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Turning depths of internal tides in the South China Sea inferred from profile data

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Acta Oceanologica Sinica 2022年第2期41卷 139-146页

作者： Kun Liu Lianglong Da wuhong guo Chenglong Liu Junchuan Sun Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266237China PLA Navy Submarine Academy Qingdao 266041China Key Laboratory of Marine Science and Numerical Modeling First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China

Theoretically,propagating internal tides in the ocean may reflect at turning depths,where buoyancy frequencies equal tidal frequencies,before colliding with the air-sea interface or rugged bottom ***,the internal tide lower turning depths(ITLTDs)in the open ocean have been mapped;however,knowledge of the presence of ITLTDs in the South China Sea(SCS)is *** this study,2125 high-quality temperature-salinity profiles(including 58 deep-sea hydrographic measurements with observational depths exceeding 3000 m)are collected and analyzed to investigate the existence of ITLTDs in the ***,the concept of the upper turning depth is first introduced in the context of internal tides,and internal tide upper turning depths(ITUTDs)are also *** are found to exist at several abyssal stations;these stations are distributed mostly in the southern part of the SCS basin,possibly due to the greater water depths *** locations show the presence of ITLTDs for K_(1) versus M_(2) tidal frequencies because of the lower tidal *** distance between ITLTDs and the seafloor ranged from 270 m to more than 1200 m,implying the possible existence of multiple internal wave evanescent regions in the abyssal *** of tens of meters are ubiquitous in the SCS;stations with the presence of ITUTDs are located mainly in the northeastern SCS due to the intensive observations ***,the calculated ITUTDs have large uncertainties;they are sensitive to the selected bin *** horizontal propagation directions of internal tides in the SCS change dramatically,and as a result,the estimated turning depths under the full Coriolis force definition are different compared to that under the traditional approximation.

关键词： turning depth internal tide buoyancy frequency South China Sea

Identification of the sensitive area for targeted observation to improve vertical thermal structure prediction in summer in the Yellow Sea

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Acta Oceanologica Sinica 2021年第7期40卷 77-87页

作者： Huiqin Hu Jingyi Liu Lianglong Da wuhong guo Kun Liu Baolong Cui Navy Submarine Academy Qingdao 266199China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266237China

The sensitive area of targeted observations for short-term(7 d)prediction of vertical thermal structure(VTS)in summer in the Yellow Sea was *** applied the Conditional Nonlinear Optimal Perturbation(CNOP)method and an adjoint-free algorithm with the Regional Ocean Modeling System(ROMS).We used vertical integration of CNOP-type temperature errors to locate the sensitive areas,where reduction of initial errors is expected to yield the greatest improvement in VTS prediction for the selected verification *** identified sensitive areas were northeast−southwest orientated northeast to the verification area,which were possibly related to the southwestward background ***,we performed a series of sensitivity experiments to evaluate the effectiveness of the identified sensitive *** show that initial errors in the identified sensitive areas had the greatest negative effect on VTS prediction in the verification area compared to errors in other areas(e.g.,the verification area and areas to its east and northeast).Moreover,removal of initial errors through deploying simulated observations in the identified sensitive areas led to more refined prediction than correction of initial conditions in the verification area *** results suggest that implementation of targeted observation in the CNOP-based sensitive areas is an effective method to improve short-term prediction of VTS in summer in the Yellow Sea.

关键词： targeted observation sensitive area vertical thermal structure(VTS) conditional nonlinear optimal perturbation(CNOP)

Capturing uncertainties of the underwater acoustic environment based on an ocean-acoustic coupled model

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Chinese Journal of Acoustics 2015年第3期34卷 267-282页

作者： DA Lianglong guo wuhong ZHAO Jianxin FAN Peiqin Navy Submarine Academy

Considering the uncertain effects of temporal and spatial changes in the marine en- vironment on the underwater acoustic environment, we established an ocean-acoustic coupled numerical model and performed a parallel calculation. This model incorporated acoustic calcu- lations into the dynamic ocean, thereby achieving a dynamic forecasting and assessment of the acoustic environment. Furthermore, we adopted the ensemble prediction method to predict the vertical structure of temperature in a classic cross-section, the sound speed of the cross-section of the investigated sea area, and transmission losses. We gave the prediction errors of the sound speed profile as well as the 90% probability interval of transmission losses and the uncertainty histograms of the sound speeds, transmission losses, and sonar ranges at different depths and frequencies. The results reflected the influence of marine temporal and spacial variations on the uncertainties of the underwater acoustic environment, and the results also quantified the uncertainties of the underwater acoustic environment parameters. The experimental results indicate that the method used in this study is able to delineate and quantify the uncertainties of the underwater acoustic environment caused by marine dynamic changes.

