October 25th, 2016 by Maria-Jose Viñas
By Alek Petty
A mix of old and new sea ice floating through the northern Beaufort Sea during one of the last days of the cruise that we observed sea ice.
After 65 Rosette casts, 59 XCTD probes, 61 Bongo tows (nets that collect zooplankton samples), 212 surface water profiles, 40 ocean drifters released, three buoys deployed, one buoy recovered, three deep sea moorings collected and redeployed, eight ice cores collected, and 27 scientists deployed and partially recovered, our expedition around the Beaufort Gyre is finally over! The cruise was a huge success, with virtually all instruments operating successfully. The only downer was the lack of sea ice and our inability to get out onto the ice after Ice Station 1. The lack of ice wasn’t actually a problem for most of the scientists onboard, as they were more focused on measuring the state of the ocean, with the lack of sea ice providing interesting, albeit worrying, context for their measurements compared to previous years.
Final Joint Ocean Ice Study 2016 cruise map (Sept. 22-Oct. 18, 2016)”. Courtesy of Chief Scientist Sarah Zimmermann.
As I said back in my first blog entry, one of the key objectives of the expedition was to produce an up-to-date assessment of the freshwater content of the Beaufort Gyre. Based on a preliminary analysis of the data collected on this cruise, my colleagues reckon the total freshwater content of the Gyre could be at a record high. A chemical analysis of the ocean surface suggests that sea ice melt contributed around 20 percent of the fresh water mixed up within the surface waters, compared to around 80 percent from Canadian and Russian rivers flowing into the Arctic. The sea ice contribution was thought to be neutral a few decades ago, but the ice is now melting more than it’s growing, as we clearly witnessed, causing an imbalance. The wind circulation is also important in driving the ocean circulation that sucks in fresher surface waters into the Gyre (see an earlier blog of mine for more details).
Why does this all matter? Well, some scientists posited that the Beaufort Gyre oscillates between periods of spinning up and sucking in freshwater, and spinning down and releasing fresh water. A kind of breathing, if you like. The Gyre has been spinning up and sucking in fresh water for a few decades now (2008 saw a big increase) and we keep waiting, with similarly bated breath, for this trend to reverse. If the Gyre does reverse (breathe out), the Arctic Ocean will likely dump a load of fresh water into the Atlantic Ocean (as we think it did in the 1970s), which could cause some big impacts on weather patterns across the Northern Hemisphere. We’re not expecting a scene out of The Day After Tomorrow, but we’re not entirely sure what could happen either.
Hacky sack on the helideck. You can spot me by the bright orange hat.
It will take scientists a while to pour through all the data collected on this cruise and place this year’s findings into context. We spent our last few days compiling reports to summarize and document the data collected (in between games of hacky sack on the helideck). I’ve taken a look at some atmospheric data since I got back, and it appears the Beaufort Sea region was experiencing really warm, maybe even record warm, air temperatures throughout October. The data collected this year could therefore offer us a glimpse of what might be a new normal for the Beaufort Gyre and other regions across the Arctic Ocean.
I wasn’t able to cover all the science that happened on the ship during this blog series, but I hope you got a flavor for some of our primary scientific activities and have a better understanding of why it is we keep coming back to profile the Beaufort Gyre. I’m not sure if I will be out again next year, but I’ll be sure to let you know if I do. Thanks for reading, and do get in touch if you have any questions!
The Joint Ocean Ice Study is a collaboration between the Department of Fisheries and Oceans Canada (DFO) researchers with colleagues in the USA from Woods Hole Oceanographic Institution (WHOI). The scientists from WHOI lead the Beaufort Gyre Exploration Project, which maintains the Beaufort Gyre Observing System as part of the Arctic Observing Network. In addition to WHOI and DFO, the 2016 participants (those on board plus those on shore) come from three Japanese, five American, and six Canadian universities and research laboratories. Annual sampling of set oceanographic stations and mooring re-deployments since 2003 aboard the CCGS Louis S St-Laurent have built a time-series of physical and chemical properties of seawater, phytoplankton, zooplankton, and ice observations reaching from shelf waters to 79N across the Beaufort Sea. More information can be found on the Fisheries and Oceans Canada website.
October 21st, 2016 by Maria-Jose Viñas
By Eric Lindstrom
Science party on the R/V Revelle.
Salinity Processes in the Upper-ocean Regional Study #2 is underway for the next year. Lots of science remains to be done, so it is very early to be writing an epilogue! However, the first big field campaign with a large research ship is completed and it seems right to sum up some of the operational conundrums be articulated as we plan for further operations with the Lady Amber over the coming year and the R/V Thomas Thompson in October 2017.
