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Clim Dyn (2012) 38:379389
DOI 10.1007/s00382-011-1031-3
Ekman heat transport for slab oceans
Francis Codron
Received: 22 July 2010 / Accepted: 11 February 2011 / Published online: 1 March 2011 Springer-Verlag 2011
Abstract A series of schemes designed to include various representations of the Ekman-driven heat uxes in slab-ocean models is introduced. They work by computing an Ekman mass ux, then deducing heat uxes by the surface ow and an opposite deep return ow. The schemes differ by the computation of the return ow temperature: either diagnosed from the SST or given by an active second layer. Both schemes conserve energy, and use as few parameters as possible. Simulations in an aquaplanet setting show that the schemes reproduce well the structure of the meridional heat transport by the ocean. Compared to a diffusive slab-ocean, the simulated SST is more at in the tropics, and presents a relative minimum at the equator, shifting the ITCZ into the summer hemisphere. In a realistic setting with continents, the slab model simulates correctly the mean state in many regions, especially in the tropics. The lack of other dynamical features, such as barotropic gyres, means that an optimal mean-state in regions such as the mid-latitudes will require additional ux corrections.
Keywords Slab ocean Ekman Heat transport
1 Introduction
The slab ocean model, in which the ocean is represented as a single xed-depth layer with a homogeneous temperature, is the simplest ocean model for studies of ocean-atmosphere interactions after the swamp ocean (Meehl
1992). Even now that computational constraints are less restrictive, it still has a number of important uses.
The rst one is to provide a simple model for mechanistic studies, that retains the physics of ocean-atmosphere coupling through surface heat uxes, and is very easy to interpret. Exemples of studies in realistic settings include Blade (1997) or Lau and Nath (1996). The slab ocean is also useful in idealised geometries such as aquaplanets, where it is a simple energy-conserving model of the surface. This framework can be used to study moist atmospheric dynamics (Frierson et al. 2006) or to compare atmospheric physics as proposed with xed SSTs by Neale and Hoskins (2000). Experiments with climate models requiring very long integrations or multiple simulations with varying coefcients, that are common for...