Possible modulation of migrating diurnal tide by latitudinal gradient of zonal wind observed by SABER/TIMED

Temperature data from SABER/TIMED and Empirical Orthogonal Function(EOF) analysis are taken to examine possible modulations of the temperature migrating diurnal tide(DW1) by latitudinal gradients of zonal mean zonal wind(■). The result shows that z increases with altitudes and displays clearly seasonal and interannual variability. In the upper mesosphere and lower thermosphere(MLT), at the latitudes between 20°N and 20°S, when ■ strengthens(weakens) at equinoxes(solstices) the DW1 amplitude increases(decreases) simultaneously. Stronger maximum in March-April equinox occurs in both z and the DW1 amplitude. Besides, a quasi-biennial oscillation of DW1 is also found to be synchronous with ■. The resembling spatial-temporal features suggest that ■ in the upper tropic MLT probably plays an important role in modulating semiannual, annual, and quasi-biennial oscillations in DW1 at the same latitude and altitude. In addition, ■ in the mesosphere possibly affects the propagation of DW1 and produces SAO of DW1 in the lower thermosphere. Thus, SAO of DW1 in the upper MLT may be a combined effect of ■ both in the mesosphere and in the upper MLT, which models studies should determine in the future.

A numerical study on nonlinear propagation and short-term variability of the migrating diurnal and semidiurnal tides

By using a three-dimensional fully nonlinear numerical model in spherical coordinates and taking the linear steady solutions of the migrating diurnal and semidi-urnal tides in January from the Global-Scale Wave Model (GSWM) as the initial values, we simulate the linear and nonlinear propagations of the migrating diurnal and semidi-urnal tides in the atmosphere from the ground to the lower thermosphere. A comparison of our simulations with the results of GSWM is also presented. The simulation results show that affected by the nonlinearity, the migrating diurnal and semidiurnal tides propagating in the middle and upper atmosphere exhibit evident short-term variability. The nonlinear interactions between the migrating tides and the background atmosphere can obviously alter the background wind and temperature fields, which suggests that the nonlin-ear propagations of the migrating diurnal and semidiurnal tides impact significantly on the transient dynamical and thermal structures of the background middle and upper at-mosphere and the nonlinear effect is an important cause of the difference between the results of GSWM and observa-tions.

Semiannual oscillation,annual oscillation,quasibiennial oscillation,and solar cycle variation of the OH airglow emission in the mesopause region

The vertically integrated emission rate,centroid altitude,peak emission rate,and peak height of the hydroxyl(OH)airglow were calculated from Thermosphere Ionosphere Mesosphere Energetics and Dynamics(TIMED)/Sounding of the Atmosphere using Broadband Emission Radiometry(SABER)observations to study the seasonal and interannual variations in the intensity and location of the OH emission.The emission rate is inversely proportional to the height of the emission,with the semiannual oscillation dominating at low latitudes and the annual oscillation dominating at higher latitudes.The OH emission is modulated by the quasibiennial oscillation at the equator,and the quasibiennial oscillation signal is weak at other latitudes.We represented the vertical transport of atomic oxygen by using atomic oxygen concentrations obtained from a global atmospheric model,the Specified Dynamics Whole Atmosphere Community Climate Model with thermosphere and ionosphere eXtension simulations.Compared with the amplitudes of the migrating diurnal tide(DW1)calculated from temperature data observed by TIMED/SABER,we found that both the vertical transport of atomic oxygen and DW1 amplitudes in the equatorial region exhibit semiannual oscillation and quasibiennial oscillation,which have a strong correlation with the variations in the amplitude and phase of semiannual oscillation and quasibiennial oscillation in OH emission.It is likely that the DW1 affects the vertical transport of atomic oxygen that is involved in the reaction to produce O3,thus affecting the OH emission.We analyzed the relationship between OH emission and solar activity by using the solar radio flux at 10.7 cm as a proxy for solar activity.The results showed that the OH emission is well correlated with solar activity,and the modulation of OH emission by solar activity has a significant latitudinal variation.The small correlation between emission height and solar activity indicates that solar activity modulates OH emission mainly through chemical rather than dynamic processes.

Design Tide Hydrograph with A Given Risk Threshold by A Copula-Based Multivariate Method

This paper describes the development of a T-year design tide hydrograph （DTH）. A core innovation is that the proposed technique uses the design risk threshold and copula-based conditional risk probability to analyze the optimal combination of high waters and low waters of the DTH. A brief description of the method is presented. The in situ semi-diurnal tide data at the coast of Jiangsu Province in China are analyzed. Marginal distributions for high waters and low waters of tides are examined. Furthermore, the joint distributions, condition risk probabilities and risk thresholds of high waters and low waters are presented. Results of the DTH from the proposed method are compared with those from the traditional same-multiple enlarging design approach. It is demonstrated that the proposed method is preferable.

