4.13
A simple model of the convective internal boundary layer and its application to surface heat flux estimates within polynyas
Ian A. Renfrew, British Antarctic Survey, Cambridge, United Kingdom; and J. C. King
A simple model of the convective (thermal) internal boundary layer has been developed for climatological studies of air-sea-ice interaction, where in situ observations are scarce and first-order estimates of surface heat fluxes are required. It is a mixed-layer slab model, based on a steady-state solution of the conservation of potential temperature equation, assuming a balance between advection and turbulent heat-flux convergence. Both the potential temperature and the surface heat flux are allowed to vary with fetch, so the subsequent boundary-layer modification alters the flux convergence and thus the boundary-layer growth rate. For simplicity, microphysical and radiative processes are neglected.
The model is validated using several case studies. For a clear-sky cold-air outbreak over a coastal polynya the observed boundary-layer heights, mixed-layer potential temperatures and surface heat fluxes are all well reproduced. In other cases, where clouds are present, the model still captures most of the observed boundary-layer modification. Although there are increasing discrepancies with fetch, due to the neglected microphysical and radiative processes. The application of the model to climatological studies of air-sea interaction within coastal polynyas is discussed.
Session 4, Convective Boundary Layers (Bls)
Wednesday, 9 August 2000, 10:15 AM-4:45 PM
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