Weakening thermohaline circulation in the Adriatic Sea

Abstract

In this paper, we document observational support for the long-term weakening of the northwestern part of the Adriatic-Ionian thermohaline cell (AITHC), one of the 3 cells that drive the deep Mediterranean thermohaline circulation. The AITHC weakening is detected from longterm temperature, salinity and dissolved oxygen trends estimated from data measured between 1952 and 2010 along the Palagruža Sill, Adriatic Sea. We assumed that the weakening of the AITHC may be deduced from long-term changes in the dense water outflow characteristics across the sill, which are characterized by a strong decrease in dissolved oxygen content, slight warming and shallowing of the outflow and by lower advection of saline and warmer Levantine Intermediate Water (LIW) toward the northwestern Adriatic. The latter was deduced from the negative temperature trends and the lowest salinity trends estimated for the area of LIW inflow. Further weakening of the AITHC may have a noteworthy impact on deep aquatic systems and should therefore be monitored and assessed regularly. © Inter-Research 2013.