CCGS Henry Larsen in Nares Strait - August 2007

        For three weeks in August 2007 I will be aboard the CCGS Henry Larsen, a Canadian coastguard icebreaker, to recover and redeploy oceanographic instruments in the Canadian Arctic Archipelago. Most of the time will be spent in Nares Strait, which lies between Greenland and Ellesmere Island. This is one of three major passages to the west of Greenland which connect the Arctic to the Atlantic, through which relatively fresh sea water and ice flows southward. We aim to measure this flow and understand what drives it.

This summer's expedition is part of the NSF-funded Canadian Archipelago Throughflow Study, which began in 2003. It is also an International Polar Year project.

Life at sea will be busy, but I will try to use this page to keep a diary of what we get up to! You can also keep track of where the CCGS Henry Larsen is via its ship track.

To see a higher resolution version of any image simply click on it. See the IPY project summary for some background science and motivation, and click here for further details on the influence of the fresh Arctic outflow into the Atlantic......

Oceanographic instruments

We'll be working with several different types of instrument during this project. First, there's the SBE37 conductivity, temperature and pressure recorder - we've got more than 30 of these, most of which are deployed in sets of four on "string" moorings which reach from the bottom of the strait to within 30m of the surface. Here's a picture of some we recovered last year - some get a lot of biological growth on them, and a large part of servicing these instruments involves removing this from the inside of the conductivity cells.
Then there's the Acoustic Doppler Current Profiler (ADCP) moorings, which sit on the bottom looking upwards, and use the doppler effect to measure the velocity of the water flowing above them. They give us a vertical profile of flow speed through the whole water column.

We also deploy ice-profiling sonars (IPS) which measure the draft of the ice passing over them, and shallow pressure sensors in sheltered bays on either side of the channel to help us understand what drives the flow through the strait.

And of course we'll be working with a CTD (conductivity, temperature and depth instrument) to take vertical profiles along lines we'll call "sections" across the strait. CTDs are the bread and butter of observational oceanography, allowing us to visualize the temperature and salinity on a cross-section of the strait, and calculate a first guess at the vertical structure in the flow.

The science team

And here are the team! It's a relatively small group, including (in no particular order):

Humfrey Melling
the Chief Scientist, from the Institute of Ocean Sciences in Sidney, BC, Canada (IOS)
Andreas Muenchow
the Principal Investigator on the project, from the University of Delaware, US
Berit Rabe
a graduate student at the University of Delaware
Jo Poole
a mooring technician from IOS
Ron Lindsay
an electronics and instrument technician from IOS
Dave Riedel
a scientist from IOS
Dave Spear
a mooring technician from IOS!

Also part of the science team are Michelle and Richard from the National Research Council Canada. Michelle is an ice scientist interested in the change in properties of multi-year sea-ice as it flows south, and on the forces this ice produces on the ship's hull.
Michelle Johnston
ice scientist from the National Research Council Canada (NRCC)
Richard Lanthier
technician from NRCC

Sunday 5 August

Only a couple of days until we join the ship, and we are all keenly watching the ice conditions up in Nares Strait. Large amounts of multi-year (i.e. thick!) sea-ice in the strait seriously impede our ability to deploy and recover moorings, and prevent us from being able to get to the northern parts of the region. Here's the latest MODIS satellite image from 1245 today. It shows lots of multi-year ice streaming southwards (right to left) through the strait. This is relatively unusual for this time of year, and will not make things easy for our mooring operations in the area...

Monday 6 August

Today's the day I head off to St. Johns in Newfoundland, Canada, to meet the rest of the team. We'll be flying on from there to Thule in Greenland where we'll join the ship on Wednesday. Having recently been flooded out of my house in Oxford, packing has been a bit of a challenge, but I think I'm just about ready now!

Wednesday 8 August

Up at 4am this morning to catch a charter flight from St. John's up to Thule in Greenland. The coastguard crew on the Larsen are changing over at the end of one six week shift and the beginning of another, so we caught a ride on the plane which brought the new crew north. It's always a strange feeling at this stage to be surrounded by the 40 or so Newfoundland strangers that are going to be the only people I see over the next few weeks! I'm looking forward to getting to know them well (once I can start to understand their accent?). I'm also excited to see the rest of the science party again, most of whom I HAVE sailed with before - they are a great bunch of people to work with!

Thule is a US airforce base on the northwestern side of Greenland, close to the southern end of Nares Strait. I've flown through here on several occasions now, and every time I'm struck by how desolate and soulless it is - row upon row of colourless low, square buildings, all the pipework above ground, no green in sight and, at this time of year, lots of mud around. From the air though, the view of Thule is pretty spectacular!

This picture, taken last year from the plane as we flew in, shows the clouds spawned by a pointy little island just outside the entrance to the bay. The view from the Larsen, moored in the harbour which we reached after a 5 minute bus ride from the airport, is impressive too, with plenty of icebergs around, flat-topped mountains, and the edge of the Greenland icesheet in the distance. Thule claims that it is the northernmost deep water port in the world, but there's not much traffic today - we were the only ship in sight.

We arrived just in time to move into our cabins before supper - we have a cabin each this year, which was a nice surprise. Supper (the Newfoundlander evening meal) is at 4.30-5.30pm, and was a great opportunity to meet the helicopter pilot Bob and the helicopter engineer Steve. They'll be carrying Michelle and others onto the ice to collect samples and measure the thickness of ice floes - fingers crossed that I'll get to go with them at some stage. The ship sailed early this evening, and we're now headed north through some beautiful icebergs. It's time to catch up on some sleep though as tomorrow's bound to be a super-busy day!

Thursday 9 August

I'd forgotten how much heavy lifting there always is to do on day one of a trip like this! Most of the science gear arrived on the ship in two large containers, and we've spent today unpacking and finding a proper secure home for everything. The containers will then be used as workshops on the deck - one for the delicate electronics work, and the other for assembling all the instrument frames and hardware. We've unpacked lots of mooring components, including bright coloured floats up to a metre in diameter and tens of extremely heavy boxes full of battery packs and instruments. I've managed to track down most of the things I'll need for servicing, testing and re-programming the SBE37s, and we're slowly getting organised!

Meal times come round very fast on the Larsen - it already feels as if we're always eating! Today I think I've burned enough energy to deserve the vast mountain I've eaten (yes, even including the blueberry cobbler, apple streusel and home-baked cookies?) but that won't always be the case - I might have to resort to visiting the gym down below decks if I can't burn enough calories just keeping warm :-) The weather today has been mostly foggy, with some surreal moments when beautifully shaped icebergs with only their tops visible have drifted by. We've been heading north through Smith Sound and have already encountered a fair bit of multi-year ice. I was shaken awake at 6am when we made impact with our first piece - it's quite a shock until you get used to it!