Conundrum#1: Finding “Just Right”
Like Goldilocks, the R/V Revelle team went in search of very special conditions. Conceptually, SPURS-2 is built around observing all the processes that lead to rainfall mixing into the ocean and the resulting large-scale variations of salinity that we detect from space.
One of the concepts is that rain falling into the ocean will reveal itself as low salinity “lenses” at the surface than mix into the ocean over time. Well, not unexpectedly, if the wind is anything but calm, the rain mixes quickly into the upper ocean mixed layer and cannot be seen as a lens – only tiny variations of salinity that build up over time. In order to see the strong signal of a lens of fresher water, one needs to observe the ocean during calm winds and rain. The difficulty with this is finding the simultaneous occurrence of rain and low wind conditions in a vast ocean with a platform with a top speed of about 12mph. During SPURS-2, it became apparent that the regions with more certain rainfall (those large cells and fronts visible from space) were also stormier and windier than ideal for measurement. In areas of calm winds, there are patches of rainfall but they don’t seem predictable (“It’s the tropics” says Jim Edson!)
So, the perfect observing condition for us were more difficult to find than we expected ahead of time. Probably no surprise that mother nature throws a great curve ball! In the end, we targeted the low-wind regime by following the surface wind forecasts and hoped to run into rain (which we did). After a few weeks at sea we learned and prevailed.
It is always tricky to balance risk and reward. Equipment deployed at sea is always at risk of loss. The reward for taking the risk is valuable data to expand our scientific understanding. We had several occasions to examine and balance these risks and rewards.
For example, the CODE drifter was an instrument that was modified ashore by addition of a salinity sensor but not tested prior to shipping five of them to R/V Revelle. In the parlance of oceanography, drifters float at the surface, while floats are neutrally buoyant and can sink and return to the surface to transmit profiles of the ocean. In a test deployment of one drifter, it appeared to stay at the surface (just), but when released from the ship it simply sank, never to be seen again! Not the behavior you like to see in a drifter! So, although modification to its four sister drifters were undertaken, it was eventually decided that these drifters were not ready for prime time. Lucky we tested one! The small experiment with CODE drifters will have to wait until next year.
The Lighter-Than-Air InfraRed System (LTAIRS) balloon deployments were quite complicated by variations in the balloon lift during rain and by variations in wind speed and direction. Dipping the balloon payload (expensive camera) in the water is a big risk. However, the data – infrared movies of the sea surface skin temperature in rain – are super interesting and scientifically novel. We learned a lot about making waterproof payloads, the best material and size of balloons, and weather characteristics unfavorable for ballooning. This knowledge was hard won with near misses and close calls and exhaustion of the helium supply. We all think it cost our chief scientist Andy Jessup some new gray hairs! However, the grin on his face when he shows you the data is priceless. Well worth the drama and risk in the process. LTAIRS work will go more smoothly next year on the R/V Thompson and the team will likely make some interesting discoveries about the thermal properties of the sea surface during rain.
It was a great pleasure to work with and support the scientists and crew on R/V Revelle. It is a capable ship and crew and the science party was very well prepared for the challenges and risks. Morale was high during the entire voyage – maintained by a busy schedule, everyone pitching in, and good food and fellowship. The teams from University of Washington Applied Physics Laboratory, University of Connecticut, Woods Hole Oceanographic, and Scripps Institution of Oceanography came to R/V Revelle super-prepared and ready for action. The schooner, Lady Amber, will be making periodic voyages during the coming year to service and renew out drifting (Lagrangian) experiment. As always, your blogger enjoyed every minute of our six weeks at sea. Its wonderful to watch scientists and engineers face the challenges of understanding the ocean while in its grip. I’ll keep you posted on developments during the coming year!
October 12th, 2016 by Maria-Jose Viñas
By Alek Petty
View from a helicopter of our ice breaker, the CCGS Louis S. St. Laurent, taken after Ice Station 1.
The sea ice didn’t last long. We continued the hunt for sea ice suitable enough for another ice station – hoping for something thicker and more stable than last time around. Unfortunately our search was fruitless. The Woods Hole team tried for a quick installation of one of their ice tethered profilers (ITPs) –an ocean surface water profiler- on a thick ice floe that was only around 164 feet (50 meters) in diameter, but the ice was too ridged and porous to be suitable and the operation was quickly abandoned. They instead resorted to deploying two of their ITPs directly into the ocean from the side of the ship (this is less stable than wedging the surface buoy component of the profiler into an ice floe, hence why they’re called ice tethered profilers). Our hopes of getting out onto the ice again quickly vanished.
