Thin Ice on the Arctic Ocean

Dear Carol,

Pretty exciting day today. But first, let me tell you a little about what we do every day.

We have five “lines” extending north to south, with about 8 to 11 stations to sample along each line. Each station is roughly five miles south of the previous one. We had done the far stations on line 3 yesterday, and we planned to do the final four stations today. So we were maybe 50-60 miles off-shore.

We set up a winch and lower special sample bottles, called NISKIN bottles, into the hole we drill in the ice. Arctic ice, typically, is six feet thick. Our drill can only go to nine feet, so if we don’t hit water (maybe two ice sheets have crashed into one another and one is on top of the other and too thick to drill through), we have to look for another place to drill a hole. This is a pain, because the winch and portable generator we use to drive the winch weigh a ton and no one likes to have to man-handle them very far.

Drilling Through the Ice Normal sea ice is 6 feet thick, but we can cope with ice 9 feet thick. While John and Claude drill the hole, and Sarah gets our GPS coordinates and prepares to use the depth finder to determine the depth of the ocean at this location, I am suppose to be setting up the tent, which we will drag over the hole to keep warm as we sample.

Plus, it is cold while you drill the hole because the tent isn’t up yet. I’m suppose to be setting it up, but typically I’m over there somewhere muttering and swearing trying to get the holes in the tent poles to line up so I can get the cotter pins though them, and my balaclava has fallen over my eyes again, and my parka has blown up over my head and I can’t see a damn thing. (Forget about glasses, which would probably make seeing the holes a lot easier.) But, it finally all comes together, and we get the tent set up over the winch, and all the boxes containing the instruments into the tent, get the hair dryers going to melt ice off the instruments and winch and provide ourselves with a little warmth. (It gets to about freezing in the tent, which may sound cold to you but is nearly nirvana to us.)

The Niskin bottles are open at both ends, the tops and bottoms held open by a spring-like contraption. The idea is that you set the bottle open, attach it to the steel cable on the winch, and lower away. The spring can be released, causing the top and bottom of the bottle to snap shut, thereby trapping water in the bottle at a particular depth. We put 3-4 of these bottles on the line at any one time, and that way can sample the water at different depths.

The trick is getting the bottle to close at the proper time. This is accomplished by attaching “messengers” to each bottle, which are small two pound weights that clip onto the line. A messenger comes down the line, hits a bottle and trips the spring, which closes the bottle and releases the next messenger, etc. You haul it all back up, empty the bottles into sample containers, put them back on for different depths, etc.

Sampling a Niskin bottle Sarah is taking samples from a Niskin bottle of John’s design that we call a “Christensen bottle” in honor of his contributions. John is a tinkerer of the first order and can improvise equipment that works from whatever parts we happen to have at hand. This is an unbelievably important skill when you are far away from anywhere. Claude and Sarah are nearly as good. As for my skills, if it doesn’t improve my tennis game, I haven’t learned it.

In practice it is a bit more complicated. The first time I was in charge of the messenger I heard the command “send the messenger” and I tossed the thing into the hole without attaching it to the wire. Whoops!

Fortunately, we have a couple of extra. (Actually, I accidentally kicked it in, but its a better story this way, and Claude says he actually saw this happen on one of this first science field sessions.) It doesn’t much matter how it happens, if it is not attached to the wire, those little guys don’t come back. John, the principle investigator, clipped one into the wire yesterday, but apparently some ice got into the clip and it opened and sailed to the briny deep (along with his new wrench today). We can buy more wrenches at the hardware store, but even they don’t carry messengers. We have one extra now!

Anyway, I promised excitement. And while losing things down an ice hole may be exciting to us, it’s probably not for you.

Helicopters are short range vehicles, so they typically have enough gas to get there, but not enough to get back. This can be a problem, to say the least. We solve the problem by having a plane (which has a much longer range) fly out to the furthest point of the day’s sampling and meet us with three 50 gallon barrels of gas. We have to find a relatively flat spot for the plane to land, and he has to have at least 1000 feet or so of clearance to be able to take off again.