This evening's job was to get our CTD (conductivity, temperature and depth) instrument working. We will lower this through the water column to take vertical profiles of conductivity, temperature and depth, from which we can calculate the density of the water. The gradients in density give us a first guess at what the currents are doing. Right now the instrument is not playing ball, and we have no idea why - it's late though (the first of many 14 hour days) and the fog has cleared, so time for a quick turn around the deck and then bed...

Friday 10 August

I think we're finally there with the CTD! It's taken us a whole day of trouble-shooting and I've learned more about baud rates and the vagaries of Seabird instruments and software than I ever thought I'd want to know, but we now seem to have it working :-) And in the nick of time for our first CTD section, which will be across Smith Sound.

While I've been closeted in Ron's electronics container, peering at the guts of the CTD, all kinds of other exciting things have been going on. We've spent most of the day in Alexandra Fjord, a picturesque bay on the western side of the strait, where Michelle had some equipment cached from her last fieldtrip in the spring. Bob in the helicopter took a couple of flights to bring the gear on board, and then whisked Dave, Dave and Jo off to collect the dataloggers from a couple of small weather stations nearby - one on Pim Island and the other at Cape Isabella. These small Met masts measure air temperature, pressure, wind speed and wind direction - unfortunately their batteries did not last through the dark winter (only charging up again through their solar panels when the sun came up in March) and so they didn't collect data during the most interesting portion of the year!

I've been to Alexandra Fjord several times before (because we have a shallow pressure mooring site here - we deployed a new one of these moorings this morning) but it's never been sunny and calm - today there's a beautiful clear view of the Ellesmere Island mountains all around, reflected in the water. I'll post a picture of it when I get home, but for now here's one from last year, with walruses sleeping on the sea-ice - we haven't seen walruses yet this year, but we DID see a polar bear swimming by on our way out of the fjord this evening!

Saturday 11 August

The highlight of my day today was a trip in the FRC (fast response craft, or rigid inflatable boat) to Foulke Fjord on the Greenland side of Smith Sound. We were trying to recover a shallow pressure mooring that was deployed there last year. These moorings sit on the sea floor at a depth of about 20m in sheltered bays and, essentially, measure the change in sea level above them. From this we're hoping to be able to calculate the pressure gradients along and across the strait, and see how these relate to the amount of water flowing through. We weren't successful today - maybe the instrument has been scoured out by the grounded icebergs we could see all around? Or perhaps the acoustic release hook holding it to the bottom isn't working properly (more about these acoustic releases later!). But it was still an incredible experience :-) The FRC is launched from the boat on an open-air elevator of sorts which whistles down the side of the ship until it hits the water, and then there's a bouncy ride to your destination.

Foulke Fjord is very colourful compared to the rest of the Greenland coast, with lots of grass on the mountainsides. Since green is usually totally missing from the spectrum of colours up here that was a very pleasant surprise! Lots more bird-life too - funny black and white seabirds with bright red feet. We were extremely disappointed not to have any success in finding the mooring, but returned to the ship after a couple of hours to find massive T-bone steaks waiting for us, and to hear about Berit's ice reconnaissance flight. Here's her account of what she got up to:

Ice observations from the air (from Berit)

The CCGS Henry Larsen has one helicopter, one pilot and one technician on board for this trip for multiple different tasks. This morning I got the chance to join the ice observer on his flight to evaluate ice conditions for the rest of the day and the next days. At the beginning of the cruise all scientists had already gotten a short briefing by the pilot about safety and procedures so I was ready to go. We boarded the chopper before the rotors were turned on otherwise you have to be very careful about the rotors (always approach a helicopter from the front, never walk to the back!). You have to wear a life jacket, a headset and buckle up. Then the ride begins. You lift up vertically from the helicopter deck, swing around and fly away from the ship.

The Larsen was stationed on the western side of Nares Strait and we were planning on running a CTD (conductivity-temperature-density) section across the strait so the ice observer wanted to get a view of the conditions and report back to the chief scientist. The ship stayed close to a huge ice floe during the night and it was an impressive view from above. We saw a couple of big ice floes on the eastern side, each of them being a few miles long and all of them multi-year ice. A characteristic of multi-year ice in comparison to one or two-year ice is that the small puddles on top of the floe are joined together by little streams caused by flooding in the past. These floes can be around 10 years old and, as the ice team measured yesterday, over 10 meters thick! There had been a big ice floe on the eastern side of the strait in the last days, as the ice observer saw on satellite images, but it seemed that one had broken into several smaller pieces. The middle of the strait looked better for our observations with an ice cover of only about 2/10 (ice coverage is described in tenth). Further north we saw big ice floes scattered across the strait but with open water interleaved.

The weather was great for flying with good visibility, and we flew a little bit above Greenland. (Greenland actually IS green in parts, as the name implies!) The rocks were red though along the shoreline, and the Humboldt glacier lies big and white on top and tongues reach down into fjords. We saw arctic hare, trying to hide in the vast landscape of brown and red rocks when we flew above them. They were whiter than snow and really fast. On the way back we circled around an iceberg and tried to guess its size from the air, it turned out to be 100 feet tall. The trip gave good indications of the ice conditions and the ice observer will go on more of these flights during the next two weeks.

Sunday 12 August

Pim Island, at the western end of our CTD section across Smith Sound, is steeped in International Polar Year history! During the first International Polar Year from 1881-1883 Greely, a US cavalry officer, commanded a scientific expedition to the far north. His base was Fort Conger on the north east side of Hall Basin at the northern end of Nares Strait, and he spent two winters there with his team studying meteorology, tides, magnetics and all kinds of other things, as well as exploring the area. His scientific report makes impressive reading (according to Humfrey who has waded through it!).

The expedition was expecting a supply ship to arrive in its second year, but this didn't make it through. Since the back up plan was for the ship to leave supplies on Pim Island, Greely's party made the treacherous journey south in late July 1883 in a small boat. Sadly, they found no supplies waiting for them when they got here, and were forced to over-winter at Cape Sabine on the north east side of the island, without enough food to see them all through until spring. Getting desperate, they made another daring crossing to Littleton Island on the Greenland shore, hoping to find a cache of food from somebody else's expedition there, but had no luck. Back on Pim Island, and weaker than ever, they lived on plankton collected from the water in the spring.

When a supply ship finally did arrive at Pim Island in July 1884, less than half of the expedition's members were still alive. And in the ensuing US government enquiry, the scientific success of the project was sadly forgotten....

Far more successful was the well-supplied expedition of Sverdrup in 1903, on board the Fram. Sverdrup spent a winter on the other end of Pim Island (now called Fram Fjord?) and used this as a base for exploring what are now the Sverdrup Islands.

We are certainly following in the footsteps of some inspiring scientists! While the challenges posed by the environment and weather up here have not changed very much in the 125 years since the first IPY, I'm very grateful for the comforts of a modern ice-breaker. And on that note it's time to eat again - I think I saw pinacolada cake on the menu!

