P4.1 A 118 - year continuous snow accumulation record along the Greenland ice divide from NGRIP to NEEM

Monday, 2 May 2011
Kennedy Room (1st Floor) (Omni Parker House )
Claude M. Laird, University of Kansas, Lawrence, KS; and S. L. Buchardt, A. M. Hoch, H. L. Barbour, D. J. Mailhot, D. A. Braaten, and C. J. van der Veen

Data from an ultra-fine resolution, frequency modulated, continuous wave (FMCW) surface radar system were collected continuously during a 375-km traverse in 2007 along the Greenland ice divide from NGRIP to NEEM field camps and have been processed into water equivalent accumulation using interpolated density profiles from ice cores at these two sites. Absolute dating was accomplished by tracing annual layers, using the 2007 surface and 1889 melt layer observed in both ice cores and the radar echograms as tie points. Radar-derived accumulation at the beginning and end of the traverse correlates well with δ18O dated annual accumulation from the NGRIP and NEEM ice cores. Significant correlations are also observed with coastal temperature records, especially during the positive phase of the NAO when zonal circulation predominates. Layer tracing of the radar data continues and is expected to produce an accumulation record covering more than 400 years.

The accumulation history of ice sheets has previously been derived from essentially 1-D spatial or point sources (i.e. ice cores and snow pits). This data set represents the first absolutely dated, mesoscale, annual snow accumulation series offering continuous, 2-D spatial coverage of the Greenland ice sheet and ties together two major ice cores. The data will be used to characterize both spatial and temporal accumulation variability along the ice divide between NGRIP and NEEM and are suitable for use in climatology and ice sheet modeling studies.

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