基于卫星高度计资料提取热带印度洋Rossby波传播速度与变形半径

Rossby波是地球流体中的一种低频大尺度波动,在全球海洋动力过程的调整中发挥着关键作用。利用1993~2011年多卫星高度计融合的月均海平面高度异常数据,基于二维Radon变换方法提取了热带印度洋南北纬5°~20°区域的Rossby波纬向传播速度。结合斜压Rossby波的理论模型,利用1993~2008年多年平均的简单海洋再分析数据集的温盐资料,计算了自由线性的一阶斜压Rossby波的理论波速值。通过对比理论波速与高度计的观测波速,发现在印度洋5°~20°S间理论值与观测值比较接近,在5°~20°N间两者差别较大,其误差可能来源于两个方面:1)该区域较多陆地阻隔引起了Rossby波的绕射和反射;2)多边界激发的多个Rossby波发生相互作用。利用卫星高度计观测提取的Rossby波波速计算了热带印度洋南北纬5°~20°范围内的Rossby波的变形半径,给出了Rossby变形半径与纬度的解析表达式。该式能够很好地描述热带印度洋不同纬度的Rossby变形半径,为今后热带印度洋Rossby波速的应用提供了理论和观测依据。     

全球海洋高频波动主振荡周期的纬向带状分布特征

基于1992年10月至2000年12月的TOPEX/Poseidon和ERS-1/2卫星高度计资料,分析了周期短于150d的高频波动及其能量的空间分布特征.在功率谱密度计算基础上,分析特定频段所含能量占周期短于150d的高濒波动总能量的百分比,发现该频段最强振荡(下文称主振荡)所对应的周期从近赤道的1个月逐步增加至南北纬30°附近的4个月,进一步分析表明主振荡周期的这种变化是连续的,与西向行星Rossby波的相速随纬度增加而变慢相对应.主振荡所对应的周期在全球海洋中呈显著的带状分布.进而表明在14°N(S)附近60d周期的振荡除通常所认为的由于潮汐混淆所造成的虚假信号之外,主要是行星Rossby波形态的真实信号.     

基于Radon 变换获取东沙群岛附近 三个内孤立波的传播速度

由于大振幅非线性内波对东沙群岛附近的海上石油平台具有很大的破坏性,已有多名学者对该海域的非线性内波的 传播波速进行了研究。主要根据2009 年6 月24 日15 时40 分至25 日16 时40 分“科学一号”考察船在东沙岛东北部陆架 上K106 站进行的长达25 h的X波段雷达、温度链、ADCP 同步观测数据,在该海域利用Radon 变换技术获取了本次观测到 的内孤立波的传播速度。利用孤立波到达前30 min的ADCP流速值,计算得到内波传播方向上的背景流大小为0.04 m/s。最终 得出6月24 日22时30 分时的内孤立波传播速度为3.04 m/s,传播方向约为297毅;6 月25 日8 时30 分的内孤立波传播速度 为2.73 m/s,传播方向约为289毅;6 月25 日12 时内孤立波的传播速度为2.59 m/s,传播方向约为283毅。第一个孤立波与后 两个孤立波,在振幅和速度大小上存在明显不同,其生成机制也可能不同。     

Rossby波临界周期与海面高度异常能谱临界周期在南海的空间分布特征

本文利用WOA01(the Word Ocean Atlas 2001)海水各层气候态温盐数据计算南海Rossby波临界周期,并与其在同纬度西北太平洋中的分布对比.结果显示,在南海中Rossby波临界周期随纬度增加而逐渐增加,并且由于南海的特殊地形,海盆中Rossby波临界周期呈北东-南西向分布,与其在大洋中呈纬向带状分布不同.通过分析南海各网格点上海面高度异常(SSHA,the sea surface height anomaly)的能谱,我们发现在海盆中部其临界周期与当地Rossby波临界周期基本相同,其值也随纬度增加而逐渐增加,因而从观测上验证了模式结果,即在海面风应力旋度能谱临界周期小于等于当地Rossby波临界周期的条件下,海洋响应能谱临界周期等于当地Rossby波临界周期.     

