Formation of sea ice bridges in narrow straits in response to wind and water stresses. Issue 7 (13th July 2017)

• Record Type: Journal Article
• Authors: Rallabandi, Bhargav; Zheng, Zhong; Winton, Michael; Stone, Howard A.
• Is Part Of: Journal of geophysical research. Volume 122:Issue 7(2017)
• Page Start: 5588
• Page End: 5610
• Publication Date: 2017-07-13
• Subjects: sea ice -- ice bridges; Oceanography -- Periodicals; 551.4605
• DOI: 10.1002/2017JC012822
• Languages: English
• ISSNs: 2169-9275

Abstract

Abstract: Ice bridges are rigid structures composed of sea ice that form seasonally in the many straits and channels of the Canadian Arctic Archipelago. Driven primarily by atmospheric stresses, these ice bridges are formed when sufficiently thick ice "jams" during the course of its flow between land masses, resulting in a region of stationary compacted ice that is separated from a region of flowing open water (a polynya) by a static arch. Using a continuum description of sea ice that is widely used in climate modeling, we present an asymptotic theory of the process of formation of such bridges in slender channels when the motion of the ice is driven by external wind and water stresses. We show that for an arbitrary channel shape, ice bridges can only form within a range of ice properties that is determined by the channel geometry and the external stress. We then compare the results of our theory with direct numerical simulations and observational evidence. Finally, we provide simple analytical expressions for the mean velocity of the ice flow as a function of the channel shape, the properties of the ice, and the wind and water stresses along the channel. Plain Language Summary: Ice bridges are stationary structures that form in narrow straits due to a stoppage of sea ice flow. Such ice bridges connect the land masses that make up the strait and are important both for local climate and ecology. We develop a theory that exploits the slenderness of the straits, showing that the formation of an ice bridge can be understood using techniques commonly used to describe fluid flows. We find that ice bridges are formed only for a range of ice properties that depends on the shape of the strait and the forcing conditions. These insights on the flow of sea ice can aid climate modeling efforts and help interpret sea ice measurements in straits. Key Points: Continuum theory for the formation of sea ice bridges Analytical predictions of ice fluxes through narrow straits Reduced‐order model for subgrid sea ice dynamics in straits