Monday 13 August

Today has been a day of nights! Dave Riedel and I operated the CTD from 1-7am this morning on a section across the sill in Kane Basin. It was perfectly calm and beautifully sunny so it didn't feel like a night shift at all (although by 7am we were definitely flagging!). A CTD section involves stopping the ship at a series of stations, where we lower our CTD instrument to the bottom using a small winch, measuring conductivity, temperature and pressure every 10cm or so on the way down. The data is sent back up the winch cable so that we can look at the numbers as they come in (and let the winch operator know when he's getting to the bottom - the last thing we want to do is crash our newly-mended CTD into the mud and rocks!) On other ships, the CTD is often accompanied by a rosette of bottles for collecting water from different depths, but we have a fairly simple system without that here.

The stations on our line were only 2.5km apart, so not much time for napping as the ship moved between them. Luckily there were lots of icebergs around to look at, and chocolate brownies from the galley to munch on. (If you're starting to get the impression that I'm eating a lot of dessert, it's all Jeff's fault - he's the "second cook" who's here entirely to make bread, cakes, puddings and cookies, and he's very good at his job!)

After a few hours sleep, I spent the afternoon reading the manual for the SBE37 conductivity and temperature recorders - to remind myself how to program them for deployment which is one of my next jobs. It's a very dry read, but lovely to be sat outside on deck in sunny Scoresby Bay while Ron and Dave were off in the FRC attempting to recover another pressure mooring. I even had to dig out my suncream! Sadly, they didn't have any more luck with this mooring than the last, and after lots of effort trying to drag for it were forced to give up on that least for now.

More CTD's this evening from 11pm-3am. It's windier now, and not so nice to be outside. Berit and Andreas have just woken up to replace us, so I'm off to warm up in my bunk.

Tuesday 14 August

What a frustrating day!! We were less than an hour from Kennedy Channel (the middle part of Nares Strait, where most of our mooring sites are located) when we heard from the captain that the wife of one of the crew members is seriously ill. We have turned around to head south again and drop him off somewhere from where he can get home. It will be at least three days now until we're back here. Of course, our sympathies are all with the crewman and his family - it is situations like this which really make me realize how far away from civilization we are up here, and cause me to think of my own family and friends back home...

Nevertheless, time is valuable because there's such a short window in which the ice conditions allow us access to our working area, and this is a serious blow to the program. We will use the time to get our instruments ready for deployment, and to catch up on sleep (having worked non-stop 14-hour days since we got on board). Then we'll be ready for action once we get back up to Kennedy Channel. Now though I'm off to watch a darts match - the shipboard tournament starts today!

Wednesday 15 August

We've been steaming south as fast as we can today, only slowing when there's lots of ice around. We're now in Jones Sound, bound for Grise Fjord on the southern end of Ellesmere Island - the view of Coburg Island off to our starboard side is incredible! Most of my day has been taken up with testing our acoustic release system. Each of the moorings already in the water (as well as those we plan to deploy) is held to its anchor by a latch which can be opened by sending it a sound signal. We call these devices "acoustic releases" since, when the hook is opened, the mooring is released from the bottom and the buoyant floats attached to it will bring it to the surface. The picture shows two acoustic releases from a mooring we recovered last year.

To communicate with an acoustic release, we dangle a hydrophone or transducer over the side of the ship and send pulses of sound at very specific frequencies (in the 9-14 kHz range) - the release will reply by sending a pulse of sound back (at a slightly different frequency). We can calculate how far away the release is if we know the time it takes for its response to arrive. Once we know exactly where the release is (and if there isn't a huge ice floe sat directly above it!) we send it a coded sound signal and the release mechanism operates, freeing it from the bottom. Then it's just a case of spotting the instrument when it gets to the surface!

This afternoon we've been testing the communications between a release and transducer on the deck. The electronics which decode what the transducer hears back from the release are new to us this year, and aren't working as we expect them to! We've been busy experimenting to try to figure out what's wrong. Getting our various brains together to solve problems like this is one of the things I love about being at sea :-) After testing the system in 500m of water this evening we are closer to the answer, and should be able to make the system work provided we're not too close. Now though it's after 9pm and time for my first round darts match - wish me luck!

Thursday 16 August

My darts partner Howard (Chief Officer of the Larsen) is actually something of a darts shark! We won comfortably (much to Andreas' annoyance....), although I can't claim to have been much help. There's something very worrying about throwing pointy objects on a ship that's lurching around in the ice....

It's been great to have a little time off to take advantage of the social side of things. For the coastguard crew on board, the Larsen is home for half the year, and there are lots of things to keep them occupied during their spare time. As well as the dartboard, there's a table football set, a gym, enough movies to last a lifetime, a small bar open for 2 hours each evening, a sauna and even a Wii (for those not in the know, this is an electronic games system which seems to involve players standing in the middle of the lounge pointing at the TV and swinging their arms around - one way to get exercise I suppose!). Darts is just the start of the tournaments this trip - crib and poker are also under way, and Saturday night is bingo night. We will no doubt be way too busy to sample all that's on offer, but it's nice to have a distraction now that we've got a couple of slower days.

Another consequence of heading south for a while was the spectacular "sunset" we had last night. The sun got low enough on the horizon at 1am to actually disappear behind the mountains of Ellesmere Island, covering everything in beautiful pink and orange light. Photos to follow once I'm back home!

This morning Berit and I programmed all the SBE37 conductivity and temperature recorders ready for deployment. Ron and Dave are busy testing and programming the ADCPs and Jo's working hard assembling moorings on the foredeck. Now we're heading north again, and by the time we get back to Kennedy Channel hopefully everything will be ready to go...

Friday 17 August

The CCGS Henry Larsen is named after one of Canada's greatest northern seafarers. Born in Norway, Henry Larsen immigrated to Canada in 1928 where he joined the Royal Canadian Mounted Police (RCMP). He became first mate of the St. Roch, a two-masted sailing ship built to withstand pressure from the ice, which patrolled the western Arctic - enforcing hunting regulations, visiting communities and supplying RCMP outposts. Eventually promoted to captain (and becoming a Canadian citizen) Larsen set out in 1940 to sail the St. Roch through the Northwest Passage.

Such a voyage might not seem like a high priority during war time, but with the establishment of US airfields and weather stations in the region, as well as a successful voyage through the Northwest Passage by the Norwegian Roald Amundsen, the Canadian government was becoming increasingly worried about its sovereignty in the Canadian archipelago. It was looking for ways to demonstrate its authority (and keen to make a successful transit through the Northwest Passage before the US did!)

The St. Roch, with a crew of eight, set out heading east. They were forced to overwinter twice when trapped in the ice, freeing themselves on the second occasion only by using gunpowder charges to break up the ice around the bow. They stopped off at Pond Inlet on Baffin Island to make repairs after one of the ship's cylinders blew, but eventually arrived triumphant in Newfoundland in September 1942 after a voyage of more than two years.

