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

Abstract:

Observations from the past century and projections for the end of this century show a decrease in precipitation over the Eastern Mediterranean Sea and surrounding land areas. 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. Models included in the fifth and sixth phases of the Coupled Model Intercomparison Project (CMIP5 and CMIP6) exhibit a wide spread in the magnitude of expected drying in the Eastern Mediterranean region, as well as other meteorological variables. Such a spread 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 and mean thermodynamic components and relating these components to the variance across models in projected large-scale processes. The analysis illuminates the link between large-scale processes and projected changes in regional precipitation.

[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.