A comparison of age-depth scales derived from shallow ice cores and an FMCW radar in West Antarctica
Abstract
The Satellite Era Accumulation Traverse (SEAT) collected near-surface firn cores and Ultra High Frequency (UHF) Frequency Modulated Continuous Wave (FMCW) radar data across the West Antarctic Ice Sheet (WAIS) divide in 2010. Five firn cores were collected with average accumulation rates ranging from approximately 200 to 275 mm of water equivalent per year. Age-depth scales for each core were developed using the seasonal signals of the δ18O and δD records. ECM and density profiles were used to refine sections of the age-depth scale where the isotopic seasonal cycles were noisy or unclear. Age-depth scales were determined from the radar data by picking spatially continuous (approximately 1 km) layers in the radar echograms at the core sites. The continuous radar layers were assumed annual and dated. This study used data from the Ku-band Radar developed by the University of Kansas' Center for Remote Sensing of Ice Sheets operating between the frequencies of 12.5 GHz to 15.132 GHz, giving a vertical resolution of approximately 4.5 cm in the firn. Radar travel time was converted to depth using 2 cm density data from the ice core. A comparison of the core and radar derived age-depth scales shows that at higher accumulation sites the independent age-depth scales agree relatively well with maximum errors of up to +/-3 years in a given year. At lower accumulation sites dating errors from the radar age-depth scale are larger which is attributed to the difficulty in distinguishing annual layers from sub-annual peaks in density in the radar echogram.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.C33B0655K
- Keywords:
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- 0726 CRYOSPHERE / Ice sheets