Anticyclonic Activity over South Europe and its Relationship to Orography

Abstract

This is a study of anticyclonic activity over a past of southern Europe in which several anticyclogenetic areas have been noted. There is also a relationship between cyclonic and anticyclonic activity in this region. We also indicate that there is a very close association between the number of anticyclones and cyclones generated over a given ?point? (a square 1° longitude by 1° latitude) and the Laplacian ?z0 = ?2z0/?x2 + ?2z0/?y2 up to these points. If the height of the earth's orography is denoted by z0 = z0(x,y), then the regions with concave terrain forms are such that ?z0 > 0, and vice versa. The above-mentioned close relationship between the number of anticyclones and cyclones generated and ?z0 is due to vertical motions in the real atmosphere, motions which appear because of the concavity and convexity of the terrain, i.e., because of ?z0. The conclusion drawn is that the vertical velocity component W?z0, which arises because of ?z0, depends only on the magnitude of the wind velocity |V| but not on its direction, i.e., W?z0 = f(|V|,?z0). The value of ?z0 is one of the causes, possibly the most important one, determining whether a given area is cyclogenetic or anticyclogenetic.