Long lost mooring recovered!

The CCGS Henry Larsen team have just, incredibly, recovered a mooring we deployed in 2003 to measure sea surface elevation (which tells us something about what drives the flow through Nares Strait).  This mooring proved impossible to recover in 2006, 2007 and 2009, and we had given up hope of seeing it again.  Incredible that we now have it back on board the Larsen!  But will it still be storing its precious data…??!

 

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Mooring day!

6 August

Today is mooring day! My function on board has officially been changed from scientist to full-time photographer for the day. We want as many photos as we can get from the equipment as it comes out of the water, so that we can always go back later and see if something happened before, during or after the recovery. And it is a beautiful sunny day; very photogenic!

Recovering the moorings is really our number-one priority on this field trip, so everyone is both excited and anxious whether we will be able to recover all of the seven moorings in this section. Ron has already contacted three of them yesterday evening, so that is a very good start. Contacting a mooring works as follows: Ron sends out a signal to the mooring at a given frequency. If the mooring receives this signal it will respond with another signal. Because these moorings are in the water for a very long time (three years in this case), the release switches are programmed to be asleep two thirds of the time and awake only one third of the time to save battery. The mooring only responds if it is awake, so it may take a few minutes to get a response. Once the mooring has confirmed that it is still in the position where it was left three years ago and awake, we go towards the mooring and check that there is no ice overlaying the site (or if there is a little and it is not too thick, ‘just push it away a little bit’ with our icebreaker). Then Ron sends out another signal to lure the mooring to the surface. This signal opens the acoustic release that holds the mooring down to its anchor. The floatation devices that are attached to the mooring line rush upwards to the surface. At this point everyone stares over the railing to try and be the first one to spot it. Today the weather was so calm that we could actually hear them come up, so it was easy. When the mooring is spotted, the FRC is launched with two crew members, who tow the mooring to the boat and attach the heavy things one by one to the crane. Then the crane tows them up to the deck.

Recovering an Acoustic Doppler Current Profiler (ADCP) mooring in 2009.
 

The first four moorings were recovered before lunch (which is from 11.30 to 12.30 here) and it looked like we were going to set a new record today. The fifth mooring after lunch also came in according to plan, but then our luck had run out. The sixth mooring refused to respond, no matter how long we tried. After a while we decided to try and contact the seventh mooring, but again without success. We steamed to the location of the seventh mooring in the hope of getting a response, still with no success. Then suddenly the sixth mooring decided it was willing to communicate after all. Apparently it had just been having some puberty issues refusing to wake up, but now it responded to our mating call. Quickly we steamed back to the site of the sixth mooring, opened the released and successfully recovered the mooring. We tried to get into contact with the last mooring, but unfortunately it was all in vain. We will probably try again on the way back, but we may need to accept that the mooring is just not there anymore.

The scientific successes and endavours of this day were celebrated at the bar that night with a drink. It was a long, eventful and in the end scientifically successful day.

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Nares Strait from the air, and the first CTD section

5 August 2012

Today started with a nice surprise! During the eight-o-clock science meeting after breakfast the chief officer popped in to say that the helicopter would fly out for an ice survey and that it could take two extra passengers. I immediately volunteered, and as Allison and I had never flown in a helicopter before we would be the lucky ones today.

Ice along the Ellesmere Island coast viewed from the helicopter during an ice survey in 2007.

