Dynamics of the Mediterranean droughts from 850 to 2099 AD inthe Community Earth System Model

Abstract. In this study, we analyze the dynamics of multi-year long droughts over the western and central Mediterranean region for the period of 850–2099 AD using the Community Earth System model version 1.0.1. Our study indicates that Mediterranean droughts during the period of 850–1849 AD are mainly driven by the internal variability of the climate system. A barotropic high pressure system together with a positive temperature anomaly over central Europe and the Mediterranean is the prominent pattern that occurs in all seasons with droughts. Modes of variability, i.e. the North Atlantic Oscillation and El Nino Southern-Oscillation, play an important role at the initial stage of droughts. However, the persistence of multi-year droughts is determined by the interaction between the regional atmospheric and soil moisture variables. This interaction becomes stronger during the 1850–2099 AD period, reducing the importance of modes of variability and inducing a constant dryness over the Mediterranean region. Additionally, the discrepancy among diverse drought metrics in representing past droughts is shown, re-affirming the necessity of assessing a variety of drought indices even in the paleoclimate context.