The WKBZ mode approach to pulsed propagation in ocean channels

In the paper, the WKBZ normal mode approach has been applied to the propagation of the pulsed energy and waveform in ocean channels. The numerical results in two different channels are given. Comparison between the WKBZ and conventional normal mode codes shows that the WKBZ mode approach is a fast and accurate method and the running time by the WKBZ approach is reduced by about two orders of magnitude.

Two dimensional Wigner-Ville spectrum of the linear random time-variant ocean channel

In this paper, the ocean acoustic channel is considered as a time-variant channel. In order to analyse the conjoint time-shift - frequency-delay distribution or the fading and spread statistical characteristics of the channel. The TDWVS (Two Dimensional Wigner-Ville Spectrum) of the time - variant channel is defined. The relation between the WVS (Wigner-Ville Spectrum) of the input and the output of the channel is discussed and some examples for the specific channel are shown. Finally, the applications on the detection of signals in noise using the WVS and TDWVS are given and the advantage is obvious, when the detected signal is linear frequency-modulation signal.

An Assessment of Indo-Pacific Oceanic Channel Dynamics in the FGOALS-g2 Coupled Climate System Model

Lag correlations of sea surface temperature anomalies （SSTAs）, sea surface height anomalies （SSHAs）, subsurface temperature anomalies, and surface zonal wind anomalies （SZWAs） produced by the Flexible Global Ocean-Atmosphere-Land System modeh Grid-point Version 2 （FGOALS-g2） are analyzed and com- pared with observations. The insignificant, albeit positive, lag correlations between the SSTAs in the south- eastern tropical Indian Ocean （STIO） in fall and the SSTAs in the central-eastern Pacific cold tongue in the following summer through fall are found to be not in agreement with the observational analysis. The model, however, does reproduce the significant lag correlations between tile SSHAs in the STIO in fall and those in the cold tongue at the one-year time lag in the observations. These, along with the significant lag correlations between the SSTAs in the STIO in fall and the subsurface temperature anomalies in the equatorial Pacific vertical section in the following year, suggest that the Indonesian Throughflow plays an important role in propagating the Indian Ocean anomalies into the equatorial Pacific Ocean. Analyses of the interannual anomalies of the Indonesian Throughflow transport suggest that the FGOALS-g2 climate system simulates, but underestimates, the oceanic channel dynamics between the Indian and Pacific Oceans. FGOALS-g2 is shown to produce lag correlations between the SZWAs over the western equatorial Pacific in fall and the cold tongue SSTAs at the one-year time lag that are too strong to be realistic in comparison with observations. The analyses suggest that the atmospheric bridge over the Indo-Pacific Ocean is overestimated in the FGOALS-g2 coupled climate model.

Role of the Oceanic Channel in the Relationships between the Basin/Dipole Mode of SST Anomalies in the Tropical Indian Ocean and ENSO Transition

The relationships between the tropical Indian Ocean basin （IOB）/dipole （IOD） mode of SST anomalies （SSTAs） and ENSO phase transition during the following year are examined and compared in observations for the period 1958-2008. Both partial correlation analysis and composite analysis show that both the positive （negative） phase of the lOB and IOD （independent of each other） in the tropical Indian Ocean are possible contributors to the E1 Nino （La Nifia） decay and phase transition to La Nifia （El Nifio） about one year later. However, the influence on ENSO transition induced by the IOB is stronger than that by the IOD. The SSTAs in the equatorial central-eastern Pacific in the coming year originate from subsurface temperature anomalies in the equatorial eastern Indian and western Pacific Ocean, induced by the IOB and IOD through eastward and upward propagation to meet the surface. During this process, however the contribution of the oceanic channel process between the tropical Indian and Pacific oceans is totally different for the IOB and IOD. For the IOD, the influence of the Indonesian Throughflow transport anomalies could propagate to the eastern Pacific to induce the ENSO transition. For the IOB, the impact of the oceanic channel stays and disappears in the western Pacific without propagation to the eastern Pacific.