Observation of Internal Tides in the Qiongzhou Strait by Coastal Acoustic Tomography

In this study,power spectral density and inverse analyses were performed to obtain the frequency characteristics and spatial distribution of temperature in the Qiongzhou Strait using reciprocal sound transmission data obtained in a coastal acoustic tomo-graphy experiment conducted in 2013.The results reveal three dominant types of internal tides(diurnal,semidiurnal,and terdiurnal).Spectral analysis of the range-average temperature deviation along the northern and southern transmission paths shows that along the northern path,the energy of the diurnal internal tides was significantly larger than that of the semidiurnal tides.The semidiurnal internal tides,in contrast,were more pronounced along the southern path.A terdiurnal spectrum with an energy level equivalent to that of the semidiurnal internal tide was discernable for both the northern and southern paths.These three types of internal tides can also be recognized in the time variation of the zonal-average temperature deviation.The diurnal internal tides were strengthened along the northern coast,implying their westward propagation and the existence of coastally trapped effects.The other two types of internal tides,which have smaller wavelengths than the diurnal internal tides,were less resolved over the entire tomographic domain due to the insufficient resolution of the inversion.The data quality was verified to be satisfactory by error estimation.

南海中部深水海盆的潮流垂直结构

南海季风实验（SCSMEX）期间,由台湾大学在南海中部深海盆投放了3个定点ATLAS浮标,用来观测长时间序列的水温、海流和气象数据。利用调和分析和EOF方法对1998年10月至1999年4月3个站点近6个月的流速观测资料进行分析,研究了观测海区的潮流空间结构特征。调和分析结果表明,该海区以全日潮流为主,潮流椭圆随深度旋转,且潮流以顺时针旋转为主,潮流振幅存在显著的垂向变化。对实测海流进行10-30 h的带通滤波保留潮周期部分,滤波后的潮流进行EOF分解得到潮流存在不同的垂向模态,证明南海深水海盆潮流具有较强的斜压性。

大亚湾的潮汐动力学研究--I.潮波系统的观测分析与数值模拟

文章作为大亚湾潮汐动力学系列研究的第一部分,展现了大亚湾水动力的最新观测结果,并借助于不规则三角网格海洋模式建立了高时空分辨率的三维潮汐潮流数值模型,重现大亚湾潮位和潮流变化状况。结合实测资料与模拟结果,得到了较以往更为精细的大亚湾潮波系统特征。浅水分潮,尤其是六分之一日分潮在大亚湾内快速增长,成为大亚湾潮波系统的显著特征。在大亚湾范和港M_6分潮振幅达到与M_4、S_2分潮相同的量级。大亚湾外开阔海域的潮流以旋转流为主,但进入湾内后潮流椭圆迅速扁平化,往复流占据主导。在湾内主要潮流通道内,M_6潮流椭圆主轴流速超过了M_4和K_1分潮。潮能通量分析揭示了大亚湾内高频分潮的强耗散,M_6分潮的能量耗散率和半日周期内耗散的总能量均超过了M_4、M_2和K_1分潮。观测到的欧拉余流表现出其湾内不一致的大小潮变化以及湾外所受沿岸流的影响。模拟出的欧拉余流则揭示了大亚湾内的余流多涡旋结构和水体弱交换能力。

日潮特征海域回归潮平均高高潮位的计算方法

针对海岸线定义不适用于日潮特征海域的问题,分析了不同潮汐类型海域潮汐高潮位与月相和月赤纬间关系,提出并实现了日潮特征海域顾及日潮龄值的回归潮平均高高潮位计算。结果表明,在不规则日潮海域月赤纬极值与回归潮高高潮位表现出强相关性。海岸线定义明确为平均大潮高潮面或回归潮平均高高潮位与海岸的交接线更科学。

