Title: Turbulent mixing processes in Microtidal Coastal Flows Fluxes and Structuresin Fluids 05
1Turbulent mixing processes in Microtidal Coastal
FlowsFluxes and Structuresin Fluids 05
Philippe Fraunié et al
Laboratoire de Sondages Electromagnétiques de
lEnvironnement Terrestre (Université de Toulon
et du Var)
2Physics
- Coastal flows are basically fully 3D and mainly
baroclinic - 3D upwellings / density currents
- Wind forcing relevant scales?
- Baroclinic instability in complex bathymetry
- Density fronts
3I River dischargein Microtidal sea
- River plume dynamics (Garvine )
- - Nutrients inputs (tap)
- - density flows (including fronts, interfaces and
intenal waves) - - Region of Fresh Water Influence (Simpson 97)
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6Ebro site
7Nested Models (P. Garreau)
Mediterranen model (rank 0)
DX12 km DT1200s
8Upwelling Location
wind
9Rhone river dischargeTypical situation 2001
10Aladin Winds / Mars currents, SSS and SeaWiFS
image
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16II. The Rhône river plume
17Rhône site G. Reffray et al
Surface velocity and Salinity
SPOT Image Suspended matter
18Secondary flows.
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203D Flows
5 m depth
Transport
21Direct Simulations
22Factor Analysis
Transport (SW equations) a) upwelling b) plume,
c) background and d) NL interactions
23III. Mixing processes
- High stratification mechanisms
- - Vertical mixing
- - fronts
- - internal waves
24River plume front
25Radar measurements
26VHF Radar Measurement of dynamical stratification
(Broche et al)
(dB)
0 Doppler Frequency(Hz)
U1
Bragg line 25 cm
U2
hydrodynamic line 50 cm
électromagnetic line37.5 cm
27III The layering effect
28Successive infinitesimal perturbation (1)
29Piecewise quadratic rebuilding of a salinity
discontinuity. 1st line initial distribution
but also the piecewise constant rebuilding
(UPWIND scheme). 2nd line PPM scheme without
the traitment for the monotonicity 3rd line
complete PPM scheme (continue line) and QUICKEST
scheme (dots line).
30SAMPOS floating System(JL Devenon)(ADP DL7
GPS)
31Stratification in the Rhône river plume BIODYPAR
field campaign (PNEC, 1999)
salinity
velocity
32CTD and velocity profiles
33Settling velocity
34Active transport (JJ Naudin)
35Conclusion
- Characteristics of stratified coastal flows
- non linear interaction barotropic/baroclinic
modes - Secondary flows
- complex turbulent mixing
- Mixing processes
- scalar fields dispersion
- breaking internal waves
- Layering effect
- thermocline
- river plumes