Together with helicopter pilot Don and ice surveyor Erin we flew off in northeasterly direction. Erin’s job was to maps the ice conditions in the channel ahead of the boat, and see whether there was possibly a better route (less ice-covered) for the boat to take. As Hans Island lay in the helicopter range, we decided to land on this island and do a quick check of the weather station there. The weather station looks like a pole on the top of the island (Hans Island is basically a bit-oversized rock…), firmly held down to the ground with three strings. On top of the pole is a weather vane that also measures the wind speed, and attached to the pole on other heights are a thermometer and a fancy measurement device that measures the incoming solar radiation. The pole also has batteries and a solar panel to provide electricity, and a communication device that sends the data to the more populated part of the world so that it is available immediately. This is unlike our oceanographic moorings under water, which we need to physically recover on the site before we can get the data. Dave had asked us to take photos of the instruments, so we landed the helicopter for a close look. All the instruments appeared to be in remarkably good shape. The previous time this weather station was serviced a polar bear had taken a fancy on it, but fortunately none of the kind had happened this time. When we had done all our duties we flew back over Ellesmere Island to see a glacier from closer by: astonishing!

At the end of the day we finally arrived at the site of our mooring array. As we need the deck crew for mooring recoveries (in particular for the crane and the FRC, which is the small inflatable boat that can be launched from the ship), and the deck crew on Canadian coastguard vessels works from 8 to 5 on weekdays, chief scientist Humfrey decided to do a CTD (Conductivity-Temperature-Depth) section first. This had the additional advantage that we would have the CTD data from this section and the moorings overlapping for an intercomparison between the two.

The multi-coloured mountains of Ellesmere Island

Around 7 o’clock in the evening we were ready for the first trial cast. We had already done ‘dry’ tests, which means we just checked whether the computer was willing to talk to the CTD sensors and the other way around, and whether the values we got were somewhat reasonable. The quantities we measure are the conductivity, the temperature and the pressure. From those quantities we can calculate the salinity of the water (the other way to measure salinity is to take a water sample and take it to a laboratory, so by using the conductivity of the water we can measure the salinity at every location from the surface to the bottom which gives a lot more information than just a few samples), as well as the density. For a CTD cast the sensors are tied to a frame, and the frame is lowered, using a winch, from the deck to the water and subsequently from the surface to just above the bottom of the ocean. The data is sent to our computer real time through the cable that is holding the frame, so we can do a visual inspection and get all excited during the cast. After the trial run things started to really speed up and everyone took up a task. Humfrey supervised, Jo did the winch, Dave (after a subtle hint) kindly provided tea with goodies (thanks Dave!), I monitored the data on the computer screen and made sure the data was saved, and Andreas did a quick-and-dirty first post-processing of the data which enabled us all to see the results of our measurements in almost real time. Just before midnight the section was completed, I took some pictures of the midnight sun and we could all go to sleep.

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Science going well!

Life at sea involves long days and there’s not always time for writing blog posts.  You can keep up with the science developments onboard the Larsen in the meantime via our collaborator Andreas’ Muenchow’s blog at IcySeas.org.  With several ocean moorings recovered already things are going well and the crew are in good spirits!

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Preparations for the science ahead

4 August 2012

We have been sailing for two days now. On the east of us, on the Greenland side, we pass Humboldt glacier, Greenland’s largest glacier that runs into the ocean. The occasional ice berg has gradually changed into a field of ice floes surrounding the ship for almost as far as I can see. When the fog clears we can see the high cliffs of Ellesmere Island on the left and Greenland on the right.

We have used the past two days to rearrange our space and equipment on the ship so that we can start measuring as soon as we arrive on the spot. We have two containers on deck that have been converted into a far-away-from-home workshop. Ron’s container, about halfway the port side of the ship, was filled with both empty and filled boxed. The empty boxed we will fill up with equipment from the moorings we will be recovering; the other boxes contained batteries, CTDs, and probably a lot more exciting things I have not yet seen uncovered. Rearranging equipment means walking up and down a lot of stairs. There is a fitness room on this ship but I honestly do not think we will need it!

Jo’s container is positioned on the foredeck. Today we invaded the container with CTD equipment that we had so far been testing ‘dry’. We now tested it while attached to the winch to make sure that all the cables are working. With a notebook to retrieve the GPS position and two sets of a ‘deck unit’ plus a laptop for the two CTD systems, this begins to look like an operational lab at sea.

