Nested modeling of the east Adriatic coastal waters

Abstract

          The middle Adriatic coastal area was numerically modeled with a 1 km resolution in order to simulate temperature, salinity and currents. The model employed was a modification of the Princeton Ocean Model (POM), forced with surface momentum, heat and water fluxes and discharges from four rivers: Jadro, Žrnovnica, Cetina and Neretva. The coastal model was nested into the whole-Adriatic model having a 5 km resolution, using a simple off-line one-way nesting technique. Results of a three-year long experiment with perpetual atmospheric and river forcing were characterized by a strong annual signal, in reasonable agreement with temperature and salinity data taken at permanent oceanographic stations along the Split-Gargano transect. Current reversal obtained between the islands of Hvar and Vis in summer also agreed with previous measurements. The simulation also revealed the way Dalmatian islands – in particular Lastovo and Vis – influence the East Adriatic Current prevailing in winter, with wakes being formed behind the islands and jets among them. Comparison of an interannual simulation with corresponding measurements showed good agreement for temperature, whereas a discrepancy in salinity was related to the model being forced with climatological water fluxes. Experimental forecasts, produced over a six-month period, enabled some experience to be gained in operational oceanography, but also pointed to an additional problem – the model overmixing when the wind forcing is pronounced. Moreover, low spatial resolution of atmospheric forcing was suspected of reducing the quality of current forecasts for some wind directions.