, flying in to Arequipa, I was surprised to see so much cloud. Normally, with this being the dry season, the sky in this desert region is blue and the mountains dry. Perhaps we should prepare for some wet, snowy field work!
Thankfully, nothing has changed at La Casa de Melgar, our Arequipa base, and I dug out my sampling tools from where I’d stashed them last year, a little dusty but in perfect working order. The rest of our gear, due to its incredible weight, is making its way slowly from Lima by road and should be here tomorrow morning. As for Matt, we found him in the airport, looking surprisingly fresh-faced after his red-eye flight, and so our field team is now complete.
We’ll spend the rest of the day organizing our transport and, in the interests of science, sampling the rather incredible local cuisine.
Every field location comes with logistical hurdles, and the Alaska Peninsula is no exception. Weather, wildlife and modes of transport pose the greatest challenges. We are hardly the first scientists to encounter these: Lamont-Doherty Earth Observatory has a long, rich history of collecting seismic data in this region (e.g., Shumagin Seismic Network, which ran for >20 years), and many groups continue to collect geophysical data here today.
The Alaska Peninsula is too rugged and wild for a network of roads, so planes, helicopters or boats are the only transportation options. We opted for planes, which immediately imposed a restriction on the locations of our seismic stations: they must be near airstrips. Happily, the Peninsula is sprinkled with small communities and lodges with airstrips, most of which lie close to the Pacific or Bering coasts rather than in the remote interior. Back in the office before our deployment, we chose the most ideally located airstrips for our stations and connected the dots between them with the most efficient possible flight plans. But, our plans quickly changed once we were in the field. The weather dictates when and where you can fly each day, and it varies dramatically. We have been lucky enough to have several clear days (even saw some blue skies and sunshine!), but other days we have been grounded by weather and wiled away the time indoors at the inn in Nelson Lagoon.
Once we arrive in each location, we need a quiet, safe place to install our equipment and a ride from the airstrip. On both counts, local communities have been unwaveringly helpful and friendly. The two school districts here kindly granted us permission to install our seismic stations at any of their schools, and we also obtained permission to place equipment at various lodges and village offices. Residents volunteered to take our gear and us from the airstrip to our sites. In one town, our pilot made a general plea over the radio: “Is anyone listening on Channel 3? I’m here at the airstrip with scientists who need a ride to the school”. Someone answered immediately and picked us up 5 minutes later.
Many of our sites are in spectacular places near remote lodges or in towns nestled between mountains and the ocean. All of them are home to impressive wild life that poses a risk to our equipment, particularly bears. We can protect the equipment against curious small animals but fully bear-proofing a station for a short (two-month-long) deployment is not feasible. Instead, we hope that placing our stations in villages (rather than in the wild) will provide some protection, but we will also need good luck. Fingers crossed…
18th June 2011 Lima, Peru
Our 2011 field season is underway. After a full day’s travel from New York, we arrived in Lima, the capital of Peru. This sprawling city perched on the edge of the Pacific Ocean is home to more than nine million people and, after Cairo, is the largest desert city in the world. Being winter in the Southern Hemisphere, the Peruvian coast is swamped by fog rolling in off the cold Humboldt Current and the sky over Lima is grey with smog and cloud. It’s surprisingly cool, too. Only the palm trees, cacti, and spectacular Spanish colonial architecture remind you that this is indeed the tropics.
Since our work will focus on detailed mapping and sampling of glacial deposits, we are heavily reliant on high-resolution aerial photographs of the field sites. Therefore, our first port of call this morning was the Instituto Geografico Nacional, a cartographer’s dream where enormous collections of maps and imagery are stored. It’s a spartan building with a distinct military air – a real throwback to more austere times – but the personnel there were very helpful, dutifully returning from store rooms with stacks of black and white photographs for us to peruse. Incidentally, these photos were taken in the 1960s by the United States Air Force and it never ceases to amaze me just how much the has retreated over the past 50 years. Some of the glaciers have vanished.
With that chore done, we’re currently packing (and repacking) our equipment for the next leg of our journey. Tomorrow we fly to Arequipa, Peru’s second city, located at 2300 m at the foot of the famous Volcan Misti. There we’ll meet up with Matt, who’s on his way from Tacoma as I write. Though we’ve been here only a few hours, it’ll be great to leave the coastal smog for the blue skies of the Andes.
