gmmc symposium, june 2017 toulon bay high resolution model: a circulation model … ·...

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Toulon Bay high resolution model: a circulation model for pollutant analysis Camille Mazoyer¹², Anne Molcard¹, Yann Ourmières¹, Cédric Galusinski², Sofiane Meradji² ¹ University of Toulon, AMU, CNRS, IRD, Mediterranean Institute of Oceanography, UM110, 83957 La Garde, France ² University of Toulon, IMATH, EA2134, 83957 La Garde, France Contact : [email protected] Acknowledgement : The authors wish to thank LEFE GMMC (MAREMED project). Numerical simulations are conducted with the support of Aix-Marseille Université and IDRIS/CNRS for their HPC resources. The authors also wish to thank MétéoFrance and Mercator-Océan for supplying numerical data. NOAA/AVHRR thermal image provided by the CMS- SATMOS/MeteoFrance. TRANSMED is funded by the MISTRALS/HyMeX program GMMC symposium, june 2017 Toulon Bay is a shallow semi-closed area (~ 10km x 15 km), close to the marine protected area of Port-Cros national park and edged by the Northern Current (NC). Strong wind events force its surface circulation: these wind events occur with an important spatial and temporal variability. Toulon bay is connected to the open sea by the NC: through meanders and vortices dynamics, this current can either act as a barrier or favour in- and off-shore water mixing. The small bay appears to be a highly contaminated area (regarding trace elements such as Pb). Our aim is then to study the current dynamics in the bay, to analyse pollutant transport and dispersions. These pollutants can impact the near-by marine protected area and can also be transported far away by the NC within the western Mediterranean basin. Conclusion Toulon Bay circulation is mainly driven by winds and a two-layer circulation often appears for significant wind events So far, a good agreement between the observations and TBAY100 simulations is reached, especially regarding drifters trajectories. Future work Data collections and TBAY100 validations Comparison of hydrostatic and non hydrostatic simulations Production of different scenarii to analyse pollutant dispersion The realistic high resolution configuration : TBAY100 for T oulon B ay at 100 m resolution Ocean model : MITgcm v65t Hydrostatic approximation Horizontal resolution : ~ 100m x 100 m Vertical resolution : 75 z-levels (0.5 m for the first 5 m, 1m for and to a maximum spacing of 30 m near the seabed) Atmospheric forcing : ARPEGE METEOFRANCE model (3 hours data, horizontal resolution: ~10 km) Open Boundaries forced with a NEMO configuration at 1/192° (NIDOR192; Declerck et al., 2013) Validations : Hovmöller diagram - comparison with ADCP data Hovmöller diagram (time vs depth), ADCP measurement, january-february 2012 (from C.Dufresnes, 2014) Hovmöller diagram (time vs depth), TBAY100 ADCP localisation (from C.Dufresnes, 2014) 1 2 1 2 1 2 TBAY results are compared to ADCP, for the equivalent wind conditions (but different period). For a medium mistral wind, ADCP data and TBAY results show a anti cyclonic circulation (the current enters at (1) and goes out at (2), for the whole water column. For a strong mistral event, ADCP data and TBAY show a two-layer circulation (see frame 1) Configuration and model settings 0 5 km References: Dufresne, Christiane. « Compréhension et analyse des processus hydro-sédimentaires de la Baie de Toulon. : Apport à la modélisation de la dispersion des radionucléides. » Phdthesis, Université de Toulon, 2014. https://tel.archives-ouvertes.fr/tel-01135325/document. Declerck, Amandine, Yann Ourmières, et Anne Molcard. « Assessment of the Coastal Dynamics in a Nested Zoom and Feedback on the Boundary Current: The North-Western Mediterranean Sea Case ». Ocean Dynamics 66, n 11 (1 novembre 2016): 1529‑42. doi:10.1007/s10236-016-0985-4. Taupier-letage I.; Bachelier C.; Rougier G.; (2014): Thermosalinometer TRANSMED, Marfret Niolon, definitive data set; SEDOO OMP. http://dx.doi.org/10.6096/MISTRALS-HyMeX.1127 Thermal NOAA/AVHRR images: www.ifremer.fr/osis_2014 TRANSMED program: www.ifremer.fr/TRANSMED TBAY 100 Domain Nested models: NIDOR192 (black box), and TBAY100 (blue box) NIDOR192 TBAY100 Comparison of the averaged modelled SST for NIDOR192 and TBAY100 TBAY100 NIDOR 192: - Black box is for Toulon bay zoom - Red box for the whole NIDOR domain Good agreement for tracers between the two nested configurations First TBAY100 assessment First comparisons between buoys campaigns and model results show coherent trajectories Lagrangian buoys computed on-line with MITgcm simulation (22 janv 2014) Equivalent wind conditions 7 february 2017, buoys campaign, with a ~ 6 hours drift Ongoing validation lagrangian buoys campaign Good agreement for upwelling between the two nested configurations NIDOR192 and TBAY100 Upwelling dynamic modification : impact of higher resolution (small bay and sea-wall effect) Upwelling during a strong mistral event Surface anticyclonic circulation (movement in the whole water column). Water intrusion comes from Cap Cépet at the western side (1), and flows to the east along Les Oursinières (2) Two-layers circulation: a bottom layer enters into the bay, while the wind- driven top layer flows out Mistral (N-W wind) Wind > 8-10 m/s Wind < 8-10 m/s Easterly wind A two-layers circulation appears for easterly wind events. The top layer flows into the bay while the bottom water flows offshore. But easterly winds may also induce an eastern in- flow and a western out- flow. Part of the entering vein can be diverted at the entrance of the bay (red arrow) 1 2 1 1 2 2 1 1 2 2 1 2 2 1 Wind-driven circulation Conclusions Toulon Bay circulation is mainly driven by winds and a two-layer circulation often appears for significant wind events So far, a good agreement between the observations and TBAY100 simulations is reached, especially regarding drifters trajectories. Future work Data collections and TBAY100 validations Comparison of hydrostatic and non hydrostatic simulations Production of different scenarii to analyse pollutant dispersion SST (°C), TBAY100 SST (°C), NIDOR192 SST (°C), GLAZUR64 SST (°C), GLAZUR64 NOAA/AVHRR thermal image for 18/09/2013 03:56 (temperatures increase from blue to red). Credit: I. Taupier-Letage (CNRS). Observations of this upwelling, during the 18/09/2013 TRANSMED thermosalinograph data recorded on 16-17/09/2013. Credit : I. Taupier-Letage (CNRS)

