Studying coastal recirculation with a simplified analytical land-sea breeze model

Abstract

The diurnal cycle of the land and sea breeze is of high importance in determining many aspects of the living conditions in coastal areas. One of these aspects is the buildup of air pollutants concentrations due to air mass recirculation. In order to study the main factors governing the recirculation of an air mass under land-sea breeze conditions, a single station characterization of the recirculation potential in an airshed is implemented using a simplified land-sea breeze analytical model. The factors studied are latitude, ambient wind intensity, breeze intensity and friction. A sensitivity analysis performed reveals that the highest potential for coastal recirculation exists around latitude 30° with low friction values. It is found that the combined effect of latitude, breeze intensity and the meridional component of the ambient wind has the biggest influence on the model and is responsible for 31% of its variance. Also, latitude and breeze intensity account each for about 20% of the variance. The recirculation model is found to be highly sensitive to latitude, particularly in mid latitudes and to breeze intensity for weak breeze winds. The performance of the recirculation model is compared to 5-year measurements of recirculation at the East Mediterranean Sea during typical summer conditions. In spite of its rudimentary nature, the model does succeed in giving good quantitative measure of the recirculation, in the order of 0.3 on a scale of 0-1, very close to the observed values in the region. Copyright 2008 by the American Geophysical Union.