Oil Spill Risk Management

Preface xiii Part 1: Applied Oil Spill Modeling (with applications to the Deepwater Horizon oil spill) 1 1 The 2010 Deep Water Horizon and 2002 Supertanker Prestige Accidents 3 1.1 Introduction 3 1.2 The Oil Spills Described 5 1.3 How Much Material Remains in the Gulf? 6 1.4 The Role of Ocean Models to Explain what Happened 7 References 8 2 Gulf of Mexico Circulation 9 2.1 General Characteristics 9 2.2 Exchanges at Lateral and Surface Boundaries 11 2.3 Loop Current Eddies 12 2.4 Blocking by the Pycnocline 13 2.5 Fate of the Deepwater Horizon Well Blowout Material 14 2.6 Summary 15 References 16 3 Geophysical Fluid Dynamics and Modeling Challenges 17 3.1 Modeling the Circulation and Mixing of the Gulf Waters 17 3.2 External Boundaries 18 3.3 Addressing the Water Column Contamination and Fluxes 18 3.4 Eff ects of Bottom Dynamics on Accumulated Hydrocarbons 20 3.5 Churning by Extreme Weather Events 20 3.6 Summary 21 References 22 4 Flow and Oil Transport Model Choices, Setup and Testing 23 4.1 The DieCAST Ocean Circulation Model 23 4.2 Korotenko Oil Transport Module KOTM 24 4.3 Gulf Modeling Approach 25 4.4 Model Vertical Eddy Viscosity and Diff usivity 25 4.5 Surface Wind Driving and Open Boundary Conditions 26 4.6 Comments on Modeling Equatorial Dynamics and the Gulf of Mexico 26 4.7 Modeling Multi-Century Gulf Currents 27 References 29 5 Modeling the 2010 DWH Oil Spill 31 5.1 Introduction: the BP/Deepwater Horizon Accident 31 5.2 Deepwater Blowouts: Processes Affecting the Transport and Fate of Oil throughout the Water Column 32 5.3 Oil Spill Model for Gulf of Mexico (GOSM) 57 5.4 Results and Discussion 68 5.5 Summary 82 References 86 Part 2: Special Topics in Oil Spill Modeling 95 6 DieCAST Model Origin and Development 97 6.1 Introduction 97 6.2 Recent Model Attributes 98 6.3 Challenges in Modeling the Gulf of Mexico Circulation 99 6.4 Complications of Modeling near-Equatorial Circulation 99 6.5 Non Hydrostatic Effects 101 6.6 Sponge Layers in the Global Model 101 6.7 Inflow Considerations 101 References 102 7 Brief History of the Community Ocean Modeling System (COMS) 105 7.1 COMS history 105 7.2 Background and motivations 106 7.3 COMS elliptic solver history 107 7.4 Evolution of DieCAST 108 7.5 Outlook 108 References 110 8 DieCAST Model Equations 113 8.1 Model Equations 113 8.2 Model Layer Depths 115 References 116 9 Some Basic Physical, Mathematical and Modeling Concepts 117 9.1 Buoyancy, Density and the Hydrostatic Approximation 117 9.2 Pycnocline Slope: Geopotential Surface as a Natural Vertical Coordinate 119 9.3 Rotation and Coriolis Terms 120 9.4 Pycnocline and the Florida Strait Sill Depth 121 9.5 Surface and Bottom Mixed Layers 121 References 122 10 Modeling Challenges, Validations and Animations 125 10.1 Incompressibility, Geostrophy, Data Assimilation and Initialization Issues 125 10.2 Thermocline Maintenance, Ventilation and Extreme Events 127 10.3 Nesting, Grid Coupling and Open Boundary Conditions 127 10.4 Validation of Simulated Major Current Patterns in the Gulf 127 10.5 Note on Data Assimilation 133 10.6 Gulf Circulation Animations 134 10.7 Animation 1 134 10.8 Animation 2 135 10.9 Animation 3 136 References 136 11 A Five-Century Gulf Simulation using DieCAST 139 11.1 Motivation 139 11.2 Basic Flow Patterns 140 11.3 Some Results Observed during the 5th Century 142 11.4 Internal Waves 143 11.5 Island /Headland Wake Eff ects in the Yucatan Channel 143 11.6 Deeply Suspended and Bottom Deposited Material 144 References 145 12 Extreme Events and Oil Rig Stability 147 12.1 Introduction 147 12.2 An Unusual Northern Gulf Eddy Event 148 12.3 Detailed Discussion of Run A 148 12.4 Some Comments 151 12.5 Other Extreme Events Found during the 500-year simulation 152 References 153 13 Initialization and Data Assimilation; MAM Procedure 155 13.1 Introduction 155 13.2 Preliminary Comment 156 13.3 MAM Procedure 156 13.4 Refinements, Variations, Generalizations and Specializations of the MAM Approach 158 References 160 14 On the Simulation of Density Currents by z-level Models 161 14.1 Motivation 161 14.2 Introduction 162 14.3 Analysis 164 14.4 Summary and Conclusion 167 14.5 Acknowledgements 168 References 168 Appendix I: Notes on Modeling Hurricanes with DieCAST 171 A1.1 Introduction 171 A1.2 Model Setup 172 A1.3 Results and Discussion 174 A1.4 Final Remarks 178 A1.5 Summary 179 A1.6 Acknowledgements 179 References 179 Appendix II: A Model Study of Ventilation of the Mississippi Bight by Baroclinic Eddies: Local Instability and Remote Loop Current Effects 181 A2.1 Abstract 181 A2.2 Introduction 182 A2.3 Model Setup 183 A2.4 Results 184 A2.5 Concluding Remarks 208 References 213 Index 215