Coastal Acoustic Tomography

Description

Coastal Acoustic Tomography begins with the specifics required for designing a Coastal Acoustic Tomography (CAT) experiment and operating the CAT system in coastal seas. Following sections discuss the procedure for data analyses and various application examples of CAT to coastal/shallow seas (obtained in various locations). These sections are broken down into four kinds of methods: horizontal-slice inversion, vertical-slice inversion, modal expansion method and data assimilation. This book emphasizes how dynamic phenomena occurring in coastal/shallow seas can be analyzed using the standard method of inversion and data assimilation. The book is relevant for physical oceanographers, ocean environmentalists and ocean dynamists, focusing on the event being observed rather than the intrinsic details of observational processes. Application examples of successful dynamic phenomena measured by coastal acoustic tomography are also included. Provides the information needed for researchers and graduate students in physical oceanography, ocean-fluid dynamics and ocean environments to apply Ocean Acoustic Tomography (OAT) to their own fieldsPresents the benefits of using acoustic tomography, including less disturbance to aquatic environments vs. other monitoring methodsIncludes the assimilation of CAT data into a coastal sea circulation model, a powerful tool to predict coastal-sea environmental changes Cover Coastal Acoustic Tomography Copyright Contents Preface 1 Fundamental Knowledge 1.1 Ocean Acoustic Tomography 1.1.1 Break Corner (Projected Rays on a Horizontal Slice) 1.2 Advancement by Coastal Acoustic Tomography 1.3 Coastal-Sea Environmental Monitoring 1.4 Coastal-Sea Sound Propagation 2 Instrumentation 2.1 System Design 2.2 Field Deployment Methods 2.2.1 Nearshore Platforms 2.2.2 Necessity for Permanent Platform 2.3 Transmit Signals 2.4 Cross-Correlating the Received Data 3 Sound Transmission and Reception 3.1 One-Dimensional Sound Wave Equation 3.2 Sound Transmission Losses 3.2.1 Spreading Losses 3.2.2 Absorption Losses 3.2.3 Bottom Losses 3.2.4 Surface Losses 3.2.5 Receiving Transmission Sound 3.3 Processing the Received Data 3.3.1 Ensemble Average 3.3.2 Arrival Peaks Identification 3.3.3 Processing the Noisy Received Data 3.3.4 Multi–Arrival Peak Method 4 Range-Average Measurement 4.1 Vertical Section Averages 4.2 Resolution and Errors 4.3 Position Correction 4.4 Clock Correction 4.5 Conversing From One-Line Current to Along-Channel Current 4.6 Conversing From Two-Line Current to North–East Current 4.7 Along-Strait Volume Transport and Energy Estimate 4.8 Conversing From Sound Speed to Temperature and Salinity 4.9 Travel-Time Errors Due to the Station Movements 4.10 Errors From the Time Resolution of M Sequence 5 Forward Formulation 5.1 Sound Wave Equation With a Velocity Field 5.2 Ray Simulation 5.3 Modal Simulation 5.4 Time-of-Flight Equation Along the Rays 6 Inversion on a Horizontal Slice 6.1 Grid Method 6.2 Function Expansion Method 6.3 Adding the Coastline Conditions 6.4 Validating the Observed Data 6.4.1 Comparing the Pre- and Postinversion Results 6.4.2 Energy Balance 6.4.3 Direct Comparison With the Standard Oceanographic Data 7 Inversion on a Vertical Slice 7.1 Ray Method 7.1.1 Layered Inversion 7.1.2 Layered Inversion Deleting Clock Errors 7.1.3 Explicit Solution 7.2 Acoustic Normal Modes With a Constraint of Narrowband Sound 7.3 Function Expansion Using Various Normal Modes 7.4 The Three-Dimensional Mapping 8 Data Assimilation 8.1 Conventional Ensemble Kalman Filter 8.1.1 Introductory Remarks 8.1.2 Ensemble Kalman Filter Scheme 8.1.3 Innovation Vector 8.1.4 External Forcing 8.1.5 Kalman Gain Smoother 8.2 Time-Efficient Ensemble Kalman Filter 8.2.1 Time-Invariant Model Error Covariance 8.2.2 Assimilation Scheme for Coastal Acoustic Tomography Data 9 Applications for Horizontal-Slice Inversion 9.1 Nekoseto Channel 9.1.1 Oceanographic State 9.1.2 Experiment and Methods 9.1.3 Differential Travel Times 9.1.4 Inversion 9.1.5 Mapping Current Velocity Fields 9.2 Tokyo Bay 9.2.1 Oceanographic State 9.2.2 Experiment and Methods 9.2.3 Differential Travel Times 9.2.4 Inversion 9.2.5 Mapping Current Velocity Fields 9.3 Kanmon Strait 9.3.1 Oceanographic State 9.3.2 Experiment and Methods 9.3.3 Differential Travel Times 9.3.4 Inversion 9.3.5 Mapping Current Velocity Fields 9.4 Zhitouyang Bay 9.4.1 Oceanographic State 9.4.2 Experiment and Methods 9.4.3 Differential Travel Times 9.4.4 Inversion 9.4.5 Mapping Current Velocity Fields 9.4.6 Tidal Harmonics 