Hydrography in the north–western Barents Sea, July–August 1996

CTD profiles from the north–western Barents August 1996, have been analysed and characteristics of have been compared with former analyses and investigations The barotropic and baroclinic modes of the Rossby radius of deformation have been estimated in order to give an estimate in order to give an estimate of the spatial scale of variations. The first baroclinic mode of the Rossby radius of deformation is estimated to be around 3 km. Cold halocline water (CHW) is found in the southern part of the investigation area, supporting a hypothesis that the production of CHW is located in the area around Storbanken, and not closer to the shelf break further north. Another hypothesis is proposed: tidal induced horizontal circulation and vertical currents may explain a northward transport of warmer water across sills and banks in the north–western Barents Sea.     

Tidal gravity in Britain: tidal loading and the spatial distribution of the marine tide

Summary. Tidal gravity measurements have been made at six sites in Britain with two nulled LaCoste and Romberg Earth tide gravitymeters. The M ₂ observations from these and two further sites are compared with calculations of the tidal loading from the seas around the British Isles and the major oceans. Models of the M ₂ marine tides are convolved with Green's functions for appropriate radially stratified Earth models. The differences between the M ₂ observations and the theoretical calculations are less than 0.6 μ gals and it is shown that these differences contain further information concerning the errors in the marine tide models. The M ₂ marine tides on the north-west European continental shelf are reasonably well known and this allows a useful test of the feasibility of using tidal gravity measurements for the inverse ocean tide problem in areas where the ocean tides are less well known. The differential gravity loading signal between pairs of gravity stations is shown to be important for considerations of the uniqueness and accuracy of the inverse problem. M ₂ tidal gravity loading maps for the British Isles and Europe have been produced which are of use in making corrections to various geodetic measurements.     

Extraction of the M2 ocean tide from SEASAT altimeter data

Summary. Three complementary methods for the extraction of the M2 ocean tide using SEASAT altimetry are presented and compared. The first method (that developed by Cartwright & Alcock), which provides 'point measurements'of the tide at the crossovers of the SEASAT repeat orbit ground track, has been applied to a study of the tide in tropical ocean areas. The other two methods involve spatial expansions of M2 in terms of either surface spherical harmonics (in the case of the method developed by Mazzega) or Platzman normal modes of the world ocean. The results obtained by each method from only one month of SEASAT data reproduce many features of the tide represented in recent tidal models, and promise well for satellite altimetry as a future source of tidal knowledge.     

白令海峡及其邻近海域潮汐潮能数值模拟

基于非结构三角形网格的FVCOM(Finite-Volume Coastal Ocean Model)海洋数值模式,对白令海峡及其邻近海域的潮汐、潮能进行数值模拟研究。模拟结果同验潮站和实测海流资料符合良好,较好地反映了白令海峡及其邻近海域的潮汐、潮流分布特征和运动状况。根据计算结果绘制了主要分潮的同潮图和潮流椭圆图,对该海域潮汐潮流特征进行了系统分析。结果表明,白令海陆架区、白令海峡和楚科奇海主要以M2分潮为主,而在诺顿湾海域以K1分潮为主,M2分潮潮流在白令海陆架东南部及阿纳德尔湾较强,K1分潮潮流在诺顿湾潮流达到最大值。在此基础上,对其潮汐能的传播与耗散进行分析,结果发现研究海域潮能通量较小,主要分潮在研究海域潮能耗散总量约为751 MW,M2潮能耗散占该总量的52%,K1潮能耗散占38%,潮能进入白令海陆架后,M2分潮主要在圣劳伦斯岛以南陆架区耗散,K1分潮主要在诺顿湾海区耗散。     

洋山港海域潮动力特征及其对工程的响应

距上海陆域外约32 km的洋山港是以小洋山岛链为基础建造的中国首个离岸式深水港口, 其港区陆域是通过封堵北岛链三个主要汊道并抛填成陆而成。大规模的封堵陆连工程改变了该海域的地形边界条件, 海域潮动力特征也随之响应。通过对洋山港海域堵汊陆连工程前后潮位及潮流实测资料的分析研究, 发现洋山港海域的潮动力特征主要表现在:海域潮波倍潮及复合潮增幅随工程的进行而增大, 潮动力表现出明显的非线性特征;海域中部发生壅水;海域潮波向驻波性质变异并于憩流时段引发环状流场。     

