Linear theory of the sea breeze in a thermal wind

Abstract

This article investigates the linear dynamics of the sea breeze in an along-shore thermal wind shear. The present analysis shows that the sea-breeze circulation is tilted towards the slanted isentropes associated with the thermal wind. At a critical value of the thermal wind shear, the tilt of the sea-breeze circulation becomes equal to the slope of the background isentropes. The present analysis also shows a spatial shift between the heating pattern and the sea-breeze circulation. The present linear theory is then applied to interpret measurements made in the vicinity of New York City where there is a warm-season synoptic southwesterly jet. It is compared with observations and past numerical simulations. Agreement is found with respect to the enhanced along-coast wind that follows the tilted isentropes, the order of magnitude of the isentrope tilt and the clockwise rotating wind hodograph showing the jet maximum peaking at 1800 solar time. There is a disagreement between theory and observations on the phase lag between the jet maximum and the cross-shore pressure gradient maximum. However, this disagreement can reasonably be attributed to either the angle made by the synoptic jet to the coastline and/or the presence of friction. The inland spatial shift of the breeze indicated by the theory might also be indirectly confirmed by the coastal inland wind observations of a larger diurnal amplitude for a stronger synoptic jet. © 2011 Royal Meteorological Society.