Publication Date:
2019-04-01
Description:
t The role of riverine freshwater inflow on the
Central Mediterranean Overturning Circulation (CMOC)
was studied using a high-resolution ocean model with a
complete distribution of rivers in the Adriatic and Ionian
catchment areas. The impact of river runoff on the Adriatic and Ionian Sea basins was assessed by a twin experiment, with and without runoff, from 1999 to 2012. This
study tries to show the connection between the Adriatic
as a marginal sea containing the downwelling branch of
the anti-estuarine CMOC and the large runoff occurring
there. It is found that the multiannual CMOC is a persistent anti-estuarine structure with secondary estuarine cells
that strengthen in years of large realistic river runoff. The
CMOC is demonstrated to be controlled by wind forcing at
least as much as by buoyancy fluxes. It is found that river
runoff affects the CMOC strength, enhancing the amplitude
of the secondary estuarine cells and reducing the intensity
of the dominant anti-estuarine cell. A large river runoff can
produce a positive buoyancy flux without switching off the
antiestuarine CMOC cell, but a particularly low heat flux
and wind work with normal river runoff can reverse it.
Overall by comparing experiments with, without and with
unrealistically augmented runoff we demonstrate that rivers
affect the CMOC strength but they can never represent its dominant forcing mechanism and the potential role of river
runoff has to be considered jointly with wind work and heat
flux, as they largely contribute to the energy budget of the
basin. Looking at the downwelling branch of the CMOC
in the Adriatic basin, rivers are demonstrated to locally
reduce the volume of Adriatic dense water formed in the
Southern Adriatic Sea as a result of increased water stratification. The spreading of the Adriatic dense water into the
Ionian abyss is affected as well: dense waters overflowing
the Otranto Strait are less dense in a realistic runoff regime,
with respect to no runoff experiment, and confined to a narrower band against the Italian shelf with less lateral spreading toward the Ionian Sea center.
1
Description:
Published
Description:
1675-1703
Description:
4A. Oceanografia e clima
Description:
JCR Journal
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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