The Impact Of Synthetic Mesoscale Eddies On Sound Propagation In The Northwest Pacific And Its Tactical Applicatio

Mesoscale eddies are mesoscale phenomena commonly found in the oceans,changing the temperature and salt structure of the ocean and can have an impact on the sound propagation law.In recent years,as the operating environment of China’s naval vessels moves from nearshore to deep sea,the formulation of tactics in complex internal ocean environments such as mesoscale eddies and the organization of effective anti-submarine operations based on the performance of naval equipment have become urgent problems.In this paper,based on the synthetic mesoscale eddies in the western North Pacific Ocean,we conduct a study on acoustic propagation characteristics and propose an operational optimization scheme in the context of mesoscale eddies.In this study,the multi-year average mesoscale eddy eddies from 2000 to 2018 were synthesized based on AVISO satellite altimeter data,Argo buoy data,CARS09 climate state data and 3D eddy synthesis method using the Kuroshio extension(region I)and pro-tidal extension(region II)in the western North Pacific Ocean as the study area,and the water mass characteristics and temperature and salt anomaly distribution characteristics were analyzed,and the results showed that(1)The temperature and salt profiles of the water masses in the two regions show an "S" shape,with extreme and extreme small values of salinity near the subsurface and bottom layers,and the temperature and salt in the surface and subsurface layers of the water masses in region Ⅰ are larger than those in region Ⅱ.(2)In region Ⅰ,cold eddies will lead to negative anomalous nuclear structure of temperature below the subsurface layer of seawater,while warm eddies will produce positive anomalous nuclear structure,and the depth of nuclear structure becomes shallow with increasing longitude;in region Ⅱ,similar nuclear structure will appear in the surface layer and subsurface layer,but the depth of nuclear structure becomes deeper with increasing longitude.(3)The cold eddies lead to "negative-positive" anomalous distribution of salinity in the eddy region,while the warm eddies produce "positivenegative" anomalous salinity in two opposite layers.Based on the temperature and salinity data of the synthetic mesoscale eddies in the western Pacific,a study of their effects on acoustic propagation can be carried out.The empirical model of sound velocity was used to obtain the distribution of sound velocity anomalies in the mesoscale eddy region,and then the acoustic propagation fields in the presence of cold eddies,warm eddies,and no eddies were simulated by the BELLHOP Gaussian beam ray model,and the results are as follows:(1)The presence of cold eddies causes the convergence zone to shift toward the source and the width to decrease,while warm eddies cause the convergence zone to move away from the source and the width of the convergence zone to increase.The offset distance of the convergence zone is related to the location of the region and the maximum sound speed difference of the mesoscale eddy,the first and second convergence zones of the cold eddy in region I can cause 0.167 km and 0.345 km offset per 1 m/s sound speed difference,and the offset of region II is smaller than that of region I,which is 0.131 km and 0.252 km;the backward shift of the convergence zone from the warm eddy induced per 1 m/s sound speed difference is larger,which is 0.183 km and 0.375 km for region I.0.183 km and 0.375 km,and 0.15 km and0.305 km in region Ⅱ;(2)the presence of mesoscale eddies will lead to changes in sound velocity values at the source depth,thus affecting the inversion depth.The cold eddies cause the sound velocity contours to sink and the inversion depth to become shallow;the warm eddies cause the sound velocity contours to rise and the inversion depth to become deep.After obtaining the acoustic propagation field and acoustic propagation law under the background of mesoscale eddy,the quality factor is obtained according to the empirical formula and the actual battlefield equipment parameters,and the surface ship cooperative diving proximity warning model-frog leap tactical model is introduced to analyze the influence of synthetic mesoscale eddy on the tactical parameter configuration of the proximity warning model,and the following conclusions are obtained:(1)the presence of mesoscale eddy will reduce the towed sonar(1)the presence of mesoscale eddies will reduce the passive detection distance,and the degree of reduction in detection distance is mainly related to the nature of the eddy and the location of the region;under the same conditions,the influence of warm eddies on the detection distance is greater than that of cold eddies,and the detection distance of region II is greater than that of region I;(2)within the same eddy,the relative position of the towed sonar ship and the target submarine will affect the detection distance.When the cold eddy exists on the battlefield,the sonar ship is located inside the cold eddy and detects the submarine target outside the eddy will have a longer detection distance;when the warm eddy exists in the background field the result is the opposite,when the sonar ship is located outside the warm eddy detects the target submarine inside the warm eddy has a longer detection distance.(3)The presence of mesoscale eddies can change the configuration of frog leap tactical parameters.Both cold eddies and warm eddies lead to a reduction in exploration time and jump time,thus affecting the entire tactical cycle,with warm eddies having a greater impact on tactical parameters than cold eddies.This study is important for the construction of synthetic mesoscale eddy synthesis data in the western North Pacific region and the understanding of the influence law of mesoscale eddies on acoustic propagation as well as the optimization of military tactics under the complex internal structure of the ocean.