Larsen remained as captain of the St. Roch (later making a second trip through the Northwest Passage in the other direction!) until 1949, when he was promoted to commander of the RCMP's Arctic division. Pictures of him and the St. Roch hang on the walls of the officers' lounge on board the CCGS Henry Larsen, along with various bits of memorabilia from the original expedition, presented by Larsen's wife when the ship was commissioned. Nice, somehow, that the ship is named after someone who really understands what it's like up here!

Tonight we're in Kane Basin heading north. The weather is still unbelievably good - we've had non-stop sunshine and very little wind for most of the last week (with just occasional fog near the coasts). I hope the weather holds once we're back at our mooring sites - we expect to reach Kennedy Channel first thing so I'd better get to bed!

Saturday 18 August

Today we recovered some moorings! Using our acoustic deck box and transducer we managed to "talk" to the releases on one of the ice profiling sonar (IPS) moorings, as well as on one of the conductivity-temperature (CT) strings, and when released they both popped up to the surface :-) It's the CT moorings that are closest to my heart - I was responsible for preparing the four SBE37 conductivity and temperature instruments on each of them for deployment last year, so I've got my fingers crossed that they've survived okay and that I didn't do anything stupid! The instruments are at depths of 30m, 80m, 130m and 200m, but are designed to profile through the water column when they bow down due to tides and during strong wind events. The flotation on the moorings consists mostly of rugby-ball-shaped small plastic floats in long strings (fondly labelled "silly floats"), since these are less likely to get trapped in a crack on the bottom of an iceberg should one go by. Icebergs are a real threat to our instruments here - they have a draft of up to 250m in Kennedy Channel, and there's evidence in the data we collected last year of them pushing our upper-most instruments (usually at about 30m) down to 200m!

Once a mooring appears on the surface, the FRC is launched and tows the various mooring components to the side of the ship, from where they can be lifted on board with the crane. With the IPS mooring today this was all very straightforward, but the CT mooring came up partly under an ice floe, and it took some time to pull everything free. Now though I have some instruments back, which is very exciting - it's a great feeling to see moorings that you left behind a year ago back up on the surface :-)

Today's not been totally successful though - we've been trying to talk to the release on another CT string a few kilometres away without any luck, and the other side of the channel, where the rest of our moorings are, is under 9/10 ice. We're headed north now to do another CTD section across the northern end of Kennedy Channel - it's cold, windy and overcast out there so I'm not looking forward to getting up at midnight for my shift!

Sunday 19 August

I am definitely one of the luckiest people alive. Not many get a chance to see the amazing Petermann Fjord, off Hall Basin on the east side of Nares Strait. Here, the Petermann Glacier reaches the ocean, and extends for 50 miles or so as a floating ice-tongue in the fjord. At its grounding line it is more than 600m thick. Fifty miles downstream (and the bit we're looking at this evening) it is 50m thick, although of course only a fraction of this is above the water. On both sides of the fjord huge cliffs drop vertically to the water, capped by glacial ice. It's stunningly beautiful, and frustratingly impossible to do justice to with a photograph!

When we were here in 2003 (yes, I am lucky enough to have been here twice) we were able to get much further into the fjord before reaching the glacier - it's extent has increased by about three miles over the last four years. This might sound surprising, given global warming and tales of Greenland melting and reduced Arctic sea-ice, but there's lots of interannual and longer timescale variability in the conditions up here...

We're in the process of doing a CTD section across the fjord, in the hope of learning something about what happens to the fresh water that melts from the glacier. Earlier today, Berit and I had a chance to upload the data from the CT instruments we recovered yesterday - they seem to have worked properly, sampling every 15 minutes for the last year, and I'm looking forward to having a more detailed look at the data. The boys have been busy too - Dave R has been uploading and checking the data from the IPS, while Dave S and Ron have been trying to recover two more of the shallow pressure moorings we deployed in 2003 (at Offley Island and Discovery Harbour). No luck with either of them, even when they landed by helicopter on the sea-ice in the bay and tried to communicate with the acoustic release from there!

Since it's Sunday, the coastguard crew are all in whites today (very stylish!) and we tried to wear something a little smarter for dinner too - it's nice to have an excuse to wear something other than work clothes and steel toe-capped rubber boots!

Monday 20 August

Back on our main mooring line in Kennedy Channel, and another CT mooring on board first thing this morning! That's four more SBE37 conductivity and temperature recorders for Berit and I to take care of. Last year we recovered 29 of these instruments, keeping both of us extremely busy for well over a week uploading the data and servicing them ready for re-deployment. We have 8 so far this year, and have made great progress today getting them ready to go back in the ocean.

The first step is to upload the data and perform quality checks on it to ensure the instrument is working properly. Then the conductivity cell needs to be cleaned. What the instrument actually measures is conductance, and a scale factor or "cell constant" is then used to calculate conductivity, from which salinity can be derived. The cell constant depends on the geometry of the cell and this changes when there's any biological growth inside. By far the most important thing determining the accuracy of our salinity measurements is the cleanliness of the cell! There's a lengthy cleaning procedure, perfected last year, involving bleach, de-ionzed water, Triton X100 and lots of pumping of syringes - thankfully I have Berit for company or I think I'd go mad :-) We have a never-ending supply of cookies and banana bread from Jeff too which helps.....

Finally we open up the instruments to change their batteries, check all their screws, washers, o-rings (to stop water getting in) clamps and fittings, and then programme them again for re-deployment. We now have all 8, together with the extra 17 we recovered last year and didn't get an opportunity to redeploy, lined up in the lab upstairs ready to go.

Tuesday 21 August

We're playing a bit of a waiting game at the moment - the remaining moorings we have to recover (preferably before we start putting things in) are under heavy ice cover on the western side of the strait. We're waiting for an opportunity to pounce when there's a big enough gap. In the meantime, we've been trying to track down what's become known as the "phantom mooring"... Deployed in 2003 and missing from its mooring site in 2006, it was considered long dead, probably carried off by an iceberg to mooring heaven. But when, on the off-chance, we tried to communicate with it a few days ago, we heard a faint "I've released come and get me" set of 5 pings. Further attempts to talk to it failed. Unable to resist the challenge, and curious about the fate of poor KS15, Humfrey and I spent the night trying to talk to it with our transducers (and triangulate on its position) from a series of different locations. Aided by the extremely patient Kevin and Natasha (First and Second Officers of the Larsen) and fuelled by chocolate chip cookies, we tracked the errant mooring down in the wee small hours to a spot near Cape Jefferson 7.5km south of where we left it. Well, I should say, we tracked the acoustic release down - it may well not be attached to its flotation or instruments any more after a joy ride on the under side of an iceberg...!

So we now know exactly where it is :-) Sadly, despite lots of effort, today's attempts to drag for it from the ship using a heavy wire cable and grappling hooks (a complicated manoeuvre on the Larsen where the crane is on the foredeck) have failed. The phantom mooring clearly doesn't want to live again!

