Oil Spill Models

Oil spill models constitute an essential element in contingency planning and in preparing effective response strategies to combat hazardous oil spills at sea. Such models rely on the ability to predict meteo-marine conditions of the sea through the use of atmospheric, wave and hydrodynamical numerical models; in combination with information on the location, rate, nature and characteristics of an oil spill, the derived forecasted fields are used to provide in advance some knowledge on the fate and track that the oil slick will follow in time.  With sufficient computer power, that is nowadays becoming more affordable, such a chain of numerical model activities can be automated and run in operational mode to provide a round-the-clock service to civil protection agencies, coastguards and maritime authorities for rapid intervention against oil spills originating from the sea, to control and limit impacts and damages on the coast and essential resources and structures.

MEDSLIK Oil spill model    MEDSLIK Oil spill model

During MEDESS-4MS, the well established standalone oil spill systems (MOTHY, MEDSLIK, MEDSLIK-II, POSEIDON-OSM) in the Mediterranean, described in the following paragraphs, will be interconnected into an integrated multi model oil spill forecasting network. A common data exchange system will be also developed in order to provide the link between the necessary information that should be available to the oil spill systems, the environmental data from the Marine Core Service and the national ocean forecasting systems, the oil slick data from existing monitoring platforms and the data from supplementary resources such as AIS or VTMIS.

Immagine1

Through the User Interface (UI) and the Network Data Repository (NDR), the MEDESS-4MS service will be able to provide to the end users the possibility of using any oil spill model and environmental data available to the service for the oil drift forecasting throughout the Mediterranean Sea.

MOTHY

MOTHY is a 3D pollutant drift model implemented by Météo-France for the Mediterranean Sea and the Black Sea (worldwide actually). Operated since 1994 in the marine forecast section at Météo-France, MOTHY has been extensively used for the Erika and the Prestige incidents. The system is operated on demands of Cedre for support of the oil spill fighting operations and on demands of the Marine Rescue Coordination Centres for support of the search and rescue operations.
A meteorologist on duty is able to run the model around the clock. About 500 interventions each year are conducted with an averaged time response of 30 minutes.

MOTHY oil spill model

Pollutants can be oil or floating objects. Current in the mixed layer is computed using a combination of a shallow water model driven by the wind and the atmospheric pressure, coupled to an analytical turbulent viscosity model, so as to represent vertical current shear, and a background current provided by an oceanic model (MERCATOR or MFS). A continuous profile from surface to bottom describes the water column.
MOTHY system consists of four modules:

  • a setup module to specify the model domain and parameters, the atmospheric and oceanic forcings, the pollutant description
  • a run module that performs the simulation
  • a visual interface for viewing the outputs
  • a broadcast interface to send the results (several formats are available) to the end-user (website, e-mail, fax)

The length of the forecast is, for most cases, 2 or 3 days but 10 days forecasts are available. For specifics cases, probabilistic forecasts up to 10 days can be managed. Additional oil spill model capabilities:beaching, sedimentation, backtracking, pollutants can be oil or floating objects. MOTHY predicts each pollutant parcel in size, position coordinates (Lat, Lon), position in the water column (surface, bottom or in the column) or beached.
Model results are available in the following output formats:
- image/animation: GIF
- GIS/Microsoft EXCEL: DBF
- Google Earth/Google Maps: KML/KMZ
- GIS/GPS/interactive web-mapping: GPX

More documents on the Mothy model can be found on: http://www.meteorologie.eu.org/mothy/english.html.

