Coastal sea responses to atmospheric forcings at two different resolutions

Abstract

We investigated coastal sea responses to three, multi-day strong wind episodes that occurred in the middle Adriatic during the Target Operational Period (TOP) of the European COastal sea OPerational observing and forecasting system (ECOOP) project. A high-resolution oceanographic model (1 km horizontal, 16 vertical layers) based on the modified Princeton Ocean Model (POM) was applied to a highly complex domain located in the coastal area of the eastern Adriatic Sea. The oceanographic model was nested into the Adriatic REGional model (AREG-2) covering the entire Adriatic Sea. Meteorological forcing was prepared by two atmospheric models. The coarser model was the European Centre for Medium-range Weather Forecast model (ECMWF, with horizontal and temporal resolutions of 0.25 and 6 h, respectively), and the finer one was the Aire Limit´ee Adaptation dynamique D´eveloppement InterNational model (ALADIN, with horizontal and temporal resolutions of 8 km and 3 h, respectively, and winds dynamically adapted to a horizontal resolution of 2 km). The results show that smallscale atmospheric features, which arise due to the orographically complex mainland and the number of islands and were not reproduced by the coarser atmospheric model, substantially affected surface currents, mass transports, sea surface temperature (SST) and surface salinity in the coastal area during strong Bora. For strong Sirocco, the atmospheric model’s resolution was important for currents on the lee sides of islands.