Days 24-26

The past few days, we have broken a bit the monotony of the CTD casts by alternating them with VMP casts.
VMP stands for Vertical Microstructure Profiler : it is an instrument designed to measure the dissipation of energy in the ocean, which occurs on centimeter scale. Therefore, it must sample very fast water properties such as temperature, salinity and velocity shear. It must also not be contaminated by any spurious vibrations, and has therefore to be free-falling in the water, so that it is not subjected to any tension in the line linking it to the ship. But since it must be able to sample water properties with a resolution on the order of 1 cm, it must not be falling too rapidly in the water. Therefore, a big plastic fan is attached at the top of the instrument (see picture below, where I am in red, holding the VMP) to slow it down to about half a meter per second. The instrument sensors are mounted at the bottom, so that no structure protrude before them as the instrument is falling through the water.

The game then consists in unspooling enough cable out for the instrument to free fall, and stop it at some level above the bottom, and then respool it to prevent the instrument from hitting the bottom, which could break the fragile sensors ! Given that we do not know the depth precisely (the ship is always drifting a bit over a variable bathymetry), nor the speed at which the cable is unspooled, but only know the pressure at which the instrument is, it is quite of a gamble to approach the bottom as close as possible (turbulent dissipation is often increased near the bottom, so we like to measure it) without running into it. Below, Kjersti is anxiously watching the instrument pressure to give us the signal of spooling back ! She did a very good job : we never hit the bottom, while the people on the other watch hit it twice (without breaking the sensors, fortunately). But they were trying to get much closer to the bottom as we did, since the owner of the instrument was in their watch.

For deep casts, with a lot of cable out, the winch was sometimes not strong enough to respool the cable alone, so we had to help him a bit by pulling the cable in. A good warming exercise when it is cold.

Some winches have an automatic cable driver to help the cable respool properly, but the one we had was lacking such luxury. Therefore we had to do it ourselves with a wooden stick. I literaly became a living cable driver...
NB : the pictures where I appear were taken by Kjersti, who kindly gave them to me.

Day 23

Whales !
After breakfast, I went outside on the ship deck to take pictures of the rising sun, and suddenly I saw two whales swimming ahead of the ship. Unfortunately, I had my normal lense on, so the whales where barely visible on the shots I took. I was thinking : "do I change my lense and risk missing them, or do I watch and get only disappointing pictures ?" I decided to switch to my zoom lense. Luckily, the whales reappeared and came closer to the ship. They followed us for about 10 minutes before turning away. I took loads of shots ! Below are some of the best sequences. But before, I would like to show this cartoon I had seen earlier in the book Antarctica - A guide to the wildlife, by Tony Soper :


The characteristic features of Minke whales are the insubstantial blow (contrary to that of the fin whale, which can reach up to 6 meters), and the fact that the tail does not come out of the water when they dive (contrary to other whales). Look out for these features in the sequence below :





Now, viewed from behind, as the whales were turning away from the ship :




I can't believe how lucky I was, to be at the right place at the right time !
If I could be as lucky with a killer whale before the end of this trip, I would be blessed...

Days 21-22

On Thursday, the 21st day of the cruise, the Second Chief Officer got injured or fell ill, I don't know, and Hannah, the ship's doctor, could not figure out how to cure him, so he had to get transferred to Halley to be flown from there to the nearest hospital on the Southern American continent I guess. We therefore stopped our work and headed to the ice shelf "dock" where people and equipment are usually transferred to Halley.
The trip took us 16 hours, a welcome break from the otherwise uninterrupted work ! We played cards, then I sorted out the mooring pictures and wrote the previous post. Somehow I did not feel like working on my papers, after 3 weeks of uninterrupted 12-hour work days...

Below are some pictures of the ice shelf again.



Then the snow shuttle arrived from Halley...

and some people from Halley traded the Second Chief Officer room for a one-week trip, before we come back to Halley on February 19.

We then headed back to our work area.
The next day, we deployed another of the Norwegian moorings successfully, along with more CTD casts.

