The Ocean Mesoscale Structure Influnce Coherent Time And Space Of Sound Field

So far, the exploration about mesoscale structure is still interesting.The main of ocean mesoscale structure are mesoscale eddy,fronts,internal wave,kuroshio intrution. upwelling, and so on.The paper study the influence of mesoscale eddy.fronts,internal wave to coherent time and space of sound field.Coherent time of sound field processing describes the validity of replica field.Internal wave has been discussed when it comes to being invaild of replica field,but other mesoscale structure are barely mentioned inhere. Therefor, these are discussed in this paper. Coherent space is use of designing array of transducer or other aspect.when the simulating ocean just has depth and range,coherent space can be divided to vertical coherence and horizon coherence.Firstly,the parabolic equation(PE) is simply described in this chapter.The model of mesoscale eddy and front are discussed, the scale of analysis is offered to give the model some condition that is use of making it be more accurate to calculate the sound field.Secondly,the influence of mesoscale eddy,fronts are discussed by simulating. If a mesoscale structure is in the path of propagation, intension of mesoscale eddy or fronts,velocity,the depth of source and bottom can influence the coherence of the sound field.It is manifest that higher the intension of mesoscale eddy or fronts is faster the decreasing velocity of coherence time.Following the increment of depth source in a extent in a adequate bottom.the coherent time decrease. The incline bottom can change the coherence of sound field.In deep sea, coherent radius of downslope is shorter than other situation,especially the radius of coherent space.In shoal sea,the coherent space of downslope decrease more slowly than other species of bottom.Last,internal wave influenced the coherence of sound field is simulated based on the experiment of ASIAEX 2001.The result is compared with the experimental data.The coherent radius that the result come from simulating is fluctuated by internal wave as same as the experimental data.And the radius of coherence is relation with the center frequency of sound source.