Hydrodynamic variability based on the multi-parametric POSEIDON Pylos observatory of the south Ionian Sea

Abstract. The multi-platform POSEIDON-Pylos observatory of the south-east Ionian Sea operates since 2007 delivering near real time data for a variety of meteorological, water column and near seabed oceanographic parameters. It has been designed to contribute to long term monitoring of air–sea interaction and thermohaline processes of this key area of the Eastern Mediterranean where water masses of different origin interact and transform at various temporal and spatial scales. An inductive mooring line, with CTD instruments adjusted on, provides salinity, temperature and pressure real-time data down to 500 m depth. Recorded data, for the years 2008–2010, were extracted from the instruments internal logger providing more enhanced timeseries in terms of resolution and continuity. The reprocessed datasets are analyzed in combination with atmospheric, currents buoy measurements and CTD profiles obtained during maintenance visits on the site. The delayed mode analysis shows the hydrodynamic properties of the area and reveals the dynamic picture of the south Ionian upper thermocline as well as the variation of T & S in deeper layers. One can also observe seasonal atmospheric and circulation patterns, other synoptic and seasonal scale signals as well as important inter-annual variability such as a strong signal of Levantine Intermediate Waters (LIW) at intermediate depths during the spring of 2009.