Climate Implications of the Messinian Desiccation of the Mediterranean Basin: General Circulation Model (GCM) Simulations and Process Model Studies

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This award provides funds to model the Messinian desiccation using a suite of climate models, including a single column model, simplified stationary wave model, and general circulation model. During the Messinian period of the Miocene Epoch about 5.5 million years ago (Ma), tectonic activity near the present Straits of Gibraltar resulted in the isolation of the Mediterranean Sea. At the height of this isolation, evaporation of the Mediterranean Sea appears to have reduced the sea level within the Mediterranean basin by 1500 meters to 2000 meters. This resulted in abundant salt deposits around the Mediterranean basin, and in the erosion of deep canyons by the major rivers flowing into the Mediterranean. The researcher maintains that neither the impact of a deep, extensive subaerial basin on the general circulation of the atmosphere, nor the physical process by which the desiccation occurred has been treated using a sophisticated atmospheric model. As a consequence, the researcher aims to produce a physically consistent reconstruction of the climatic conditions within a deep basin and an assessment of the impact of the existence of such a basin on the regional climate. This impact will be examined by direct physical interaction of the deep basin with the atmospheric circulation, and by changes to transports of water vapor and dust and salt from the desiccation of the Mediterranean Sea. The project will include the use of a new flexible-grid spectral element dynamical core developed for the NCAR Community Climate System Model (CCSM) atmospheric module. The use of this new core, as well as the standard CCSM atmospheric module for a modeling study of topography so radically different from present Mediterranean topography, will involve the models under surface boundary conditions far from the standard climate in which they were developed. This may help expose hidden weaknesses, thereby allowing improvements in model design. This project provides an opportunity to model a singular event in Earth history that exposed an entire sea basin to evaporation. This could lead to some unusual findings and will provide a unique opportunity in research for a graduate student.