Joint Inversion for Sound Speed Field and Moving Source Localization in Shallow Water

This paper develops a joint approach for time-evolving sound speed field (SSF) inversion and moving source localization in shallow water environment. The SSF is parameterized in terms of the first three empirical orthogonal function (EOF) coefficients. The approach treats both first three EOF coefficients and source parameters (e.g., source depth, range and speed) as state vectors of evolving with time, and a measurement vector that incorporates acoustic information via a vertical line array (VLA), and then the inversion problem is formulated in a state-space model. The processors of the extended Kalman filter (EKF) and ensemble Kalman filter (EnKF) are used to estimate the evolution of those six parameters. Simulation results verify the proposed approach, which enable it to invert the SSF and locate the moving source simultaneously. The root-mean-square-error (RMSE) is employed to evaluate the effectiveness of this proposed approach. The interfile comparison shows that the EnKF outperform the EKF. For the EnKF, the robustness of the approach under the sparse vertical array configuration is verified. Moreover, the impact of the source-VLA deployment on the estimation is also concerned.

Download Full-text

Matched‐field source localization using incoherent frequency averaging for sound‐speed mismatch and array element location errors in a shallow‐water environment

The Journal of the Acoustical Society of America ◽

10.1121/1.404539 ◽

1992 ◽

Vol 92 (4) ◽

pp. 2447-2447

Author(s):

M. A. Akundi ◽

S. Garrel ◽

G. B. Smith ◽

H. A. Chandler

Keyword(s):

Shallow Water ◽

Source Localization ◽

Sound Speed ◽

Water Environment ◽

Array Element ◽

Field Source ◽

Location Errors ◽

Shallow Water Environment

Download Full-text

Joint Tracking of Source and Environment Using Improved Particle Filtering in Shallow Water

Journal of Marine Science and Engineering ◽

10.3390/jmse9111203 ◽

2021 ◽

Vol 9 (11) ◽

pp. 1203

Author(s):

Miao Dai ◽

Yaan Li ◽

Jinying Ye ◽

Kunde Yang

Keyword(s):

Shallow Water ◽

Source Localization ◽

Particle Filtering ◽

Source Parameters ◽

Simulated Data ◽

Environmental Parameters ◽

Performance Comparison ◽

Depth Range ◽

Parameter Uncertainties ◽

Joint Tracking

Shallow water is a complex sound propagation medium, which is affected by the varying spatial–temporal ocean environment. Taking this complexity into account, the classical processing techniques of source localization and environmental inversion may be improved. In this work, a joint tracking approach for the moving source and environmental parameters of the range-dependent and time-evolving environment in shallow water is presented. The tracking scheme treats both the source parameters (e.g., source depth, range, and speed) and the environmental parameters (e.g., water column sound speed profile (SSP) and sediment parameters) at the source location as unknown variables that evolve as the source moves. To counter sample impoverishment and robustly characterize the evolution of the parameters, an improved particle filter (PF), which is an extension of the standard PF, is proposed. Two examples with simulated data in a slowly changing environment and experimental data collected during the ASIAEX experiment are utilized to demonstrate the effectiveness of the joint approach. The results show that we were able to track the source and environmental parameters simultaneously, and the uncertainties were evaluated in the form of time-evolving posterior probability densities (PPDs). The performance comparison confirms that the improved PF is superior to the standard PF, as it can reduce the parameter uncertainties. The tracking capabilities of the improved PF were verified with high accuracy in real-time source localization and well-estimated rapidly varying parameters. Moreover, the influence of different particle numbers on the improved PF tracking performance is also illustrated.

Download Full-text

Paleoenvironment of the Lower–Middle Cambrian Evaporite Series in the Tarim Basin and Its Impact on the Organic Matter Enrichment of Shallow Water Source Rocks

Minerals ◽

10.3390/min11070659 ◽

2021 ◽

Vol 11 (7) ◽

pp. 659

Author(s):

Mingyang Wei ◽

Zhidong Bao ◽

Axel Munnecke ◽

Wei Liu ◽

G. William M. Harrison ◽

...

Keyword(s):

Organic Matter ◽

Shallow Water ◽

Tarim Basin ◽

Water Environment ◽

Water Source ◽

Major Elements ◽

Source Rocks ◽

Middle Cambrian ◽

Sedimentary Environments ◽

The Impact

Just as in deep-water sedimentary environments, productive source rocks can be developed in an evaporitic platform, where claystones are interbedded with evaporites and carbonates. However, the impact of the paleoenvironment on the organic matter enrichment of shallow water source rocks in an evaporite series has not been well explored. In this study, two wells in the central uplift of the Tarim Basin were systematically sampled and analyzed for a basic geochemical study, including major elements, trace elements, and total organic carbon (TOC), to understand the relationship between TOC and the paleoenvironmental parameters, such as paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity. The results show that the Lower–Middle Cambrian mainly developed in a fluctuating salinity, weak anoxic to anoxic, continuous dry and hot, and proper shallow water environment. The interfingering section of evaporites, carbonates, and claystones of the Awatag Fm. have higher paleoproductivity and higher enrichment of organic matter. Paleosalinity, redox, paleoclimate, paleo-seawater depth, and paleoproductivity jointly control the organic matter enrichment of shallow water source rocks in the evaporite series. The degree of enrichment of organic matter in shallow water source rocks first increases and then decreases with the increase in paleosalinity. All the samples with high content of organic matter come from the shallower environment of the Awatag Fm.

Download Full-text