Coastal Acoustic Tomography

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
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