scholarly journals Ocean Front Reconstruction Method Based on K-Means Algorithm Iterative Hierarchical Clustering Sound Speed Profile

2021 ◽  
Vol 9 (11) ◽  
pp. 1233
Author(s):  
Yuyao Liu ◽  
Wei Chen ◽  
Yu Chen ◽  
Wen Chen ◽  
Lina Ma ◽  
...  
Keyword(s):  
Hierarchical Clustering ◽  
Gulf Stream ◽  
Sound Speed ◽  
Frontal Zone ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Reconstruction Method ◽  
Speed Profile ◽  
Sound Speed Profile ◽  
Ocean Front

As one of the most common mesoscale phenomena in the ocean, the ocean front is defined as a narrow transition zone between two water masses with obviously different properties. In this study, we proposed an ocean front reconstruction method based on the K-means algorithm iterative hierarchical clustering sound speed profile (SSP). This method constructed the frontal zone from the perspective of SSP. Meanwhile, considering that acoustic ray tracing is a very sensitive tool for detecting the location of ocean fronts because of the strong dependence of the transmission loss (TL) on SSP structure, this paper verified the feasibility of the method from the perspective of the TL calculation. Compared with other existing methods, this method has the key step of iterative hierarchical clustering according to the accuracy of clustering results. The results of iterative hierarchical clustering of the SSP can reconstruct the ocean front. Using this method, we reconstructed the ocean front in the Gulf Stream-related sea area and obtained the three-dimensional structure of the Gulf Stream front (GSF). The three-dimensional structure was divided into seven layers in the depth range of 0–1000 m. Iterative hierarchical clustering SSP by K-means algorithm provides a new method for judging the frontal zone and reconstructing the geometric model of the ocean front in different depth ranges.

Ocean Front Model Based on Sound Speed Profile and its Influence on Sound Propagation

2021 ◽  
Author(s):  
Yuyao Liu ◽  
Wen Chen ◽  
Wei Chen ◽  
Yu Chen ◽  
Lina Ma ◽  
...  
Keyword(s):  
Sound Speed ◽  
Sound Propagation ◽  
Speed Profile ◽  
Sound Speed Profile ◽  
Model Based ◽  
Ocean Front ◽  
Front Model

scholarly journals Reconstruction of Ocean Front Model Based on Sound Speed Clustering and Its Effectiveness in Ocean Acoustic Forecasting

2021 ◽  
Vol 11 (18) ◽  
pp. 8461
Author(s):  
Yuyao Liu ◽  
Wei Chen ◽  
Wen Chen ◽  
Yu Chen ◽  
Lina Ma ◽  
...  
Keyword(s):  
Sound Speed ◽  
Frontal Zone ◽  
Transmission Loss ◽  
Structural Characteristics ◽  
Kuroshio Extension ◽  
Reanalysis Data ◽  
Reconstruction Method ◽  
Ocean Front ◽  
Sea Area ◽  
The Kuroshio

As a mesoscale phenomenon of the ocean, the ocean front can directly affect the structural characteristics of sound speed profiles and further affect the acoustic propagation characteristics of the sea area. In this paper, we use the fuzzy C-means (FCM) algorithm to cluster the surface sound speed in the sea area of the Kuroshio Extension (KE) and detect the frontal zone of Kuroshio Extension (KEF). At the same time, the sound speed profile (SSP) is used instead of the temperature profile to establish the model of the sound speed field in the front area of the Kuroshio Extension and to improve the theoretical model of the ocean front. Compared with the actual ocean front calculated by reanalysis data, the root means square error (RSME) of the transmission loss (TL) calculated by the model is controlled below 6 dB, which proves the validity of the model. Finally, we propose the melt function in the model to forecast the depth change of the acoustic convergence area. Compared with the actual calculation result based on reanalysis data, the root means square error (RSME) of the depth forecasting after the frontal zone is 43.3 m. This reconstruction method does not rely on the high spatial resolution data of the whole sea depth and can be of referential significance to acoustic detection in the ocean front environment.

DEPENDENCE OF THE AXIAL WAVE ON RANGE AND SOUND-SPEED PROFILE PROPERTIES IN A RANGE-INDEPENDENT OCEAN

2005 ◽  
Vol 13 (02) ◽  
pp. 259-278 ◽  
Author(s):  
NATALIE S. GRIGORIEVA ◽  
GREGORY M. FRIDMAN
Keyword(s):  
Numerical Simulation ◽  
Sound Speed ◽  
Three Dimensional ◽  
Two Dimensional ◽  
Speed Profile ◽  
Wave Fields ◽  
Sound Speed Profile ◽  
Average Profile ◽  
Ducted Propagation ◽  
Dimensional Range

For ducted propagation in a waveguide when the source and receiver are placed closely to the depth of the waveguide axis, there exist cusped caustics repeatedly along the axis. In neighborhoods of these cusped caustics, the interference of the wave fields that correspond to near-axial rays occurs. This results in the formation of a coherent structure (the axial wave) that propagates along the waveguide axis like a wave. In this paper the integral representation of the axial wave obtained before for an arbitrary waveguide in a two-dimensional range-independent medium is generalized to a three-dimensional range-independent medium. Through numerical simulation, the dependencies of the axial wave on range, sound-speed profile properties, and geometry of the experiment are studied for two sound-speed profiles: the average profile from the AET experiment and the Munk canonical profile. The sound source frequency is taken equal to 75 Hz; the propagation range is up to 3250 km. The strong difference between shapes of the axial wave for the average profile from the AET experiment and the Munk canonical profile is shown for all the examined models.

scholarly journals Effect of Azimuthal Asymmetry Caused by Upwelling on 3D Ocean Acoustic Propagation

2019 ◽  
Vol 69 (2) ◽  
pp. 136-141
Author(s):  
R. P. Raju ◽  
P. Anand ◽  
Dominic Ricky Fernandez ◽  
A. Raghunadha Rao
Keyword(s):  
Sound Speed ◽  
Transmission Loss ◽  
Three Dimensional ◽  
Acoustic Propagation ◽  
Speed Profile ◽  
Sound Speed Profile ◽  
Azimuthal Variation ◽  
First Case ◽  
Upwelling Event

3-D underwater parabolic equation model based on implicit finite difference method has been implemented for South Eastern Arabian Sea (SEAS). The bathymetric and geo-acoustic features have been integrated in the model for a 50 km circular region in SEAS. The model can simulate the effects of azimuthal variation in oceanographic features and compute azimuthally coupled pressure due to an omni-directional source. The azimuthal variation in oceanographic conditions can be observed during an upwelling event. In the first case study, the effect of upwelling event on three-dimensional acoustic propagation has been studied by using sound speed profile data derived from INS Sagardhwani observations. The difference in Transmission loss mosaic for upslope and downslope propagation is due to bathymetry as well as upwelling. In the second case study, the effect of upwelling only, is studied by running a model corresponding to range independent sound speed profile field and range dependent bathymetry. It was observed that during this upwelling event, the transmission loss is higher at longer ranges during upslope propagation than downslope propagation. This is due to the increase in the thickness of sonic layer duct as acoustic wave propagates from shallow to deep water. The effect of azimuthal variation i

Compensation of INS Errors based on LBL References in a Quadratic Sound-Speed-Profile

2020 ◽  
Author(s):  
Yohannes S.M. Simamora ◽  
Harijono A. Tjokronegoro ◽  
Edi Leksono ◽  
Irsan S. Brodjonegoro
Keyword(s):  
Sound Speed ◽  
Speed Profile ◽  
Sound Speed Profile
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