Climate variability and predictability associated with the Indo-Pacific Oceanic Channel Dynamics in the CCSM4 Coupled System Model

An experiment using the Community Climate System Model(CCSM4), a participant of the Coupled Model Intercomparison Project phase-5(CMIP5), is analyzed to assess the skills of this model in simulating and predicting the climate variabilities associated with the oceanic channel dynamics across the Indo-Pacific Oceans. The results of these analyses suggest that the model is able to reproduce the observed lag correlation between the oceanic anomalies in the southeastern tropical Indian Ocean and those in the cold tongue in the eastern equatorial Pacific Ocean at a time lag of 1 year. This success may be largely attributed to the successful simulation of the interannual variations of the Indonesian Throughflow, which carries the anomalies of the Indian Ocean Dipole(IOD) into the western equatorial Pacific Ocean to produce subsurface temperature anomalies, which in turn propagate to the eastern equatorial Pacific to generate ENSO. This connection is termed the "oceanic channel dynamics" and is shown to be consistent with the observational analyses. However, the model simulates a weaker connection between the IOD and the interannual variability of the Indonesian Throughflow transport than found in the observations. In addition, the model overestimates the westerly wind anomalies in the western-central equatorial Pacific in the year following the IOD, which forces unrealistic upwelling Rossby waves in the western equatorial Pacific and downwelling Kelvin waves in the east. This assessment suggests that the CCSM4 coupled climate system has underestimated the oceanic channel dynamics and overestimated the atmospheric bridge processes.

中缅印度洋新通道的地缘经济合作障碍及其协作机制

中缅印度洋新通道是推进中缅地缘经济合作和“一带一路”建设的重要载体,解析中缅印度洋新通道的地缘经济合作障碍及其协作机制,将为提升中缅印度洋新通道的地缘经济效应和加强中缅地缘经济合作提供重要的科技支撑。中缅印度洋新通道的地缘经济合作障碍不仅有地理环境的阻碍,更有中缅经济发展差异、复杂武装冲突干扰、大国干预掣肘和多元利益主体博弈的地缘风险的束缚。中缅印度洋新通道的地缘经济合作并不是一种区域控制战略工具,而是打造一条交通物流、供应链、产业链、价值链深度关联的国际贸易走廊。为了推进中缅印度洋新通道的地缘经济合作,中缅印度洋新通道建设应构建多层次的地缘经济合作协作机制。在国家层面,应通过推动中缅印度洋新通道与“一带一路”倡议的融合、强化中缅政策沟通机制对接、制定中缅印度洋新通道长远发展战略规划来加强中缅发展战略对接。在通道层面,应通过推动内外部基础设施联动、强化跨境地缘经济要素流动和产业协作、深化面向缅甸及印度洋地区的经贸合作来升级中缅印度洋新通道地缘经济效应。在利益主体层面,应通过强化多方利益对接、统筹中缅口岸协调对接机制、创建立体化新通道风险防范机制来构建多元利益主体参与的协商机制。

冬季海洋锋面对大气河影响的理想数值试验研究

本文利用天气研究和预报(Weather research and forecasting,WRF)模式设置了两组具有不同海洋锋面强度的“渠道模型”理想数值试验,忽略地形作用,探讨了冬季海洋锋面对大气河(Atmospheric river,AR)的影响。结果表明,在不同强度的海洋锋面试验中,大气低层风速、湍流热通量等物理量的响应与海温的变化同位相,且大气低层各变量对海洋锋面南侧海温变化的响应较北侧更大,呈现出南北不对称性。海洋锋强度的增强促进了向高空的涡动热量和水汽输送,导致高空风速加强和风暴轴北移。海洋锋面的增强还为经过其上空的气旋提供了更多的动量和水汽,加强了气旋南侧的水汽输送带,从而促进了大气河发生频数的增加和大气河强度的增强。

水下无线光通信动态阈值判决技术研究与性能分析

针对海洋湍流信道环境下固定阈值判决方案导致水下无线光通信系统性能恶化的问题,提出了一种动态阈值判决方案。该方案基于水下湍流信道慢衰落的特性,在发送端将数据以帧为单位进行发送,接收端则根据接收帧前导码的幅度每帧更新一次判决阈值。采用蒙特卡洛法和Gamma-Gamma信道模型对水下无线光通信系统进行仿真,仿真结果表明:在弱湍流信道环境下,当系统误码率为10^(-6)时,动态阈值判决方案比固定阈值判决方案的误码性能提升5.4 dB;在中、强湍流信道环境下,动态阈值判决方案能够有效抑制误码率门限现象的产生。

