Simulations of Mesoscale Circulations in the Center of the Iberian Peninsula for Thermal Low Pressure Conditions. Part II: Air-Parcel Transport Patterns

Abstract

This paper discusses the variability of air-parcel transport under similar summer thermal low pressure conditions over the Iberian Peninsula. Three-dimensional trajectories were estimated by means of the Topography Vorticity-Mode Mesoscale model. Four cases of the 1992 summer thermal low pressure system have been considered, covering most of the variability of this synoptic meteorological situation. Transport patterns were very different among the four studied cases. Results indicate that synoptic wind forcing can influence trajectories under thermal low conditions. It was found that a remarkable difference exists between the transport of air parcels released at low levels, which are affected by thermally driven flows, and those released at higher levels, which are more influenced by the synoptic wind. Moreover, potentially polluted air parcels (released in the daytime) travel farther than the potentially nonpolluted ones (released at night) in the case of lower-level releases. In addition, important differences between the transport patterns of polluted morning air parcels and polluted afternoon air parcels are detected and discussed.