Dispatch 15: Ice Based Observatory Number 2     Print

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Mengnan Zhao

October 2, 2015

Following rosette casts, we headed north again to begin our second and last ice deployments. At around 80N, it was not long before we found suitable ice for our buoys and ice measurements. We did not even need the helicopter to deliver people to ice; it was a thick multi-year ice floe that the Louis could park beside, and we only needed to walk down some steps that were positioned over the side of the Louis.

Low temperatures with strong winds and snow reminded us that we were far north in the Arctic. The thick layer of blown snow on the ice made it difficult to walk; Sigrid Salo (NOAA) described later how you would never know what you would step on – solid ice under a thin layer or deep snow up to your knees. It took me quite a long time to struggle my way from the Louis to the buoy installation site.

Activities at this ice station were similar to last – ice thickness measurements, ice core extractions, deployment of an Ice Mass Balance buoy, O-buoy, Ice-Tethered Profiler, and an additional buoy this time: the Autonomous Ocean Flux Buoy (AOFB). The AOFB is designed to measure turbulent ocean fluxes (maybe most importantly, heat transport in the ocean to the underside of the sea-ice), to measure the crucial influence of the ocean on sea-ice melt. The WHOI group led by Rick, and with the help of others, worked efficiently and skillfully as usual to successfully deploy all 4 buoys.

At the last ice station, I described the buoy deployments, so this time let’s turn our eyes to the ice measurements. The thickness of our floe was measured both by the EM (Electro-Magnetic Induction device) as introduced in an earlier dispatch and by hand as validation for the EM measurements. An L-shaped, undisturbed section of 100 m on each side was first selected, and red flags were placed every 10 m for a hole to be dug/drilled to measure snow and ice thickness. This was group work by scientists Sarah Zimmerman (IOS), Sigrid Salo (NOAA) and Deo Florence Onda (University of Laval). Meanwhile, along the same section, Kazu Tateyama (KIT) and Shin Toda (KIT) were taking snow samples and measurements at every meter to analyze temperature, salinity and density. On the other side of the floe, a team led by scientist Jenny Hutchings (OSU) was taking ice cores. With the help of Edward Blanchard-Wrigglesworth (University of Washington), Celine Gueguen (Trent University) and David Walsh (Concordia University), ice cores were removed with a special drill. Jenny and her colleagues would bring them home to study the water composition, structure, and density through the cores. For example, by knowing the density, we are able to infer the age of the ice.

It was a cold, exhausting day, but a scientific success all around.