The first component of our program is to deploy seismometers onshore around the Alaska Peninsula. These instruments are very sensitive, so they can record small, local earthquakes, distant large earthquakes and (importantly for our project) the sound source of the R/V Langseth. However, there are no roads connecting towns on the Alaska peninsula, so one must go by air or by sea to get around. We decided to charter a plane with a pilot based in Nelson Lagoon, a town of 80 people situated on a long, narrow sandy spit jutting out into the Bering Sea.
Katie Keranen (U. Ok), Guy Tytgat (PASSCAL) and I took a series of commercial flights on progressively smaller planes to arrive in Nelson Lagoon. The last of these flights was a 45-minute jaunt aboard a Piper Saratoga (held 5 people and some bags) from Cold Bay to Nelson Lagoon. Before take off, the pilot passed around a packet of gum (“Snack service”, quipped Guy). When asked what the inflight movie would be, the pilot responded (without missing a beat), “Scenic Alaska – it’s a rerun”.
And unbelievably scenic it is! During our flight to Nelson Lagoon, and subsequent flights around the Alaska peninsula deploying seismic stations, we have seen majestic, snow capped volcanoes shrouded in clouds, expansive views of the sparsely vegetated Alaska Peninsula, which is riddled with rivers and lakes, and lots of wildlife: caribou, bears, seals, walruses and eagles (just to name a few). It is a landscape that seems remarkably untouched by humanity. In between widely spaced small towns, only the very occasional fishing gear float or rusty old oil drum testifies to the impact of humans.
High above the tropical lowlands, the Andes form a formidable topographic barrier separating the coastal deserts in the west from the Amazon rainforest to the east. The Peruvian Andes are the highest peaks in all the tropics and, despite their proximity to the equator, are mantled with snow and ice. However, the glaciers clinging to the summits today are small remnants of much larger ice caps that grew there during the last ice age, when the tropical climate was very different. Since the first people entered these highlands more than 11,000 years ago, glaciers have played a central role in human land use, providing water, supporting rich biodiversity, directing settlement, and even forming a basis for religion. Now, however, as air temperatures continue to rise in response to greenhouse-gas emissions, these glaciers are disappearing rapidly.
How will tropical glaciers respond to global warming and what will be the repercussions for water resources? These questions are central to our project, which is developing records of past glacier behavior in order to determine the sensitivity of the tropical climate to ongoing change. Glaciers are one of the most sensitive and visible indicators of climate change, advancing and retreating in response to small changes in temperature and precipitation. A valuable record of these glacier events lies in the ridges of rubble, called moraines, deposited along the ice margin. Therefore, our first step will be to visit moraines in the Andes and determine their age using cosmogenic surface-exposure dating. With these new data, we can reconstruct both the timing and magnitude of past climate events in the Andes and, subsequently, learn just how the tropics responded to climate change. The second step will be to collaborate with experts at Columbia University and other institutions to incorporate the geologic data in computer models and project future glacier and hydrological scenarios for the tropical Andes.
The fieldwork – documented in this blog feature – will take our field team to sites in both the arid and humid Andes of Peru. We chose this approach because the tropics consist of starkly different environments and we need to know how these diverse zones respond to climate change. This year, we’ll work primarily at Laguna Aricoma in the Cordillera Carabaya, on the wet side of the Andes. During an exploratory visit to the area in 2009 we found a promising moraine record potentially extending from the last glacial maximum to the present. This year, Gordon will be sampling these moraines for cosmogenic dating, thereby producing a high-resolution record of Pleistocene and Holocene glacier fluctuations in the humid Andes. Three weeks at the lake will be sufficient to map and sample the moraines. The next stop is Nevado Coropuna, in the arid western Andes, to conduct similar mapping and sampling work there. At each of these sites, Kurt will be conducting archeology surveys of the surrounding landscape in addition to our geologic research, searching for artifacts and evidence of early human presence. In all, it promises to be a long and highly productive field season and we are looking forward to their dispatches from the high Andes.
Two tectonic plates converge along a 2,500-kilometer-long subduction zone offshore southern Alaska. Stress builds up at the contact between these plates, which is released in large, destructive earthquakes like the recent event offshore Japan. One of the big conundrums about these settings is how large of an area locks up on the contact between these plates (called the ‘megathrust’) and then moves suddenly in earthquakes. To tackle this question, my colleagues and I will be collecting data on land and at sea this summer to produce an image of the megathrust, constrain the properties of rocks around and within the megathrust and link these fault properties to the earthquake history.
