Annual Layers in Polar Firn Detected by Borehole Optical Stratigraphy
Robert L. Hawley, Edwin D. Waddington
Department of Earth and Space Sciences, University of Washington, Seattle, Washington, USA.

Richard B. Alley
Department of Geosciences, Pennsylvania State University, University Park, PA, USA

Kendrick C. Taylor Desert Research Institute, Reno, NV, USA

Abstract:

We have developed a system called Borehole Optical Stratigraphy which can detect annual layers in boreholes in polar firn. Borehole Optical Stratigraphy consists of a downhole camera package and post-processing routines, which allow us to measure the intensity of light emitted from an on-board source and returned from the borehole wall. We manually identify the annual layers in this optical signal. We used this system at Siple Dome, Antarctica, in the 2001-2002 austral summer season. Our results agree well with counts of annual layers detected with two different methods in an ice core recovered 50 meters from our borehole.