It's CTD time now - tonight it will be every hour, on the hour, at one location. We're hoping this will tell us something about the effect of the tide on the vertical profiles of temperature and salinity that we're collecting with our moored instruments. There's just about time first though for a second piece of chocolate marble cheesecake (which wins best dessert so far by a mile!). And did I mention that Howard and I have a bye in the next round of the darts tournament....?

Wednesday 22 August

Arctic oceanography certainly requires great patience! We spent this morning trying to sneak up on an IPS mooring deployed last year on the western side of the channel. The ice over there is still very heavy, so we located a patch of open water upstream and settled down to wait for it (and us) to drift south at about 1 m/s over the mooring site. We know exactly where the mooring is from our acoustic ranges, and things were looking great for a recovery. Three hours later though, the size (and shape) of our patch had changed a lot, and the mooring passed by to the side of us - frustratingly still under the ice!

Our mooring deployments this afternoon were much more successful - we put in two of our six ADCPs on the eastern side of the strait. These acoustic doppler current profilers sit on the bottom looking upwards and use the doppler effect to measure the velocity of the water as a function of depth. They send out a ping every 10 seconds or so from four transducers and then listen to the sound scattered back to them from tiny particles in the water. From the time the sound arrives they can identify which part of the water column they are measuring (they listen in short time windows which correspond to 15m deep bins) and the frequency of the sound they hear in each bin tells us the velocity of the small particles (and hence the water). All very clever!

The ADCP moorings are what we call "torsionally rigid", which means they have a special joint holding them to their anchors which allows them to bend over in all directions but not to rotate. That's because we need them to have the same orientation throughout their deployment - when we get them back we can work out how they were sat on the bottom (and hence the direction of the currents in the profile) from the tidal direction in the data. We can't use a compass for accurate monitoring of direction in the instruments up here because they're so close to the magnetic north pole that the horizontal component of the Earth's magnetic field is quite weak. (Humfrey's group at the Institute of Ocean Sciences have been using the torsionally-rigid approach successfully elsewhere in the Canadian Archipelago for many years. Just one of many challenges they've had to overcome to collect reliable data up here!) The ADCP moorings have become known as "lollipops" by the crew this year because of their shape :-)

The backdrop to all our mooring operations is the stunning coastline of either Ellesmere Island or Greenland. On the Greenland side there are two flat-topped islands called Crozier and Franklin, while on the Ellesmere side there are incredible red, black, beige and grey rock layers which outcrop in the sheer 800m cliffs. They are more familiar to me now than mountains anywhere else in the world I think! I'm looking forward to asking my new colleagues in the Earth Sciences Department about the geological processes that shaped the landscape up here...

Thursday 23 August

More mooring deployments today. We started with an ADCP "lollipop" mooring, and then moved on to a couple of the CT strings. We use the FRC for the CT strings - Howard (who drives the FRC with one of the deck crew to help) takes the top of the mooring away from the ship, keeping it taught and tangle free as we pay out the line from the foredeck. We lift the final portion of the mooring (yellow float, acoustic release and a pile of old chain that serves as an anchor) over the ship's rail using the crane, instruct Howard to let go of his end, and then drop the anchor. The floating components of the mooring come whizzing along the surface before submerging - it's fun to watch (although with so much ice around we are all holding our breath that the mooring makes it down without damage!)

We did have one surprise - we deployed a CT string and were starting to think about a tea and cookie break, when floats appeared at the surface right next to the ship! One of the kevlar lines on the mooring had broken (we are still not sure why), and everything apart from the final float-release-anchor combination had popped straight back up. In characteristically jovial fashion, the coastguard crew recovered the mooring as if we'd planned it that way. We released the acoustic release from its anchor so that it could pop up again too, and the boys scrambled around for spare anchor chain so that we could deploy the mooring a second time! Thankfully this time it stayed put :-)

Thursday is "barbecue your own steak" night on board, when the cook fires up a couple of barbecues on the towing deck and marinades a few buckets full of huge chunks of meat. Quite possibly the best steak I've ever eaten - although that may just be because I was famished after a long day working in the fresh air! There was time for a Guinness or two in the bar with everybody afterwards, which was lovely. Even John Prine (who, for those who don't know, is a famous old southern-states country singer with very seventies hair) put in an appearance, bearing a strong resemblance to Ron.......

Friday 24 August

The heavy ice on the west side of the channel is causing a real problem. We're running out of time here, but still haven't had a proper window in the multi-year ice to get the other half of our array in the water. The wind direction has changed to southerly, and is forecast to increase, which should help to spread the ice away from the Ellesmere coast, so we've all got our fingers crossed....

This afternoon I was lucky enough to go on an ice reconnaissance flight to check out the ice conditions both north and south in the channel. It was spectacular! There's nothing quite like the feeling of lifting off from the deck and seeing the ship shrink to a small dot as the helicopter gains height :-) Such a different perspective on the ice and landscape too. We flew as far south as Scoresby Bay, and then back at mountain-top height past John Richardson Fjord and several other bays, up towards Franklin Island. We saw arctic hare, and even a couple of startled musk ox! (I'll post a photo of the arctic hare once I'm back - my musk ox shot is nothing more than a fuzzy black dot... for now here's a picture of the helicopter from last year's trip.) We also flew over Michelle and Richard who were out working on an ice floe, taking measurements of thickness and ice strength. They looked so tiny out there! Michelle has been working Richard hard - he has already drilled through nearly a kilometre of sea ice in total this trip. More about what they get up to out on the ice to come soon.

Some paperwork to get done now, and then some CTD data to look at with Berit before we head downstairs to help Mark (coastguard electrician) celebrate his 29th birthday.

Saturday 25 August

The ice has finally loosened up a little on the Ellesmere side of our mooring line, and we were able to get to some of our remaining sites today. Great news! We deployed two ADCP moorings this morning, and have spent the afternoon drifting towards a CT mooring site in the hope that when we arrive there'll be space to deploy a CT string. The FRC has to be able to get a mooring length (about 300m) away from the ship, in a straight line and without ice in the way, which is very tricky with the conditions we've had so far.... Keep your fingers crossed.

Last night's birthday party was a lot of fun - the crew on board the Larsen are incredibly friendly, and when they throw a party they do it in style! Don the bosun kicked off the karaoke, and through a combination of bribery, flattery and persistence cajoled most other people into singing too. Those of you who know me well will be devastated to hear that I sang (or at least squealed) several songs, but the real stars where Dave R, Nick (senior engineer), Rhonda (steward), Julia (oiler) and Shannon (quartermaster), all of whom can actually carry a tune! They were so good, in fact, that the rest of us decided to dance :-) Songs ranged from old irish classics through seventies metal to standard karaoke crooners, and a great time was had by all. Today I've had "Crazy" by Patsy Cline stuck in my head all day after my opening duet with Ron...

Off now to put in the CT string - there's a huge patch of open water out there, and it looks like it might be in the right place for once!

