Extension of summer climatic conditions into spring in the Western Mediterranean area

Abstract

From a local point of view, in May/June there is an important and positive 2 m temperature trend at Palma (Mallorca), which is simultaneous and highly correlated with a strong increase in the 500 hPa geopotential height. The present study analyses this fact as well as the observed tendencies in a wider seasonal and geographical context. We confirm the particularly high correlation between 2 m temperature and 500 hPa geopotential during the warm months as opposed to the much weaker correlation in winter. This suggests that mechanisms for thermal changes act differently throughout the year in this region. Besides the direct radiative effect, warm season near-surface temperatures are linked to the presence of deep anticyclones, which effectively determine the northern edge of the Hadley cell. Accordingly, the strong warming trend in the area of Palma during the warm months of the year is purportedly related to the poleward extension of the Hadley cell.