人类活动对磨刀门水道河床地形和潮汐动力的影响

基于实测地形和水文资料,探讨人类活动对近期磨刀门水道河床地形和枯季潮汐动力变化的影响。研究结果表明:(1) 磨刀门上游河段大规模河床挖沙引起河床高程显著降低,水深增大,河槽容积增加,底坡降减小;口门围垦整治导致磨刀门口门区水域面积变小,入海口门向海延伸,入海水道增深。(2) 磨刀门水道河床地形变化引起枯季潮汐动力发生变化:上游河段低潮位降低,潮差增大,进潮量增加,潮汐动力明显增强;口门区潮差减小,横洲水道潮能汇聚,水位壅高;水面坡降减小,潮波传播速度增加,咸水界上移。     

Tidal asymmetry in a coastal lagoon subject to a mixed tidal regime

Tidal asymmetry is a key factor in the geomorphology of many coastal lagoons. Whilst tidal asymmetry in semi-diurnal tidal regimes has been extensively studied, its occurrence in mixed tidal regimes is less well understood, and has a number of unique causes and characteristics. Tidal phase duration analysis and least squares harmonic analysis have been used to study the temporal and spatial nature of asymmetry in both offshore and coastal lagoon tides at the Murray Mouth in south-eastern Australia. GIS analysis of bathymetric survey data has been used to study the roles of lagoon bathymetry on tidal distortion.Tidal asymmetry in the Murray Mouth coastal lagoon results from frequency relationships between major astronomical driving tides as well as bathymetry-induced tidal transformations. The frequency difference between the K₁ and S₂ tides produces an important 6-monthly ebb/flood-dominant asymmetry cycle in the incoming oceanic tides, whilst phase relationships between the K₁ and K₂ tides contribute to persistent asymmetry. The use of standard relationships between the M₂ and M₄ tides as asymmetry indicators is shown to be invalid for this mixed tidal regime. In this shallow, microtidal system, the impacts of bathymetry on tidal asymmetry within the lagoon are profound, with inlet and channel configurations identified as the most important controlling factors.The results of this study may inform the strategic management of tidal inlets in mixed tidal regimes, such as the Murray Mouth, that are subject to intermittent or long-term constriction.     

珠江河网横向汊道水面线演变过程及原因探讨——以东平水道为例

基于1960－2016年东平水道三水、紫洞、澜石、浮标厂月均潮差、余水位数据及三水、马口站月均流量数据,以1993年三水－马口分流比突变为切入口,探讨余水位坡度及潮波衰减率等径－潮动力改变下,东平水道水面线与余水位曲率的时空演变特征及其影响因素。结果表明：东平水道在1993年三水分流比剧增之后,1）余水位坡度或潮波衰减率与流量的双累积曲线斜率下降,即余水位坡度或潮波衰减率对流量的依赖性减弱;2）东平水道水面坡度整体下降且上游（紫洞－三水河段）降幅最大,不同季节坡度的变化率介于-67%~-4%,水面线由下凹转为上凸,即曲率由正转负。同时,曲率波动幅度明显减弱,1993年前曲率波动介于2×10^-10~5.48×10^-10,而1993年后波动介于-0.9×10^-10~-0.07×10^-10。上述曲率变化在冬季较夏季显著;3）上述水面线异变的主要原因为,东平水道中上游河道挖沙导致河床地形大幅下切、水位下降、来水量增大,且同时期的航道疏浚加剧这一变化;下游主要受滩涂围垦影响,河道淤浅。以上地形变化导致河道中游径、潮流量增大,径－潮双向顶托使水面线转变为上凸型。受北江上游飞来峡水库调蓄影响以及过水断面宽深比、海平面变化等季节性调节作用,东平水道冬季水面线及曲率变化较夏季显著。     