Sunday 26 August

We're headed south now, after deploying as much of our array as we can given the ice conditions - 5 ADCPs, 4 CT strings and 2 IPS moorings, all scheduled for recovery in 2009. We haven't managed to put any instruments really close to the Ellesmere shore (and this is the side of the channel along which the fresh arctic outflow travels) but I'm learning that science up here has to be a compromise! The ice team have now drilled through 1200m of multi-year ice, and we have taken 91 CTD profiles. The most recent section north-south along the strait kept me and Andreas (who has become the northern night winch man!) busy from 1 - 7am this morning.

As we passed by Foulke Fjord this afternoon, I had another chance to try retrieving the shallow pressure mooring there (after failing to communicate with it from the FRC on the way north two weeks ago). Jo and I flew in by helicopter, landing on the little promontory on the southern side of the fjord, and deployed our hydrophone in shallow water from the beach. We immediately managed to communicate with the acoustic release, which was where we had left it last year in 20m of water about 40-50m out from the beach. We sent a release command and waited with baited breath - the command was received by the acoustic release, but nothing popped up to the surface :( We took off in the helicopter to fly over the fjord and check that we hadn't missed it, but saw nothing. Disappointed, we headed back to the ship (via a circuitous route over the mountains nearby, where we saw more arctic hare, the remains of the old settlement Etah, and two local hunters carrying recently killed musk ox meat down to their small boats in the cove!). Dave Spear and I then returned to Foulke Fjord in the FRC with Howard and crew member Izzy to try dragging for the mooring - the most likely scenario is that the float which is supposed to pop to the surface when the release mechanism operates is stuck or tangled somehow, and we need to snag it with a grappling hook to bring it up. We had several attempts at this, but no luck, and eventually the fog rolled in forcing us to abandon our efforts and head back to the ship. So frustrating to be able to hear the acoustic release chirping his five "I've released come and get me" pings (even without any transducer in the water because we were so close and the mooring so shallow!) yet not be able to retrieve him....

The two Daves also returned the weather station data loggers to their sites today. Here's Dave Riedel's account of what they got up to:

Weather stations set to go again (by Dave Riedel)

Amidst grey skies, 20 knots of wind, and patches of fog, we returned to the Met stations to reinstall the data-loggers. Hardly the sunshine and calm conditions of our original trip to collect them, but reasonable working conditions nonetheless. At Pim Island, the station required very little mechanical work - just some tightening of the guy-wires. The big change to both the stations on this trip was the installation of an additional battery which should enable the station to operate through the dark of winter (the second battery triples the original number of amp-hours). Thanks to Israel "Izzy" Strickland for his custom-made Canadian Coast Guard, red-with-white-stripe, wooden boxes that will protect the extra batteries from wind and precipitation. After reconnecting the control box to the sensors, we connected the logger to a laptop to confirm that everything was operating correctly. Pressure, air temperature, relative humidity, wind speed, and wind direction all checked out. Dave Spear then established a rough heading with a handheld GPS unit corresponding to the station vane's direction which enabled us to confirm that the orientation of the mast was correct.

Pilot Bob (also in charge of manning the shotgun and keeping a lookout for stalking polar bears) then flew us further south to Cape Isabella. This station required a little more repair - one guy-wire was broken and the others had become somewhat slack. As at Pim, we wired everything up and tested the station's basic operation without any problems. The reference GPS heading, however, suggests that this station may be as much as -25 degrees off in its alignment to true north.

Just as it began to get drizzly, we climbed back onboard CG-360 (the helicopter's call letters), and headed back to the Larsen, stopping only to pick up a hitch-hiker who was on his way to Pim Island to collect plankton...

Monday 27 August

Heading for Grise Fjord today, where we'll pick up a Canadian reporter from CBC who's interested in the science we've been doing. He'll join us for the next few days while we recover and redeploy some moorings in Cardigan Strait to the west. Hopefully the ice conditions when we get there will be favourable! We have been plagued by lots of heavy, multi-year ice this trip, so I asked Humfrey (who has spent his whole career studying arctic sea ice) for his view on how this fits in with the expectation of melting due to global warming:

Why are we complaining about the ice in Nares Strait? (by Humfrey Melling)

The Henry Larsen, an 8400-ton icebreaker of the Canadian Coast Guard, is our home and transport for this project. We have reported earlier that the pack ice drifting down this strait from the Arctic Ocean is a serious challenge even to our modern ship, which has 16000 horsepower to drive her ahead. We know that Arctic climate is warming and that the Arctic ice cap is shrinking. Why is this icebreaker not slicing with ease through the remnant floes of a former and harsher age?

An answer to this conundrum is one of the motivations for our study of Arctic outflows across the Canadian polar shelf.

Pack ice comes in two fundamental types: annual ice, which forms in autumn and melts the following summer, and multi-year ice; the latter starts as annual ice but does not melt completely in summer and survives to thicken and harden through subsequent winters. The area occupied by multi-year ice defines the extent of sea ice at the end of summer. The progressive reduction in end-of-summer ice extent over recent years reflects a corresponding reduction in the area covered by multi-year ice.

The Arctic pack is now on average thinner, in part because thinner seasonal ice has replaced multi-year ice in some areas, and younger multi-year ice has replaced older thicker multi-year ice in others. It is also possible that Arctic climate has warmed to the point at which the thick multi-year ice of times past can no longer develop. Unfortunately, there is little empirical support for the latter suggestion, since observations of very thick ice have been rare and unsystematic in the past and continue to be so today.

In the CAT study we are striving to measure the flux of "freshwater" carried by sea ice moving through the Arctic straits as well as by diluted seawater. To calculate ice flux, we measure ice draft year-round using ice-profiling sonar on two moorings in Nares Strait. We are as well surveying ice thickness across individual floes using bore-holes (a collaboration with Michelle from the Canadian National Research Council). We are finding some very thick sea ice. The sonar has measured many floes with average thickness exceeding 10 m. One floe passing over late in 2006 reached a maximum draft of about 42 m, a value measured only once before in the early 1970s. The on-ice surveys also have documented the presence of floes much thicker than 10 m. It is no wonder that CCGS Henry Larsen is meeting her match. Ships may with extreme caution work between such gargantuan floes, but there is not an icebreaker in the world that could break through such monsters.

The average thickness of Arctic multi-year ice is about 3-4 m, a value that conceals appreciable regional disparity. The circulation of ice within the Arctic Ocean results in a general movement of ice away from Siberia and an accumulation of the oldest and thickest ice against northern Greenland and the Canadian Archipelago. A few transects by submarine sonar more than 30 years ago measured average ice draft of 5-8 m (add 15% to get thickness in rough ice) in these areas. It is these reservoirs that feed the stream of ice through the straits of the Canadian High Arctic. Since our new data are not dramatically inconsistent with those from years long past, we tentatively conclude that the Canadian side of the Arctic remains capable in 2007 of nurturing multi-year floes as thick as have ever been observed. A careful look at the maps of the shrinking perennial Arctic pack reveals that the primary area of loss has been on the other side of the Arctic, eastward along the Eurasian coast from the Kara Sea to the western Beaufort.

