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Field and CPL Updates

2011 Core Processing Line

July 1, 2011

Update provided by Peter Neff

The visible layer in the image is indicated by the arrow on the plot of electrical conductivity. The low DC-ECM in the ice around the layer indicates all the acids have been neutralized. The AC-ECM is high and DC-ECM is low because there is material in the layer that can conduct an alternating electrical current by rotating in the ice lattice, but which is too large to move through the ice lattice and conduct a direct current. It is likely the visible layer is high in calcium. This information is used during core processing to adjust the depths where gas samples are collected, allowing us to avoid sampling for gases at depths that have anomalous chemistry. Seasonal changes in chemistry also form electrical conductivity peaks, and are used to date the ice core. These annual peaks are most obvious to the right (down core) of the arrowed peak, and are clearly interrupted by the anomalous chemistry of the visible layer. It is not yet known if the visible layer is tephra, continental dust, or something else. Photo: Peter Neff; Data: TJ Fudge.

In our last week of work before a planned vacation the week of July 4th, we managed to process 136 meters of core. This brings our current depth to 2530 meters, just shy of the last ice drilled during the 2009-2010 drilling season.

We saw dozens of cloudy layers in the ice this week, as well as some distinct ash layers. There is a band of heavy volcanism, or a visible layer rich section of core, spanning 100m in the ice around 2500 meters, which we hypothesize relates to the "Old Faithful" radar layer seen across the West Antarctic Ice Sheet. We do not yet have an updated age count for this depth, but it is approximately 17,500 years before present based extrapolation from the Byrd ice core.

Our visiting scientist this week was Joe McConnell (DRI), who shared some aerosol data from the WAIS Divide core. Once again, it's been a pleasure to see so many of our PIs at the lab this summer.

Attached to the update this week is a "science-tidbit" from TJ Fudge (UW). We've been excitedly watching the electrical conductivity measurements as we cross potential volcanic layers - here is the first for your viewing and educational pleasure.

As we approach the halfway mark of the 2011 CPL, I want to thank everyone involved for their hard work, attention to detail, and participation from near and far. Spirits are high here, though I think this week off will be healthy for all. Happy 4th of July to all of those in the States - I hope you all have a great holiday weekend with friends and family.

Peter Neff
WAIS Divide SCO Representative, 2011 CPL

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