MEDSLIK

MEDSLIK is an oil spill and trajectory 3D model, developed and implemented at the Oceanography Centre of the University of Cyprus (OC-UCY), that predicts the transport, fate and weathering of oil spills andthe movement of floating objects in the Mediterranean, the Black and the Baltic seas.
The MEDSLIK incorporates the evaporation, emulsification, viscosity changes, dispersion in water column, adhesion to coast. The transport of the surface slick is governed by currents, waves (Stoke’s drift) and wind while its diffusion is modelled by a random walk (Monte Carlo) model. Oil may be dispersed into the water column by wave action but dispersed oil is moved by currents only. The oil is considered to consist of a light evaporative component and a heavy non evaporative component. Emulsification is also simulated, and the viscosity changes of the oil are computed according to the amounts of emulsification and evaporation of the oil. The pollutant is divided into a large number of Lagrangian parcels of equal size. At each time step, each parcel is given a convective and a diffusive displacement. Mechanical spreading of the initial slick is included with fate processes included in the model as the evaporation of the lighter oil fractions and the mixing into the water column by wave action and emulsification.

MEDSLIK oil spill model AIS     MEDSLIK oil spill model slick position

Oil viscosity changes and beaching on the coast and absorption depending on the coastal type. MEDSLIK covers the Mediterranean sea, the Levantine basin, the Black Sea and the Baltic Sea, but it can be used for any user-selected region in the world if the appropriate map, bathymetry and forecast files are provided.

MEDSLIK consists of four modules:

  1. a setup module for model domain and parameters
  2. a visual interface for input of the spill data;
  3. a run module that performs the simulation and
  4. a visual interface for viewing the output

Additional oil spill model capabilities arebeaching, hindcast, automatic connection to EMSA CSN SAR detections, use of ESA images. Other features of MEDSLIK:

  • It includes a built-in database (from REMPEC) of over 220 oil types that are the most common in the Mediterranean Sea.
  • It allows to switch from coarse to high resolution ocean forecasting data, when the oil slick passes from a coarse to a higher resolution domain.
  • It allows assimilation of observations, in-situ or aerial to correct the oil spill predictions.
  • The effect of deployment of oil booms and/or oil skimmers-recovery can be examined.
  • Continuous or instantaneous oil spills from moving or drifting ships whose slicks merge can be modeled together.
  • Hindcast simulations for tracking the source of pollution.
  • Integration with the AIS in the Levantine Basin
  • It includes a simple GIS to allow information on coastal and open sea resources.
  • Simulation of sub-surface oil spills
  • It can be installed under Windows or Linux

The length of the forecast is from few hours up to 3 weeks, but there is a Restart option, so the length of the forecasts can be extended further.

MEDSLIK oil spill model

MEDSLIK predicts the oil slick at sea surface, evaporated, dispersed in the water column, stack on coast. Then the oil slick viscosity, oil density, oil slick volume. The results of the oil spill and trajectory predictions are available in the following output formats:
- image: BMP or PNG, TIF,GIF, JPG
- ASCII
- Google Earth: KML

An automatic version of MEDSLIK (internally known as AutoMedTrack) is used without any operator intervention, along with ASAR satellite data for short, 24 hours forward and backwards predictions. The model has been used with satellite images, MODIS and ASAR during the Lebanese oil pollution crisis, in summer 2006, which is considered the biggest oil pollution in the Eastern Mediterranean so far.

MEDSLIK-II

MEDSLIK-­‐II oil spill model

MEDSLIK-II, implemented at INGV in Bologna (Italy), is designed to be used to predict the transport and weathering of an oil spill, using a Lagrangian representation of the oil slick. It simulates the transport of the surface slick governed by the water currents and by the wind in the whole Mediterranean Sea. Oil particles are also dispersed by turbulent fluctuation components that are parameterized with a random walk scheme. In addition to advective and diffusive displacements, the oil spill particles change due to various physical and chemical processes that transform the oil (evaporation, emulsification, dispersion in water column, adhesion to coast).
MEDSLIK-II includes a proper representation of high frequency currents and wind fields in the advective components of the Lagrangian trajectory model, the introduction of the Stokes drift velocity and the coupling with the remote-sensing data.

