The Impacts of Stratification on High Latitude Ocean Mixing: a case study of internal waves in Storfjorden, Svalbard

• Published in: Continental Shelf Research
• Main Authors: Beitzel Barriquand, Tamara, Bouruet-Aubertot, Pascale, Cuypers, Yannis, Vivier, Frédéric, Lourenço, Antonio, Le Goff, Hervé
• Other Authors: Interactions et Processus au sein de la couche de Surface Océanique (IPSO), Laboratoire d'Océanographie et du Climat : Expérimentations et Approches Numériques (LOCEAN), Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Muséum national d'Histoire naturelle (MNHN)-Institut de Recherche pour le Développement (IRD)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut Pierre-Simon-Laplace (IPSL (FR_636)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris Diderot - Paris 7 (UPD7)-École polytechnique (X)-Centre National d'Études Spatiales Toulouse (CNES)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Développement Instrumental et Techniques Marines (DITM)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2015
• Subjects: Stratification; Internal Waves; Mixing; Turbulence; Storfjorden; Arctic; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; [SDV.EE.ECO]Life Sciences [q-bio]/Ecology; environment/Ecosystems; [PHYS.PHYS.PHYS-GEO-PH]Physics [physics]/Physics [physics]/Geophysics [physics.geo-ph]; Svalbard
• Online Access: https://hal.sorbonne-universite.fr/hal-01220406; https://hal.sorbonne-universite.fr/hal-01220406/document; https://hal.sorbonne-universite.fr/hal-01220406/file/Beitzel_Barriquand_The_Impacts_of.pdf; https://doi.org/10.1016/j.csr.2015.10.001

International audience Hydrographic and velocity measurements were taken over four different time periods from April and May 2005–2007 at adjacent stations in Storfjorden, Svalbard. Different environmental conditions, including winds, ice cover, and water mass contributions, yield notably different stratification (N 2 ) profiles among the time series. When classified according to the Gerkema (2001) classification system, the stratification profiles span the spectrum with two profiles resembling that of a two-layer fluid, one resembling more closely a fluid of constant stratification, and one falling in between the two extremes. The different N 2 profiles elicit sharply contrasting modal responses from the internal wave field, which is dominated by mode 1 during the two time series most resembling a two-layer fluid, and nearly evenly spread out among the first five modes during the time series with a nearly constant stratification. Turbulent dissipation rates determined from fine-scale parameterizations reveal an average rate on the order of 10 −9 W kg −1 for all time series with an associated average diapycnal diffusivity of 10 −5 m 2 s −1 –10 −4 m 2 s −1 . Turbulent heat fluxes, determined from the estimated turbulent dissipation rates, ϵ , were found to have a relative maximum at the tops of the pycnoclines, with values up to 1 W m −2 , typical of ice-covered conditions. The turbulent dissipation rate and diapycnal diffusivities for each time series vary with the Gerkema (2001) stratification profile rankings, and are elevated for the time series most resembling a fluid of constant stratification, and reduced for the time series most similar to a two-layer fluid.