Imaging a major fault boundary that lies tens of miles under the seafloor is not an easy task, but we have exceptional tools for the job. We will use sound waves to essentially make a sonogram of the upper part of the earth offshore Alaska. The R/V Marcus G. Langseth is a research vessel designed especially for this purpose. An array of airguns towed behind the ship produces sound waves that travel down through the earth and back again. We record these returning sound waves on a variety of very sensitive instruments: two five-mile-long cables filled with pressure sensors that are also towed behind the ship, seismometers placed on the seafloor and seismometers onshore around the Alaska peninsula. Collecting all of these data requires a lot of manpower: a team of scientists and students from Lamont-Doherty Earth Observatory of Columbia University, Dalhousie University and the University of Oklahoma will work together to get the job done.
Our expedition will focus on a particularly interesting area off of the Alaska Peninsula. Some areas of the plate boundary here lock up and then rupture catastrophically in big earthquakes, while in other areas, the plates appear to be smoothly sliding by each other and thus do not produce great earthquakes. The Semidi segment last ruptured in a great earthquake (magnitude 8.2) 73 years ago in 1938. This area has an estimated recurrence interval of about 50 to 75 years, and thus might be due to produce another big earthquake soon. It lies just west of the area that produced the second largest earthquake ever recorded in 1964. However, just to the west lies the Shumagin gap, an area that has not produced a great earthquake historically. Our study will provide new insights into how this megathrust (and other similar tectonic settings around the world) work. Stay tuned…
In the semi-arid Andes, glaciers store water and control the runoff of mountain rivers. They feed water to big cities such as Lima and Arequipa and irrigate the surrounding lowlands. But as the planet warms, mountain glaciers in the tropics are receding steadily. Despite their paramount importance, we don’t know the scale and the rate of the ice retreat and what its loss will mean for the regional climate and the people who depend on mountain glaciers for water and hydropower.
Gisela Winckler, Gordon Bromley and Joerg Schaefer, — all climate scientists at Columbia University’s Lamont-Doherty Earth Observatory — with Brenda Hall at the University of Maine, have recently started an NSF-funded project to study long-term glacier fluctuations in the Peruvian Andes. Our goal is to combine field geology techniques with cosmogenic dating techniques in the lab to analyze rocks that tell us how glaciers in this region have ebbed and flowed here for the last 20,000 years.
With the Columbia Water Center and other climate experts, we will use this historical information to understand how tropical glaciers respond to climate forcing. This project may help us anticipate how the glacial-hydrological system will react to future climate change, allowing experts to adapt and manage water resources more effectively.
On June 15, our field team—a mix of geologists and archeologists– left for Peru.
- Gordon Bromley, a field geologist and Lamont postdoctoral fellow, has traveled extensively in Peru and Antarctica.
- Kurt Rademaker, an archaeologist and Ph.D. student at the University of Maine, is investigating the settlement of the first Americans in the Andes at the close of the last ice age and how climate and environment shaped their farming.
- Matthew Hegland, a geology student at Pacific Lutheran University, will provide field assistance.
Gordon, Kurt and Matt will report from their field trip on this blog while I will facilitate communication with them in the field and answer questions about the project and, specifically, the laboratory analyses. If you have any questions or comments, please don’t hesitate to ask. I will field questions and send them over to the Peruvian Andes from where the team, whenever possible, sends back answers.
May 22: The 2011 field season has been a very very successful year, in fact the most successful one we have ever had. The weather has been great, the equipment proved to be mostly reliable, the people have been great and the samples are plenty. In the month to come, we will analyze the water samples and eventually end up with a tremendous amount of very exciting data. Thanks to everyone who made this happen.
We left Alert yesterday and are on our way back home. We are stranded in Kangerlussuaq, Greenland, for a couple of days until the Air National Guard can take us and our valuable freight back to the U.S.
The Switchyard Team.
