The 3rd International Workshop on Next Generation Climate Models for Advanced High Performance Computing Facilities Tokyo, Japan, March , 2001 Performance and Verification of the Oil Spill Modeling System for the Sea of Japan Sergey M. VARLAMOV Institute of Environmental Sciences, RISSHO University Jong-Hwan YOON Research Institute for Applied Mechanics, Kyushu University

rThe risk of environmental disasters related with the spilling of oil products into the sea forces the development of the high-quality oil spill simulation and prediction system. It would be an important tool for the planning of the spill protection and spill response operations etc. rSimulation of the oil spreading and fate in the sea is one of practical applications that requires and integrates the results of meteorological, oceanographical and the “oil spill” modeling communities... Motivations:

rWhere will go the oil after it was spilled in to the sea? - from the start of incident up to it removing from the sea due to any processes rWhat will be the oil state at all stages of spill? - density (buoyancy) - viscosity (recovery techniques) - emulsion state (amount to recover) - [chemical composition - toxicity] etc. Most important questions:

Fate of oil spilled at sea Spreading Horizontal and vertical transport by wind and sea currents Natural dispersion Buoyancy Emulsification Evaporation Dissolution Photo-oxidation Sedimentation and shoreline stranding Biochemical degradation

Oil spill simulations system (Varlamov et. al., 2000) Oil spill model * Spill Transport and Weathering Particles Tracking Model Graphical analysis subsystem Ocean Circulation Models Meteorologicalsubsystem Oil property data Environmentaldata Ocean currents data Meteorologicaldata Oil spill simulations

Ocean circulation models At nowadays the ocean circulation models is a part of system Reasons: no products similar to meteorological analysis and forecasts, i.e. 3D currents, temperature, salinity, waves field are available... OCM’s spatial resolution and model domain defines the scale and applicability area of the oil spill analysis and prediction system although the simplified version with the local wind drift currents model could be applied for any area covered by meteorological forecasts and with the land-sea mask defined (GTOPO30 for the global version).

Ocean circulation models r3-D primitive equations Modular Ocean Model (GFDL MOM) -1/6° grid (12  18 km horizontal resolution) -19 vertical levels (step 15 m in upper layers; up to 600 m below 1500 m) -rigid grid approximation rwind drift shear local current model + 2-D shallow water nonlinear model (2.5 dimensional model) -bi-linear vertical turbulent eddy viscosity profile (Poon & Madsen, 1991) -variable vertical step (from 1 m in upper sea layer) -1/12° grid (6  9 km horizontal resolution) -16 tidal constituents are used at the open boundaries etc. Oil spill analysis and prediction system was tested with two types of the Japan Sea ocean circulation models:

Outline of Oil Spill Fate and Trajectory Model (year 2001 version)-1 Particles tracking model: Spill is presented as an ensemble of particles each characterized by its properties that includes - position on plane and the depth - diameter - density - viscosity - fraction of water in oil (emulsion) - fraction evaporated - fraction [biochemically] degradated etc.

Outline of Oil Spill Fate and Trajectory Model (year 2001 version)-2 Depending on position, model oil particles are - transported by wind (at the sea surface) - transported by 3D sea currents - experience buoyancy effect - 3D random diffusion (wind and current dependant) - oil–coastal line interaction - evaporation at the sea surface (Fingas, 1996) - emulsification at the sea surface (Mackay et al, 1980) - biochemical degradation - [oil-sea bottom interaction]

Outline of Oil Spill Fate and Trajectory Model (year 2001 version)-3 Other model properties: - universal 2D horizontal bicubic spline interpolation from arbitrary meteorological, bottom topography, and ocean circulation model grids (with masking of land surface meteorological data) - initial droplet diameters distribution in accordance with observed dispersion droplet size distribution (Delvigne and Sweeney, 1988), modified by weathering processes, both “permanent” surface slick and oil dispersed into the water column are simulated - modification of oil particles density and viscosity as result of emulsification, evaporation and biochemical degradation - assimilation of observed oil slick position for long-term spill simulation

Technical Characteristics and the Improvement of System Performance Model properties: - programming languages: C (system routines and meteorological GRIB data decoding software) and FORTRAN-90 (ocean circulation and spill models) - OpenMP directives are used for the parallelization of ocean circulation and spill physical core modules - computational effects on the parameterization of physical processes was analyzed and fixed (buoyancy-vertical diffusion- particles diameter-integration time step problem)

Routine oil spill simulation and prediction system parameters rMeteorological analysis and forecasts data are received once a day. Total 3.7 Mb are received, and at 18:00 UTC (local night) it usually takes approximately minutes rSW OCM is started and run the currents simulation and prediction for 126 h (5 days). With 10s time step it takes 1 h 03 min on 667 MHz Alpha processor (GFDL MOM 1/12° - 25 min) rOil spill simulation could be run by operator and for 5 days with droplets it will take less then 14 min

System Verification: Simulation of the Osung No 3 Oil Spill in the Sea of Japan Fragment of the Ocean Circulation Model Domain in Tsushima strait area ( TerrainBase topography) Korea Japan Hakata Pusan Tsushima Isl.

Volume Transport - Camelia Line Runing average total volume transport through Tsushima strait at the Hakata-Pusan section (‘Camelia’ Line, ) Monitoring results ( Data of Takikawa & Yoon, 2000 ) Total Eastern Channel Western Channel

Model simulations with TerrainBase topography Model simulations with smoothed ETOPO5 topography (Eastern/Western channel volume transport ~2.2 when ~0.8 expected)

Tidal Sea Level Variations Idzuhara (upper) and Hakata (lower) tidal stations, February 2000 Observed (blue, black) and simulated(red) sea level anomalies, cm. RMS Error = 12 cm RMS Error = 9 cm

- 229 kl of Bunker C oil spilled - Largest part of oil was recovered (April 8-9) - April 9, :45 JST coastline of N.Tsushima Isl. was polluted Animated Simulation Results: Push on the map to start demonstration, esc to stop it, the label fields pass to the next slide. Model particles in upper 2 m layer, size by color. Sea current and surface wind drift (4% of wind speed) Oil spill accident with Korean tanker Osung No 3

Oil concentration in upper 2 m layer It is strongly related with the model particles size and trace mainly the surface drifting slick position Oil concentration in upper 2 m layer It is strongly related with the model particles size and trace mainly the surface drifting slick position Animated Simulation Results: Push on the map to start demonstration, esc to stop it, the label fields pass to the next slide. Sea current and surface wind drift (4% of wind speed)

Tanker Osung No 3 oil spill incident simulation Relative mass of oil stranded at the shoreline Some spill model integral parameters Mean (volume weighted) diameter of floating model oil particles,  m Total number of active model oil particles Mean (volume weighted) dynamic viscosity of floating oil, cP Mean (volume weighted) dynamic viscosity of floating oil, cP

Conclusion rOil spill numerical simulation system could provide important information for the short term (at least up to 4-5 days) planning of accidental oil spill recovery operations