High-resolution climate modelling of the Adriatic (Mediterranean Sea)

With the aim to study the impact of climate change on the processes driving the Adriatic-Ionian thermohaline circulation (including Adriatic-Ionian Bimodal Oscillating System, dense water formation, etc.) and its manifestation in coastal regions, the ultra-high resolution (3-km for the atmosphere and 1-km for the ocean) Adriatic Sea and Coast (AdriSC) Climate component was developed in the framework of the ADIOS project. The main challenges posed by such an approach are (1) the relative slowness of the modelling suite (1 month of simulation per day), and (2) the low temporal and spatial resolutions (only few vertical levels for daily or monthly data) of the coupled Regional Climate Models (RCMs) available to provide boundary conditions for the AdriSC models. In consequence, the classical climate change approach (consisting in 30-year evaluation, 50-year historical and 100-year scenario runs) could not be implemented within our study and the surrogate climate change approach was used instead. This approach was developed and well tested for atmospheric studies only, while this study extends the methodology to the ocean. It mostly consists in adding a climatologic differential (derived from the difference between scenario and historical results of a given RCM for a given period) to the forcing of a 30-year high resolution evaluation run. Here, we will present (1) the set-up of the AdriSC Climate component, (2) the first results of the evaluation run performed for the 1987-2017 period, and (3) the methodology used to adapt the surrogate climate change approach to the coupled ocean-atmosphere model.