Role of the Mid-Adriatic deep in dense water interception and modification

Mauro Marini*, Vittorio Maselli, Alessandra Campanelli, Federica Foglini, Federica Grilli

*Corresponding author for this work

Research output: Contribution to journalArticle

18 Citations (Scopus)

Abstract

This study set out to gain insights into: i) the route of dense water (DW), which leaves a morphological signature including large-scale erosion, moats, and contourite sediment drifts, and ii) the physical and chemical modifications undergone by Northern Adriatic Dense Water (NAdDW) due to its entrapment in the Mid-Adriatic Deep (MAD) for one or more years, which leads to biogeochemical transformation into Mid-Adriatic Dense Water (MAdDW), a less dense and colder water mass with reduced oxygen content as a result of prolonged biological consumption. The paper provides an accurate description of how NAdDW, on its way to the Southern Adriatic basin, mixes with MAdDW on Palagruza Sill. Analysis of water column data (CTD) collected in spring 2005 and 2012 showed that part of the NAdDW flowing down the Western Adriatic shelf swerves left, splitting into a branch that fills the western MAD pit and another flowing along the 170 m contour towards the eastern pit and then south through Palagrda Sill. Due to the density difference, the recently formed NAdDW flows as a bottom-trapped current underneath the older MAdDW, lifting and pushing it over Palagrda Sill, thereby promoting water exchange among the MAD pits. The two water masses eventually mix as they flow over Palagrda Sill, in proportions that depend on NAdDW volume and the changes undergone by MAdDW, thus generating a new mixed bottom flowing DW with a distinctive chemical signal. The bottom water pattern disclosed by LW transects is consistent with seafloor and sub-seafloor morphologies detected on high-resolution seismic profiles, which show both erosion and deposition features along bottom water routes. Moreover, confinement of the mixed water within structural highs as it flows southward through Palagrda Sill promotes formation of shallow water contourites and giant sediment drifts, demonstrating a significant role for topography in the flow of all Adriatic DW. (C) 2015 Elsevier B.V. All rights reserved.

Original languageEnglish
Pages (from-to)5-14
Number of pages10
JournalMarine Geology
Volume375
Early online date29 Aug 2015
DOIs
Publication statusPublished - 1 May 2016

Keywords

  • nutrate
  • dissolved oxygen
  • bottom water
  • contourite drift
  • Adriatic sea
  • submarine canyons
  • continental-shelf
  • sea hydrography
  • surface fluxes
  • Bari Canyon
  • Jabuka-Pit
  • winter
  • circulation
  • transport

Cite this

Marini, M., Maselli, V., Campanelli, A., Foglini, F., & Grilli, F. (2016). Role of the Mid-Adriatic deep in dense water interception and modification. Marine Geology, 375, 5-14. https://doi.org/10.1016/j.margeo.2015.08.015

Role of the Mid-Adriatic deep in dense water interception and modification. / Marini, Mauro; Maselli, Vittorio; Campanelli, Alessandra; Foglini, Federica; Grilli, Federica.

In: Marine Geology, Vol. 375, 01.05.2016, p. 5-14.

Research output: Contribution to journalArticle

Marini, M, Maselli, V, Campanelli, A, Foglini, F & Grilli, F 2016, 'Role of the Mid-Adriatic deep in dense water interception and modification', Marine Geology, vol. 375, pp. 5-14. https://doi.org/10.1016/j.margeo.2015.08.015
Marini, Mauro ; Maselli, Vittorio ; Campanelli, Alessandra ; Foglini, Federica ; Grilli, Federica. / Role of the Mid-Adriatic deep in dense water interception and modification. In: Marine Geology. 2016 ; Vol. 375. pp. 5-14.
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AU - Grilli, Federica

N1 - The authors are grateful to Elisabetta Campiani for drawing the 3D pictures. This research was supported by the Bandiera RITMARE Project - La Ricerca Italiana per il Mare – coordinated by the National Research Council and financed by the Italian University and Research Ministry, National Research Program 2011-2013. The authors wish to thank all scientists and crew members of R/V Minerva I and R/V G. Dallaporta for their help in sampling activities during the cruises.

