ACINN Graduate Seminar - WS 2024/25
2024-10-30 at 12:00 (on-line & on-site)
Mediterranean precipitation response to climate change during extreme cyclones
Marco Chericoni
University School for Advanced Studies (IUSS), Pavia and ENEA, Rome, Italy
The Mediterranean basin is well recognized as a climate change “hot-spot” due to a pronounced decrease in precipitation and fresh water availability which could have substantial socio-economic and environmental impacts. This drying trend is linked to changes in cyclone activity due to increased anticyclonic circulation associated with a northward shift of the Atlantic storm track. However, there is a large spread for the projected changes in Mediterranean cyclone characteristics. To increase confidence in these projections, it is important to physically understand how this precipitation reduction occurs.
This study investigates how climate change might affect Mediterranean precipitation by altering cyclone activity and moisture content due to rising temperatures. To this end, four simulations are performed using the ENEA-REG regional Earth system model driven by MPI-ESM1-2-HR (CMIP6): one hindcast (1982-2014) and three climate projections (2015-2100), under different SSP scenarios (SSP 5-8.5, SSP 2-4.5, and SSP 1-2.6). The system uses the mesoscale WRF model with a 12 km horizontal resolution, coupled with the MITgcm ocean model with a 1/12° horizontal resolution, over the Med-CORDEX domain. A cyclone track method, based on mean sea level pressure, is applied to each simulation to evaluate the impact of climate change on cyclone climatology and characteristics, and to identify changes in both mean and extreme (99th) precipitation associated to the cyclones.
The results align with previous studies, indicating a significant reduction in mean precipitation in the Mediterranean region, strongly related to a decrease in the number of cyclones. However, with one dynamical downscaling of one global model, the present study does not aim to investigate specific changes in the location and frequency changes of cyclones and the associated uncertainties. Instead, leveraging the high-resolution regional coupled model’s ability to better resolve SST structures and sea surface fluxes, as well as low/mid-level transport of moisture during cyclones activity, the research seeks to deeper explore how changes in moisture advection and surface diabatic processes due to rising temperatures, locally impact cyclones’ precipitation, leading to a complex rainfall response to climate change in the Mediterranean region.
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