1ST CONSIDERATIONS ON THE STRUCTURE AND DEVELOPMENT OF THE IBERIAN THERMAL LOW-PRESSURE SYSTEM

During the summer a thermal low-pressure system is locked over the Ibe rian Peninsula. We present a first analysis of such a system using the potential vorticity approach. Our results show that its main characte ristic is the existence of a negative potential vorticity (PV) dome an d a funnel-like structure for potential temperature, both located at t he centre of the low. The build-up and evolution of this PV dome can b e understood in terms of the dot products of the absolute vorticity an d the gradient of diabatic heating vectors and the curl of the frictio n forces and the gradient of potential temperature vectors. The inhibi tion of the Algerian Mediterranean cyclogenesis during the summer seem s to bear some relation to the existence of this kind of low-pressure disturbance over the Iberian Peninsula.