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Indexed by:Journal Papers

Date of Publication:2016-01-01

Journal:ACTA OCEANOLOGICA SINICA

Included Journals:SCIE、PKU、ISTIC、Scopus

Volume:35

Issue:1

Page Number:53-59

ISSN No.:0253-505X

Key Words:sea ice; drag coefficient; parameterization; free drift; modeling

Abstract:Many interesting characteristics of sea ice drift depend on the atmospheric drag coefficient (C (a)) and oceanic drag coefficient (C (w)). Parameterizations of drag coefficients rather than constant values provide us a way to look insight into the dependence of these characteristics on sea ice conditions. In the present study, the parameterized ice drag coefficients are included into a free-drift sea ice dynamic model, and the wind factor alpha and the deflection angle theta between sea ice drift and wind velocity as well as the ratio of C (a) to C (w) are studied to investigate their dependence on the impact factors such as local drag coefficients, floe and ridge geometry. The results reveal that in an idealized steady ocean, C (a)/C (w) increases obviously with the increasing ice concentration for small ice floes in the marginal ice zone, while it remains at a steady level (0.2-0.25) for large floes in the central ice zone. The wind factor alpha increases rapidly at first and approaches a steady level of 0.018 when A is greater than 20%. And the deflection angle theta drops rapidly from an initial value of approximate 80A degrees and decreases slowly as A is greater than 20% without a steady level like alpha. The values of these parameters agree well with the previously reported observations in Arctic. The ridging intensity is an important parameter to determine the dominant contribution of the ratio of skin friction drag coefficient (Cs'/Cs) and the ratio of ridge form drag coefficient (C (r)'/C (r)) to the value of C (a)/C (w), alpha, and theta, because of the dominance of ridge form drag for large ridging intensity and skin friction for small ridging intensity among the total drag forces. Parameterization of sea ice drag coefficients has the potential to be embedded into ice dynamic models to better account for the variability of sea ice in the transient Arctic Ocean.