Eastern Mediterranean Drying: Projected Changes in Dynamics and Thermodynamics and Their Relation to Large-Scale Processes

Observations from the past century and projections for the end of this century exhibit a decrease in precipitation over the Eastern Mediterranean Sea and surrounding land areas, but the magnitude of the expected drying is unknown. Changes in precipitation are controlled by both thermodynamic (moist) and dynamic (dry) processes, but the relative contributions of these processes, in particular on regional scales, is not well understood. Previous studies have analyzed the ability of the fifth phase of the Coupled Model Intercomparison Project (CMIP5) multi-model mean to represent the spatial and seasonal patterns of the Mediterranean hydroclimate. A wide spread exists among the individual models, which can be exploited to better understand the factors controlling future climate. Garfinkel et al. (2020)^[i] found that large-scale mechanisms contribute about 50% of the model spread in Eastern Mediterranean drying. This study further explores the variance across models in projected changes of the moisture budget by decomposing them into mean dynamic, mean thermodynamic and transient components. These components are then related to the variance across models in projected large-scale processes. Through these analyses, uncertainties regarding future changes in precipitation can be reduced.

^[i] Garfinkel, C. I. et al. (2020) ‘The role of zonally averaged climate change in contributing to inter-model spread in CMIP5 predicted local precipitation changes’, Journal of Climate, 33, pp. 1141–1154. doi: 10.1175/JCLI-D-19-0232.1.