黄河三角洲潮沟网络形态特征的时空分异规律及其发育过程

潮沟是陆海生态系统交互作用的主要通道,具有高度的时空动态性。以黄河三角洲新旧河道为界,划分黄河北岸（Ⅰ区）、南岸东（Ⅱ区）、南岸西（Ⅲ区）为对比研究区,选择1998—2018年5个关键时间节点的遥感影像为数据源,利用GIS空间分析功能,定量表征了潮沟发育程度的典型形态特征参数,剖析了黄河改道、湿地恢复工程和外来物种入侵等因子对潮沟发育过程的影响,挖掘潮沟网络的时空演变规律。结果表明：① 潮沟的形态特征具有明显的时空异质性。从1998年黄河改道初期至2004年湿地恢复初期,Ⅰ区各等级潮沟数量大幅减少;由于潮滩淤进和互花米草固滩作用,Ⅱ区潮沟数量、密度、分汊率呈现增长趋势,在2013年互花米草的快速扩张期,潮沟曲率、分汊率明显增大;Ⅲ区潮沟发育的等级、长度、密度最大,等级间的转化频率最高,湿地恢复工程导致低等级潮沟数量、长度明显减少,较强的海洋动力抑制了潮沟曲流的发育。② 黄河改道和侧弯丁坝建设导致平均归槽长度（OPL）增大,潮沟网络的排水效率减少。互花米草的快速扩张使排水效率增大,OPL不断降低;潮沟发育程度Ⅲ区>Ⅱ区>Ⅰ区。③ 潮沟系统由快速变化青年期整体进入缓慢变化中年期,发育状态趋于动态平衡。研究成果有助于了解大范围潮沟的发育过程及演变机制,为沿岸潮滩开发与利用提供科学的决策支撑。     

Evolution of sedimentary environments of the middle Jiangsu coast, South Yellow Sea since late MIS 3

An evolutionary model of sedimentary environments since late Marine Isotope Stage 3 （late MIS 3, i.e., ca. 39 cal ka BP） along the middle Jiangsu coast is presented based upon a reinterpretation of core 07SR01, new correlations between adjacent published cores, and shallow seismic profiles recovered in the Xiyang tidal channel and adjacent northern sea areas. Geomorphology, sedimentology, radiocarbon dating and seismic and sequence stratigraphy are combined to confirm that environmental changes since late MIS 3 in the study area were controlled primarily by sea-level fluctuations, sediment discharge of paleo-rivers into the South Yellow Sea （SYS）, and minor tectonic subsidence, all of which impacted the progression of regional geomorphic and sedimentary environments （Le., coastal barrier island freshwater lacustrine swamp, river floodplain, coastal marsh, tidal sand ridge, and tidal channel）. This resulted in the formation of a fifth-order sequence stratigraphy, comprised of the parasequence of the late stage of the last interstadial （Para-Sq2）, including the highstand and forced regressive wedge system tracts （HST and FRWST）, and the parasequence of the postglacial period （Para-Sql）, including the transgressive and highstand system tracts （TST and HST）. The tidal sand ridges likely began to develop during the postglacial transgression as sea-level rise covered the middle Jiangsu coast at ca. 9.0 cal ka BP. These initially submerged tidal sand ridges were constantly migrating until the southward migration of the Yellow River mouth to the northern Jiangsu coast during AD 1128 to 1855. The paleo-Xiyang tidal channel that was determined by the paleo-tidal current field and significantly different from the modern one, was in existence during the Holocene transgressive maxima and lasted until AD 1128. Following the capture of the Huaihe River in AD 1128 by the Yellow River, the paleo-Xiyang tidal channel was infilled with a large amount of river-derived sediments from AD 1128 to 1855, causing the emergence of some of the previously submerged tidal sand ridges. From AD 1855 to the present, the infilled paleo-Xiyang tidal channel has undergone scouring, resulting in its modern form. The modern Xiyang tidal channel continues to widen and deepen, due both to strong tidal current scouring and anthropogenic activities.     

