Long-term variability and trends of relative geostrophic currents in the middle Adriatic

• We estimated long-term trends in geostrophic currents in the middle Adriatic.
• A southward deflection of Eastern Adriatic Current has been found.
• Western Adriatic Current exhibits strong seasonal variability.
• We found long-term trends opposing mean currents.
• A climate model does not reproduce observed trends.

The paper documents dynamics of the middle Adriatic region, and is based on computation of relative geostrophic currents from temperature and salinity data taken along the Palagruža Sill transect between 1957 and 2010. The strongest westward current is found in the central part of the sill, corresponding to the offshore deflected Eastern Adriatic Current (EAC). The Western Adriatic Current (WAC) is, as expected, found in the southern part of the measured transect. The WAC is most significant during the summer season and exhibits stronger variability than the EAC due to the frequent growth of eddies within it. Long-term trends in both the central and southern parts of the sill oppose mean currents, indicating the weakening of the EAC and WAC and therefore of the entire Adriatic thermohaline cell. These opposing trends have not been reproduced by a climate model.