So why is there less multi-year ice in the Arctic?

There is a general consensus that the decrease was initiated by a rather sudden change in Arctic ice circulation brought on by a change in prevailing winds in the late 1980s, of unknown cause. During the early 1990s, winds drove ice from a much enlarged area of the Arctic through Fram Strait and out into the Atlantic Ocean, where it was lost to melting. The reason for the prolonged trend to reduced ice is now actively debated. There is no consensus. However, it is probably fair to say that global warming has yet to be convincingly implicated.

We hear frequently that the North West Passage is soon to become an international shipping route. However, the hazardous floes that we are now meeting reach the North West Passage in about a month and Newfoundland waters in half a year. We feel that shipping through the passage will be hazardous and therefore commercially unappealing for as long as there in multi-year ice in the Arctic Ocean.

Tuesday 28 August

We're in Cardigan Strait today, an 8km wide channel between North Kent Island and Devon Island in the heart of the Canadian Archipelago. It's a beautiful spot, although right now we can't see anything at all because of the fog! When we arrived at the southern end of the strait via Fram Sound last night the sky was spectacular - we're far enough south and late enough in the year now for the sun to actually set, which makes for some amazing colours :-)

Having ploughed on undaunted past the Bay of Woe, Cape Turnback and Devil Island, we've spent much of the day trying to recover two ADCP moorings. The first popped up instantly (in spectacular fashion - these moorings have more floatation than those in Nares Strait and practically leap out of the water!). We're still trying to communicate with the acoustic release on the second - the tides are so strong here and the ice so heavy that we think there may be too much background noise in the water for it to hear the signal from our transducer. We'll try again later at slack tide and when there's more of an ice window.

Whilst there's lots of ice around, most of what we're seeing today is first year ice, and the Larsen is happily crunching through it (about as fast as I'm munching through Jeff's fantastic chocolate brownies!) In an attempt to measure the ice thickness we have a couple of small cameras out on a boom over the side - the idea is that when the cut blocks of ice roll over as they pass along the side of the ship we may be able to see them in cross-section, and then calculate their thickness if we know the camera field of view and height above the water. The thicker ice up in Nares Strait was simply not rolling over far enough, but the plan might just work with this first year stuff. There's lots of new ice about too - completely see-through and only about an inch thick. Winter is definitely on the way....

This evenings CTD section across the northern end of the strait in Norwegian Bay was cold and foggy with 9/10 ice at some stations and strong currents - all of which made it quite a challenge! We're up to 108 CTD stations now though, and Berit, Dave R, Dave S and myself took the opportunity between stations to plot and scheme about costumes for Friday night - the Larsen crew are throwing a Hawaiian party (since they're missing out on the best of the Newfoundland summer up here!) and we'd like to get into the spirit of things!

Wednesday 29 August

Michelle and Richard, with Sasa the CBC reporter in tow, have been out on the ice today measuring thickness, taking samples and strength testing (...that's the strength of both Richard AND the ice!). Here's Michelle's explanation of the various types of measurements she's taking this trip:

MOTAN & Ice Floe Party (by Michelle Johnston)

My work on the CCGS Henry Larsen involves two, different ice-related components. The first part uses an inertial measurement system called MOTAN to measure the ship's motions as it transits through the ice, a video overlooking the ship's bow to provide information about the ice conditions and data from the ship's global positioning system to provide information about the ship's position and speed. In effect, MOTAN uses the ship's response to back calculate the forces that would have been required to produce the measured ship motions in six degrees of freedom. We have installed MOTAN on five ice strengthened ships since its first installation on the USCGC Healy in the year 2000. MOTAN is recording data 24 hours a day, so there will be a huge amount of data to sort through by the time we finish these field trials in early September. To help with that process, we have installed a small, hand held device to identify the most significant impacts from where we stand on the bridge. Whenever the ice impact causes the ship to respond in a `lively manner' (appreciable movement in pitch, roll or sway for example), I push the button on the hand held box. That sends a signal to MOTAN telling it that a noteworthy impact occurred. Those type of `event markers' will make it much easier to process the data at the end of the trip.

Big, thick floes cause more significant ship motions than impacts with small, thin floes and multi-year ice - the focus of our efforts in this study - causes the highest loads on ships and structures. Getting more information about the thickness and strength of the ice requires leaving the comforts of the ship's bridge and getting out on the ice. The objective of the second part of my work on the CCGS Henry Larsen is to measure the thickness and strength of multi-year ice. Richard Lanthier, my colleague, is helping me with the on-ice measurements. So far, we have visited 9 multi-year floes and drilled more than 1200 m. We are comparing the ice thickness that we measure from drill holes to measurements from two ground conductivity meters, each with a different operating frequency and, therefore, different penetration depths. The advantage of using instruments like the ground conductivity meter, which uses the electromagnetic induction technique, is that these types of instruments operate from the ice surface. If either of these instruments is proven to give reliable results during this study, it would eliminate the need to drill holes through the ice, which is very labor intensive (just ask Richard!).

Drilling holes with the 2 inch auger is labor intensive, but nothing like the work that is required to drill 6 inch holes in the ice - and those are the kind of holes that we need to use the borehole jack to measure the in situ confined compressive strength of the ice. Our holes are made with a 6 inch fiberglass corer. An ice corer is used, as opposed to an ice auger, because it is very important to have information about how the temperature and salinity of the ice change with increasing depth. That information can only be obtained by taking ice cores. During this trip we will measure the temperature, salinity and strength of a number of ice floes in Nares Strait down to a depth of 5 m. That information is necessary because it provides the information that we need to infer the strength of ice floes in other geographic regions, at different times of the year. And that is relevant to ships and structures that operate in ice-covered waters. In fact, earlier this year, Richard and I worked from the Polar Continental Shelf Project in Resolute, Nunavut to document how two multi-year ice floes decreased in strength during the summer - our measurements were made in May, to June and July. Measurements showed that the ice warmed and became weaker as the summer advanced. Our measurements on first-year ice in the Arctic and sub-Arctic Labrador showed a similar trend, but it has taken five years of measurements on multi-year ice to begin to understand how rapidly those changes proceed. Because this work has direct relevance to engineering, our funding has come from Transport Canada and the Program for Energy Research and Development (PERD), and oil companies. We have also recieved considerable in-kind support from the Canadian Coast Guard, the Polar Continental Shelf Project and the Canadian Ice Service.

Thursday 30 August

We deployed our final two ADCP moorings today in Cardigan Strait - it's a good feeling to have everything off the deck and in the water. Dave S and Ron also went out in the FRC to have a go at recovering the mooring on the western side of the channel that we failed to communicate with on Tuesday. The idea was to get away from the background noise generated by the ship, but they still had no response from either of the acoustic releases. We have to resign ourselves to the fact that we're not going to get this particular mooring back...

