Detection of subsurface permafrost features with ground‐penetrating radar, Barrow, Alaska

• Published in: Permafrost and Periglacial Processes
• Main Authors: Hinkel, K. M., Doolittle, J. A., Bockheim, J. G., Nelson, F. E., Paetzold, R., Kimble, J. M., Travis, R.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2001
• Subjects: La Table; Active layer monitoring; Barrow; Ice; permafrost; Permafrost and Periglacial Processes; wedge*; Alaska; pergélisol
• Online Access: http://dx.doi.org/10.1002/ppp.369; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1002%2Fppp.369; https://onlinelibrary.wiley.com/doi/pdf/10.1002/ppp.369

Abstract A ground‐penetrating radar (GPR) survey was conducted in May 1999 on the 1 km 2 Circumpolar Active Layer Monitoring (CALM) grid 5 km east of Barrow, Alaska. Spatially continuous measurements were collected along established transects while the active layer remained frozen. The primary objectives were to determine the ‘long‐term’ position of the permafrost table, to recognize ice wedges and ice lenses, and to locate the organic–mineral soil interface. GPR signal and core collection were performed in tandem to verify signal interpretation, to calibrate the instrument, and to determine optimal GPR data‐collection parameters. Two‐way travel times from the antenna to subsurface reflectors were compared with measured depths obtained from soil cores to estimate an average pulse propagation velocity of 0.13 m/ns through the frozen soil. The most conspicuous subsurface reflectors were ice wedges, which gave high‐amplitude hyperbolic reflections. Owing to its higher ice content, the approximate long‐term position of the permafrost table could be traced laterally across the profile. Radar interpretations were obscured by the effects of cryoturbation, and because some horizons lack sufficient contrast in electrical properties. Highly detailed information can be obtained by collecting radar data at relatively slow speeds of advance, by using faster scanning rates (>32 scans/s), and by employing high‐frequency antennas (>400 MHz). Copyright © 2001 John Wiley & Sons, Ltd. RÉSUMÉ Un levé réalisé avec un radar dont les ondes pénètrent dans le sol a été réalisé en mai 1999 sur un km 2 appartenant à la grille établie pour suivre l'évolution de la couche active circumpolaire (CALM), 5 km a l'est de Barrow, Alaska. Des mesures ont été réalisées le long de transects alors que la couche active était gelée. Les premiers objectifs étaient de déterminer la position à long terme de la table du pergélisol, de reconnaître les coins et les lentilles de glace, et de localiser le contact entre les sols organiques et ...