The IOD-ENSO precursory teleconnection over the tropical Indo-Pacific Ocean:dynamics and long-term trends under global warming

The dynamics of the teleconnection between the Indian Ocean Dipole(IOD) in the tropical Indian Ocean and El Ni?o-Southern Oscillation(ENSO) in the tropical Pacific Ocean at the time lag of one year are investigated using lag correlations between the oceanic anomalies in the southeastern tropical Indian Ocean in fall and those in the tropical Indo-Pacific Ocean in the following winter-fall seasons in the observations and in high-resolution global ocean model simulations. The lag correlations suggest that the IOD-forced interannual transport anomalies of the Indonesian Throughflow generate thermocline anomalies in the western equatorial Pacific Ocean, which propagate to the east to induce ocean-atmosphere coupled evolution leading to ENSO. In comparison, lag correlations between the surface zonal wind anomalies over the western equatorial Pacific in fall and the Indo-Pacific oceanic anomalies at time lags longer than a season are all insignificant, suggesting the short memory of the atmospheric bridge. A linear continuously stratified model is used to investigate the dynamics of the oceanic connection between the tropical Indian and Pacific Oceans. The experiments suggest that interannual equatorial Kelvin waves from the Indian Ocean propagate into the equatorial Pacific Ocean through the Makassar Strait and the eastern Indonesian seas with a penetration rate of about 10%–15% depending on the baroclinic modes. The IOD-ENSO teleconnection is found to get stronger in the past century or so. Diagnoses of the CMIP5 model simulations suggest that the increased teleconnection is associated with decreased Indonesian Throughflow transports in the recent century, which is found sensitive to the global warming forcing.The dynamics of the teleconnection between the Indian Ocean Dipole(IOD)in the tropical Indian Ocean and El Ni?o-Southern Oscillation(ENSO)in the tropical Pacific Ocean at the time lag of one year are investigated using lag correlations between the oceanic anomalies in the southeastern tropical Indian Ocean in fall and those in the tropical Indo-Pacific Ocean in the following winter-fall seasons in the observations and in high-resolution global ocean model simulations.The lag correlations suggest that the IOD-forced interannual transport anomalies of the Indonesian Throughflow generate thermocline anomalies in the western equatorial Pacific Ocean,which propagate to the east to induce ocean-atmosphere coupled evolution leading to ENSO.In comparison,lag correlations between the surface zonal wind anomalies over the western equatorial Pacific in fall and the Indo-Pacific oceanic anomalies at time lags longer than a season are all insignificant,suggesting the short memory of the atmospheric bridge.A linear continuously stratified model is used to investigate the dynamics of the oceanic connection between the tropical Indian and Pacific Oceans.The experiments suggest that interannual equatorial Kelvin waves from the Indian Ocean propagate into the equatorial Pacific Ocean through the Makassar Strait and the eastern Indonesian seas with a penetration rate of about 10%–15%depending on the baroclinic modes.The IOD-ENSO teleconnection is found to get stronger in the past century or so.Diagnoses of the CMIP5 model simulations suggest that the increased teleconnection is associated with decreased Indonesian Throughflow transports in the recent century,which is found sensitive to the global warming forcing.

Short Baseline Positioning with an Improved Time Reversal Technique in a Multi-path Channel

The existence of a multi-path channel under the water greatly decreases the accuracy of the short baseline positioning system.In this paper,the application of a time reversal mirror to the short baseline positioning system was investigated.The time reversal mirror technique allowed the acoustic signal to better focus in an unknown environment,which effectively reduced the expansion of multi-path acoustic signals as well as improved the signal focusing.The signal-to-noise ratio（SNR） of the time reversal operator greatly increased and could be obtained by ensonifying the water.The technique was less affected by the environment and therefore more applicable to a complex shallow water environment.Numerical simulations and pool experiments were used to demonstrate the efficiency of this technique.