基于热含量探究PDO的三维结构及信号传播特征

基于1815—2013年SODA(Simple Ocean Data Assimilation)数据不同深度的温度数据资料,进行了热含量的计算,并通过EOF分解、功率谱分析等统计方法探究太平洋年代际振荡(Pacific decadal oscillation,PDO)的三维结构和周期性特征。结果表明,太平洋的年代际变化不仅仅存在于海洋表层,海洋300 m以浅均存在年代际变化特征,其中次表层(70 m左右)的年代际变化特征最为显著。功率谱分析的结果显示,北太平洋的年代际变化周期约为18 a。利用SODA数据的温度和盐度资料对北太平洋的Rossby(罗斯贝)波波速进行了计算,计算结果显示,Rossby波向西传播,其波速随着纬度的增大而减小。对300 m以浅水体的热含量时间序列与PDO指数做了超前滞后相关,在热含量序列滞后9 a时相关系数分布与同期相关反相。对不同层次的热含量与PDO指数进行了超前滞后相关,分析PDO的演变特征,结果表明,PDO在低纬度通过Rossby波向西传播,在传播过程中深度逐渐加深。     

太平洋涌浪分布特征及其对海-气边界层的影响

本文对海-气边界层波致风机制的相关理论进行了阐述,并利用ERA-40再分析资料给出了太平洋谱峰速度、波龄、波陡等描述涌浪和波致风机制物理量的年际和季节空间分布特征。分析表明:东太平洋赤道地区等海域涌浪速度最大且涌浪由南向北传播明显;太平洋波边界层高度基本呈现出东高西低的分布形势;波致风机制主要发生在赤道热带海域,北半球夏季波致风机制偏强,冬季偏弱,南半球反之;北半球北部海域夏季更易发生波致风机制,赤道附近海域相反;南海为风浪与涌浪组成的混合浪,对其波候等相关研究有必要分开进行讨论。     

Rhines效应对高度计观测的海洋中尺度涡空间分布特征的影响

Rhines效应是指Rossby波和大湍流（中尺度涡）相互作用,将涡动能量以波的形式传播出去,从而使中尺度涡发生形变,最终消亡的一种动力学机制。本文通过比较海洋里涡特征速度和Rossby长波波速的方法,研究了一种广义的Rhines效应对高度计观测的海洋中尺度涡空间分布特征的影响。结果显示,广义Rhines效应比只考虑行星涡度梯度的传统形式对中尺度涡的分布具有更显著的影响。大部分中尺度涡分布在涡特征速度（U_e）大于由广义Beta值计算的Rossby长波波速（U_cg）的区域。这些涡可以由动能反向串级过程获取能量,成长为振幅和空间尺度较大的涡。热带海域以外的“涡旋沙漠”区域,中尺度涡的数量稀少,强度很弱,大都分布于U_ecg的海域。广义Rhines效应可能是这些海域中尺度涡难以成长的动力学机制。     

北太平洋SST的时空分布特征及其与黑潮大弯曲和El—Nino的关系

用EOF分析方法对北太平洋及赤道太平洋地区1949～1979年31年海表面温度距平场进行分解,得到几个主要距平海温模态(EOF1～3),分析了EOF1～3的时空分布特征。得到海温距平场的EOF1和EOF2～3模态分别对E1—Nino事件和黑潮大弯曲有很显著的相关性,指出SST第三模态场对黑潮大弯曲的影响具有很好的持续性,持续时间为1～2年。最后讨论了相互的影响过程,为黑潮大弯曲和E1—Nino事件的预报的可能性提供了依据。     

Zonal Wavelengths of Planetary Rossby Waves Derived from Hydrographic Transects in the Northeast Atlantic Ocean?

Using hydrographic data of three extended zonal sections, which cover the upper 1000 dbar layer along 10°, 21°, and 32°N in the North-East Atlantic between 20° and 45°W, observational evidence is presented for zonal wavelengths of resonantly excited, first mode, long, baroclinic Rossby waves. The amplitudes of associated anomalies in the mass field decrease with increasing offshore distance. The associated zonal wavelengths reach several hundred kilometres and decrease with increasing latitude. Due to the Rossby dispersion, the detected wave patterns slowly propagate westward, somewhat faster in the south than in the north. The results obtained confirm the data sets remotely sensed by satellites, as well as the outcomes of analytical and numerical models.     

