Two-sided turbulent boundary layer parameterizations for assessing ocean – atmosphere fluxes

Abstract

<p><span>Standard </span><span>methods for determining air – sea fluxes typically rely on bulk algorithms derived from the Monin-Obukhov stability theory (MOST), </span><span>using ocean surface fields and atmosphere near-surface fields. In the context of coupled ocean – atmosphere simulations, </span><span>the </span><span>shallowest ocean vertical level is usually assimilated to </span><span>the surface, and the turbulent closure is one-sided: it aims at extrapolating atmosphere near-surface solution profiles (for wind speed, temperature and humidity) to the prescribed ocean surface values. </span><span>Assimilating near-surface ocean fields as surface ones is equivalent to considering that in the ocean surface layer, solution profiles are constant instead of also being determined by a turbulent closure. Here we introduce a method for extending existing turbulent parameterization</span><span>s</span><span> to a two-sided </span><span>context, by including the ocean surface layer and the viscous sublayers, which are also generally neglected in </span><span>standard air – sea fluxes computation. </span><span>The formalism we use for this method is derived from that of classical turbulent closure, so that our novelties can easily be implemented within existing formulations.</span> <span>Special care is taken to </span><span>ensure the smoothness of </span><span>resulting solution profiles. </span><span>We</span> <span>investigate the </span><span>impact of such two-sided bulk formulations on air - sea fluxes and </span><span>discuss further implications such as resulting bulk formulation retuning. We also present leads on incorporating </span><span>other mechanisms impacting air – sea fluxes within our framework, such as waves and radiation penetration.<br></span></p>