NUMERICAL SIMULATION OF DENSE
WATER FORMATION PROCESSES IN
THE NORTHERN ADRIATIC SEA
STEFANO QUERIN1, CÉLIA LAURENT2, ALESSANDRO CRISE1, COSIMO SOLIDORO2
1 – ISTITUTO NAZIONALE DI OCEANOGRAFIA E DI GEOFISICA SPERIMENTALE (OGS)
2 – UNIVERSITÉ DE VERSAILLES SAINT-QUENTIN-EN-YVELINES
([email protected] / +39 040 2140376)
OVERVIEW
• simulation of dense water formation processes (VECTOR
project)
• preliminar numerical study of the hydrodynamic features of the
Northern Adriatic Sea during winter
• case study: winter 2006/2007
THE NUMERICAL MODEL
MITgcm Ocean General Circulation Model [Marshall et al., 1997]
MITgcm main features:
• designed to study both atmospheric and oceanic phenomena
• includes non-hydrostatic capability
• adopts the KPP vertical turbulence parametrization
• adopts a finite volume technique
• developed to perform efficiently on a wide variety of
computational platforms including MPI parallelizing directives
MODEL EQUATIONS
Du
1 ∂p
− fv +
= Eu
Dt
ρc ∂x
Dv
1 ∂p
+ fu +
= Ev
Dt
ρ c ∂y
ε nh
momentum equations
Dw
ρ
1 ∂p
+g
+
= ε nhEw
Dt
ρc ρc ∂z
∂u ∂v ∂w
+
+
=0
∂x ∂y
∂z
continuity equation
ρ = ρ(θ , S)
equation of state
Dθ
= Qθ
Dt
heat equation
DS
= QS
Dt
salt equation
PRESSURE INTEGRATION
p = ps + ph + pnh
ps(x,y)
pressure due to surface elevation (2-D elliptic equation)
ph(x,y, z)
hydrostatic pressure (2-D elliptic equation)
pnh(x,y, z)
non-hydrostatic pressure (3-D elliptic equation)
GRAVITY PLUME ON A CONTINENTAL SLOPE
Temperature after 23 hours of cooling. The cold dense water is mixed
with ambient water as it accelerates down the slope and hence is
warmer than the unmixed plume.
• ∆ X = 12 ÷ 40 m
• ∆ Z = 3.33 m
• heat flux = 200 W/m2
TRACER ADVECTION
MODEL CONFIGURATION
• f-plane, 0.0225° spatial resolution
• 43° rotation
• 128 x 116 x 38 cells
• 20 (2 m) + 18 (4 m) levels
• bathymetry:
9 experimental data set
9 small manual adjustments
• I.C.:
9 horizontally uniform
9 climatology
• B.C.:
9
9
9
9
9
lateral no-slip
quadratic bottom friction
surface atmospheric forcing
passive open boundary conditions
Po river freshwater input
COUPLING WITH ETA006 (CREST s.r.l.)
Read-in uwind, vwind, atemp, aqh, swdown, lwdown,
precip, and runoff.
Compute ustress, vstress, hflux, swflux, and sflux.
EFFECT OF BORA WIND
1/6 - weak Scirocco before the Bora episode
EFFECT OF BORA WIND
2/6 – no wind before the Bora episode
EFFECT OF BORA WIND
3/6 – strong Bora wind forcing
EFFECT OF BORA WIND
4/6 – decreasing wind forcing
EFFECT OF BORA WIND
5/6 – no wind after the Bora episode
EFFECT OF BORA WIND
6/6 – no wind after the Bora episode
EFFECT OF BORA WIND
Vertical sections of density anomaly
DONE...
• successful implementation of a 3-D hydrodynamic model for
the Northern Adriatic Sea
• application to real a case study (winter 2006/2007)
UNDER CONSTRUCTION...
• application to several case studies
• which are the phenomena that trigger the dense water flux?
• computation of dense water mass production/fluxes
ACKNOWLEDGEMENTS
• VECTOR project
• Alessandro Allodi (Regione Emilia Romagna, ARPA – SIM, Area
Idrologia, PARMA)
• CREST s.r.l.
• Andrea Cimatoribus
• Vanessa Cardin (OGS)
THANKS!