Chin. Phys. B, 2019, Vol. 28(10): 104301    DOI: 10.1088/1674-1056/ab3f93
 ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS Prev   Next

# Theoretical framework for geoacoustic inversion by adjoint method

Yang Wang(汪洋)1,2, Xiao-Feng Zhao(赵小峰)2,3
1 School of Marine Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China;
2 Key Laboratory of Marine Intelligent Equipment and System of Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China;
3 College of Meteorology and Oceanography, National University of Defense Technology, Nanjing 211101, China
Abstract  Traditional geoacoustic inversions are generally solved by matched-field processing in combination with meta-heuristic global searching algorithms which usually need massive computations. This paper proposes a new physical framework for geoacoustic retrievals. A parabolic approximation of wave equation with non-local boundary condition is used as the forward propagation model. The expressions of the corresponding tangent linear model and the adjoint operator are derived, respectively, by variational method. The analytical expressions for the gradient of the cost function with respect to the control variables can be formulated by the adjoint operator, which in turn can be used for optimization by the gradient-based method.
Keywords:  geoacoustic inversion      adjoint method      parabolic equation      non-local boundary condition
Received:  21 July 2019      Revised:  26 August 2019      Accepted manuscript online:
 PACS: 43.30.Pc (Ocean parameter estimation by acoustical methods; remote sensing; imaging, inversion, acoustic tomography) 43.30.Ma (Acoustics of sediments; ice covers, viscoelastic media; seismic underwater acoustics) 02.30.Zz (Inverse problems)
Fund: Project supported by the Foundation of Key Laboratory of Marine Intelligent Equipment and System of Ministry of Education, China (Grant No. SJTU-MIES1908) and the National Natural Science Foundation of China (Grant No. 41775027).
Corresponding Authors:  Xiao-Feng Zhao     E-mail:  zxf_best@126.com