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N2 - This study set out to gain insights into: i) the route of dense water (DW), which leaves a morphological signature including large-scale erosion, moats, and contourite sediment drifts, and ii) the physical and chemical modifications undergone by Northern Adriatic Dense Water (NAdDW) due to its entrapment in the Mid-Adriatic Deep (MAD) for one or more years, which leads to biogeochemical transformation into Mid-Adriatic Dense Water (MAdDW), a less dense and colder water mass with reduced oxygen content as a result of prolonged biological consumption. The paper provides an accurate description of how NAdDW, on its way to the Southern Adriatic basin, mixes with MAdDW on Palagruza Sill. Analysis of water column data (CTD) collected in spring 2005 and 2012 showed that part of the NAdDW flowing down the Western Adriatic shelf swerves left, splitting into a branch that fills the western MAD pit and another flowing along the 170 m contour towards the eastern pit and then south through Palagrda Sill. Due to the density difference, the recently formed NAdDW flows as a bottom-trapped current underneath the older MAdDW, lifting and pushing it over Palagrda Sill, thereby promoting water exchange among the MAD pits. The two water masses eventually mix as they flow over Palagrda Sill, in proportions that depend on NAdDW volume and the changes undergone by MAdDW, thus generating a new mixed bottom flowing DW with a distinctive chemical signal. The bottom water pattern disclosed by LW transects is consistent with seafloor and sub-seafloor morphologies detected on high-resolution seismic profiles, which show both erosion and deposition features along bottom water routes. Moreover, confinement of the mixed water within structural highs as it flows southward through Palagrda Sill promotes formation of shallow water contourites and giant sediment drifts, demonstrating a significant role for topography in the flow of all Adriatic DW. (C) 2015 Elsevier B.V. All rights reserved.

AB - This study set out to gain insights into: i) the route of dense water (DW), which leaves a morphological signature including large-scale erosion, moats, and contourite sediment drifts, and ii) the physical and chemical modifications undergone by Northern Adriatic Dense Water (NAdDW) due to its entrapment in the Mid-Adriatic Deep (MAD) for one or more years, which leads to biogeochemical transformation into Mid-Adriatic Dense Water (MAdDW), a less dense and colder water mass with reduced oxygen content as a result of prolonged biological consumption. The paper provides an accurate description of how NAdDW, on its way to the Southern Adriatic basin, mixes with MAdDW on Palagruza Sill. Analysis of water column data (CTD) collected in spring 2005 and 2012 showed that part of the NAdDW flowing down the Western Adriatic shelf swerves left, splitting into a branch that fills the western MAD pit and another flowing along the 170 m contour towards the eastern pit and then south through Palagrda Sill. Due to the density difference, the recently formed NAdDW flows as a bottom-trapped current underneath the older MAdDW, lifting and pushing it over Palagrda Sill, thereby promoting water exchange among the MAD pits. The two water masses eventually mix as they flow over Palagrda Sill, in proportions that depend on NAdDW volume and the changes undergone by MAdDW, thus generating a new mixed bottom flowing DW with a distinctive chemical signal. The bottom water pattern disclosed by LW transects is consistent with seafloor and sub-seafloor morphologies detected on high-resolution seismic profiles, which show both erosion and deposition features along bottom water routes. Moreover, confinement of the mixed water within structural highs as it flows southward through Palagrda Sill promotes formation of shallow water contourites and giant sediment drifts, demonstrating a significant role for topography in the flow of all Adriatic DW. (C) 2015 Elsevier B.V. All rights reserved.

KW - nutrate

KW - dissolved oxygen

KW - bottom water

KW - contourite drift

KW - Adriatic sea

KW - submarine canyons

KW - continental-shelf

KW - sea hydrography

KW - surface fluxes

KW - Bari Canyon

KW - Jabuka-Pit

KW - winter

KW - circulation

KW - transport

U2 - 10.1016/j.margeo.2015.08.015

DO - 10.1016/j.margeo.2015.08.015

M3 - Article

VL - 375

SP - 5

EP - 14

JO - Marine Geology

JF - Marine Geology

SN - 0025-3227

ER -