Propagation of Rossby Waves over Ridges Excited by Interannual Wind Forcing in a Western North Pacific Model

Numerical experiments with a multi-level general circulation model have been performed to investigate basic processes of westward propagation of Rossby waves excited by interannual wind stress forcing in an idealized western North Pacific model with ocean ridges. When the wind forcing with an oscillation period of 3 years is imposed around 180°E and 30°N, far from Japan, barotropic waves excited by the wind can hardly cross the ridges, such as the Izu-Ogasawara Ridge. On the other hand, a large part of the first-mode baroclinic waves are transmitted across the ridges, having net mass transport. The propagation speed of the first-mode baroclinic wave is accelerated (decelerated) when an anticyclonic (cyclonic) circulation is formed at the sea surface, due to a deeper (shallower) upper layer, and to southward (slightly northward) drift of the circulation. Thus, when the anticyclonic circulation is formed on the northern side of the cyclonic one, they propagate almost together. The second-mode baroclinic waves converted from the first-mode ones on the ridges arrive south of Japan, although their effects are small. The resulting volume transport variation of the western boundary current (the Kuroshio) reaches about 60% of the Sverdrup transport variability estimated from the wind stress. These characteristics are common for the interannual forcing case with a longer oscillation period. In the intraseasonal and seasonal forcing cases, on the other hand, the transport variation is much smaller than those in the interannual forcing cases. This revised version was published online in July 2006 with corrections to the Cover Date.     

Influence of Coupled Rossby Waves on Primary Productivity and Tuna Abundance in the Indian Ocean

Interannual coupled Rossby waves in the extratropical Indian Ocean propagate westward in covarying pycnocline depth, sea surface temperature, and meridional surface wind anomalies from the west coast of Australia between 15°S and 35°S, taking 3–4 years to transit the interior ocean to Madagascar. In the interior subtropical gyre, where the tuna longline catch (TLC) mainly concerns two species (albacore and bigeye), these waves have been observed to affect year-to-year changes in catch, with wave crests (troughs) in the main pycnocline associated with high (low) TLC anomalies. This suggested that tuna longline catch is associated with the entrainment of nutrient-rich pycnocline water into the photic zone and a subsequent increase in primary productivity there. Here, this hypothesis is examined within the context of SeaWiFS chlorophyll concentration (CC). We find the situation the opposite of that expected, with wave crests (troughs) in the main pycnocline associated with low (high) CC anomalies averaged over the photic zone. These results are shown to be consistent with a model relating the anomalous CC tendency to upper-layer divergence in the wave, not unlike that relating surface slicks to upper-layer divergence in internal gravity waves. Thus, the connection between interannual coupled Rossby waves and TLC in the interior subtropical gyre does not appear to derive from wave-induced modulation of the pelagic food web. This revised version was published online in July 2006 with corrections to the Cover Date.     

波速线性变化介质中地震波传播特征

根据变速介质中地震波传播所满足的变系数波动方程,推导出波速线性变化介质中一维波动方程的解析解,讨论了波速不均匀性对地震波传播的影响：地震波振幅衰减大小与介质速度梯度有关;频率转折点两侧地震波传播性质;频率与地震波波速关系。     

Research on the Propagation Acting of the Equatorial Planetary Waves on the Western Equatorial Pacific Warm Pool Heat

1 IntroductionIn the Equatorial Pacific, due to the difference between the atmospheric circulation and air-sea interaction, the near-surface seawater heat structure in the eastern and western Pacific presents two ℃obviously different characteristics: warm pool ( > 28 ) in the western equatorial Pacific and cold ℃tongue ( < 24 ) in the eastern equatorial Pacific. The water bodies of these two heat structures would give rise to change in spatial distribution under the action of the equato…     

Application of Wavelet Algorithm to Spectral Analysis of Oceanic Waves and Offshore Structure Responses

Fourier transform (FT) is a commonly used method in spectral analysis of ocean wave and offshore structure responses,but it is not suitable for records of short length.In this paper another method,wavelet transform (WT),is applied to analyze the data of short length.The Morlet wavelet is employed to calculate the spectral density functions for wave records and simulated Floating Production Storage and Offloading (FPSO) vessels' responses.Computed wave data include simulated wave data based on JONSWAP spectr...     

