Meteorological Processes Relevant to Forest Fire Dynamics on the Spanish Mediterranean Coast

Abstract

The Valencian region on the Spanish east coast has experienced a significant increase in wildfires in the last 20 years, as have other areas in the Mediterranean basin. Experimental data and modeling results, obtained within several European Commission (EC) projects in southern Europe, indicate that specific mesometeorological circulations develop in these regions during the summer. Analysis of the available evidence further indicates that the resulting flows could be instrumental in the evolution of wildfires in this area. Three situations have been identified that cover the most likely interactions between the synoptic conditions and the regional winds, and their implications for the dynamics of fires in this region. These situations are 1) diurnal cycles of sea and land breezes with a thermal low developing over the Iberian Peninsula; 2) ?ponientes,? that is, a Föhn effect producing westerly winds when a traveling low-pressure system crosses the Iberian Peninsula; and 3) combined cycles, when the diurnal cycle of sea breezes is followed by coupling of the land breeze and drainage flows with upper westerlies at night. In the Valencian region, the highest frequency of fires and the largest burnt areas appear to occur under the latter conditions. For the Spanish Mediterranean coast, the meteorological situations described can be identified easily, and their most probable evolution scenarios forecasted 12?24 h before their occurrence. Equivalent situations may be expected in other parts of the Mediterranean basin and, to this effect, this work is also intended to serve as a stimulus to study the relations between synoptic meteorological conditions and the orography, the resulting local winds, and the fire dynamics in other southern European regions.