Variations in the sedimentation in Kara Bogaz Gol Bay related to sea level fluctuations during the Novocaspian time

The structure of the bottom sediments in Kara Bogaz Gol Bay is correlated with the history of the sea level fluctuations in the Caspian Sea during the Novocaspian time based on the radiocarbon geochronology of the coastal and bottom sediments. Instrumental observations of the sea level and the hydrochemical regime of the bay are considered to substantiate the correlations obtained.     

Recent saltmarsh accretion and sea level fluctuations in the Dyfi Estuary,central Cardigan Bay,Wales, UK

Rates of saltmarsh accretion were determined for the Dyfi Estuary, central Cardigan Bay, Wales, using marker layers and X-ray radiographic laminae counts. A three-month study revealed the amount of sediment that had accumulated, totalling 2.5 mm, equivalent to 10.0 mm/yr. The saltmarsh sediment accretion rate estimated by laminae counts is 11.5 mm/yr. These data, compared with previous published data, indicate that the rate of sediment accretion has decreased since the 1920s. This is cautiously proposed as suggesting that the upward trend of relative sea level in the Dyfi Estuary may have been decreasing over the last 80 years.     

Response of the low-frequency fluctuations of sea level to atmospheric forcing along the coasts of the Huanghai Sea and the East China Sea

In this paper, the low-frequency fluctuations of sea level and their relationship to atmospheric forcing along the coasts of the Huanghai Sea and the East China Sea are studied. Spectrum analyses are made for the time series of daily mean sea level, atmospheric pressure and wind stress at seven coastal stations. It is found that at all the stations, the main part of the energy of the sea level fluctuations, within the (2-60)-day period, is concentrated on the (12-60)-day period band and that an obvious spectral peak appears at the 3-day period. Along the coast of the Huanghai Sea, variations in the sea level are greater in winter than in summer. In winter, along the coasts of the Huanghai Sea and the East China Sea there is a kind of sea level fluctuations propagating southwards. Among the many factors causing sea level variation, the most obvious one is atmospheric pressure, followed next by the alongshore wind stress.     

Intraannual variability of sea level around Tosa Bay

Through analysis of monthly in situ hydrographic, tide gauge, altimetry and Kuroshio axis data for the years 1993–2001, the intraannual variability of sea level around Tosa Bay, Japan, with periods of 2–12 months is examined together with the intraannual variability of the Kuroshio south of the bay. It is shown that the intraannual variation of steric height on the slope in Tosa Bay can account for that of sea level at the coast around the bay as well as on this slope. It is found that the steric height (or sea level) variation on the slope in this bay is mainly controlled by the subsurface thermal variation correlated with the Kuroshio variation off Cape Ashizuri, the western edge of Tosa Bay. That is, when the nearshore Kuroshio velocity south of the cape is intensified [weakened] concurrently with the northward [southward] displacement of the current axis, temperature in an entire water column decreases [increases] simultaneously, mainly due to the upward [downward] displacement of isotherms, coincident with that of the main thermocline. It follows that the steric height (or sea level) decreases [increases].     

日本广岛湾非潮汐的水位变化

Nontidal sea level changes generated in Hiroshima Bay of the Seto-Inland Sea in Japan are studied over various time scales, from the sub-tidal （2 d to 1 month） to inter-annual scales （〉2 years）. The total sea level variation produces a standard deviation （STD） of 12.5 cm. The inter-annual component of the sea level variation in Hiroshima Bay oscillates with a STD of 3.4 cm, forming a long-term trend of 4.9 mm/a. The STD of the sea level variation is 9.8 cm for the seasonal component （8 months to 2 years） and 4.7 cm for the intra-seasonal one （1 month to 8 months）. Significant sea level variations with a STD of 4.2 cm also occur in the sub-tidal range. Special attention is paid to the sub-tidal sea level changes. It is found that the upwelling and associated transient sea level changes generated along the north coast of Hiroshima Bay （opened southward） by the strong northerly wind, play a significant role in sub-tidal sea level changes. The transient sea level changes are over 10 cm in most cases when caused by typhoons that pass through the Pacific Ocean offthe Kii Peninsula, located at about 400 km east of Hiroshima Bay. Reasonable sea level changes are evaluated by the balance of pressure forces at the onshore and offshore boundary of the study domain.     

Study on fluctuations of plume front and turbidity maximum in the Hangzhou Bay by remote sensing data

On the basis of the time series of AVHRR data from NOAA satellites and the geographical information system PURSIS, fluctuations of the plume front and the turbidity maximum in the Hangzhou Bay, reflected by the distributions of temperature and suspended sediment concentration respectively, are studied in view of long-term behaviors or seasonal and tidal cycles. The data suggest that the effect of front plays an important role in the development of the turbidity maximum close to the Changjiang Estuary > while the effect of tide dominates over the development of another very turbid water situated in the shoal areas in the southern Hangzhou Bay.     