9.4.7 Rotation of Tidal Currents With the Tidal Phase 9.5 Qiongzhou Strait 9.5.1 Oceanographic State 9.5.2 Experiment and Methods 9.5.3 Range-Average Current and Volume Transport 9.5.4 Inversion 9.5.5 Mapping Current Velocity Fields 9.6 Dalian Bay 9.6.1 Oceanographic State 9.6.2 Experiment and Methods 9.6.3 Differential Travel Times 9.6.4 Inversion 9.6.5 Mapping Current Velocity Fields 9.6.6 Validation 9.7 Bali Strait (June 2016) 9.7.1 Oceanographic State 9.7.2 Experiment and Methods 9.7.3 Range-Average Currents 9.7.4 North-east Currents 9.7.5 Along-Strait Volume Transport and Energy Balance 9.7.6 Inversion 9.7.7 Mapping Current Velocity Fields 9.7.8 Specialty of the 3-h Oscillation 9.8 Hiroshima Bay 9.8.1 Oceanographic State 9.8.2 Experiment 9.8.3 Position Correction 9.8.4 Range-Average Temperature 9.8.5 Inversion 9.8.6 Mapping Reconstructed Temperature Fields 9.8.7 Coastal Upwelling and Diurnal Internal Tides 9.8.8 Sea Surface Depression Associated With Upwelling 9.8.9 Upwelling Velocity and Mixing Rate 10 Applications for Vertical-Slice Inversion 10.1 Bali Strait (June 2015) 10.1.1 Experiment 10.1.2 Ray Simulation 10.1.3 Identifying the First Two Arrival Peaks 10.1.4 Range-Average Current and Temperature 10.1.5 Inversion 10.1.6 Profiling the Current and Temperature 10.1.7 Power Spectral Densities 10.1.8 Nonlinear Tides 10.1.9 Concluding Remarks 10.2 Luzon Strait 10.2.1 Oceanographic State 10.2.2 Site and Experiment 10.2.3 Data Acquisition and Errors 10.2.4 Modal Simulation 10.2.5 Identifying Arrival Peaks in the Received Data 10.2.6 Profiling the Sound Speed Deviation 10.2.7 Retrieving the Periodic Phenomena 11 Applications for Data Assimilation 11.1 Nekoseto Channel 11.1.1 Model and Methods 11.1.2 Mapping 2D Current Fields 11.1.3 Validation 11.2 Kanmon Strait 11.2.1 Model and Method 11.2.2 Mapping Two-Dimensional Current Velocity Fields 11.2.3 Along-Strait Volume Transport 11.2.4 Validation 11.3 Sanmen Bay 11.3.1 Model Site and Data 11.3.2 Methods 11.3.3 Model 11.3.4 Mapping Two-Dimensional Current Velocity Fields 11.3.5 Validation 11.4 Hiroshima Bay 11.4.1 Model 11.4.2 Methods 11.4.3 Mapping Three-Dimensional Current Velocity and Salinity Fields 11.4.4 Volume Transports 11.4.5 Transport Continuity and Mixing Fractions 12 Modal Function Expansion With Coastline Constraints 12.1 Fundamental Remarks 12.2 Formulation 12.3 Application to Hiroshima Bay 12.3.1 Experiment and Methods 12.3.2 Observed Data 12.3.3 Modal Expansion Functions 12.3.4 Mapping Two-Dimensional Current Velocity Fields 12.3.5 Validation 12.4 Application to Jiaozhou Bay 12.4.1 Oceanographic State 12.4.2 Experiment and Model 12.4.3 Modal Expansion Functions 12.4.4 Mapping Two-Dimensional Current Velocity Fields 13 Application to Various Fields and Phenomena 13.1 Yearly Measurement of the Residual Current 13.1.1 Specific Features 13.1.2 Experiment 13.1.3 Ray Simulation 13.1.4 Received Data 13.1.5 Along-Channel Current 13.1.6 Yearly Variations of the Observed Current and Temperature 13.1.7 Residual Current Calculated From Upslope Point Method 13.2 Bay With Multiinternal Modes 13.2.1 Specific Features 13.2.2 Experiment and Methods 13.2.3 Range-Average Sound Speed 13.2.4 Spectral Analyses 13.2.5 Propagation of Internal-Mode Waves 13.3 Bay With Resonant Internal Modes 13.4 Strait With Internal Solitary Waves 13.4.1 Background 13.4.2 Experimental Site and Methods 13.4.3 Travel Times and Range-Average Temperatures for the Largest Arrival Peak 13.4.4 Distance Correction 13.4.5 Sound Transmission Data With Multiarrival Peaks 13.4.6 Ray Simulation and Inversion 13.4.7 Profiling Temperatures 13.4.8 Concluding Remarks 13.5 River With Tidal Bores 13.5.1 Specific Features 13.5.2 Experiment and Methods 13.5.3 Cross-River Surveys by Shipboard Acoustic Doppler Current Profiler 13.5.4 Cross-River Surveys by Coastal Acoustic Tomography 13.5.5 River Discharges 13.5.6 Concluding Remarks 13.6 Large Circular Tank With Omnidirectional Waves and Currents 13.6.1 FloWave Circular Tank 13.6.2 Simulating Flow Fields 13.6.3 Experiment and Methods 13.6.4 Identifying Multiarrival Peaks 13.6.5 Mapping the Two-Dimensional Current Velocity Fields 13.6.6 Remaining Issues 14 Mirror-Type Coastal Acoustic Tomography 14.1 Introductory Remarks 14.2 Mirror-Type Coastal Acoustic Tomography System Design 14.3 Enhancing the Positioning Accuracy 14.4 Feasibility Experiments 14.5 Ray Simulation 14.6 Arrival-Peak Identification 14.7 Range-Average Currents 14.8 Compact Mirror-Type Coastal Acoustic Tomography Array 14.9 Further Advancement Bibliography Index Back Cover