关键词： Capturing uncertainties of the underwater acoustic environment based on an ocean-acoustic coupled model

Passive ranging of a moving sound source using three-dimensional measured information

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Chinese Journal of Acoustics 2021年第3期40卷 345-361页

作者： ZHAO Jianxin DA Lianglong XU guojun guo wuhong Navy Submarine Academy Qingdao266199 College of Meteorology and Oceanography National University of Defense TechnologyChangsha410073

To solve the problem of passive ranging of a moving sound source,a method of estimating the initial distance of target is presented by using the measured information of target azimuth,Doppler frequency shift and distance characteristic *** pseudo linearization,a linear model with heteroscedasticity is *** system can uniquely determine the distance,velocity and course of a non-radial moving sound source target by using the observed information of three target bearings,two Doppler frequency shifts and two distance characteristic quantities,but the system is unobservable only by using the observed information of the target azimuth and distance characteristic quantity under the condition that the sonar platform moves in a straight *** the condition that the initial distance is 5 n mile,the Monte Carlo simulations show that the average convergence time of the three-dimensional information measured method is about 200 s less than that of the reference method,and the standard deviation of the convergence time is about 40 s *** the initial distance between the target and the sonar platform,the average convergence time difference between the two methods tends to increase,which means the robustness of the three-dimensional information construction method is better than that of the reference *** experimental data further verify that the estimation of target distance tends to converge in about 300 ***,this method can realize passive ranging of a moving sound source under the condition of stable interference structure.

关键词： structure. moving sound

The rapid uncertainty prediction of the ocean-acoustic coupled model

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Chinese Journal of Acoustics 2018年第4期37卷 435-447页

作者： CUI Baolong DA Lianglong guo wuhong ZHAO Jianxin Navy Submarine Academy Qingdao 266071 Joint Laboratory for Marine Civil-Military Integration of Qingdao National Laboratory for Marine Science and Technology Qingdao 266237

Focusing on the rapid prediction of acoustic field uncertainty in environment with temporal and spatial sound speed perturbation, evolvement of sound speed structure over time is predicted based on the ocean-acoustic coupled model to obtain the uncertainty distribution of the vertical structure of sound speed. Further, a method combining the arbitrary polynomial chaos expansion with the empirical orthogonal function is proposed to reduce the dimensionality of uncertain parameters and to obtain the uncertainty distribution of the acoustic field. Simulations have shown that the computational complexity can be reduced by 2 orders of magnitude compared to the conventional polynomial chaos expansion while ensures the same ***, the computational complexity is not influenced by the complexity of the sound speed profile. The acoustic field and uncertainty predicted in uncertain environment by proposed method also have been tested with the experimental data.

关键词： The rapid uncertainty prediction of the ocean-acoustic coupled model PCE SSP EOF

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海洋-声学耦合模式捕捉水声环境不确定性

声学学报 2015年第3期40卷 477-486页

作者：笪良龙过武宏赵建昕范培勤海军潜艇学院青岛266071

考虑到海洋环境的时空变化对水声环境不确定性的影响,建立了海洋-声学耦合数值模式,实现了并行计算。该模式将声学计算纳入到运动的海洋中,从而实现了对水声环境的动态预报和估计。同时,采用集合预报方法对典型断面的温度垂直结构、实... 详细信息

考虑到海洋环境的时空变化对水声环境不确定性的影响,建立了海洋-声学耦合数值模式,实现了并行计算。该模式将声学计算纳入到运动的海洋中,从而实现了对水声环境的动态预报和估计。同时,采用集合预报方法对典型断面的温度垂直结构、实验海区声速剖面和传播损失进行预报,并给出了声速剖面的预报误差、不同深度与频率下,传播损失90%的概率区间以及声速、传播损失、声呐作用距离的不确定性直方图。结果反映了海洋时空变化对水声环境不确定性的影响,量化了水声环境中不确定性的大小。实验结果表明该方法可以刻画海洋动态变化引起的水声环境不确定性,并对其进行了量化和描述。

