Drivers of the decadal variability of the North Ionian Gyre upper layer circulation during 1910–2010: a regional modelling study

Abstract A long simulation over the period 1901–2010 with an eddy-permitting ocean circulation model is used to study variability of upper layer in North Ionian Gyre (NIG) Eastern Mediterranean Sea (EMed). The driven by atmospheric forcing from twentieth century reanalysis data set ERA-20C, ensuring a consistent performance entire period. main modes known EMed, particular decadal reversals NIG observed since late 1980s are well reproduced. We find that simulated prior observational characterized long-lasting cyclonic phases weak during years 1910–1940 and 1960–1985, while in-between (1940–1960) quasi-decadal occur similar characteristics those recent decades. Our indicates rather prone mode occasional kicks anticyclonic mode. coherent Adriatic Deep Water (AdDW) outflow implies triggering strong AdDW formation required kick into 1–2 later. sensitivity experiment mimicking cold winter event supports this hypothesis. shows it multi-decadal salinity leads periods where low prevents events. This explains absence 1960–1985.