The tidal dynamics of the Irish and Celtic Seas

Summary. Current meter data collected over periods of more than 14 day from the Irish and Celtic Seas are harmonically analysed and presented in maps of tidal stream information. Making use of the analysed current data, and by constructing time series of frictional and inertial stresses which are also harmonically analysed, harmonic constituents of the surface tidal slopes at current meter stations are obtained. Using these with data collected from offshore tide gauges, and in conjunction with coastal tide data, cotidal maps are drawn with some confidence for M ₂, S ₂, O ₁ and K ₁, the M ₂ chart resolving the discrepancy which exists between the different charts of the Celtic Sea already produced. Cotidal maps for M ₃ and M ₄ are also presented.
The mean over a tidal cycle of the energy flux for M ₂, S ₂ and O ₁ is also presented in the form of the total energy flux in these constituents which crosses different sectional lines. A flux of 44 × 10⁶ kW is observed to enter the Celtic Sea from the Atlantic and this is compared with previous estimates. An energy budget is also performed for M ₂, including all the effects of astronomical forcing and Earth tides to enable comparison to be made between the true energy inflow and the estimated frictional dissipation. Finally, comparison is made between the mean of the instantaneous energy flux and the sum of the energy fluxes associated with the major harmonics.     

The tidal regime of the Bristol Channel: a numerical modelling approach

Summary. Two-dimensional numerical models are used to examine the tidal regime of the Bristol Channel. The effect of including S2 in addition to M2 in the models on both the tidal elevations and the residual Eulerian circulation is investigated. The spatial distribution of the maximum spring currents and the time of their occurrence are also computed.
The Eulerian and Lagrangian residual circulations are compared and the effect of model grid size on the former is examined.
Finally the spatial distribution of energy dissipation within, and the total flux of energy into, the Bristol Channel are given.     

南黄海辐射沙脊群里磕脚11DT02孔沉积相分析及环境演化

11DT02孔位于南黄海辐射沙脊群东北部里磕脚沙脊南坡,通过沉积相分析、粒度统计,结合年代地层数据,重建晚更新世以来里磕脚沙脊的长周期环境演化,分析沙脊成因、厘定沙脊发育年代。研究表明:里磕脚沙脊从下至上由潮滩相、硬黏土相、潮滩相和潮流沙脊相组成。潮流沙脊和潮滩由粉砂、细砂和少量黏土组成,两者均成正偏态分布。潮流沙脊和潮滩在概率累积曲线上分别表现为三段式和四段式分布,以跳跃次总体为主,并呈双跳跃特点。研究区晚更新世经历海平面下降发育潮滩环境,到完全暴露形成标志性的“硬黏土”层;全新世初期经历海侵,研究区复又开始潮滩沉积,随后被海水完全淹没,潮流作用渐强,改造下伏潮滩和“硬黏土”,逐渐堆积成高差最大达30 m的脊槽地形。     

On analysis and prediction of tides on the west coast of Great Britain

Summary. Long-period tidal records from eight ports on the west coast of Great Britain are analysed, using both the harmonic method and the response function. Time series up to 9.5 yr were used so that fine structure of certain regions of high energy in the tidal residual spectrum may be examined. This also assisted in accurate separation of tides from surges. According to the currently accepted formulation of M₁, its composition is not compatible with its actual composition in the real tide and, as such, has no useful purpose to serve in computation of predictions. Constituents Sa, Ssa, MA, and MB, are adversly affected by weather and long records are essential for their accurate separation. It has been observed that annual perturbations of S₂, similar to those confirmed in recent years for M₂, also exist but these are not readily recognisable because their speeds are the same as those of constituents T₂ and R₂. These perturbations, being highly sensitive to meteorological forces, are mainly responsible for cusps or humps in the vicinity of major tidal constituents in tidal residual spectra. The relationship of radiational and gravitational tides is found to be in very good agreement with theoretical results. In summer months non-predictable variance reduces to about half of the annual variance, reflecting the regional weather conditions of summer and winter.     

Geomagnetic lunar analysis—the estimation of errors

Summary. It has recently been proposed that a reliable estimate of the errors of tidal harmonics present in geomagnetic data can be obtained by the following method: (1) randomly assign each observation to one of 10 subsets, (2) determine the tidal harmonics separately for each subset, and (3) calculate the standard deviation of the mean from the scatter among the 10 determinations. This method is valid if the subsets are statistically independent, but will lead to an underestimate of the errors if they are not. Here we show that, for real geomagnetic data, the assumption of statistical independence is valid.     

