Impact of Ice Keel Geometry on Internal Solitary Wave Dynamics

This study explores the transformation processes and energy dissipation of internal solitary waves (ISWs) in the Arctic Ocean under varying ice keel geometries. Using a nonhydrostatic numerical model based on Reynolds-averaged Navier–Stokes equations under the Boussinesq approximation, we simulate the interaction of ISWs with groups of ice keels characterized by different configurations. The computational domain represents a simplified 2D stratified fluid with an idealized vertical density profile mimicking summer conditions on the Yermak Plateau.  The ice keel geometries were parameterized using the Versoria function. The experiments involved ISWs with an amplitude of 20 m interacting with groups of ice keels characterized by varying numbers and lengths.The shapes of the ice keels were designed with common envelopes of differing heights and lengths, incorporating configurations with varying numbers of keels (1, 7, and 13).This approach allows for systematic and consistent comparisons of their effects on wave dynamics, energy dissipation, and the resulting mixing processes within the ocean's stratified layers. These shapes closely approximate the geometry of ice keels studied in the MOSAiC project, which provided valuable observational data and insights into the physical processes governing wave-ice interactions in the polar environment [1].

Key findings indicate significant energy dissipation for ISWs propagating through ice keel fields, with greater losses observed for larger numbers of keels. The highest energy dissipation occurred in cases with 13 keels due to increased reflections and turbulent mixing. Additionally, the interaction of ISWs with multiple keels enhances mixing in the stratified ocean layer beneath the ice. Variations in keel geometry and number intensify turbulence, contributing to a more complex wave field. Furthermore, these interactions generate second-mode internal waves that interact with first-mode waves and other second-mode waves, further intensifying energy dissipation and wave transformation. This mode-mode interaction creates a dynamic wave environment, emphasizing the role of keel morphology in polar ocean mixing.

These findings highlight the importance of ice keel geometry in modulating ISW dynamics and their contribution to upper ocean mixing processes. The study offers valuable insights into wave-ice interactions and their implications for Polar Ocean dynamics, with broader applications for understanding polar mixing processes and their influence on global ocean circulation.

 

[1] Nicolaus, Marcel & Perovich, Donald & Spreen, Gunnar & Granskog, Mats & von Albedyll, Luisa & Angelopoulos, Michael & Anhaus, Philipp & Arndt, Stefanie & Bünger, H. Jakob & Bessonov, Vladimir & Birnbaum, Gerit & Brauchle, Joerg & Calmer, Radiance & Cardellach, Estel & Cheng, Bin & Clemens-Sewall, David & Dadic, R. & Damm, Ellen & Boer, Gijs & Wendisch, Manfred. (2022). Overview of the MOSAiC expedition: Snow and sea ice. Elem Sci Anth. 10. 10.1525/elementa.2021.000046.