Nicolas Ferry Pierre Daniel

1
Oil spill drift forecast and operational
oceanography systems the Prestige case and
others

• Nicolas Ferry Pierre Daniel
• Mercator-Ocean Météo-France
• Training Roses project, Satellite data for oil
  spill monitoring Starlab, Barcelona, 3
  June 2004

2
Outline

• MOTHY operational oil spill prediction system
• How to improve this system with operational
  oceanography systems ? - example with the
  Mercator system
• Incidents
• Prestige 2002 (Off Galicia)
• Lyria 1993 (Med. Sea)

3
MOTHY Modèle Océanique de Transport
dHydrocarbures)

• A pollutant drift model operated since 1994
• Intensive use for Erika (1999) and Prestige
  (2002) events

France
Spain
MOTHY operational oil spill prediction system
4
MOTHY
A trajectory model Includes a hydrodynamic ocean
model With direct access to weather (wind)
forecast
MOTHY operational oil spill prediction system
5
Hydrodynamic model

• Horizontal mesh 1.5 km resolution
• What does control the surface currents ?
• - the bathymetry ? strong currents near the
  shelves / coast
• - the high frequency temporal and spatial
  variations of wind
• the tides ? 12h25 period, strong impact near
  the coast grounding
• the large scale currents
• But also
• the oil viscosity, density, its solubility in
  the water or its ability to evaporate

6
Surface drift speed

• What governs the oil drift ?
• The wind stress ? 23 of the surface wind
  speed
• 20 km/h wind speed ? a drift of 9 km/day
• The ocean currents 100 of the surface current
• 5 cm/s current ? a drift of 4
  km/day

• the wind field strongly impacts the oil spill
  prediction
• Difficult to perform long range forecast for
  oil spill drift 7-10d

7
Some examples
The large scale ocean currents alone the
Prestige case
SPAIN
work by Sophie Besnard, Mercator
8
Some examples
of the wind speed
The impact of the surface wind the Spanish
trial in Gijón
8-13 May 2004
Buoy 2
work by Sophie Besnard, Mercator
9
Prestige oil spilled on the track
Prestige November 2002
10
Prestige oil spilled on the track
MOTHY operational alone
MOTHY and operational oceanography systems
11
How to improve this system with operational
oceanography systems?

• Use both an oil spill model and operational
  oceanography systems
• combination of large scale currents from an
  operational oceanography system (Mercator) and
  the surface drift from MOTHY

12
How to include large scale currents into MOTHY ?

• MOTHY wind and tide currents, medium to high
  frequency spectrum.
• MERCATOR wind current (low to medium frequency)
  and large scale current.
• How to use such a current in MOTHY, without
  counting 2 times the effect of the wind ?

• ? Current at the base of the mixed layer.
• For example 100 m depth on the Prestige area

13
Prestige oil spilled on the track
In green, areas with positive impact of Mercator
currents In red, areas where MOTHY alone is better
14
Prestige oil spilled on the track December 13,
2002
MOTHY operational
MOTHY is late. Addition of Mercator current at
103 m improves the simulation.
MOTHY Mercator 103m
MOTHY and operational oceanography systems
15
MERCATOR and FOAM currents
Prestige
16
Prestige oil spilled on the track December 13,
2002
Observations black triangles MOTHY alone
blue MOTHYMercator green MOTHYFOAM red
MOTHY and operational oceanography systems
17
But there is a new MERCATOR version

• From MERCATOR Newsletter N12

18
Oil spill drift at depth (3000m) ??

• The PRESTIGE wreck lies at 3500m depth, 125t
  fuel /day rejected
• ? Potential use of the Mercator deep currents
  analyses / forecasts

Current at 3000m depth
19
Lyria (1993)
Lyria
20
Lyria incident (1993) 3 weeks drift

• Without large scale current
• With climatology from in situ measurements (MODB)
  ?
• ? With climatology from an ocean model (Mercator)
• satellite altimetry (ERS1TP) ?

Lyria
21
Lyria, August 17, 1993
Lyria
22
Lyria, August 23, 1993
Lyria
23
Summary

• Direct use of operational oceanography system
  needs
• Hyper refinement in the first meters below the
  surface.
• Use of high resolution wind forecasts
• High resolution grid near the coast (1/60)
• Combine currents from an operational ocean system
  and MOTHY
• Current at 100 m depth improve the drift, but
  this is not perfect
• A need for new product a current at the base of
  the mixed layer, other ?
• Strong impact of the wind products used (MOTHY,
  MERCATOR)
• Strong impact of the data assimilated (SLA, SST)
  on the forecast currents from Operational
  Oceanographic Systems

24
Acknowledgment

• This work was supported by the Marine and
  Oceanography section at Météo-France and the
  Mercator-Ocean team.
• A large number of individuals help us in this
  work.
• We would particularly thank
• P. Daniel (Météo France)
• N. Pinardi and C. Fratianni (INGV, Italy)
• M. Bell and M. Holt (Met Office, UK)
• M. Jouhan and P. Lazure (IFREMER)
• G. Caniaux (Météo-France, CNRM)

http//www.meteorologie.eu.org/mothy/ http//www.m
ercator-ocean.fr