The Adriatic Sea and Coast (AdriSC) modelling suite: coupled atmosphere-ocean kilometer-scale assessments of present and future climates

We present a variety of applications of the climate component of the coupled atmosphere-ocean kilometer-scale Adriatic Sea and Coast (AdriSC) modelling suite.  The AdriSC modelling suite has been implemented to represent both atmospheric and oceanic dynamics in the Adriatic Sea region and, in particular, to reproduce processes at the mesoscale (i.e. at the kilometer-scale or higher resolutions) like meteotsunamis (atmospherically-generated long-ocean waves in the tsunami frequency band) or orographically-driven winds. For that reason, two different modules have been developed conjointly in the AdriSC model. First, the basic module provides the kilometer-scale atmospheric and oceanic Adriatic baroclinic circulation with the Weather Research and Forecast (WRF) model at up to 3 km resolution in the atmosphere and the Regional Ocean Modelling System (ROMS) in the ocean, coupled with the Simulating WAves Nearshore (SWAN) model for surface waves at up to 1 km resolution. Second, the dedicated nearshore module is used to better reproduce atmospherically driven extreme sea level events, and couples offline the WRF 1.5 km grid in the atmosphere with the ADCIRC-SWAN unstructured mesh down to 10 m resolution along the Adriatic coastline.

Two different approaches – based on Pseudo-Global Warming (PGW) methodology – have been implemented to assess the impact of climate change in the Adriatic Sea: (1) short-term event-oriented simulations to represent the dynamics of extreme events with the nearshore module, and (2) long-term simulations (31-years), based solely on the basic module, to derive statistics of present (1987-2017) and future (2070-2100) climates. More precisely, the numerically unexpansive short-term simulations were used (1) to verify the implementation of the PGW methodology in the ocean and (2) to derive the impact of climate change on the bora wind dynamics and the associated wintertime cooling in the northern Adriatic Sea, as well as on the surface wave dynamics generated by dominant winds (sirocco, bora) and meteotsunamis. Concerning the expansive 31-year long simulations, they each took 18 months of run on the European Centre for Middle-range Weather Forecast (ECMWF) supercomputer to provide, for the very first time, a reliable kilometer-scale coupled atmosphere-ocean dataset – fully evaluated against observations in both atmosphere and ocean. Consequently, kilometer-scale coastal hazards under extreme climate changes can now be fully assessed by researchers, but also environmental agencies in the Adriatic region.

The research was supported by the Croatian Science Foundation (projects BivACME and ADIOS).