HLY1502 letter 02 from Jim Swift

Sunday, 16 August 2015, 4:30 pm, local date and time (0030 17 August UTC)

68°N, 168°W (in the Chukchi Sea, about 100 miles north of Bering Strait, above the Arctic Circle)

air 8.2 degC / 47 degF

water 6.4 degC / 44 degF

wind 15 knots from NNE

On Station 6

Dear Family, Friends, and Colleagues,

We have been carrying out sampling over the continental shelf of the Bering Sea and Bering Strait, and are now in the Chukchi Sea. In a few days we will leave the shelf behind and head north into the Arctic Ocean proper. The region we are working at present is shallow - 50 meters deep, compared to 4000 meters depth or more in the Arctic deep basins. Most of the shelf here is solidly ice covered in winter. But this part of the ice pack melts early in the season, so there is no ice in the area now; we will not encounter sea ice for another few days.

Arctic Ocean ice conditions ahead are much in the thoughts of the chief scientist (Dr. David Kadko, Florida International University) and the ship’s captain and officers. On the whole, the Arctic Ocean ice cover is light this year - not the lightest ever but still “2 standard deviations less than the mean”. But it matters a good deal where the ice is, how heavily it is concentrated, and how thick and old it is. The ship requires more power, and uses fuel more quickly, the heavier its icebreaking chores. It is easy to understand that if the ice has frequent, well-placed openings - these are called “leads” - the ship can make way more quickly and efficiently. Just as obviously, it can go through thinner ice more readily than thicker ice. Perhaps not as obvious to some readers, the younger the ice, the easier the icebreaking: first-year ice is easier to traverse than ice more than one year old. Fortunately, with today’s satellites, it is possible to picture or estimate ice extent, concentration, thickness, and age - but not on a small enough scale for navigation, because the ‘footprint’ of some of those satellite data is on the order of tens of miles (though finer than that for some types of remote imaging). The short version is that the present and predicted ice conditions seem to favor working north on the track we were originally planning to take south. Then we will try the other track southbound. We will know soon which track Dave choses.

My team has been using a water sampling system equipped with 12 30-liter water sampling bottles, which go down open and are closed at selected depths as we haul the system up. These are large bottles (most of my work on past cruises has been with 10-liter bottles) and we knew from experience they are touchy in terms of leaks: there are 65 lbs of water pushing at the bottom end caps, held tight onto an O-ring by a strong spring in the bottle. The techs have been working out the kinks and we are satisfied with progress - one way we stop a leak is to hit the bottom end cap with a non-metallic mallet (see photo, taken by Joseph Gum, SIO, showing oxygen sampler Andrew Barna and hammer-wielder Melissa Miller of SIO). Yes, using a hammer is still how some equipment is fixed!

Most of the water sampling and analysis programs I work with are doing well, but though the ocean carbon team (UofMiami) has been generating good data, their lab van has been overheating. Their analysis equipment generates appreciable heat, but needs a stable lab temperature for best performance. They have a fine air conditioning system but the ship cannot connect it, and so they must attempt to cool the van by leaving a van door part-way open to the cold outside air. This requires that they use headlamps in their van at night (even though we are well north we currently still have a dark period) because their van is in front of the bridge, and the normal lab lights shining out the open door would affect the vision of personnel on the bridge. There is attention being paid to this issue, and progress may lie ahead.

The food aboard has been good. There is a cafeteria-style line - we choose and they serve - with a salad bar, condiments, and dessert nearby - and we are chowing down the fresh vegetables while they last. Some of us work a set watch (for example mine is 11:30 am to 11:30 pm) for which others cover our off time. But most of the science staff on board do their work whenever the ship gets to that particular point in the program, so continual adjustments and naps-when-you-can are standard routine for many others. The work is spread out just enough to allow catch-up from time to time.

Because it’s interesting and uniquely “Alaska”, I’m also including a photo taken by Croy Carlin, OSU, of bald eagles on the beach near Dutch Harbor - pretty wild to have bald eagles instead of seagulls at the beach! (These eagles were hanging out where people were fishing - looking for an easy meal?)

All is well.

Jim Swift

Research Oceanographer

UCSD Scripps Institution of Oceanography