基于FIO-COM的海洋声学预报系统的构建与应用

将海洋模式与声传播模型结合在一起,设计开发了一种适用于高性能计算机的全球海洋声学预报系统FIO-GOAFS,该系统以自然资源部第一海洋研究所全球0.1°分辨率海浪-潮流-环流耦合模式(FIOCOM)为基础,利用海洋模式预报的温、盐、深参数计算声速剖面,并对声速剖面进行水声环境特征诊断,之后将海洋模式与水下声场传播模型协同连接,结合地声模型(海底地形和底质参数),实现了全球海域的水声环境特征诊断及水下声场及相关结果的预报。海洋模型提供水下声学预报所需的水体声速、海浪波高等参数,地声模型提供海底地形、底质声速、密度以及衰减等参数,通过调用海洋-声学连接模块提取声传播路径的地形及海洋环境参数剖面,实现海洋模型和声学模型的有效连接。全球海洋声学预报系统在高性能计算机上并行实现,主要包括声场计算中的频点、方位角并行以及声学预报时针对地理空间区域的并行。最后,利用该系统预报并分析了全球海域的水声环境特性及声呐作用距离的季节变化和空间分布特征,为现代声呐的设计、操作和水下应用提供参考。

水下量子通信的数值模拟及误码率分析

水下量子密钥分配可以为水下通信提供绝对安全的保密手段。本文采用蒙特卡洛方法,结合海水信道的光学性质和光子的量子特性模拟了光子在海水中的传输过程,研究其衰减和偏振特性,计算了接收到的光子数随接收端口径、视场角和传输距离的变化,从保真度的角度分析散射光的偏振变化情况,并结合背景光的影响分析了水下量子通信误码率。结果表明,水下量子通信理论上可以实现百米量级的安全通信。

海洋信道仿真软件HJRAY及其在水声通信中的应用

海洋声信道特性十分复杂,对水声通信信号传输构成严重影响,包括能量衰减、多途扩展以及多普勒频移等。为了具体模拟海洋信道对其中传输的声信号的影响,给出了一个新的海洋信道仿真软件—HJRAY。HJRAY通过对海洋环境中各种物理特性的模拟以及对声线轨迹常微分方程组的解算,合成海洋信道的时变冲激响应,获取通信链路接收水听器端信号,为仿真评估现实信道条件下水声通信系统性能提供基础。结合一个具体的直接序列扩频方案,验证了HJRAY在水声通信仿真中的有效性。

关于中国在南亚区域选取印度洋出海口的战略推进构想

鉴于美国战略重心已经转向亚太地区,蓄谋在太平洋上部署重兵展开战略封堵,致使中国海上通道安全面临的严峻挑战。应对这一严峻挑战,中国必须另辟蹊径,大力开拓印度洋出海大通道,构建"两洋出海"的战略互动格局,打破马六甲海峡困局,进一步增加中国海上通道的安全系数。为此,应当扫描在南亚区域选取印度洋出海口的态势而确定进取方向,选定位于巴基斯坦的瓜达尔港口和孟加拉国的吉大港作为开拓对象,并且与缅甸的仰光港和若开港一起来考察与规划,采取先易后难的策略循序渐进,下功夫促成印度洋出海大通道的整体阵容,以保障中国走向世界,实现和平崛起。

水下量子密钥分配的误码率和成码率

水下量子密钥分配可以为水下通信提供绝对安全的保密手段。水下量子密钥分配系统的误码率和成码率受到海水信道的光学性质、天气环境和通信系统硬件参数等的影响。本文从理论和实验上分析水下量子密钥分配的信道特性和系统硬件特性,估算其误码率和成码率,并给出系统参数的门限值,结果表明可在百米范围内进行绝对安全的水下量子密钥分配。