梯度淹水胁迫下全日潮海区秋茄幼苗的生长和生理反应

以秋茄(Kandelia candel L.Druce)幼苗为材料,在全日潮海区广西英罗湾开展为期5个月的野外梯度淹水胁迫实验。3座平台作为重复,每座设置8个梯度,相邻高程组间的高度相差10cm。实验5个月后测定幼苗的生长状况和一些生理指标。结果表明:秋茄幼苗的生长高度、节数、叶数和大根数这4个外部形态特征指标的最大值均出现在360cm高程组。生长高度、节数、叶数的曲线较为一致,幼苗大根数的略有不同,但总体上可看出太低的高程均不利于这4个指标的增长。叶面积对淹水胁迫的反应与叶数一致,但高程组之间的差异更大。叶绿素含量则表现长时间淹水胁迫促进含量增高。在任一高程组,秋茄幼苗各新生器官生物量分配均表现为:茎>根>叶。各新生器官及全株生物量的最大值出现在360cm高程组,它们的干重曲线表现比较一致。幼苗根系中的活性氧清除酶类活性均高于叶片。根系中SOD酶和POD酶的分布规律较为一致,都以360cm高程组的活性最高。叶片中SOD酶和POD酶的变化则相反,叶片SOD酶随高程增大而降低,POD酶则随高程增大而增大。根系中活性氧清除酶类活性的水平与幼苗全株生物量的关系均呈显著相关,叶片中的则无此相关性。360cm及以上高程组幼苗全部存活,较低高程组有部分死亡。综合本文实验结果,可初步判断北部湾沿海秋茄造林的滩涂高程不宜低于当地平均海平面。

大气中层顶区域波相互作用的一个观测个例

利用 ＳＯＵＳＹ ＶＨＦ雷达的观测数据分析了极区中层顶 ８３．４—９１．２ ｋｍ范围内大气风场波动的非线性相互作用．大气风场的谱在不同高度上均有明显的潮汐分量峰值，纬向风分量中 ３５ ｈ波、半日潮和 ８．９ ｈ惯性重力波构成共振相互作用对，经向风分量中 ３３ ｈ波、半日潮和 １９ ｈ惯性重力波构成共振相互作用对．双谱分析表明，这些共振对在许多高度上都发生耦合．３５ ｈ或 ３３ ｈ波振幅的极小值与半日潮的极大值出现的高度几乎相同，呈现出明显的非线性相互作用特征．说明波的非线性相互作用在空间上不是局域的，而是存在于中层顶区域的几乎所有高度上，这种相互作用不仅导致半日潮振幅随时间的变化，也使半日潮的振幅随空间变化．３５ ｈ和 ３３ ｈ波动可能是在其他时段或其他位置通过行星波与周日潮相互作用产生的，然后传播到观测点并与半日潮发生相互作用．

基于数字图像和激光测距技术的海水潮位研究

海洋潮位数据是海洋领域的基础数据之一,对于开展海洋预报、工程建设、科学研究等涉海业务具有极其重要的意义。我国于20世纪90年代建立了海洋验潮仪检定装置,人工从显示屏读取CCD摄像头拍摄到的液位值,但此方式的读取过程存在人为因素误差,精度无法保证且无法实现实时测量。随着科学技术的不断进步,海洋科研事业对潮位检测技术提出了更高、更严格的要求。本文对CCD采集到的海洋潮位图像进行处理,自动识别潮位值,实现海洋潮位的自动化、高精度、实时测量及测量数据分析,提高计量检测标准技术水平,提升我国海洋潮位监测水平,对海洋预报、海洋综合管理及海洋国防建设都将产生重大意义,具有重要的理论和现实意义。

环台湾岛海域全日分潮的特征和潮汐、潮流的综合性质

用97版POM海洋模式 ,对环台湾岛海域的全日分潮和整个潮汐、潮流综合特征进行三维数值研究。研究海域全日分潮是由太平洋传入的 ,且来自台湾岛北部海区传入的潮波穿越海峡。由吕宋海峡传入的全日分潮对维持南海的潮运动起着重要作用。全日分潮最大流同时线分布表层有5个圆流点 ,其中4个本文首次得到。台湾海峡及其以北海区和台湾东部洋区为不规则半日潮区 ,台湾东南为全日分潮为主的混合潮区。台湾岛北部为气旋式余流涡旋区 ,环绕台湾浅滩为反气旋余流涡旋区 ,澎湖水道开始的转向流预示着海峡及其邻近海区的涨潮流或落潮流的来临。

罗源湾全日潮汐和潮流数值计算

采用不规则三角形网格的分步杂交法,建立罗源湾海域二维变边界全日潮汐和潮流数值模型。将计算值与实测资料比较,结果表明符合程度良好。给出了同潮时线与等振幅线、潮流椭圆、最大潮流及不同时刻潮流场分布。应用该模型可以较系统地了解罗源湾全日潮的潮汐、潮流状况。

地电阻率日变化成因分析

中国部分长期连续观测的地电阻率台站的观测数据呈现出清晰的日变化形态,依据单一测道的变化特征,日变化可分为2类相反的形态:一类观测数据白天下降夜间上升;另一类则白天上升夜间下降。文中结合含水岩土介质电阻率的影响因素、台站电性结构和地电阻率影响系数理论,分析认为固体潮引起的介质电阻率变化幅度太小,以目前地电阻率观测仪器的分辨率还不足以记录到固体潮的影响,地电阻率的日变化主要由昼夜温差所引起。昼夜温差将使浅层介质电阻率发生大幅度的昼降夜升变化,对于浅层介质影响系数为正的测道,其日变化呈现昼降夜升的形态,而浅层介质影响系数为负的测道,其日变化则呈现出昼升夜降的形态。