It is a love-hate relationship I have with the National Science Foundation (NSF). I love them when they accept my grant proposals and I hate them when they don’t. In fairness, the majority of the time my proposals have been rejected (and it is the majority of my proposals that have been rejected) I can clearly see the reasoning behind it, because for the most part the system works as it is supposed to. As I noted before it is a competitive business, and some really brilliant people are competing against me, and this number increases every year (in direct proportion to my decreasing success rate). There are times when I have gotten reviews back that make me think the reviewers had no idea what they were talking about and I completely disagree with their assessments, and other times where I felt I was personally attacked. I have also been mystified when I got funded for a proposal I was convinced was not my best effort, so it really works both ways. Most of the time I feel the system is fair and I accept when I haven’t been good enough to make the grade. That is the nature of the beast that is the world of science funding and I am happy to play by the rules of the game.
Recently I had two perplexing exchanges with NSF. In the first instance, we got reviews back on a proposal I was included on (not as the lead principal investigator (PI)) that got the highest recommendation from the panel for funding. The peer reviews were mostly excellent and our proposal landed in the top 15 percent of the proposals based on the panel rankings. Then the program director, having decided to fund the top 20 percent of proposals in that batch, rejected ours from the chosen few, in spite of the recommendation of the panel to fund our proposal based on peer review. I am sure he had his reasons for doing so, but these weren’t explained to us in any way that I am aware of. If I had been lead PI, I would have been spitting fire, but the lead PI calmly allowed the issue to die a quiet death, which was the correct and adult decision (“live to fight another day” and all of that), though I would have at least asked for an explanation.
The second issue was more perplexing, involving a proposal that I am the lead PI on. In this case the program director decided not to even send our proposal out for review because we didn’t format the biosketch for one of my foreign co-PIs exactly right (we omitted a section heading). To be fair there are clear guidelines for such formatting, but we weren’t terribly far off from what is required. It seemed patently unfair to be rejected for a very minor infraction, and not at all in keeping with the spirit of the rules. I worked so hard to get this proposal submitted on time that I felt compelled to complain and lobby the program to reconsider. To my utter surprise they did reconsider (the squeaky wheel and all of that), and my proposal is now at the mercy of the peer review process, but at least it has a fighting chance to sink or swim on its merits. I believe that this is a really solid proposal, cutting edge even, and I would hate to see it not even get into the ring, as it were, regardless of its fate once it gets there. I think this example illustrates that the spirit of the review system is alive and well, when you can make your case on a matter such as this, and the very overtaxed “powers that be” at NSF can actually be persuaded. The love end of my relationship was, at least until the next rejection, restored.
One of the comments to my last entry regarding this matter was by another blogger, Eli Rabbet, who wrote:
As a hard money person who reviews soft money grants over the last 20 years I have noticed an increase in the number of proposals and a decrease in proposal quality as the soft money folk chip themselves up into smaller and smaller pieces (seriously 3 percent on one proposal). I have seen people chew themselves up as funding shrinks. Because you have to write more proposals, less time is spent doing science. I have remarked on this in my usual quiet way to a number of program managers.
Eli makes a good point, and I agree with him to a large extent. We do have to spread ourselves very thin, taking too few months per project and having to juggle several projects at a time, each with their own suite of administrative duties (and these duties increase in number every year). We spend less time “doing our science” than we would like to, and more time fulfilling an increasingly long list of administrative requirements attached to less money per project. But I still defend this system of science as perhaps the best terrible system we can come up with. If we received full support we might find the creative energy needed out of stark necessity, but few of us would complain about the increase in freedom to research without the constant anxiety about funding. As I said before, the system is by no means perfect. But it is the system we’ve got, and so far (knock wood) I have kept the lights on and the heat cranking.
More worrying to me than the system we are using, however, is the increasing anti-science clamor that is permeating our society. That is the biggest threat to getting good science results per dollar invested. We have always used our NSF to encourage the freest of thinking to take place. Instead of putting out strongly mission-driven calls for proposals, the NSF has always given miles of latitude for free thinking scientists to push the envelope of their respective fields. That is what put U.S. science at the forefront of global research, and it makes a compelling argument for increasing our commitment to science rather than decreasing it. Time will tell how far this trend continues, but we are all watching it closely. Soft money institutes like ours are finding it increasingly difficult to retain the brightest young scientists who understandably are going where the hard money is.
I have been terribly busy since my return from Asia two months ago, and this blog has been nearly mothballed during that time. But I have a few things I do want to write about, so for those who haven’t lost faith stay tuned.
Recent research has discovered a major settlement of the Uigher empire dating to the 8th and 9th century in the Orkhon Valley [full text of link password protected].