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Page 1: GMMC symposium, june 2017 Toulon Bay high resolution model: a circulation model … · 2017-07-13 · Toulon Bay high resolution model: a circulation model for pollutant analysis

Toulon Bay high resolution model: a circulation model for pollutant analysis

Camille Mazoyer¹², Anne Molcard¹, Yann Ourmières¹, Cédric Galusinski², Sofiane Meradji²¹ University of Toulon, AMU, CNRS, IRD, Mediterranean Institute of Oceanography, UM110, 83957 La Garde, France

² University of Toulon, IMATH, EA2134, 83957 La Garde, FranceContact : [email protected]

Acknowledgement : The authors wish to thank LEFE GMMC (MAREMED project). Numerical simulations are conducted with the support of Aix-Marseille Université and IDRIS/CNRS for their HPC resources. The authors also wish to thank MétéoFrance and Mercator-Océan for supplying numerical data.

NOAA/AVHRR thermal image provided by the CMS- SATMOS/MeteoFrance. TRANSMED is funded by the MISTRALS/HyMeX program

GMMC symposium, june 2017

Toulon Bay is a shallow semi-closed area (~ 10km x 15 km), close to the marine protected area of Port-Cros national park and edged by the Northern Current (NC). Strong wind events force its surface circulation: these wind events occur with an important spatial and temporal variability. Toulon bay is connected to the open sea by the NC: through meanders and vortices dynamics, this current can either act as a barrier or favour in- and off-shore water mixing.The small bay appears to be a highly contaminated area (regarding trace elements such as Pb). Our aim is then to study the current dynamics in the bay, to analyse pollutant transport and dispersions. These pollutants can impact the near-by marine protected area and can also be transported far away by the NC within the western Mediterranean basin.

ConclusionToulon Bay circulation is mainly driven by winds and a two-layer circulation often appears for significant wind events So far, a good agreement between the observations and TBAY100 simulations is reached, especially regarding drifters trajectories.