We get meals here three times a day. Normally there is table service, but today was BBQ-your-own-T-bone-steak-day. Complete cows were put on the BBQ! Or, as everything is now compared to the Manhattan since someone used it as reference size for ice islands calving of the Petermann Glacier: steaks the size ofManhattan. Tonight is bingo night, which is apparently taken very seriously here. More about that on the next blog post!

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Excitement on joining the ship

3 August 2012

After the first day of delay the journey has proceeded smoothly. As we went further north the warm summer was slowly replaced by first fog and cold at the stopover in Iqaluit (aptly summarized by Andreas’s summer student Allison: “I should have put on socks”) and later sunny and not so cold in Thule.

As we arrived on the ship all the crew members whom we had joined on the flight here immediately disappeared in the ship. As I learned later they were being briefed by their colleagues who had sailed the previous leg. It is a very smooth running system that I will get to see from close by over the coming weeks. The crew is almost as excited as we are about this trip as Nares Strait does not have any settlements and it is therefore not an area they normally get to see. The ice observer is excited because of the large amounts of ice (“Is there a nine? Is there a nine?”; the ice coverage scale goes from zero to ten). The helicopter pilot is excited because a lot of ice means likely some ice surveys by helicopter, while we will also need his services for access to the weather stations. One of the stewards is just excited because of some new scenery (“I bought a new lens for my camera!”).

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The challenge of getting to the Arctic

1 August 2012

The official plan for today: 4.45 am: take a taxi to the airport; 5.00 am: check in at the airport charter hangar; 6.00 am: take off to Thule (Greenland) via Iqaluit (Nunavut, Canada).

The real sequence of events: the night before: find out wireless internet in the hotel does not work and decision to do a last email check in the morning using the hotel lobby computer as there will be no internet on the ship; 3.30 am: alarm, shower and pack bags; 4.00 am: to lobby, check out, last check for email messages; 4.30 am: ready to go; 4.45 am: take a taxi to the airport together with the Canadian folks in the science party; 5.00 am: check in and get a cup of coffee; 6.00 am: no sign of intensions to leave any time soon.

The others reassure me that up to two hours delay is normal. 8.00 am: still no signs of a leaving airplane. Rumour has it that it has something to do with a phone call to Ottawa. 9.00 am: the airplane is missing a piece, which has just arrived, as we speak, in Ottawa. It is still unclear whether the part will get here in time to fix the plane and get to Thule before 4 pm when the airport there closes down (the situation is complicated further by the unconvenient fact that the airplane is needed tomorrow to fly another crew to another ship. The first option may then be on Friday, but if the weather does not permit landing in Thule we would have to wait till Monday as the airport is closed over the weekend). By this time the hangar had long ran out of coffee and almost non of us had had any decent breakfast. We were asked to stand by until a decision was made, with no prospect on when that would be. A shuttle was arranged to get some coffee and bagels. Around noon the final decision was made: we would try the whole operation again tomorrow at the same time.

A good exercise in patience! Much more waiting may be ahead of us with the current ice conditions in Nares Strait?

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Petermann ice island nears fjord mouth

Petermann Glacier, Fjord, and Ice Island on July 31, 2012 at 08:05 UTC. Nares Strait is to the top left. Petermann Glacier, Greenland is on bottom right. PII-2012 is at the centre. Image courtesy of Andreas Muenchow at the University of Delaware (http://IcySeas.org).

The ice island that calved from Petermann Glacier’s floating ice shelf two weeks ago received a push from easterly winds this weekend and is nearing the mouth of the fjord.  Once out in Nares Strait it may well prevent access to the oceanographic moorings the science team hope to recover this summer.  As Renske heads to St. Johns to join the science and coastguard crews destined for the CCGS Henry Larsen, we are all watching the progress of the ice island closely!

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Peter and Renske will both be posting about their experiences here.

CCGS Henry Larsen

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