Indications of Climate Regime shifts in the Middle Adriatic Sea

The Adriatic Sea, as adjacent sea of the greater Mediterranean Sea, is under direct influence of atmospheric processes and their variability. Cold deep water formed under strong winter outbursts of Bura wind in the Northern Adriatic plays crucial role in the overall Adriatic circulation. Interannual variability of temperature and salinity in the Adriatic Sea is firstly interplay of Northern Adriatic Dense water (NAdDW) formation and intrusions of Levantine Intermediate Water (LIW) (BULJAN, 1953; ZORE-ARMANDA, 1963; VILIBIĆ & ORLIĆ, 2001). The LIW continuously enters the Adriatic in the intermediate layer but with variable intensity depending on wider scale atmospheric conditions (ZORE-ARMANDA, 1972; GRBEC et al., 1998), which are of global character. It is supposed that El Nino Southern Oscillation (ENSO) was one of the mechanisms Applying sequential t-test analysis for regime shift detection on 52 years (period 1963-2004) of continuous summer thermohaline data at the three ocean stations in the Adriatic Sea, the two shifts in sea temperature were evidenced, around 1987 and 1998. These shifts separated three climate regimes, where the first climate regime is rather similar to the third one. The first climate regime (1963-1986) is characterized by moderate temperatures and rather high salinities. The first shift occurred in 1987, triggering the second climate regime, influenced by East Mediterranean Transient (EMT). The temperature and salinity in the Adriatic in the second climate regime were lower for one standard deviation than in the previous regime. In the third regime, after second shift the temperatures and salinities abruptly increased. All these conditions were influenced by changes in wind field pattern over the Mediterranean.