近50年来杭州湾七姊八妹列岛海域海床演变分析

七姊八妹列岛海域位于杭州湾南部的灰鳖洋内,除了岛礁周围局部存有深沟外,其余地区海床平缓.为了探究该海域海床演变情况,在了解杭州湾来水来沙特征基础上,分析了七姊八妹列岛海域的水动力、悬沙和底质分布特征.不同时期海图的对比分析表明,该海域近岸水深较小,人类活动频繁,围涂筑堤工程较多,一直处于淤积状态,属淤涨型岸滩,而离岸较远的海域,泥沙难于落淤而随潮反复搬运,基本处于冲淤平衡状态.1962～2008年这46 a间,七姊八妹列岛海域总体呈现与岸线走向一致的淤积、冲刷间隔分布的冲淤带.平均淤积厚度约2.2 m,淤积幅度约5.0 cm/a,大多数地方平均冲刷厚度约2.4 m,冲刷幅度约5.0 cm/a.这些特点与当地的水动力条件和泥沙沉积特性相一致.     

Subtidal sea level and current variations in the northern reach of San Francisco Bay

Analyses of sea level and current-meter data using digital filters and a variety of statistical methods show a variety of phenomena related to non-local coastal forcing and local tidal forcing in the northern reach of San Francisco Bay, a partially mixed estuary. Low-frequency variations in sea level are dominated by non-local variations in coastal sea level and also show a smaller influence from tidally induced fortnightly sea level variations. Low-frequency currents demonstrate a gravitational circulation which is modified by changes in tidal-current speed over the spring-neap tidal cycle. Transients in gravitational circulation induce internal oscillations with periods of two to four days.     

GPS技术在杭州湾跨海大桥首级控制网测量中的应用

应用GPS技术对杭州湾跨海大桥进行首级控制网测量,结果表明:(1)合理布设GPS控制网,并采用设置深桩固埋测量标志、增加有效观测时间、加强数据可靠性与精确性的检验、选择科学及合理的坐标系统等方法,可提高观测数据的质量和精度。同时,对观测数据采用Bernese高精度基线处理软件和精密星历进行基线解算、网平差和坐标转换,保证了杭州湾跨海大桥首级控制网的精度在厘米级之内,使成果的质量达到优良。(2)Bernese基线数据的闭合环及复测基线的检核表明:同步环、异步环闭合差量值及复测基线互差量值全部符合限差要求,且在允许值的1/3以内的基线环数分别占93.3%、77.7%和100%,其成果精度达到优良。(3)GPS控制网的控制点点位的中误差全部满足±20mm的技术设计要求,并且有96.6%的控制点点位中误差在限差的1/3范围以内,精度较高。使用精密星历和广播星历两种不同的数据处理方法进行数据处理,其坐标互差吻合得较好,全部互差值均在限差允许值的1/2范围以内,且使用精密星历计算的成果精度明显高于使用广播星历计算的成果精度。     

Coastal sea level variability in the Bohai Bay: influence of atmospheric forcing and prediction

The sea level variabilities, especially the atmosphere-driven sea level variabilities, which are diff erent in studies on diverse areas and timescales, need to be further documented in the Bohai Bay. Coastal sea level data and coincident meteorological data collected hourly at two observation stations (E1 and E2) in the Bohai Bay, which is a typical semi-enclosed coastal sea in China, are analyzed for the period from 19 August 2014 to 18 November 2014. The sub-sampled low-pass (<0.8 cpd) sea levels (SLSLs) at E1 and E2 are almost the same as each other, while the winds are not. On the whole, SLSLs at E1 and E2 are dominantly influenced by the across-shore wind;in detail, the dominant wind orientation at E1 is 65° measured clockwise from north, and SLSL at E2 is significantly influenced by the sub-sampled wind (SW) at 55°. Regression of SLSL onto the corresponding SW in dominant orientation and the atmospheric pressure is used to predict SLSL, which make the frequency of occurrences when the predicted total sea level is within 0.15 m from the observed values increase to 66.03% and 58.08% at E1 and E2 from original 36.71% and 34.80% without using it, respectively. The results indicate that for the prediction of the total sea level variability in the coastal shallow waters, the SLSL influenced by the atmospheric forcing, including local wind and atmospheric pressure, can be predicted using the multivariable linear regression model.     

杭州湾海水碱度研究

用ｐＨ法测定了杭州湾海水的碱度。结果表明,１９９４ 年５ 月份,杭州湾海水在盐度１２ ．０９７～２６ ．３９７ 之间的碱度变化范围为１．５５ ～２．２３ｍｍｏｌ．ｄｍ － ３ ,平均值为１ ．７５７ｍｍｏｌ．ｄｍ － ３ 。相应的比碱度变化范围为０．１０６ ～０ ．３２４,平均值为０．２０２ ． 碱度高值出现在北岸上海石化总厂附近。因受北岸工业废水排放影响,湾内碱度自西北向东南降低。丰水期湾内海水比碱度显著增大,主要受径流的影响。枯水期湾内碱度和比碱度与盐度或氯度呈负相关关系。     

Effect of sea level rise on tidal circulation in the Hooghly Estuary,Bay of Bengal

