Linear breeze scaling: from large‐scale land/sea breezes to mesoscale inland breezes

Abstract Sea/land breezes and inland breezes have in common the ‘breeze’ appellation but are essentially different. The land/sea‐breeze horizontal extent exceeds 100 km, with the Coriolis effect dominating its dynamics. Conversely, inland breezes are confined between alternating patches of cold and warm surface temperature, over horizontal ranges never exceeding a few kilometres, with negligible Coriolis effect. Both land/sea‐breeze and inland‐breeze systems are embedded within the planetary boundary layer. Despite their superficial resemblance, however, their physics differs and this article attempts to determine the parameters controlling the transition between the processes driving large‐scale land/sea breezes and those driving inland breezes. Rotunno's linear model of the sea breeze is extended in order to describe the transition from the sea‐breeze regime to the inland‐breeze regime, especially in terms of scaling laws. The scaling in the sea‐breeze regime obtained by Rotunno is recovered. In this regime, the breeze cell tends to have a horizontal extent comparable to the Rossby radius. For the inland‐breeze regime previously studied by Anthes, an important contribution of the present work is to take into account the effect of friction. This effect is non‐trivial, as it introduces an inner region with depth controlled by friction. We demonstrate this effect by performing an asymptotic analysis over a range of horizontal scales that are smaller than the Rossby radius but still much larger than the planetary boundary‐layer depth, hence near‐hydrostatic. All the dominant terms of the breeze circulation budget are within the inner layer, where friction and buoyancy dominate the Coriolis effect and the outer‐layer terms and determine the breeze‐cell shape and intensity. Copyright © 2009 Royal Meteorological Society