Zur Dynamik des antarktischen Zirkumpolarstromes

• Main Author: Wolff, J.
• Format: Doctoral or Postdoctoral Thesis
• Language: German
• Published: Universität Hamburg 1990
• Subjects: Munk; Antarktis*
• Online Access: http://hdl.handle.net/21.11116/0000-0005-8272-7; http://hdl.handle.net/21.11116/0000-0005-8274-5

This work gives a detailed account of the dynamical balance of a wind-driven zonally unboun- ded flow over topography. The problem is investigated with a quasigeostrophic 6-plane channel model with two layers and eddy resolution. The channel has a width of 1500 km and a zonal periodicity of 4000 km. Apart from the dimensions the model structure is similar to the one used by McWilliams et a.l. (1978). The experiments with this model address the problem of the relative role of transient and standing eddies as well as bottom friction and topographic form stress in the balance of a current driven by a steady surface windstress. The response of the system is investi- gated for different values of the friction parameter and various locations of topographic obstacles in the bottom layer of the channel. The principal momentum balance emerging from these ex- periments supports the concept of Munk and Pa.l100én (1951) for the dynamics of the Ahtarctic Circumpolar Current, which proposes that the momentum input by the windstress is transferred to the deep ocean - in the present model by vigorous eddy activity - where it leaves the system by topographic form stress. Frictional effects in the balance of the circumpolar flow may thus be of minor importance. This concept is confirmed in simulations over more complex topographies. Here the channel dynamics are investigated for two differently scaled representations of the highly resolved bottom relief in the Macquarie Ridge area. The flow in these simulations is virtually frictionless. Values from theoretical considerations of the parameterization of the quasigeostrophic eddy field (in terms of an explicit diffusion of potential vorticity) are compared with results from flat bot- tom experiments with eddy resolution. The transfer coefficients are of comparable magnitude but their horizontal variation is greatly underestimated in earlier parameterization schemes (Marshall 1981) and analytical calculations (Ivchenko 1984). A different parameterization (Ivchenko et al. 1990) is ...