Welcome to Acta Oceanologica Sinica!

Set as Homepage | Add to favorites

LU Peng,LI Zhijun,HAN Hongwei. 2016. Introduction of parameterized sea ice drag coefficients into ice free-drift modeling. Acta Oceanologica Sinica, 35(1):53－59

Introduction of parameterized sea ice drag coefficients into ice free-drift modeling

引入拖曳系数参数化的海冰自由漂流模拟研究

Received:November 01, 2014 Revised:March 18, 2015

DOI：10.1007/s13131-016-0796-y

Key words:sea ice drag coefficient parameterization free drift modeling

中文关键词: 海冰拖曳系数参数化自由漂流模拟

基金项目:

Author Name	Affiliation	E-mail
LU Peng	Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China	lupeng@dlut.edu.cn
LI Zhijun	Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China
HAN Hongwei	Laboratory of Coastal and Offshore Engineering, Dalian University of Technology, Dalian 116024, China

Hits: 2434

Download times: 1747

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 α and the deflection angle θ 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 α increases rapidly at first and approaches a steady level of 0.018 when A is greater than 20%. And the deflection angle θ drops rapidly from an initial value of approximate 80° and decreases slowly as A is greater than 20% without a steady level like α. 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 (C_s'/C_s) and the ratio of ridge form drag coefficient (C_r'/C_r) to the value of C_a/C_w, α, and θ, 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.

中文摘要:

海冰运动的很多特征都依赖于冰与大气的拖曳系数(C_a)以及与海洋的拖曳系数(C_w)。与定义为常数的拖曳系数相比,利用参数化的拖曳系数可以更清楚的认识海冰运动特征随冰情的变化。在本研究中,将拖曳系数参数化引入到海冰的自由漂流模型中,从而探讨风速系数α、偏转角度θ、C_a/C_w等特征参数随局地拖曳系数、浮冰和冰脊几何形态的变化情况。结果显示,在理想的静止海洋中,对于边缘区的小尺寸浮冰,C_a/C_w随冰密集度(A)增大显著增大;而对于中心区的大浮冰,C_a/C_w的变化相对较小(0.2-0.25)。风速系数α随着密集度增加快速增加,但当A>20%后,α趋于稳定值0.018。偏转角度θ随着密集度增加从80°快速减小,当A>20%后,θ的减小趋势变缓,但是并无稳定值。这些参数的变化范围与前人在北极的现场观测结果非常吻合。冰脊强度是确定摩拖曳系数值(C_s'/C_s)与冰脊形拖曳系数值(C_r'/C_r)在C_a/C_w、α和θ中谁占支配地位的重要参数,因为冰脊强度大时,冰脊形拖曳力在总拖曳力中占优;而冰脊强度小时,冰面摩拖曳力在总拖曳力中占优。拖曳系数参数化在将来可以嵌入到其他海冰动力学模型中,从而更好的解释快速变化的北冰洋。

HTML View Full Text View/Add Comment Download reader