By David Ho, LDEO
Well, it finally happened. We were supposed to get in at 2 am, then it was changed to 4 am, then to 8 am, then to 11 am, and we finally docked at 12.01 pm. It was a fitting end to the cruise in 2 ways: The first is just the unpredictability of everything, and the second is that Herb won the pool predicting when we would get in. Herb and Richard from the galley fed us really well the entire cruise, and being a vegetarian, it was certainly the best cruise I’ve ever been on in terms of the food selection.
The agent in Montevideo was great, and had all the containers waiting for us. With everyone helping unload the ship and load the containers, everything going back to the US via ocean freight was unloaded in less than 4 hours. The air freight will go out on Monday.
Now it’s time for everyone from the scientific party to…well…party. We will meet up soon for drinks and food before disbanding and returning to our respective homes.
After anchoring all night off Montevideo, the moment the ship started moving was probably the happiest moment in the entire cruise for Burke.
A view of the ship’s berth in Montevideo.
Shipping containers getting loaded with scientific gear.
By David Ho, LDEO
Chris was prescient when he wrote his blog. We were suppose to get into Montevideo earlier today, but it turns out the port had no berths for us until tomorrow. So, it’s 11 pm on Friday night, and we’re sitting in the mouth of the Río de la Plata, a few miles off the coast of Montevideo. We can see the lights of the vibrant city, much like prisoners on Alcatraz could see the great city of San Francisco, but everything the city has to offer is entirely out of our reach. To make things worse, we’re out of honey and Vegemite. It’s officially a crisis.
The scientist and crew onboard all have extreme cases of channel fever. People pass the time by playing board games, watching movies, catching up on work, and sitting around discussion things they miss on land (e.g., favorite foods, activities, etc). We all hope that tomorrow will come soon, and we’ll finally be dockside and unloading our gear. Stay tuned.
Pete with the empty jar of Vegemite moments before its burial at sea.
Alejandro and Bertrand engage in an international game of chess.
Scrabble hawk Bob takes on another unsuspecting victim in Byron, while Geoff and Sarah catch up on some work in the background.
By David Ho, LDEO
About 3 years ago, I took on the challenge of planning and championing a gas exchange experiment in the Southern Ocean. I had no illusion that it was going to be easy, but I had plenty of help from the group that I assembled, which consisted of leadership from the previous GasEx experiments, and others who were as passionate about understanding air-sea gas exchange as I was. Our first job was to sell the idea to the community at large, and to the various funding agencies. After that, the real planning began.
From the beginning, SO GasEx was going to be a collaborative experiment, requiring everyone involved to work together towards a common goal. Since many of us involved in the planning of this experiment had previously worked on GasEx-98 and/or GasEx-2001, we knew the challenges involved in staging an experiment that requires the ship to operate in very different modes; combining that with trying to operate in the harsh conditions of the Southern Ocean added to the challenge.
On the cruise, every detail, from lab assignments on the ship, to distribution of water from the CTD, to scheduling of different sampling events, had to be planned carefully. As I mentioned in a previous blog, there are various projects on the ship that required it to operate in different modes. Without the cooperation of all participants involved, this would have been a difficult task.
Many people on the cruise made my job easier, both in my role as co-Chief Scientist and as a PI for the 3He/SF6 component of the experiment. My co-Chief Scientist Chris Sabine was a pleasure to work with. He and I shared responsibilities for various tasks and decisions making (and we had to make some difficult decisions). While we were on the same page on most things, sometimes we would disagree but our divergent opinions lead us to compromises and to better solutions than either of us had thought of. I’m most grateful for the fact that Chris took care of navigating the NOAA-specific bureaucracy, which made it a lot easier for me to concentrate on the scientific aspects of the cruise.
Kevin Sullivan did a masterful job of creating the 3He/SF6 tracer patches, and measured all the SF6 samples from the CTD casts. Matt Reid and Paul Schmieder took turns to chase the tracer patches around for weeks, and never lost it (the patch, but I’m not sure about their sanity). Pete Strutton, Dave Hebert, Roberta Hamme, Burke Hales and Bob Castle helped with the study site selection. Geoff Lebon, Steve Archer, Mike Rebozo, Sarah Purkey helped with various aspects of the tracer injection and sampling. Paul Covert and Byron Blomquist helped us with computer issues. Mete Uz, Program Manager of the Global Carbon Cycle Program in NOAA’s Climate Program Office, rallied the troops on land when it wasn’t clear if the ship could stay at our study site in high winds, and made sure that we were able to get back on track. The Captain and the crew of the NOAA Ship Ronald H Brown, in their various roles, ensured that we were safe, well fed, and to a large extent, able to execute our various scientific projects.