关键词：不确定性水声环境海洋环境海洋声学耦合模式捕捉传播损失声速剖面

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海洋—声学耦合过程不确定性快速预报

声学学报 2017年第5期42卷 535-542页

作者：笪良龙崔宝龙过武宏赵建昕海军潜艇学院青岛266071 青岛海洋科学与技术国家实验室海洋军民融合联合实验室青岛266237

针对海洋声速空间非均匀和时变条件下的声场不确定性快速预报问题,根据海洋-声学耦合模式预报声速场时空变化过程,获取声速垂直结构不确定性分布规律,提出经验正交函数-随机多项式展开方法,以降低不确定参数维度,得到声场不确定性分布.... 详细信息

针对海洋声速空间非均匀和时变条件下的声场不确定性快速预报问题,根据海洋-声学耦合模式预报声速场时空变化过程,获取声速垂直结构不确定性分布规律,提出经验正交函数-随机多项式展开方法,以降低不确定参数维度,得到声场不确定性分布.数值计算表明该方法在保证同等精度的同时可大幅减少计算量,相比常规随机多项式展开方法计算效率可提高2个数量级,且计算量不随声速剖面复杂程度变化而改变.经海上实验验证,结果表明该方法可实现环境不确定性条件下的声场及其不确定性的快速预报。

关键词：结构不确定性模式预报耦合过程海洋声学随机多项式声速剖面经验正交函数

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三维信息测量的运动声源无源测距

声学学报 2020年第5期45卷 625-636页

作者：赵建昕笪良龙徐国军过武宏海军潜艇学院青岛266199 国防科技大学气象海洋学院长沙410073

针对运动声源无源测距问题,给出了目标方位、多普勒频移和距离特征量作为测量信息来估计目标初始距离的方法。通过伪线性化的处理方法,构造了一个异方差的线性模型。在声呐平台直航条件下,证明了非径向运动的声源目标,利用3个目标方位、... 详细信息

针对运动声源无源测距问题,给出了目标方位、多普勒频移和距离特征量作为测量信息来估计目标初始距离的方法。通过伪线性化的处理方法,构造了一个异方差的线性模型。在声呐平台直航条件下,证明了非径向运动的声源目标,利用3个目标方位、2个多普勒频移和2个距离特征量的观测信息,可以唯一地确定目标的距离、速度和航向,而仅利用目标方位和距离特征量的观测信息,系统是不可观测的。蒙特卡洛数值模拟表明:对于初始距离5 nm(海里)的情形,三维信息测量方法比参考方法的目标距离的平均收敛时间要少200 s左右,收敛时间标准差要少40 s左右。随着初始距离的增加,两种方法收敛时间差有变大的趋势,这意味着三维信息构造的方法的稳健性优于参考方法。实验数据也进一步验证了在300 s左右,目标距离的估计逐渐趋于收敛。因此,该方法可以在稳定的干涉结构条件下,实现运动声源的无源定位。

关键词：多普勒频移无源定位运动声源目标距离三维信息蒙特卡洛目标方位初始距离

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海洋-声学耦合过程初始温度误差传递与发展

声学学报 2019年第4期44卷 463-470页

作者：过武宏笪良龙范培勤刘敬一崔宝龙海军潜艇学院青岛266199 青岛海洋科学与技术试点国家实验室海洋军民融合联合实验室青岛266237

针对海洋初始温度场误差到水声传播误差的传递以及随时间演变发展的问题,优化海洋-声学耦合模式,通过对比遥感数据,验证了模型的可靠性。在此基础上,采用在控制试验温度初始场上加扰动的方法进行传播损失全局误差发展和区域误差发展试... 详细信息

针对海洋初始温度场误差到水声传播误差的传递以及随时间演变发展的问题,优化海洋-声学耦合模式,通过对比遥感数据,验证了模型的可靠性。在此基础上,采用在控制试验温度初始场上加扰动的方法进行传播损失全局误差发展和区域误差发展试验。结果表明,初始温度场全局扰动在经过5天繁殖后使传播损失误差达到饱和,且扰动分布结构和海洋运动规律基本保持一致;对于在黑潮流域设定的目标海区,其上游区域的初始扰动发展最快。该结论可为开展海洋声学适应性观测提供依据。

关键词：海洋声学误差传递初始温度耦合过程扰动发展传播损失试验温度适应性观测