August 08 - Over the line
Update (08th August 2004)
Noon Position : lat 67° 40.5' N, long 25° 04.9' W
Air temperature @ noon today : 6.0°C
Sea temperature @ noon today : 4.6°C
Over the line once more - The week in brief.
It's been a week of contrasts onboard as the weather has see-sawed from storms to still nights and idyllic dawns. Though one statement does seem to be true for this part of the world " if you don't like the present weather, just wait a minute."
This is not why we come to sea! Click to enlarge.
Though this is!
Similarly the views have gone from the pack ice and the glaciers of Greenland to fog where you can only just see the bows of the ship, don't worry we will skip the fog views; there wasn't a lot to see anyway, but there was a lot of it!
One of the many glaciers flowing into the sea from the Greenland ice cap around Kap Tupinier. Click to enlarge.
Despite the picturesque views of this week we have to report Emma's request for polar bears wasn't granted, maybe next cruise! Though we did bump over the line so to speak, in that we crossed the Arctic circle at 66° 33.6' N and so those who wished were granted their certificates (See Below)
This caused some excitement amongst the science party, although the crew played it all a little more low key - after all this is just the first of three northbound crossings we're due to make before heading home.
JCR Sports News.
More excitement, however, was gained by sporting events onboard this week, with reports that Keith Von Der Heydt beat Selina Näf in the table tennis tournament, we are however still awaiting independent verification! In the engineering sports division Nick Dunbar (ETO) beat Gerry Armour (2nd Eng) on the table tennis table, though Gerry did go on to extract revenge on the darts board with a shock win against Charlie "double top - Mate!" Smith. Charlie is apparently claiming the loss to a drop in recent form and other mitigating circumstances; something about the board moving? All this burst of activity has been blamed on the Doc starting the annual round of crew medicals, so we'll have to monitor how long those trips to the gym continue. One new activity seen this week has been the introduction to the ship of power walking. This is apparently a demonstration sport this trip and is being performed by Mindy Hall and Terry McKee, they can be seen most afternoons striding out around the decks. They did however confuse Calum Hunter (2nd Off) when they arrived on the bridge on the first afternoon asking for a map of the ship. Apparently the ship's lack of a port outside alleyway was causing problems in deciding a route. We will just have to monitor the decks over the coming weeks to see if it has taken hold, the closest we've seen so far was after somebody declared "Smoko" (Merchant Navy for tea break).
Science bit in the middle - Conveyor Belt Magic
Friday evening saw our Principal Scientist, Bob Pickart, updating us on the reasons for our being here and the questions that cruise participants are trying to answer. All this education reminded us that it has been sometime since we did a little bit of oceanography in diary class. So in an effort to redress the science balance a little away from moorings and explain the later part of this cruise let us begin.
Probably two of the most important properties of sea water for an Oceanographer are its temperature and its salinity. This leads us nicely to the CTD, the one we are presently using is pictured below.
CTD stands for Conductivity (related to the amount of salt in the water), Temperature and Depth. In fact the CTD unit is just the very bottom set of instruments and the grey tubes above that are bottles to collect water samples, but we generally just refer to the whole thing as the CTD.
Why do we want to know salinity, temperature and depth? Well this allows us to work out how dense the water is at different depths. This difference in densities produce currents in the world's oceans. The movement of water due to density differences is referred to Themohaline Circulation and is often described as a conveyor belt connecting all the worlds oceans together.
To try to explain this we'll look at the North Atlantic. The Gulf Stream carries warm, salty water, northwards to the colder polar seas. When it reaches these high latitudes, heat is removed as the bitter cold polar winds blow across its surface creating a layer of chilled water. This increase in density means the surface water is now heavier than the water layers below it and so it sinks. This sinking is called vertical convection and forms deep water layers which are one of the building blocks of ocean circulation. These layers are very slow moving and can remain at such depths for tens if not hundreds of years. The formations of these deep waters are important, but yet only occur in a few areas of the world's oceans and even then the truly deep layers require the right weather conditions to reach the lowest depths. In the North Atlantic the known areas are the Greenland, Iceland and Labrador Seas (show on the map below) However, the conditions might also exist for a fourth one; that is the Irminger Sea, and this is part of the reason we are doing this cruise. Wherever the deep water occurs its formation is still dependant on all the necessary conditions occurring together at the right time, this generally means that harsh winter winds are blowing across these particular seas.
The moorings we have deployed in previous weeks will ride out the winter storms, hopefully for several years, sending back the data which will show if the right conditions actually do occur in this area for deep water to form. This would prove that Scientists right back to Fridtjof Nansen in 1912 were correct in their thinking regarding the importance of this area.
A simplified diagram of the currents of the North Atlantic.
This project has been going on for four years now with numerous CTD casts done. We are on No.133 for this cruise alone and more to come, helping to build a very detailed picture of the conditions that exist in this part of the world.
In particular this cruise has made use of the JCR's ice strengthened features to work inside the pack ice, so allowing a much more detailed knowledge of the East Greenland Coastal Current (EGCC) to be obtained. This is a relatively fresh current which hugs the coast about which little is known. So in addition to the CTD data the waters of this current are being analysed for their nutrient contents, the aim being to answer some of the questions arising about its formation, i.e. is it just from the glaciers of Greenland or does it come all the way from the Arctic? For the final answer we will have to await the analysis of all the data and plots back in Woods Hole.
The final leg of the cruise is a transect of CTD stations, only 2.7 miles apart, all the away across the Denmark strait. This will supply a detailed image of the currents entering the region from this direction, helping Tom Haine to increase the accuracy of his mathematical model of the Irminger Sea. We can see him below at his desk pouring over the next modification to be made. Models such as these not only allow Oceanographers to simulate what is happening today and in recent years, but then to run the models into the future (and past) to see what has and what might happen.
Tom Haine pouring over the next problem for the model. Click to enlarge. The ship's company would also like to thank Tom for his interpretive skills in translating from American to English during the cruise as he is the token Brit in the science party.
A Picture Gallery
Failing to get a group shot for this weeks page as everyone's still on shifts we'll have to settle for a little gallery of shots. Team photo next week ? We'll just have to wait and see....
This week marks another round of good-byes and hellos as our new friends depart in Reykjavik and the ship mobilises for a journey to the far north. Tune in next week to hear of our Icelandic adventures. We wish a safe journey home to all our American, Swiss, Canadian, Norwegian and British colleagues and hope to see them back here real soon....
For a bit of fun and to mark the start of the football season back in the UK we thought we'd bring you our version of spot the ball - Spot the Deck Engineer.
Simon's there somewhere or is he off writing the webpage? Click to enlarge
Many thanks to Ryan Frazier, Chris Lumpkin, Emma Wilson and anyone I forgot for their photographs.