MEDSLIK-­‐II oil spill model interface

MEDSLIK-II requires as input the oil spill data, the wind field, the sea surface temperature and the three-dimensional sea currents. MEDSLIK-II can make use of atmospheric wind and oceanographic fields (i.e. currents, temperature) from several different sources. The oil spill data required to define a numerical oil spill initial condition are: location, time and area of the spill, as well as the age of the oil spill from initial arrival in the sea. This information can be easily provided to MEDSLIK-II by satellite monitoring systems.
MEDSLIK-II produces as output the oil properties evolution and the position, every hour and for the next days, of the surface, dispersed oil and of the oil arrived on the coasts. Moreover the model provides the trend over time of: the oil volume spilled, the percentage of oil evaporated, the percentage of oil on the surface, the percentage of oil dispersed, the percentage of oil on the coast, the oil-water emulsion viscosity, the oil viscosity, the oil density, the fraction of water contained in the oil-water emulsion.
The output data files are ASCII format files. The simulations can be long from few hours up to 5 days (in the future, forecast) or up to 3 weeks (in the past, hindcast), depending on the end user application requirements.
The model includes a built-in database (from REMPEC) of over 220 oil types that are the most common in the Mediterranean and the Black seas.
The model has been validated with surface drifters data, with satellite data and in-situ data in different Mediterranean regions. MEDSLIK-II oil spill model has been used to provide timely information on the oil spill evolution forecasting during several emergency cases in the Mediterranean sea (Lebanese oil pollution crisis in 2006, Und Adriyatik in 2008 and the Costa Concordia emergency in 2012).

MEDSLIK-II is a freely available community model and can be downloaded from the following website: http://medslikii.bo.ingv.it/

POSEIDON-OSM

POSEIDON Oil spill model

The POSEIDON Oil Spill Model has been implemented at the Hellenic Centre for Marine Research (HCMR) and it is used operationally for the Aegean and Ionian Seas. It is a fully 3D oil spill model capable to simulate the movement, spreading and aging of the oil particles in the 3-D space. The whole mass of the oil is represented by a large number of material particles or parcels, each of which represents a group of oil droplets of like size and composition.
The oil transport is described by two modules, the circulation module and the wind generated waves module. The horizontal displacement due to advection and the vertical transport of the oil are calculated using the output of the oceanographic model. The net current speed caused by linear waves (Stokes drift) is calculated using the wave model output.
The horizontal and vertical mixing coefficients of the hydrodynamic model are used for the horizontal and vertical diffusion calculations, while the vertical resolution of the model is tight with the relevant resolution of the hydrodynamic model. The POSEIDON-OSM is also capable to simulate several process of the oil spill weathering transformation in the marine environment such as the evaporation, the emulsification, the beaching and the sedimentation. The predicted output variables of the model contain the position of each particle in the sea (longitude, latitude and depth), the evaporated volume of the initial oil, the emulsificated volume, the volume remain in the beach and the oil volume reached the sea floor. The forecast length extends from few hours up to availability of the required forcing data (typically 5 days).

POSEIDON Oil spill model

POSEIDON OSM is a standard module of the POSEIDON Operational Oceanography System that has been implemented and operated in the Greek Seas since 2000. The model was further developed and upgraded during the ESA’s projects ROSES and MARCOAST. The POSEIDON OSM was the forecasting component of MARCOAST integrated oil spill service which is operationally provided in the Aegean Sea during three years period (2006-2008). This later service was an integration of the oil spill detection processes that was applied on satellite based SAR images together with the forecast of oil spill evolution which was provided by the HCMR oil spill system. The core user of this service was the Marine Environment Protection Division (MEPD) of the Greek Ministry of Mercantile Marine which is the responsible authority for the surveillance of the Greek Seas. The user received near real-time (in one hour after satellite overpass) synthetic information concerning the oil spill detection and the relevant forecasts in the Aegean Sea through a dedicated web site and was alerted by e-mail/fax/telephone of new information posted to the site.

Currently, the POSEIDON oil spill model can be triggered through a dedicated web based application (http://osm.hcmr.gr) where the user can specify the parameters of a real or hypothetical event, submit this scenario to the system and receives the results after few minutes. There is also the possibility for the user to receive the results in Google Earth format for a more realistic geospatial representation.