利用超导重力仪观测资料检测地球近周日共振

简要介绍了地球近周日摆动（ＮＤＦＷ）及其在周日重力潮汐中共振的理论背景，利用武汉和Ｂｒｕｓｓｅｌｓ两台站超导重力仪的潮汐观测结果，采用造积方法（Ｓｔａｃｋｉｎｇｍｅｔｈｏｄ）检测ＮＤＦＷ，根据ＮＤＦＷ在４个周日潮波的共振，得到近周日摆动的本征频率和品质因子．考虑ＮＤＦＷ，可精化地球模型，更客观的理解和分析固体潮观测值和其它一些地球物理现象．

甲藻塔玛亚历山大藻昼夜垂直迁移特性的研究

分离于香港海域的塔玛亚历山大藻单克隆藻株的昼夜垂直迁移特性的实验研究于1994年9月-1995年4月在暨南大学水生生物研究所的人工培养柱里进行。结果表明，该藻具有显著的趋光性和节律性昼夜垂直迁移行为。其昼夜垂直迁移的一般规律为光照开始后立即向上迁移，向下迁移则从光照结束前2h左右开始，直至光照结束后1h左右才在底部形成细胞的最大分布，但在连续光照或无光照的第2或第3天以后，这种规律性的昼夜垂直迁移即完全消失。因此，该藻垂直迁移的调控机制表现为显著的趋光性，但生物学节律可能也起着一定的作用。塔玛亚历山大藻垂直迁移速度与水柱温度密切相关，水柱温度越接近其最近生长温度或垂直温度梯度越小时，其垂直迁移速度越快，在125℃以下，则完全丧失垂直迁移的能力。塔玛亚历山大藻的上迁速度一般比下迁速度快，在最适温度范围甲，其向上迁移速度最高可达120m／h;而下迁速度最高只有0.70m／h。缺氮条件下塔玛亚历山大藻的迁移速度明显减慢，光照期避开表面而聚集于亚表层，并有明显的提前下移的倾向。

重现期高潮位在广西全日潮岸段警戒潮位核定等应用中的局限性分析

对广西沿海各验潮站重现期高潮位进行了计算,通过分析传统重现期高潮位计算方法发现该局限性主要为广西全日潮潮汐性质下天文潮与风暴增水叠加概率过低和广西沿海堤防标准普遍偏低所致。根据不同岸线类型,结合海堤实际防御能力、海洋灾害承灾体和风险区划,提出适用于广西的红色警戒潮位核定新方法,对其它全日潮岸段警戒潮位核定和防潮应急管理等提供新的思路。

胶州湾湾口垂直断面余流分析初探

以走航ADCP(声学多普勒海流剖面仪)在胶州湾外湾口——南起薛家岛北至团岛,对春、秋两季的大、小潮连续一日观测资料,进行垂直断面余流分析。指出湾口春、秋两季的大、小潮一日平均余流,呈现北进南出,北进余流大于南出余流,余流在湾口中间偏北地区转流,上层余流大于下层余流,大潮余流大于小潮余流,秋季余流大于春季余流。

乘潮水位下的船舶通航窗口期和候潮时间探讨

针对乘潮水位下船舶候潮的实际问题,依据我国近岸不同潮汐类型站点的潮汐表逐时数据,采用统计学方法,研究保证率为90%的2 h高潮乘潮水位下的连续可通航窗口期和船舶候潮时间,并从水位历时曲线、日高潮不等及平均海平面的周年变化等角度分析全日潮向半日潮变化时通航窗口期和候潮时间产生差异的原因,探讨乘潮时间和乘潮保证率对候潮时间的影响程度。结果表明,从全日潮向半日潮,通航窗口期逐渐缩短,船舶候潮时间逐渐延长;乘潮保证率对候潮时间的影响更明显。

调制模式、调制比预报方法应用朔望潮的理论依据

朔望潮触发和调制地震的发生已是一个基本事实。朔望潮即是半月潮幅度最大时段再迭加半日潮和全日潮。由于朔望潮量值大，所以它作用到震源系统上影响震源过程的７种效应也大，因而朔望潮与地震的相关性较好。由此作者认为用朔望潮比单纯用半日潮来判断震源过程的不稳定性更好，它可以回避震源地方的很多复杂问题而不影响预报地震的效能。