Field Update: Nov. 28, 2010

Craig Stewart and I traveled back to Mooring Site #1 today to download the data being recorded by the instruments and also transmitted up the cable.

This is the first time that we’ve come back to the site since we moved and all that remains are a scattering of flags where all the containers had been for the past several weeks and the tripods for the moorings. The sledge tracks in the snow are still visible in the uneven surface, but soon these will begin to fade as snow drifts across the site, blown steadily by the wind.

We came out to check the sensors and download the data to confirm that everything is working as expected, and also to have a look at what these data are telling us about the tidal current’s velocity and direction over the past few days. The more we learn, the more questions we have about how the oceanographic system behaves under the ice shelf. Does the water move in different directions at different vertical levels in the ice shelf cavity? Is the water just below the ice shelf fresher (less salty) because of melting ice at the bottom of the ice shelf? How fast does the ice hole close after we stop circulating water with the pumps from the hot water drill and the water freezes? Craig’s data will begin to answer some of these questions.

I watch as Craig opens the box left on the surface and connects his computer to download the data that is stored there in memory, waiting for us.

After downloading the data to his computer, Craig plots the outcomes while shielding his screen from the bright sunlight by hiding under his coat in the PB. It looks a bit odd, but you’d be surprised to learn the things scientists do in the name of their research. I wait until he’s done and then he invites me to crawl under his coat and take a look at the data myself. This is great! The currents seem to be changing over the course of the few days that we’ve been making measurements, and the patterns that are emerging will help us to understand the tidal cycles and their potential impact on our future drilling activities. We will use all of these data to model the drill riser (pipe) that we use to core deeply into the subsurface. The modeling will tell us how the currents will interact with the pipe and how long we will be able to drill and core before the we have to pull out of the seafloor. The ice shelf is moving at about 2 meters/day laterally, so when we are drilling the pipe is steadily bending at the points where it comes out below the ice shelf and at where it enters the seafloor. Understanding how the tides and other currents affect the drill pipe will allow us to potentially go deeper and have better quality cores.

Once Craig is done, we go north to the line of flags to check on the planning for the seismic experiment, and then we turn south again to return to Site #2. It’s a good day for a drive and we get home in time for dinner, bringing new data and new insights about the moorings to the rest of the science team.

I’ll be catching a helicopter in the morning, so I take a walk outside and enjoy the view across the ice on my last (sunny) night on the ice for a while.

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