Date: June 19, 2018
Source: XIA Lei, CAS Key Laboratory of Underwater Acoustic Environment
On June 19, 2018, Prof. SHANG Erchang delivered a report titled “Inversion of Intrinsic Acoustic Parameters of the Seabed”. Prof. MA Li, director of CAS Key Laboratory of Underwater Acoustic Environment, host the meeting, more than 20 researchers and graduate students attended.
Prof. SHANG Erchang pointed out that sea bottom plays important role in underwater acoustics. It has been recognized that the key issues of inverting GA (geoacoustics) parameters via MFP (Matched Filed Processing) approach is the mismatching between the assumed model and the real bottom layer structure, as well as the coupling among the parameters.
In case of model-mismatching, the inverted GA parameters could only be considered as effective parameters. Moreover, the value and the frequency dependency of attenuation coefficient will be distorted, which will lead to mistakes in broadband underwater sound field.
To solve this problem, the model-free reflective parameters of bottom should be used, so that the intrinsic bottom attenuation as well as its frequency dependency can be inverted without distortion.
Prof. SHANG Erchang was delivering his report. (Image by IOA)
In the Q&A session, Prof. ZENG Juan reported the results of an experiment conducted at Yellow Sea in January 2018, when she successfully inverted the effective bottom parameters through the modal attenuation data. Dr. ZHAO Zhendong discussed in theory how to extract the intrinsic bottom parameters without distortion from the effective GA parameters or from bottom reflective parameters.
The Q&A session. (Image by IOA)
Prof. SHANG Erchang received Bachelor of Science Degree in theoretical physics from Peking University in 1958. Since then, he worked on underwater acoustics and wave propagation at the Institute of Acoustics, Chinese Academy of Sciences. During 1982–1986, he was the Deputy Director of the Institute of Acoustics. From 1982 to 1987, he worked as a Visiting Professor at the Scripps Institution of Oceanography, University of California at San Diego, University of Wisconsin, and Yale University. From 1987 to 2001, he worked as a Research Professor at the Cooperative Institute for Research in Environmental Sciences, University of Colorado. He was a Research Advisor of the National Research Council Postdoctoral program at the Environmental Technology Laboratory, National Oceanic and Atmospheric Administration, USA. His research interest includes shallow-water acoustics, source localization in waveguide, ocean acoustic tomography, and global acoustics.
Prof. SHANG Erchang was the winner of the National Natural Science Prize in 1982 and 1990 in China. He has been a Fellow of the Acoustical Society of American since 1984.