Seasonal Distribution of the Boundary Layer Depths Over the Mediterranean Basin

Abstract

Results are given of a detailed study to determine the spatial and temporal (seasonal) distributions of the planetary boundary layer depths (PBLD) over the Mediterranean Basin. More then 65,000 upper-air measurements from 45 rawinsonde stations in the Basin were compiled and analysed for two consecutive years from spring 1986 through winter 1988. A methodology using both tested and newly developed criteria was applied to determine PBLD values. As expected, the values prove to be generally higher over land and are probably minimum over the eastern and western ends of the Mediterranean Sea. Factors influencing this spatial distribution are mainly topography, the distance from the shoreline, and to a lesser extent, synoptic weather systems. The most striking temporal effect on PBLD distribution over the Mediterranean Basin is caused by larger scale synoptic weather systems. The second effect is the diurnal cycle, which has its largest impact mainly during the summer months.