Archive for the ‘In the field’ Category

h1

More swells and an itinerant ice floe

September 17, 2012

The sun peaks over the horizon in this view of the Arctic Ocean from the MV Arctic Sunrise. (Photo by Julienne Stroeve)

It’s been a few days since I’ve written, and a lot has happened.

On the evening of September 11, we abandoned our original sailing plan of  searching for larger ice floes. We left the ice pack and headed west along the ice edge where we ran into a rather large swell. Once were in more open water, half the crew and guests were once again seasick. Luckily, we only spent half the night and half the next day along the ice edge, so I was able to resume my ice watch observations around 2 p.m. on September 12.

Along the ice edge at 82.27N, 21.27E, I observed  a lot of ice at 80 to 90 percent ice concentration. However, after a couple of hours the ice concentration dropped dramatically, typically to values of around 40 percent. I have been surprised by the vast expanses of open water that we came upon after entering the ice. The average ice concentration of the last five days has been about 65 percent, with about 36 percent of that ice being first-year ice, 14 percent being multiyear ice and 10 percent being brash ice (small broken ice floes). Air temperatures have been above freezing, even at 82.82N, 15.16E, so that there have been no new ice formation observed the last five days. Mixed sea and ice surface temperatures range from -2 to -3C.

Because our objective was to find a large ice floe, we once again sent the helicopter out to try to locate one that we could moor to. We finally had success on the 13th of September. This floe was about 100 meters long and 60 meters wide. One of Greenpeace’s objectives was to place flags from the 195 United Nations countries on a floe as a statement to turn the Arctic Ocean into a sanctuary—thus the need to find a large floe. They were able to place half the flags on the floe on September 13. The Cambridge University scientists placed their wave height buoy on the ice and I was able to make one thickness measurement (205 centimeters) before the drill got stuck and we had to spend a couple of hours digging it out. Then it was dinnertime.

After dinner, a large swell began to penetrate the ice. By 8 p.m. we could tell the floe we were moored to was flexing and it was only a matter of time before the floe would break. Sure enough around 9 p.m. the floe broke. A handful of errors caused the ship to lose the floe the following day, which still had the expensive buoy fixed to it.

The entire next day was spent searching for the floe. The weather unfortunately was not good; there were lots of low clouds making visibility difficult. The helicopter made several flights to search for it but was unsuccessful. Everyone was taking turns in the crow’s nest trying to spot it as well. We had all but given up when Grant spotted the floe around 6 p.m. on September 14.

Everyone quickly went about setting up the rest of the flags, while I drilled into the ice for another thickness measurement. This part of the ice floe ended up being a lot thicker than anticipated. After about 270 centimeters, we had to give up, as the drill couldn’t go any further. I had originally thought this was a first-year ice floe with a pressure ridge. I’m thinking now it’s likely a second-year year floe. I should note that this second hole showed biological activity in the ice (algae and other material).

Today is September 15 and I was hoping to take the helicopter out to individual floes for half the day to measure their thickness. Unfortunately the weather is not cooperating. A storm is on its way and the visibility is less than 750 meters. Instead we will moor to a few more floes so that I can make a few more measurements and the Cambridge folks can collect a few more wave height data. Ten-meter swells await us when we leave the ice pack. Looks like I’ll be skipping dinner tonight.

Locations: 82.27N, 21.27E82.82N, 15.16E

Advertisements
h1

In search of large ice floes

September 11, 2012

Julienne Stroeve, right, supervises Sara Ayech in drilling on a large ice floe in the Arctic Ocean. (Photo by Daniel Beltra / Greenpeace)

The last two days were spent searching for floes larger than 100 meters. However, since we reached the ice edge we have not found any large floes. Most have been around 20 to 50 meters in size. Today I set foot on a larger floe that was 65 by 55 meters. This floe was likely second-year ice, with a mean thickness around 2 meters. It had five frozen melt ponds. On top of the floe was a granular surface of 1- to 2-centimeter grain size ranging between 8- to 16- centimeter deep. I drilled through the largest frozen melt pond (though not entirely frozen as water came up when I drilled through the top layer), that had a total ice thickness of 165 centimeters.

According to the satellite data, we should have already reached nearly 100 percent ice concentration, yet at 83N, the ice concentration remains less than 40 percent. It could be that the heavy fog has resulted in an overestimation of the ice concentration from the passive microwave satellite observation.

As the temperatures have dropped further in the day (below -5 degrees Celsius), frazil and grease ice have increased the total ice concentration to 80 percent. Helicopter reconnaissance shows no large ice floes within at least one day of sailing.

Several polar bears were sighted today, including a mother and her two-year-old cub. Amazing to watch them from the ship. So curious!

Just heard that a storm is on its way. Appears to be some light snow now. Our plan is to start heading west in hopes of reaching some larger ice floes.

h1

In the ice

September 10, 2012

We reached the ice edge around 6 a.m. LST on Monday, September 10 at 82N. At first we encountered small first-year ice floes and some brash ice. As we went further into the pack, it was mostly first-year ice (less than 100 meters in size, and less than 1 meter thick) and brash ice, equaling 9/10ths ice concentration. Lots of polar bear footprints on the first-year ice and we saw our first polar bear off in the distance. Because of the heavy fog I wasn’t able to get a good picture of the bear. We are also not flying the helicopter until the fog lifts.

As of 11 a.m. LST, we are at 82.23N, 25.44E and it’s still foggy. Ice concentration has dropped to 5/10ths. Ice now consists of first-year ice floes between 1 to 2 meters thick (still less than 100 meters in size), second-year ice (2 meters thick), and some brash ice. A few scattered pressure ridges, but mostly undeformed ice.

Location: 82.23N, 25.44E

%d bloggers like this: