ABSTRACT
Photosynthetic Apparatus................................................................................. 69 5.2.3 Oxygen Production............................................................................................................ 69 5.2.4 Gas in Matte and Sediment .............................................................................................. 69
5.3 The
99 Experiment ............................................................................................................. 69 5.3.1 Test Site ............................................................................................................................. 69 5.3.2 Experimental ConÞguration .............................................................................................. 71 5.3.3 Acoustic Measurements .................................................................................................... 72
5.3.3.1 Signal Transmission ........................................................................................... 72 5.3.3.2 Ambient Noise Recording ................................................................................. 72 5.3.3.3 Transducer Calibration....................................................................................... 72 5.3.3.4 Equalized Matched-Filter Processing ................................................................ 73
5.3.4 Oceanographic Measurements: CTD and Dissolved Oxygen Content............................ 73 5.4 Multiscale Acoustic Effects............................................................................................................ 75
5.4.1 Time-Varying Medium Impulse Response ....................................................................... 75 5.4.2 Propagation Channel Modeling ........................................................................................ 77 5.4.3 Energy Time Distribution of Medium Response.............................................................. 80 5.4.4 Non-Photosynthesis-Related Effects................................................................................. 81
5.4.4.1 Tide..................................................................................................................... 81 5.4.4.2 Sea Surface Motion............................................................................................ 82 5.4.4.3 Water Temperature ProÞle ................................................................................. 83
5.5 Effects of Photosynthesis on Sound Propagation.......................................................................... 83 5.5.1 Time Variation of Dissolved Oxygen ............................................................................... 83 5.5.2 Effect of Photosynthetic Bubbles on Multipaths.............................................................. 84 5.5.3 Effect on Reverberation .................................................................................................... 88 5.5.4 Effect on Ambient Noise .................................................................................................. 88
5.5.4.1 Spectral Characteristics...................................................................................... 88 5.5.4.2 Time-Frequency Characteristics ........................................................................ 90 5.5.4.3 Directional Characteristics................................................................................. 91 5.5.4.4 Other Observations ............................................................................................ 91
5.5.5 Gaseous Interchange of the Leaf Blade ........................................................................... 91 5.6 Conclusion...................................................................................................................................... 92 Acknowledgments.................................................................................................................................... 93 Appendix 5.A Comparison with Earlier Experiments ........................................................................... 94 References ................................................................................................................................................ 94
To be able to prevent damage to marine and freshwater ecosystems, for example, to avert negative consequences for biodiversity, environmental surveillance and monitoring tools are required that produce data that are continuous in time and representative of extended areas of interest. In recent years, research on acoustic remote sensing of the ocean has evolved considerably, especially in studying physical and biological processes in shallow water environments.