Day 20

Yesterday, the Norwegian team started deploying their moorings. These moorings are more difficult to deploy than the SASSI moorings, because they are "anchor-first", which means the 500-600 kg anchor is deployed first so the line is always under high tension. The first mooring went well. But during the second mooring deployment, the line suddenly broke, sending the instruments already attached to it to the bottom, lost forever ! Big disappointment and frustration... The mooring was redesigned for an anchor-last deployment, and shortened with the remaining instruments. Since they had enough people helping for the deployment, I took pictures to document how a mooring deployment proceeds.

In an anchor-last deployment, the first equipment to go overboard are the buoyancy devices : glass spheres protected within plastic shells (in red in the picture). Then follows the first instrument : an ADCP (Acoustic Doppler Current Profiler, in yellow in the picture). Helge is pulling the glass spheres out, and Charlie is giving hand signs to the upper winch operator who controls the position of the block through which the line goes.

The glass spheres drift away from the ship, pulling the line out. This is the major inconvenient for anchor-last deployments in these conditions : you need a vast area of ice-free water !

Then various instruments are attached to the line at specific lengths, corresponding to specific depths once the anchor is sunk to the bottom.
Here the instrument is a CTD (Conductivity-Temperature-Depth) sensor.


Ilker in a remake of "The Matrix" !

Keith, the Principal Investigator for the cruise, driving the lower winch, which controls the speed of the line. His casual stance is in fact a way to put his weight on the lever, which is very hard to move and maintain in a fixed position. Given the fact that you have to hold the position for long periods of time when deploying thousands of meters of line at a speed of 1-2 meters per minute, it is a quite tiring job. I was driving this winch for the SASSI deployment.

Watching the line running out between two instruments...

A current meter that works like an anemometer is being attached to the line...

... before going out.
Ilker, the Principal Investigator for these moorings, is watching that everything is going according to plans.

Finally, the anchor, an old train wheel, is lifted up from the deck and held over the water, with a special device to release it when the ship is exactly over the desired location.

Ready to go !




With the big splash, the deployment ends successfully, and everyone cheers and can relax, before the next deployment...

days 17-19

These past days we have done CTD casts, deployed a mooring, and CTD casts again.
Yesterday, I saw something beautiful : the sea was covered with a very thin and transparent layer of ice, and as the ship was cutting through it, cracks were appearing and propagating from the ship's hull. The light was such that the cracks appeared like white streaks over the dark background of the sea, resembling lightnings in the sky !

Today I witnessed another beautiful show of nature : the full moon was setting ...

... as the sun was rising ...

... painting everything in warm orange and pink colors.

Below some ice raftings undulate over waves from the ship's wake.

days 15-16

Since the seal tagging, my excitement, which had reached a climax, is slowly fading out, as we are entering a more routine work schedule, which consists mainly in CTD casts, and I am starting to get used to seeing ice, penguins and seals around me. I am not getting bored for that matter, since we are kept busy by our work watches, and I am still enchanted by what I see around me. I am missing Marion and Margot, but I see them by skype about every other day, which eases the separation.

Below are some pictures of a crabeater seal, or white seal, the most abundant seal in the world, according to the book Antarctica - A guide to the wildlife, by Tony Soper. They have a creamy white pelage in the summer, and moult to a darker one in the winter.
Contrary to what their name suggest, they do not eat crabs ! They eat krill and other crustaceans. They may have been named as a result of confusion when translating from Scandinavian languages. According to my Norwegian watch buddies, Kjersti and Helge, these seals are called "kräft ätare" in Swedish, which means "shrimp eater". Kräft was then probably incorrectly translated as crab...




You don't want to annoy these animals : they can move at 25 km/h on ice !

Penguin's chat

Joe (penguin on the right) : "I'm bored, Dude, don't you have a joke you haven't told me yet ?"


Jack (penguin on the left) : "How do whales weigh themselves ?"
Joe : "...?"

Joe : "... dunno..."

Jack : "They go to a whale-weigh station !"
Joe : "Pffff..."

Joe : "How do you do to remember all these jokes ?"


Jack : "Well, I remember them, that's all !"


Jack: "Don't worry, I'll tell them to you again and again."


Joe: "Yes, but this is unjust..."


Joe : "WHY DO I ALWAYS FORGET JOKES ??"


Jack : "Look, there's a train coming !"




Jack : "Let's go to the railway station, Joe, let's get out of here !"


Joe : "All right, it's getting too cold anyway..."