Relating wave attenuation to pancake ice thickness, using field measurements and model results

• Published in: Geophysical Research Letters
• Main Authors: Doble, Martin J, de Carolis, Giacomo, Meylan, Michael H., Bidlot, Jean-Raymond, Wadhams, Peter
• Other Authors: Laboratoire d'océanographie de Villefranche (LOV), Observatoire océanologique de Villefranche-sur-mer (OOVM), Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), CNR-IREA Milan, School of Mathematical and Physical Sciences, University of Newcastle Callaghan, Australia (UoN), European Centre for Medium-Range Weather Forecasts (ECMWF), Department of applied maths and theoretical physics, University of Cambridge UK (CAM)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: [SDU.STU.GP]Sciences of the Universe [physics]/Earth Sciences/Geophysics [physics.geo-ph]; [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]; Weddell Sea; Weddell; Pancake
• Online Access: https://hal.sorbonne-universite.fr/hal-01166908; https://hal.sorbonne-universite.fr/hal-01166908/document; https://hal.sorbonne-universite.fr/hal-01166908/file/Doble_2015_Relating_wave.pdf; https://doi.org/10.1002/2015GL063628

International audience Wave attenuation coefficients (α, m À1) were calculated from in situ data transmitted by custom wave buoys deployed into the advancing pancake ice region of the Weddell Sea. Data cover a 12 day period as the buoy array was first compressed and then dilated under the influence of a passing low-pressure system. Attenuation was found to vary over more than 2 orders of magnitude and to be far higher than that observed in broken-floe marginal ice zones. A clear linear relation between α and ice thickness was demonstrated, using ice thickness from a novel dynamic/thermodynamic model. A simple expression for α in terms of wave period and ice thickness was derived, for application in research and operational models. The variation of α was further investigated with a two-layer viscous model, and a linear relation was found between eddy viscosity in the sub-ice boundary layer and ice thickness.