Future work Data collections and TBAY100 validations Comparison of hydrostatic and non hydrostatic simulations Production of different scenarii to analyse pollutant dispersion

The realistic high resolution

configuration :

TBAY100 for Toulon Bay at 100 m resolution

● Ocean model : MITgcm v65t Hydrostatic approximation Horizontal resolution : ~ 100m x 100 m Vertical resolution : 75 z-levels (0.5 m for the first 5 m, 1m for and to a maximum spacing of 30 m near the seabed) Atmospheric forcing : ARPEGE METEOFRANCE model (3 hours data, horizontal resolution: ~10 km) Open Boundaries forced with a NEMO configuration at 1/192° (NIDOR192; Declerck et al., 2013)

Validations : Hovmöller diagram - comparison with ADCP data

Hovmöller diagram (time vs depth),ADCP measurement, january-february 2012 (from

C.Dufresnes, 2014) Hovmöller diagram (time vs depth), TBAY100

ADCP localisation (from C.Dufresnes, 2014)

1

2

1

2

1

2

TBAY results are compared to ADCP, for the equivalent wind conditions (but different period). For a medium mistral wind, ADCP data and TBAY results show a anti cyclonic circulation (the current enters at (1) and goes out at (2), for the whole water column. For a strong mistral event, ADCP data and TBAY show a two-layer circulation (see frame 1)

Configuration and model settings

0 5 km

References: Dufresne, Christiane. « Compréhension et analyse des processus hydro-sédimentaires de la Baie de Toulon. : Apport à la modélisation de la  dispersion des radionucléides. » Phdthesis, Université de Toulon, 2014. https://tel.archives-ouvertes.fr/tel-01135325/document. Declerck, Amandine, Yann Ourmières, et Anne Molcard. « Assessment of the Coastal Dynamics in a Nested Zoom and Feedback on the Boundary Current: The North-Western Mediterranean Sea Case ». Ocean Dynamics 66, n 11 (1 novembre 2016): 1529‑42. doi:10.1007/s10236-016-0985-4.ᵒ Taupier-letage I.; Bachelier C.; Rougier G.; (2014): Thermosalinometer TRANSMED, Marfret Niolon, definitive data set; SEDOO OMP. http://dx.doi.org/10.6096/MISTRALS-HyMeX.1127 Thermal NOAA/AVHRR images: www.ifremer.fr/osis_2014 TRANSMED program: www.ifremer.fr/TRANSMED

TBAY 100 Domain Nested models: NIDOR192 (black box), and TBAY100 (blue box)

NIDOR192

TBAY100

Comparison of the averaged modelled SST for NIDOR192 and TBAY100

TBAY100NIDOR 192: - Black box is for Toulon bay zoom - Red box for the whole NIDOR domain

Good agreement for tracers between the two nested configurations

First TBAY100 assessment

First comparisons between buoys campaigns and model results show coherent trajectories

Lagrangian buoys computed on-line with MITgcm simulation (22 janv 2014)

Equivalent wind conditions

7 february 2017, buoys campaign, with a ~ 6 hours drift

Ongoing validation lagrangian buoys campaign

Good agreement for upwelling between the two nested configurations NIDOR192 and TBAY100 Upwelling dynamic modification : impact of higher resolution (small bay and sea-wall effect)

Upwelling during a strong mistral event

Surface anticyclonic circulation (movement in the whole water column). Water intrusion comes from Cap Cépet at the western side (1), and flows to the east along Les Oursinières (2)

Two-layers circulation: a bottom layer enters into the bay, while the wind-driven top layer flows out

Mis

tral

(N

-W w

ind

)

Wind > 8-10 m/s

Wind < 8-10 m/s

Eas

terl

y w

ind

A two-layers circulation appears for easterly wind events. The top layer flows into the bay while the bottom water flows offshore.

But easterly winds may also induce an eastern in-

flow and a western out-flow. Part of the entering

vein can be diverted at the entrance of the bay (red

arrow)

1 2

1

12

2

1

1 2

2

12

21

Wind-driven circulation

ConclusionsToulon Bay circulation is mainly driven by winds and a two-layer circulation often appears for significant wind eventsSo far, a good agreement between the observations and TBAY100 simulations is reached, especially regarding drifters trajectories.

Future work Data collections and TBAY100 validations Comparison of hydrostatic and non hydrostatic simulations Production of different scenarii to analyse pollutant dispersion

SST (°C), TBAY100SST (°C), NIDOR192SST (°C), GLAZUR64SST (°C), GLAZUR64

NOAA/AVHRR thermal image for 18/09/2013 03:56 (temperatures increase from blue to red). Credit: I. Taupier-Letage (CNRS).

Observations of this upwelling, during the 18/09/2013

TRANSMED thermosalinograph data recorded on 16-17/09/2013. Credit : I. Taupier-Letage (CNRS)