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Hydrodynamic features of the South Aegean Sea as derived from Argo T/S and dissolved oxygen profiles in the area

Abstract

In this work, the hydrodynamic picture of the South Aegean Sea is examined through an analysis of recent measurements in its sub-basins, the Myrtoan and Cretan Sea. Both sub-basins play an important role in the water circulation, exchange, and formation processes that affect the dynamics of the whole Eastern Mediterranean. For the first time, Bio-Argo floats were deployed in the area under the Greek Argo Research Infrastructure coordination. The acquired profiles cover an almost 2-year period (November 2013–July 2015) and are compared with previous Argo profiles and the re-processed time-series data recorded from the E1-M3A POSEIDON observatory operating in the area since 2007. The spatio-temporal distribution of the physical and chemical properties in each sub-basin is examined. Dense water formation events are revealed in the northern part (Myrtoan), while the wider area can be characterized as pre-conditioned. In the Cretan basin, a strong inter-annual variability of the salinity field at intermediate and deep layers is observed that is associated with water exchange from its open boundaries. Furthermore, comparison of the dissolved oxygen (DO) distribution with physical water properties within both the mixed layer, and at greater depths, indicated that relatively high but still under-saturated DO values are more likely to be associated with convection events. Finally, an updated picture of the physical properties and the DO distribution is presented based on the last 5 years of measurements and the recent introduction of Bio-Argo floats with DO sensors in the area.

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Acknowledgments

This work has been supported by the Greek Argo project funded by the National Strategic Reference Framework (NSRF) 2007–2013.

The POSEIDON I and II projects were funded by the Financial Mechanism of the European Economic Area and the Hellenic Program of Public Investments.

The “Policy-oriented marine Environmental Research for the Southern European Seas” (PERSEUS) project was funded by the EU FP7 Theme “Oceans of Tomorrow”.

We would also like to thank the GIS and Remote Sensing Lab of HCMR—Institute of oceanography and all the people of the POSEIDON team (technicians and scientists) who contributed to this effort.

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Correspondence to Dimitris Kassis.

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Responsible Editor: Aida Alvera-Azcárate

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Kassis, D., Krasakopoulou, E., Korres, G. et al. Hydrodynamic features of the South Aegean Sea as derived from Argo T/S and dissolved oxygen profiles in the area. Ocean Dynamics 66, 1449–1466 (2016). https://doi.org/10.1007/s10236-016-0987-2

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Keywords

  • Greek Argo
  • POSEIDON system
  • Dissolved oxygen
  • Deep convection
  • Cretan Sea
  • Myrtoan Sea