I want to acknowledge Kathy Tedesco, former Program Manager of the Global Carbon Cycle Program in NOAA’s Climate Program Office, with whom I worked closely during the planning stages of the experiment. She was professional yet approachable, and without her help, planning for SO GasEx would have been immensely more difficult.
Even though we did not encounter sustained wind speeds in the 15-25 m/s range at our study site, we had periods of sustained winds up to ~15 m/s, which will be a valuable addition to existing measurements of gas transfer velocities from previous experiments and other parts of the global ocean. Also, we encountered a range of wind speeds (see picture below), which should allow us to effectively evaluate existing parameterizations between wind speed and gas exchange.
The experiment had more hours of eddy covariance CO2 and DMS measurements than any other previous experiments, and the most number of 3He/SF6 samples ever taken in one gas exchange experiment. The combination of CO2, DMS, O3 flux measurements with 3He/SF6 measurements of gas transfer velocities is unprecedented; along with ancillary measurements of waves, turbulence, and bubbles from a buoy that was able to remain with the tracer patch, they should allow us to elucidate mechanisms controlling air-sea gas exchange, and determine if these mechanisms are unique to the Southern Ocean. The detailed carbon system (DIC, pCO2, TAlk), DMS, productivity, and phytoplankton measurements could also help us understand what controls CO2 and DMS dynamics in our Lagrangian patch. All in all, I think SO GasEx was a success, and the data will bear this out in time.
Today, we will pull into Montevideo, Uruguay, and the SO GasEx cruise will be officially over; however, the fun is just beginning. Over the next months, the next chapter will unfold, with all the PIs working up their respective data, coming together to synthesize their results, and disseminating their findings to the community at large.
The entire SO GasEx scientific party on the fantail, taken on the last day before arriving in Montevideo. The weather was completely unrepresentative of what we experienced during our trip, and a welcomed relief to everyone.
Wind speed histograms from SO GasEx, showing winds averaged over 24 hours and spanning 3 CTD stations, which is the time period necessary for one 3He/SF6-derived gas transfer velocity calculation. We encountered a nice range of wind speeds, from 4 to 14 m/s.
We enjoyed a nice sunset on our last evening out at sea…
…and were visited by a school of hundreds of dolphins right after sunset; a nice way to end the cruise.
Future gas exchange scientists? Kathy Tedesco’s niece and nephew proudly sporting their SO GasEx T shirts.
By Steve Archer, Plymouth Marine Laboratory
Back to the weather – it’s the limey again: flying fish off the bow, egrets off the stern, warmth, gentle rolling, blue seas: relief. The ship and folk on it have taken a bit of a pounding over the last couple of days but there’s a lot more of a relaxed atmosphere onboard today. It’s a fine way to finish up. For one, it’s a great day for packing up and clearing up after the gales (see Mike below), especially if you can do it outside. My equipment has to get flown back to the UK then Canary Islands for the next experiment in a few weeks time but first I’ve got to rebuild a couple of boxes that took a ‘green one’ over the side.
However, to a few of us, the high winds and seas that we’ve struggled through on the transect to Montevideo have been a bonus in scientific terms; we obtained what we hope are sea-to-air flux rates and transfer velocities, from the highest winds and biggest waves of the experiment (see photo). If the measurements have been successful this will certainly extend the range of wind speeds over which the fluxes between ocean and atmosphere of DMS have been recorded; shedding more light on what controls the rates of exchange at that critical, high end of the wind-speed-spectrum. Every cloud has some silver lining!
So cheerio to the generally grey, cold and not-so-windy-this-time Southern Ocean; and cheerio to my uncle Chriso who passed away the other day; his enthusiasm for fishing, wildlife, boat-building and the sea had a big influence on me as a child. There will be a lot of fish sighing with relief now he’s gone, amongst many things, he was a master-craftsman-angler; he would have done a decent job of rebuilding those two crates too!
Mike ‘dries out’
South Atlantic spray.
Cheerio to the SO; what a difference a day makes.