海洋再分析资料中IOD-ENSO遥相关的海洋通道机制分析

本文利用滞后相关分析,研究了海洋再分析资料(SODA、ORAS4和GODAS)中的IOD-ENSO滞后遥相关关系,并与观测资料进行对比。结果显示,3套再分析资料中热带东南印度洋秋季海表温度/海表高度异常和赤道太平洋冷舌次年秋季海表温度/海表高度异常之间显著相关,与观测结果一致。在次表层,观测和再分析资料均显示,热带东南印度洋秋季海表温度异常与赤道太平洋次表层海温异常之间的显著相关关系在冬季至次年秋季沿赤道太平洋垂向剖面向东移动,并于次年夏季和秋季在冷舌区上升至海表。热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系是由海洋通道机制引起的,即IOD事件引起印尼贯穿流流量异常,导致赤道太平洋温跃层异常,激发赤道Kelvin波向东传播,从而影响赤道中-东太平洋冷舌海表温度异常。观测及SODA与ORAS4资料中,热带东南印度洋和赤道太平洋冷舌滞后1年的相关关系在去除ENSO信号后仍然显著,表明海洋通道机制是独立于ENSO事件的;而在GODAS资料中,这些显著相关关系在去除ENSO信号后消失。印尼贯穿流流量异常和Nio3.4及DMI(Dipole Mode Index)指数之间超前-滞后12个月的相关关系显示,在SODA和ORAS4资料中,印尼贯穿流流量同时受到ENSO和IOD的影响,与观测结果一致;而在GODAS中,印尼贯穿流流量异常仅与Nio3.4指数显著相关,极少受到IOD事件的影响,这部分解释了GODAS资料中去除ENSO信号后,IOD-ENSO滞后遥相关关系消失的原因。

改进的实时海浪网格模型

基于深水中的长峰波波浪模型,给出了视点相关的梯形海面网格自适应模型,能快速逼真的实时生成航海仿真系统中的多通道海浪。本算法只对每个通道可见部分的网格海面进行计算,满足屏幕图像各点的分辨率,在保证较好的图像质量的同时提高了绘制效率。可以通过控制网格的疏密和波浪序列的数目,灵活的控制绘图的质量和计算时间上的花费,满足不同配置的仿真应用。

利用射线模型快速预报海洋信道对包络谱的影响

包络谱是舰船辐射噪声的特征之一,可作为目标识别的重要依据。快速预报海洋信道对包络谱传播的影响,可对目标识别提供帮助。提出并从理论上分析了用射线模型快速预报海洋信道对包络谱影响的方法,利用这种方法计算了几种典型海洋信道中包络谱随接收距离的变化,分析了声速剖面、海底参数、声源和接收深度对包络谱传播的影响。

多通道海洋荧光激光雷达溢油监测系统

主要介绍了可用于海上溢油监测的多通道海洋荧光激光雷达系统及实验研究。该激光雷达系统采用Nd：YAG激光器三倍频激光（355 nm）作为探测光源,使用口径为20 cm的卡塞格林望远镜接收海面返回的荧光信号,经光栅光谱仪分光后对380~690 nm范围内的荧光信号进行采集。通过实验室激光诱发油样本的荧光数据分析,研究了不同溢油种类的荧光光谱特征,并给出了区分溢油污染程度的快速分析方法。2009年以来在青岛近海进行多次实验并分析不同的海面污染类型和污染程度,实验结果表明,该雷达系统海面溢油监测性能可靠,能够准确判别溢油种类,并可区分溢油污染程度。最后讨论了雷达探测中存在的噪声影响。

FY-1C/1D全球海上气溶胶业务反演算法研究

介绍了基于FY-1C/1D气象卫星数据进行全球海洋气溶胶反演的业务算法,主要论述了海上气溶胶反演的单通道算法基本原理.该算法的核心内容是建立气溶胶光学厚度查算表,该查算表基于6S辐射传输模式,在假定气溶胶模式条件下,卫星的表观反射率是卫星观测几何(太阳卫星角)和气溶胶光学厚度函数,最终由卫星观测表观反射率反演出气溶胶光学厚度.业务反演过程中还考虑到数据质量检验、云检测处理和太阳耀斑区去除等.利用该算法对FY-1C卫星自2001年起的部分资料进行反演试验,并在FY-1D卫星发射后投入业务应用,自2002年8月开始能实时得到每天和每月的全球气溶胶光学厚度产品.从两颗卫星两年多连续反演结果分析可以非常清晰地发现全球气溶胶主要排放源地和全球海上气溶胶分布的季节变化,与国外卫星反演结果十分接近.