Qualified temperature, salinity and dissolved oxygen climatologies in a changing Adriatic Sea

[摘要] An updated climatology, based on a comprehensive data set (1911–2009) oftemperature, salinity and dissolved oxygen, has been produced for the wholeAdriatic Sea with the variational inverse method using the DIVA(Data-Interpolating Variational Analysis) software. Climatological maps wereproduced at 26 levels and validated with ordinary cross-validation and witha real vs. synthetic temperature–salinity diagram intercomparison. The conceptof climatology–observation misfit (COM) has been introduced as an estimateof the physical variability associated with the climatological structures.In order to verify the temporal stability of the climatology, long-termvariability has been investigated in the Middle Adriatic and the South Adriaticpits, regarded as the most suitable records of possible long-term changes.Compared with previous climatologies, this study allows a clearidentification of the seasonal dynamic of the southern Adriatic, where a clearoxygen minimum is typically observed in the centre of the South AdriaticGyre. New and better resolved features emerged from this analysis: (1) below100 m all properties profoundly differ between the central and the southernAdriatic and seem characterized by different biogeochemical dynamics; (2)the South Adriatic Pit clearly shows the remote effects of the EasternMediterranean Transient, while no effect is observed in the Middle AdriaticPit; (3) the deepest part of the southern Adriatic seems now to besignificantly saltier (+0.18 psu since the period 1910–1914, with an increaseof +0.018 decade⁻¹ since the late 1940s) and warmer(+0.54 °C since 1910–1914) even though a long-term temperaturetrend could not be statistically demonstrated; (4) the Middle Adriatic Pitshows a long-term increase in apparent oxygen utilization (+0.77 mL L⁻¹ since 1910–1914, with a constant increase of +0.2 mL L⁻¹ decade⁻¹ after the 1970s).

[学科分类] 海洋学与技术