Dynamics and thermodynamics of the mean transpolar drift and ice thickness in the Arctic Ocean

• Published in: Journal of Climate
• Main Author: Spall, Michael A.
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: American Meteorological Society 2019
• Subjects: Arctic; Sea ice; Ocean circulation; Arctic Ocean; Curl; Steele; Fram Strait
• Online Access: https://hdl.handle.net/1912/25397

Author Posting. © American Meteorological Society, 2019. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Climate 32(24), (2019): 8449-8463, doi:10.1175/JCLI-D-19-0252.1. A theory for the mean ice thickness and the Transpolar Drift in the Arctic Ocean is developed. Asymptotic expansions of the ice momentum and thickness equations are used to derive analytic expressions for the leading-order ice thickness and velocity fields subject to wind stress forcing and heat loss to the atmosphere. The theory is most appropriate for the eastern and central Arctic, but not for the region of the Beaufort Gyre subject to anticyclonic wind stress curl. The scale analysis reveals two distinct regimes: a thin ice regime in the eastern Arctic and a thick ice regime in the western Arctic. In the eastern Arctic, the ice drift is controlled by a balance between wind and ocean drag, while the ice thickness is controlled by heat loss to the atmosphere. In contrast, in the western Arctic, the ice thickness is determined by a balance between wind and internal ice stress, while the drift is indirectly controlled by heat loss to the atmosphere. The southward flow toward Fram Strait is forced by the across-wind gradient in ice thickness. The basic predictions for ice thickness, heat loss, ice volume, and ice export from the theory compare well with an idealized, coupled ocean–ice numerical model over a wide range of parameter space. The theory indicates that increasing atmospheric temperatures or wind speed result in a decrease in maximum ice thickness and ice volume. Increasing temperatures also result in a decrease in heat loss to the atmosphere and ice export through Fram Strait, while increasing winds drive increased heat loss and ice export. MAS was supported by the National Science Foundation under Grant OPP-1822334. Comments and suggestions from Michael Steele, Gianluca Meneghello, and an anonymous reviewer ...