Relationship Between Morphology and Hydrodynamics Below Arctic Sea Ice in the Vicinity of a Pressure Ridge Keel

• Main Author: Stanton, Tim
• Other Authors: NAVAL POSTGRADUATE SCHOOL MONTEREY CA DEPT OF OCEANOGRAPHY
• Format: Text
• Language: English
• Published: 2013
• Subjects: Physical and Dynamic Oceanography; Snow; Ice and Permafrost; Fluid Mechanics; *HYDRODYNAMICS; *SEA ICE; ARCTIC OCEAN; BOUNDARY LAYER; DRAG; MORPHOLOGY; PRESSURE; SONAR; UNDERWATER; PRESSURE RIDGE KEEL; Arctic; Arctic Ocean; Ice; permafrost; Sea ice
• Online Access: http://www.dtic.mil/docs/citations/ADA601280; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA601280

Drag generated as the wind pushes sea ice over the underlying ocean can be generated by flow distortion and separation over large roughness features on the underside of the ice (form drag) or by viscous stress and wakes past small-scale disturbances in a thin viscous or roughness sublayer. To date, there have been no studies in which concurrent hydrodynamic and high-resolution morphological measurements have been used to relate measured drag with directly-observed, under-ice morphology. Pressure ridge keel may occupy a significant fraction of the IOBL. The relatively large size of the keels (compared to roughness elements in the atmospheric boundary layer and the ocean bottom boundary layer, for example) makes the ridge keel problem unique. Turbulent processes in the vicinity of ridge keels, such as downstream wakes, may be a dominant source of drag and mixing in the IOBL (Skyllingstad et al 2003). The affects of a measured ice keel on the turbulent structure of the ocean mixed layer will be directly measured over a range of forcing conditions. Fine-scale morphological observations will allow estimation of the distribution of roughness elements which we will try to relate to the hydrodynamic transition from smooth to rough boundary layer flow, in which the roughness length z0 changes from being dependent on surface stress to being directly proportional to the size of the roughness elements. Previous under-ice boundary layer studies have reported roughness length values in both of these regimes (Shaw et al 2008) but without direct observations of the local ice/ocean interface morphology.