Saw‐tooth modulation of the deep‐water thermohaline properties in the southern Adriatic Sea

Abstract

In this study, we investigate the dynamics of the bottom layer of the southern Adriatic Sea (eastern Mediterranean basin) by merging experimental measurements and numerical simulations. We hypothesize that the recently observed continuous density decrease over time, which was basically related to a temperature increase, and the following sudden density rise, which was caused by the intrusion of very dense water masses (cold but relatively fresh), constitute one cycle of a general saw-tooth pattern: the alternation of long-lasting and almost linear density decreases (mixing phases) and sudden density increases (dense water intrusion phases). The model results, which provide a basin-scale view of the process, corroborate this theory because they satisfactorily reproduced the observed oceanographic features. We describe the almost linear density decrease in terms of local mixing fostered by the advection of flow instabilities that originate from the large-scale quasi-permanent cyclonic circulation. Conversely, diffusive processes play a minor role in determining the bottom layer thermohaline variability. The interpretation of the experimental findings, supported by the numerical simulations, suggests that similar dynamics might be observed in other basins characterized by similar bathymetric and hydrodynamic features

Development of BFMCOUPLER (v1.0), the coupling scheme that links the MITgcm and BFM models for ocean biogeochemistry simulations

“…The initial conditions for the hydrodynamic and biogeochemical variables were also derived from the CMEMS MED-MFC system by linearly interpolating the original fields from 1/16 • to 1/32 • . Additional details on the ADIOS model set-up are provided by Querin et al (2016).…”

Wintertime dynamics in the coastal northeastern Adriatic Sea: the NAdEx 2015 experiment

“…The dense waters that are generated are gravitationally transported towards middle Adriatic depressions though a bottom density current (Nof, 1983) mostly along the western Adriatic slope due to the Coriolis force (Artegiani and Salusti, 1987;Vilibić and Mihanović, 2013). A portion of the water travels across the southern Palagruža Sill and, when it reaches the slope and canyons of the South Adriatic Pit, it is transported down the slope to the near-bottom layers (Querin et al, 2013(Querin et al, , 2016Langone et al, 2016). This concept has been supported by a number of numerical modelling studies (e.g.…”

Unexpected Covariant Behavior of the Aegean and Ionian Seas in the Period 1987–2008 by Means of a Nondimensional Sea Surface Height Index

“…The Adriatic Sea (Figure ) has an elongated shape (approximately 800 km long and 200 km wide) and is connected through the Otranto Strait (75 km wide and approximately 800 m deep) with the Ionian Sea. Historically, the Southern Adriatic has been identified as the main source of deep waters (also referred as Adriatic Deep Water (ADW); Manca et al, ; Querin et al, ) for the Eastern Mediterranean (EMED). ADW ranges approximately between 0.1 and 0.4 Sv (1Sv = 10 6 m 3 s −1 ) with typical temperatures lower than 13.3°C, salinities higher than 38.68 and potential densities within the range of 29.17–29.18 kg m −3 (Gačić et al, ).…”