Conditions out on deck this morning were the harshest they have been all trip. We woke up to a thin coating of snow, and it's been very cold and foggy for most of the day. When Dave R put on the winch operator's headphones for a CTD cast his ears got quite a shock to discover they were covered in a layer of ice! Actually, lots of the lines and antennae on the ship have a little ice on them, and now that it's warmed up and the sun has come out there's ice tinkling and falling everywhere. We're in Hell Gate at the moment, on the other side of North Kent Island from Cardigan Strait. There's a tidal current of more than 5 knots running through this narrow channel 130m deep, and this mixes up the water so that there's almost no variability in temperature and salinity with depth - our CTD profile is almost a straight vertical line!

It's barbecue-your-own-steak night again tonight, and I can already smell good things from the towing deck. The scenery is very dramatic and wild. It's moments like this that make me realize how incredibly lucky I am to be up here! We're headed back towards Pond Inlet now though, with only some CTDs, paperwork and a lot of packing between us and the end of the science program.

Friday 31 August

We saw some amazing clouds yesterday evening, streaming down off the cliffs at the entrance to Hell Gate (perhaps generated by hydraulic effects?). These were just the latest in a series of amazing skies and interesting meteorological phenomena we've seen this trip!

The steep topography on either side of the straits, together with the cold water, often lead to a low-lying layer of cloud or fog, and earlier in the month we were lucky enough to see beautiful wave shapes known as Kelvin Helmholtz billows in the top of this layer. These waves are generated when the air in the cloud-free layer above is moving faster than the cloudy air below (what's known as shear instability). They don't seem to last for long, and are frustratingly difficult to photograph, but I'll try to post a picture when I get home. The same low layer of cloud also leads to surreal views of the mountains (particularly on the Ellesmere side) which often poke out from a white blanket!

We've seen several impressive rainbows this trip, and even a couple of fog bows (this picture was taken last year when the FRC was framed by a fog bow while recovering one of our moorings). There have also been "sundogs" or "mock suns" visible on a couple of occasions, even in the wee small hours. These small bright spots in the sky, on the same horizontal line as the sun, are formed when the sun's rays are refracted through the edges of flat hexagonal ice crystals in cirrus clouds. I always feel lucky when I see one! And there are often cumulo lenticularis (or "dinner plate clouds", as I've heard them called on board) - pancake-shaped clouds which sit in stacks above mountain peaks or islands, formed by orographic uplift as air currents are forced to rise to pass over them.

Today we're all busy with packing up our scientific gear into the two containers (they'll be off-loaded in St. Johns, Newfoundland when the ship gets back there, and then sent home by truck to the Institute of Ocean Sciences in Sidney, BC). I don't know how Ron keeps track of what is packed where! I've also been buried in paperwork, trying to make sure that we have good records of which instruments and mooring components we have deployed or recovered at each site. Tonight is the first ever Larsen Arctic Luau, so we're also working on our Hawaiian costumes when we get a chance - it's amazing what you can do with a bit of scrap kevlar line and some tissues...

Saturday 1 September

Last night's Luau was another fine Larsen party. The crew did an amazing job of decorating the lounge, with palm trees complete with very realistic-looking coconuts, a miniature volcano, lots of party lights and even a pinada. Costumes, music and food were fantastic too, with Berit winning a "best dressed" prize together with Rhonda and Julia. The engineering department produced "The Big Kahuna", which provided lots of entertainment - a series of convoluted wires to be navigated around with small metal loops without making contact for fear of setting off a system of buzzers! The karaoke machine saw lots of action again, and there was even some dancing - a great evening for relaxing with the crew as we near the end of our trip.

This morning we did our final CTD section across Lancaster Sound (filmed by Sasa for a CBC national news special to be aired at the end of September). The data we recovered looked quite different from other CTD profiles we've taken this trip - the deep layer of Atlantic water here is warmer (about 2.5 degrees celsius) and we can see it flowing in to Lancaster Sound as a warm boundary current on the northern side before flowing out again on the southern side. On top of it sits the much colder (but fresher) Arctic outflow. The fact that temperature increases as you go down through the water column up here may seem counter-intuitive (since cold water usually sinks!), but simply demonstrates how big an effect salinity has on the density. The surface layer of cold fresh water which leaves the Canadian Archipelago moves southwards along the coast of Baffin Bay into the Labrador Sea. Understanding the influence it has on the circulation and deep convection there is one of the motivations for projects like ours.

Now that we're all done with CTDs the final pieces of scientific equipment have been cleaned and packed away, and we're finishing up the preliminary data analysis, archival and paperwork. Nick (the senior engineer) gave Berit and I a tour of all the engine room spaces below decks today too - it's amazing how much of the ship we hadn't actually seen yet! Tonight we're at anchor in Pond Inlet, a small Inuit community on the north side of Baffin Island, tucked in behind Bylot Island. It's strange to see other boats around (mostly small local fishing boats, but one small cruise ship and the sailing ship Jotun Arctic too) after seeing so few signs of life for three weeks! Our approach down Navy Board Inlet was spectacular - we passed by a glacier on the Borden Peninsular which sends five long fingers of ice down to meet the ocean, and the mountains of Bylot Island look incredible dusted with recent snow. I would love to be able to spend a few days exploring them!

Sunday 2 September

Today's our last day on the Larsen - over the last 3 weeks we've recovered 4 moorings, deployed 13, taken 123 CTD profiles (some of them in regions which haven't been sampled since the 1960s) and drilled through 1583m of ice. We have tons of data to analyze and explore, and we've seen some incredible sights :-) Ice conditions have been frustrating at times, and we haven't accomplished everything we set out to, but that's the nature of Arctic science!

It will take us all some time to get home - most of the science team will leave the ship in the morning, and spend tomorrow night in Pond Inlet before flying south to Iqaluit, the capital of Nunavut, on Tuesday. From there some will head to Ottawa en route to Delaware and British Columbia, whilst I'll fly to Montreal on Wednesday (with Humfrey for company) to catch an international flight back home. Hopefully I'll make it to London early on Friday morning. For the coastguard crew there's still lots of work to be done before they finish their shift on 19 September. Tomorrow the Larsen will head to Nanisivik to take on fuel and will then escort various cruise ships through icy waters on her way south to Iqaluit.

I always find it a little sad to get off a ship after a research program like this. The Larsen has been my home for the last three weeks, and her crew (along with the science team) have been my family. We've had a successful and enjoyable trip, largely due to the enthusiasm and effort of all the people on board! I am excited to be heading home though, and looking forward to catching up with everybody back there, as well as enjoying what's left of the English summer :-)

Now there's just time left to track Jeff down and copy out some of his dessert recipes before supper. He's declared today my Larsen birthday (since I won't be here on the actual day tomorrow) and has made me a fantastic strawberry cheesecake to celebrate!


If you'd like to see more photos of the people I was working with this summer click the science team photo above :-)

This page was maintained while I was at sea by Tim Woollings - thanks Tim!
My home page at the University of Oxford, UK, can be found here.