大西洋波高熵的分布变化规律研究

使用1992年10月-1998年12月连续75个月、230个重复周期的Topex／Poseidon卫星高度计有效波高资料，对南北大西洋波高熵的空间分布特征和时间变化规律进行了研究，统计分析了大西洋波高熵的多年的空间分布特征和多年各月的时间变化规律。结果表明，大西洋波高熵呈现出中间低、南北高的马鞍形空间分布特征和明显季节变化的规律，与大西洋的平均有效波高、气候的地理分布以及大气活动分布特征和变化规律相一致。     

Annual Variability of Sea Surface Height and Upper Layer Thickness in the Pacific Ocean

The annual variabilities of the sea surface height in the Pacific Ocean were investigated by analyzing the TOPEX/POSEIDON satellite data and by solving a reduced gravity model. We discuss how adequately the simple model can capture the variabilities of the sea surface height, and what the cause of the variabilities is. Three large amplitude peaks in the satellite data are found along the 12°N longitude line. Two elongated zones with a large amplitude are also found: one extends east-west along 6°N and the other extends northwestward from South America around 25°S. These features are adequately reproduced in the numerical simulation of the reduced gravity model. The propagation of the Rossby wave is analyzed by the use of the extended Eliassen-Palm flux to investigate the mechanism of these annual variabilities. The two east peaks around 12°N can be explained in terms of the interference between the local Ekman pumping and the free wave emitted near the western coast of North America, and the most western peak is affected by the Rossby wave formed by the local wind stress. The elongated zonal area around 6°N is mainly due to the local Ekman pumping. Another area around 25°S results from the convergence of the free Rossby wave emitted from the eastern boundary and the area with the strong wind stress curl off South America. A discrepancy between the satellite data and the model results suggests that the eastern equatorial Pacific Ocean is relatively calm in the model but not in the satellite data. This revised version was published online in July 2006 with corrections to the Cover Date.     

南海一个罗斯贝标准模态的特征与归因

南海是一个准封闭海盆,其本征值问题是理解南海动力学的重要内容。本文利用一种新的泛函工具—多尺度子空间变换,从卫星观测资料中分离得到一个南海本征模态,即罗斯贝标准模态的近似场。发现该模态的周期为6个月左右、波长近250 km,在深水海盆向西传播,这与寿命为3个月左右的南海中尺度涡群体活动特征相一致。在此基础上,本文通过Liang-Kleeman信息流这一严格建立在第一性原理上的定量因果分析工具,探究南海两个最重要外部强迫,即黑潮入侵与南海季风对该罗斯贝标准模态的影响。结果表明二者与该模态均有较强因果关系,但分别影响模态的不同阶段：黑潮入侵主要影响其1/2π和3/2π位相,季风的作用则体现在3/4π位相。二者共同作用,调制该模态在近一个周期内的变化。进一步研究发现,黑潮入侵的过渡态是影响该模态的关键,这时黑潮在南海的分支与流套强度相当,有利于吕宋海峡西部形成不同极性涡旋的排列,从而影响南海内部罗斯贝标准模态。对南海季风而言,冬季风与夏季风的成熟阶段是影响该模态的重要时期,但并非整个南海的季风都发挥作用,泰国湾是季风改变南海罗斯贝标准模态的关键区域,这表明局地的强迫对激发全局模态起作用。     

太平洋波高熵的分布变化规律研究

使用1992年IO月到1998年12月连续共75个月、230个重复周期的Topex／Poseidon卫星高度计有效波高资料，对南、北太平洋波高熵的空间分布特征和时间变化规律进行了研究。统计分析了太平洋波高熵的多年的空间分布特征和多年各月的时间变化规律。结果表明，太平洋波高熵呈现出中间低、南北高的马鞍形空间分布特征和明显季节变化的规律，与太平洋的平均有效波高和气候分布特征和变化规律相一致。给出了南北太平洋模拟波高熵的计算公式及计算稳定性检验。