The ice is particularly rough this year (or so I have been told), so there are not a whole lot of choices once you get out there. The helicopter pilots don’t want to land once for the refueling and once for us (which would add another hour to the day), so we try to pick a spot within a half mile of the sampling location that works for both us and the plane.

Refueling the Helicopter Helicopters are short range vehicles and typically have enough fuel to get us out there, but not enough to bring us back. We solve the problem by having a refueling plane land with fuel barrels. So, for a short time, everyone is in close proximity on the ice.

We found a very nice flat spot today that was runway shaped, long and narrow. We landed on the right side of the site and while we dug our ice hole, the plane landed and taxied up to us to do the fuel transfer. Imagine our surprise, then, to dig the hole and find that we had a whopping 12 inches of ice under us! We had landed two aircraft and the winch (which I think weights as much as an aircraft) on 12 inches of sea ice. Holy smoke! Sea ice, while strong, is a lot more elastic than freshwater ice, and 12 inches must be a bare minimum for landing an aircraft. This was probably an open water lead just a couple of days ago.

No one said a word. We just looked at each other with raised eyebrows. I guess we were all thinking that if we weren’t currently standing on the bottom of the briny deep, the chances were probably about average that we wouldn’t be doing so any time soon. But I finally went over and moved the red bag containing our survival gear about 100 feet further from the helicopter, just in case we needed it. Fortunately, we didn’t. But we were all very relieved to be getting out of there.

The next stop turned out to be a site with polar bear tracks snaking through it! (Did I mention excitement?) I got out of the helicopter gingerly, careful to look in both directions before exiting. We were in a sort of bowl shaped field, maybe fifty yards in diameter, surrounded by a pressure ridge which had thrown up blocks of ice 4-6 feet high in a circle around us. Normally the ice is spectacularly beautiful, a soft translucent aqua color. Very seductive. But at the moment it looked like perfect polar bear cover. I’ve heard polar bears can make a 25-yard dash in about 3-4 seconds. Gulp.

Normally, we set up the tent a short distance from the helicopter and we all crowd into the tent to keep warm. But there is not much for me to do in the tent except, occasionally, drive the winch. I’ve been deemed too clumsy to get near the real work around the ice hole, which is how I like it normally, and especially in these special circumstances. In fact, I volunteered to stand out in the cold with the rifle within easy reach “just to keep an eye on things”.

(Whether or not I could remember to cock the rifle, remove the safety, aim, and pull the trigger on a rifle without half a day to think about it, let alone 3-4 seconds, is--thankfully--an academic question. But I will tell you this, you don’t have to have a especially vivid imagination to see polar bears just about everywhere in an Arctic landscape. I think I saw about 20 of them all together!

After a little while I got brave enough to venture over closer to the tracks and have a look. They were probably 3-4 days old, I would guess, but still incredibly vivid. You could see each claw mark separately, and the pads were perfectly preserved. (The snow on the ice is quite hard and packed from the wind, so these kinds of tracks are preserved for a long time.) I put a glove down next to them to take a picture. It was about one and a half glove lengths long. Probably 12 inches in diameter for the rear print, the front a little smaller. I’ve never seen a bigger print in my life. That was one great big bear!

Bear Tracks Our first close look at polar bear tracks on the ice. These were about 30 yards from one of our sampling stations, but don’t appear to be too fresh. They are big enough, though, and have us being extra watchful around our sampling site. Our pilots are particularly wary and take their rife even when moving off to write their names in the snow.

Anyway, back safely and ready for bed now. I think we are going to take a day off tomorrow. OHSHA safety rules have reached as far north as Alaska and our pilots are required to take at least two days off in every 14. No such rules for scientists yet, but since we can’t fly (and are all exhausted from 10 straight days of work anyway) we are going to take the day off and see if we can get some of our reluctant equipment to start working again. Don’t know what I’m going to do yet. Hang out at the hardware store and act like I know what I am doing there, I guess.

Love,

Dave