In-situ measurements indicate the existence of reversed near-surface airflow over the north-eastern Adriatic during the bora wind. Here we examine its structure and evolution by means of a numerical simulation. The studied phenomenon developed during typical summer frontal bora that is associated with a cold air advection from the north-east. It is characterized by a sudden increase in wind speed and a brief duration. Within a sheltered area near the town of Malinska on the island of Krk, onshore flow occurred as the bottom branch of the lee rotor-like circulation that was associated with the hydraulic jump. While the closed circulation somewhat resembles the hypothesized hydraulic-jump rotor, there are significant differences, particularly in the strength of the turbulence associated with the rotor formation.  

          Two simulations of the response of Adriatic Sea to severe wind performed by an atmosphere-ocean coupled model and the comparisons with observed data and modelled fields published in literature are presented.

          The model RAMS-DieCAST was applied to simulate the variations of sea currents and temperature profiles, from surface to bottom, induced by two episodes of intense wind over the Adriatic sea: a Bora wind event that occurred in January 1995 and a Sirocco wind event in November 2002.

          The goal of this research was to simulate and analyze the response of the Western Adriatic Current (WAC) to an abnormal event that occurred in the Adriatic Sea in mid-summer of 2003. At this time, a combination of extremely low discharge from the Po River and from other northwestern rivers caused by the prolonged dry season and the dominant Sirocco wind produced an ‘unusual’ upwelling and caused the WAC to reverse along the northern and central Italian coasts. The simulations employed a high-resolution, low dissipative version of the DieCAST circulation model that was initialized with monthly averaged temperature and salinity data and spun up with a use of climatological wind data. Numerical experiments were performed with the use of COAMPS wind stress and heat flux data. The model runs performed under Sirocco wind forcing in combination with low river discharge (a quarter of the climatic mean) revealed that such these conditions do trigger upwelling and the reversal of the WAC along the Italian coast. The upwelling relaxation caused by changes in the wind direction was also studied. Qualitative simulation results were in agreement with the observations by Poulain et al. (2004).

Keywords: Adriatic Sea, unusual upwelling event, Western Adriatic Current, Sirocco, Mistral, DieCAST.

          The northern Adriatic Sea (NA), the northernmost region of the Mediterranean Sea, is affected by strong anthropogenic pressure (e.g., tourism, fisheries, maritime traffic, discharge from agriculture and industry), superimposed to a large river runoff. The consequent pressure exerted on the NA ecosystem either triggers or worsens massive mucilage insurgence, harmful algal blooms, eutrophication and even anoxic/hypoxic events. This work focuses on the anoxic/hypoxic events. During the summer-autumn period, the NA is often exposed to these events, which can be categorised as either coastal (relatively frequent south of the Po River delta during the summer) and offshore (rare, affecting wider areas). In order to improve our knowledge about these processes and to meet the needs of local governments and decision makers, an operational system for monitoring and forecasting anoxic and hypoxic events has been set up in the framework of the EU LIFE "EMMA" project. The system is composed of a meteo-oceanographic buoy; a numerical prediction system based on the Regional Ocean Modelling System (ROMS), including a Fasham-type module for biogeochemical fluxes; and periodic oceanographic surveys. Every day since June 2007, the system provides 3-hourly forecasts of marine currents, thermohaline and biogeochemical fields for the incoming three days. The system has demonstrated its ability to produce accurate temperature forecasts and relatively good salinity and dissolved oxygen forecasts. The Root Mean Square Error of the dissolved oxygen forecast was largely due to the mean bias. The system is currently being improved to include a better representation of benthic layer biogeochemical processes and several adjustments of the model. While developing model improvements, dissolved oxygen forecasts were improved with the removal of the 10-day mean bias.          

          In the framework ADRICOSM-STAR it was possible to investigate the Boka Kotorska Bay during May and June 2008 in order to increase an understanding of optical and chemical characteristics and their evolution during these periods. In both periods station KO (located furthest from the open sea) presented different physical, chemical and biological characteristics with respect to the other stations inside the Boka Kotorska Bay.