Edge of the Arctic Shelf

CTD Surgery
Late last night, Ryan Frazier was manning the CTD controls when he noticed some strange numbers coming from the altimeter. The altimeter tells us how high the rosette is off the seafloor. This is an extremely important reading because it allows us to lower the CTD close to the bottom without crashing into it. If the CTD were to get snagged on some seafloor rocks or debris, it's possible that the entire rosette could be lost. That kind of a tragedy would cost about $250,000. So, you can see why a malfunctioning altimeter is a very serious problem. After some initial troubleshooting, Sarah Zimmermann and the Healy Marine Science Technicians traced the problem to a leaky connector. The CTD and altimeter were promptly replaced with spares, and the science continued.

But what do you do with a sick CTD? If you have a CTD doctor onboard, you can fix it. Luckily, there was a surgeon in the house. Jim Schmitt, who is analyzing the salt content of our water samples on this cruise, is also very experienced in CTD troubleshooting and repair. In a few hours, he had the CTD circuitry on a workbench and was busy attaching a new connector. Soldering iron in hand, Jim deftly reconnected the tiny wires and reassembled the unit. He mentioned to me that this was not an uncommon problem. The ocean is a very harsh, corrosive environment for electronics, and eventually things just break. That's why we carry spares of just about everything, from pencils to laptop computers to altimeters.

As the CTDs continued, Seth Danielson was pleased to report that the Barrow Canyon mooring instruments returned 100% of their data. Seth and Tom are ecstatic at this great news.

Today I received some questions from Dr. Linda Werner's sixth grade class at Morse Pond School. I will be answering them over the course of the next few days, so be sure to check back for your answers. Thanks to Vinny, Chris, Brianna, Breanna, Eliza, P.J., Chad, Ivan, Josh T., Josh B., Anna, Sarah, Jillian, Cara, Carla, Jennifer, Molly, and Devon for the questions.

In today's dispatch I will answer the questions about arctic climate and weather.

Question: Are there seasons in the Arctic region? Is the temperature below 32

F all year?
Answer: Good questions! While the Arctic is indeed much colder than Massachusetts, it does in fact have the same four distinct seasons: winter, spring, summer, and fall. Spring and fall are best described as "transition seasons" in between summer and winter. You could think of spring as a time of "melt down" and fall as "freeze up." In winter, the sun never rises, and so the temperature remains well below freezing for this entire period. As spring arrives, the temperature climbs above freezing during the day, but drops below freezing at night. In summer, the sun never sets, and so the temperature finally rises above freezing. During this time the arctic experiences a brief explosion of life. We are currently in the start of the fall freeze-up season. The temperature is hovering right around freezing. In the next two months the sea ice will reform and the sunlight will fade to cold arctic winter night.

Question: How often does it snow in the Arctic?
Answer: Not as much as you might think... In fact, only Arizona and New Mexico get less moisture each year! Why is that? Colder air can hold less moisture than warm air. In essence, in the Arctic it can be too cold to snow. The snow flurries we have seen on the ship have been very short, and the snow has been very dry and powdery. None of the snow has accumulated on deck so far.

Question: How cold does it get?
Answer: Scientists can measure the coldest winter temperatures out on the arctic icepack using ice-tethered buoys. These buoys are frozen into large ice floes and drift with the icepack, making measurements above and below the water. The coldest temperatures that these buoys have recorded has been -40�C (-40�F), with typical winter temperatures between -35 and -40�C. Historically, the coldest recorded winter air temperatures in the icepack was -56�C (-69�F) at Russian NP-22 drifting station. Even though the Arctic Ocean is farther north than Siberia, the temperature gets much colder over the continent. The ocean helps to moderate the temperature, just like on Cape Cod. The coldest temperature in the Northern Hemisphere occurred on February 6th, 1933: -90�F, Verkhoyansk, Siberia. Now that's cold. Many thanks to my friend Rick Krishfield from WHOI for that information.

Today the cobalt blue Chukchi Sea waters were as flat as I have ever seen them. We could have been floating on a small pond; the only ripples on the surface came from the Healy's bow wake. The CTD delay cost us some time today, but tomorrow we hope to finish this section and begin moving northward.