Role of soil moisture in the amplification of climate warming in the eastern Mediterranean and the Middle East

Abstract

Projections for the 21st century suggest that climate change will be associated with changes in the frequency and intensity of weather and climate extremes (e.g. heat waves, droughts, heavy precipitation events). In the already warm summertime eastern Mediterranean and Middle East (EMME) climate change may involve mechanisms and feedbacks that cause or intensify hot weather events. A potentially important feedback mechanism involves soil moisture� atmosphere interactions. When the soil water content and evapotranspiration are decreased, near- surface air temperatures are enhanced due to reduced evaporative cooling. Here we show the importance of this mechanism, especially in the northern part of the EMME, using the output of a regional climate model (HadRM3P). We applied the classical hydrology framework to define evapotranspiration regimes as a function of soil moisture and latent heat fluxes. Further, we used the correlation of summer maximum temperature and evapotranspiration as a diagnostic of this coupling, and we performed a composite analysis of maximum temperature for the dry and wet years of our dataset. Since temperature and precipitation regimes are expected to change in the EMME, we considered alterations of the relationship between soil moisture and the maximum temperature throughout the 21st century.