We were soon back to cruising through the marginal ice edge, which was dominated by newly forming young grey ice with the occasional floe of older, thicker, ice that had survived the summer melt season. We are now back to swaying our way through the high seas – not the kind of scene most people associate with an Arctic expedition. It was with a sense of deep regret that our time within the ice ended with nearly two weeks of the expedition still to go. For me, the expedition just isn’t the same without the sound of ice breaking reverberating around the ship (we’re on an ice breaker after all!)
Arctic sea ice extent as of Oct. 10, 2016.
We got a small dose of Internet after leaving the ice (I’m struggling to cope without it!) and I managed to get access to the National Snow and Ice Data Center website, which showed how the Arctic sea ice re-freeze has been really slow this year (see the sea ice extent image above), coinciding with very warm temperatures over much of the Arctic, including the Beaufort Sea. We’ve experienced temperatures only slightly below freezing on this expedition, so my thermals have stayed packed away. In the Beaufort Sea, the ice edge is clearly not heading south at any real speed, although as the temperatures are expected to drop further through the coming weeks and months, a refreeze across the entire Beaufort Sea should be inevitable.
Despite the lack of sea ice (and my associated despondence), the science was still operating at maximum speed. We had a talk from Adam Monier, a French microbiologist from Exeter University (United Kingdom) who talked about his efforts, along with collaborators from Concordia University (Montreal, Canada), to increase our understanding of the microbial communities of the Arctic Ocean. According to Adam, around 90 percent of the global ocean’s biomass is microbial (a mass equivalent to roughly 240 billion elephants!) and this was seriously underestimated as of only a few decades ago. He showed some fascinating results demonstrating how phytoplankton (a micro algae) can cope, and even adapt, to fast changing environmental conditions, like sunlight and access to nutrients – some of which can be linked to the changing Arctic sea ice state. There is still a severe shortage of Arctic data, and this cruise is trying to help fill in those gaps. As phytoplankton are the foundation of the Arctic Ocean’s food webs, understanding how they respond to rapid changes in environmental conditions will be key to understanding how the entire Arctic ecosystem responds to declining sea ice and changes in the Arctic Ocean. The expedition has been a great way for me to learn about the latest developments in Arctic science, and to appreciate how interconnected our various fields of research are.
October 3rd, 2016 by Maria-Jose Viñas
By Alek Petty
Working on thin Arctic sea ice.
After five days of cruising through open water, it was clear we had to change course and venture further north to find ice. The satellite imagery was showing ice above 76-77 degrees North (we were around 74 degrees North), and the ice edge didn’t seem to be drifting south at any real speed. After another few days voyage northwards, we thus finally found ourselves entering the Arctic sea ice pack. This wasn’t exactly a scene from the Titanic; the transition from water to ice was a gradual one, as the ice cover evolved from millimeters or centimeters of newly forming sea ice (nilas and grease ice), to thicker, consolidated ice floes (maybe a meter or two thick; 3.3 to 6.6 feet), which caused the ship to lurch and shake as it broke its way through.
Early stages of sea ice growth: nilas (top left), pancake ice (top right), young grey-white ice (bottom left) and first-year ice (bottom right). The top photos are courtesy of Jean Mensa.
Once we were well within the ice pack, the Woods Hole team was keen to get out onto the ice and deploy some buoys. This would be my chance to get out on the ice too, as I was helping lead efforts to collect ice thickness measurements and ice cores, to better understand the characteristics (like salinity, density and age) of this year’s Beaufort Sea ice pack. The microbial and microplastic scientists were keen to join in and collect their own ice cores, too, enabling them to take a deeper look at what else might be hiding within the ice.
The Woods Hole team leader flew out with the helicopter pilot early the next morning to hunt for thick ice, and seemed to find an ice floe thick and stable enough for us to work on. I joined them on the first science flight out a few hours later to set out our survey lines and coring sites, before our cargo was carried over and the rest of the team members joined us. It was soon apparent that the ice wasn’t as thick as we had hoped.
I drilled a few quick holes and the readings all came in at around half a meter, just above what might be considered safe to work on. Our polar bear guard, Leo, wasn’t too happy with the conditions either and soon found a few good sized holes and cracks circling us. We were under strict orders not to stray from the group and to test the ice for stability as we moved ahead. I’ve previously used data from satellites, planes, and sophisticated computer simulations to estimate the thickness of Arctic sea ice. Yesterday, I estimated ice thickness by hitting it with a stick.
It wasn’t quite vertical limit, and the group rebuffed my idea of roping together for dramatic effect, but there were still a few hairy moments when the odd leg found its way through the ice. Despite the added element of danger, all operations completed successfully and we hitched a lift back to the ship later that afternoon with our ice cores in tow. The Woods Hole team was working until last light to get their buoys prepped and ready to drift off through the Arctic. It was a fun, adrenaline-filled day of science, but I’d prefer it if we could find some thicker ice to work on next time around.