江苏中部海岸互花米草扩展对滩涂围垦的响应

根据2001-2013年遥感影像和野外观测数据,对江苏中部海岸互花米草(Spartina alterniflora Loisel)在滩涂围垦期间的扩展过程进行定量化分析。结果显示：2001-2013年互花米草扩展对围垦的响应大体分为三个阶段：2001-2007年,海堤外米草面积较大,每年新增米草面积及米草年扩展率均和新增围垦面积变化同步,且相关性显著;2008-2010年,海堤外米草面积较小,但米草年扩展率仍然较高;2011-2013年,随着围垦的持续进行,米草扩展进入稳定期。因此,互花米草扩展对于滩涂围垦的不同速率和阶段具有不同的响应。若围垦时保留足够宽度的堤前米草,则围垦可以提高米草的年扩展率,其机理是互花米草种子产量和前缘淤积环境是影响米草扩展的主要因素,而围垦对这两方面都有影响。在后期滩涂围垦时,应保证堤外米草宽度在0.9~1 km之间,实现土地资源的可持续利用。     

海南岛潮汐汊道的现代沉积特征研究*

海南岛存在着大量港湾溺谷型和砂坝泻湖型潮汐汊道。本文以两类潮汐汊道的典型──三亚砂坝泻湖型潮汐汊道和洋浦港湾溺谷型潮汐汊道为例,分析了两类潮汐汊道的成因和地貌发育体系;研究了两类潮汐汊道的现代沉积特征(粒度、重矿、地球化学、有孔虫);对比了两类潮汐汊道的发育模式和沉积模式;探讨了两类潮汐汊道的稳定性。     

Spatiotemporal differentiation and development process of tidal creek network morphological characteristics in the Yellow River Delta

Tidal creeks are the main channels of land-sea ecosystem interactions, and their high dynamics are an important factor affecting the hydrological connectivity of tidal flats.Taking the Yellow River Delta as the research area, we selected remote sensing images obtained during five periods from 1998 to 2018 as the data sources. Based on the spatial analysis function in GIS, the typical morphological characteristics of tidal creeks, such as the level,length, density, curvature, bifurcation ratio, and overmarsh path length(OPL), were extracted to characterize the degree of development of the tidal creeks in the Yellow River Delta wetlands. The spatio-temporal evolution of the tidal creeks was studied, and the development process and the characteristics of the tidal creeks during the different stages of development were investigated. The results revealed that(1) The number, density, and bifurcation ratio of tidal creeks exhibit an increasing trend, but the growth of the trend is slowing. The number of tidal creeks increased by 44.9% from the initial stage of the Yellow River diversion to the late stage of the wetland restoration, but it only increased by 26.2% from the late stage of the wetland restoration to the slow expansion of the Spartina alterniflora.(2) The curvature of the tidal creeks on the landward side is greater than that on the seaward side.(3) The development degree of tidal creek has spatial heterogenetiy, which is Area Ⅲ Area Ⅱ Area Ⅰ.(4)The drainage efficiency is significantly correlated with the tidal creak density and bifurcation ratio. Based on the analysis of the various morphological parameters and the drainage efficiency, it was found that after the rapid change in the tidal creek system in the early stage, the tidal creeks entered a state of slow change, and the development state of the tidal creeks tends to be in dynamic balance. The results of this study are expected to provide scientific support for the sustainable development and utilization of coastal tidal flats.     

近代以来江苏沿海滩涂围垦历史演变研究

近百年来江苏沿海进行了大规模的滩涂围垦开发。本研究评估了近代以来江苏沿海滩涂围垦历史演变情况,分析其演变机理。研究搜集整理了清末至今多种历史地形图、地方志、遥感资料,利用统计分析以及空间分析,定量地揭示近百年来江苏沿海围垦时空变化,并简要分析变化背后的机理。研究结果表明：（1）在围垦的时间分布上,不同时期的历史围垦程度不同,其中民国时期1910 年代和解放以后的1950 年代的围垦规模分别为解放前和解放后的两个围垦高峰时期;（2）在围垦的空间分布上,总的来说,盐城市围垦面积最大,总量占全省总围垦面积近70%,南通、连云港市相对较少,而沿海三市围垦面积排名前五名的分别是大丰市、射阳县、连云区、响水县、如东县;（3）从围垦特点看,空间缓冲区分析显示历史上江苏沿海围垦多为鱼鳞似的圈围,用途则以农业生产、水产养殖、国营盐场为主,工业用地、港口建设用地大大不足,用地综合效益不高。