The issue of sea level rise is receiving considerable attention all over the world. Although the Indian stations have shown mixed trends, a positive sea level trend has been noticed in the Hooghly Estuary, situated on the east coast of India. The Hooghly River serves as a navigable waterway to Calcutta and Haldia ports. The river is tidal for nearly 250 km. To study the water levels and tidal currents in the lower part of the Hooghly Estuary, from sea face at Sagar to Hooghly Point, a vertically integrated numerical model has been used. The model is fully nonlinear and uses a semiexplicit finite‐difference scheme to solve the basic hydrodynamic equations on a staggered grid. This model is coupled with a one‐dimensional model, which has been used for the upper estuary from Hooghly Point to Swarupganj, where the flow is unidirectional. The computed water levels and currents are found to be in good agreement with the available observations. This model is applied to study the alterations in tidal circulation for a rise and fall in the sea level. The results have shown a substantial increase in the amplitude and velocities of the tidal wave due to the sea level rise.     

Geochemical characteristic of hydrocarbon compounds in the Hangzhou Bay

The source and distribution of the organic pollutants such as the oil , n-alkanes籥romatic,and the pesticide in the water column, suspended particulates and surface sediments in the Hangzhou Bay (HB) during winter 1987 and summer 1988 are studied with analytical method of fluorometry, GC, LC, GC-MS, etc.The influence of the tide and salinity on the distribution of dissolved and paniculate organic matter is investigated in this paper. The data show that the highest content of suspending silt, organic matter > and chemical oxygen demand (COD) occurs at salinity 15. This results from the fact that the water front limits the transfer and dispersion of the matter in different water mass, and enriches the suspending silt and organic matter in water column.The running direction of the oil-content equivalue lines is similar to that of the water front, and interrelated closely with the terrestrial materials from the Changjiang River.     

罗源湾南岸上元—坑园牡蛎礁与海平面变化

上元-坑园牡蛎礁位于高潮位以下3m,主要成分为长牡蛎和近江牡蛎,其~(14)C年龄为3043±82a,B.P.。据此推算出罗源湾一带海岸处于缓慢上升状态,速率为1.15mm/a。根据上元-坑园牡蛎礁的上述特征,并结合断块差异升降运动的表现,作者认为这一地区中、晚全新世以来以“陆动型”海平面变化占主导地位。     

长江三角洲120 kaB.P.以来孢粉记录反映的古气候变化及其与海平面的耦合

对上海地区晚第四纪钻孔地层中的孢粉以及较高分辨率测年资料进行了分析.根据孢粉组合恢复了6个植被演替以及古气候期,和该区的海水进退吻合很好.研究发现,120～96 ka B.P.间处于里斯冰期末期,沉积物粗,孢粉稀少;96～84 kaB.P.间处于里斯一玉木问冰期,孢粉以落叶栎一松一枫香一常绿栎一栲为主,气候温暖略湿,海平面上升;84～64 kaB.P.间处于早玉木冰期,气候寒冷,孢粉稀少,海水退出本区;64～20]kaB.P.间处于玉木问冰期,孢粉组合以落叶栎-栗-麻栎-常绿栎-栲-蒿-水龙骨为主,常绿树种大量出现,气候温暖湿润,海平面回升,其中37～34 kaB.P.间气候稍微变凉;22～10 kaB.P.间为末次冰盛期,孢粉含量以及种类稀少,主要以针叶树种和耐干草本植物为主,反映气候冷凉干燥,海水全面退出本区;10 kaB.P.以来,气候开始转暖,尤其进入全新世大暖期后,孢粉以落叶栎-松-常绿栎-禾本科为主.     

杭州湾的三维水流数值模拟

建立了一个基于σ变换和内外模式分裂技术三维水流数学模型，采用有限节点法（平面）和变步长差分法（σ向）对方程进行了离散；通过风生流和环岛水流两个理论模式对所建模型进行了校验，并将该模型应用到杭州湾的三维水流数值模拟中，效果良好，所建模型垂向分辨率高，简单实用，可应用于河口，海岸，湖泊等大范围水域的水流数值计算。     

杭州湾海水中的硼和锶的研究

采用作者研究的ＯＰ－ 乳化剂增敏姜黄素分光光度法测定海水中的溶解硼,用ＩＣＰ－ ＡＥＳ法测定海水中的溶解锶。发现在杭州湾海水盐度５ ．５６３ ～２６ ．３９７ ,氯度３．０２２ ～１４ ．５８２ 范围内,硼浓度为０ ．６８ ～３．２４ｍｇ／ｋｇ,锶浓度为１ ．２９～５ ．８８ｍｇ／ｋｇ,Ｂ（ｍｇ／ｋｇ）／Ｃｌ 比值为０ ．２１９～０ ．２４５,平均值为０．２３２±０ ．００７ ,Ｓｒ（ｍｇ／ｋｇ）／Ｃｌ 比值范围为０．３９８ ～０．４４０ ,平均值为０．４１７ ±０．０１１ 。结果表明,湾内海水中的硼和锶浓度与海水盐度或氯度均有很好的线性正相关关系,丰水期与枯水期水样数据关系相同,不因采水时间不同而变化。实验数据统计回归线与理论稀释线比较后表明,湾内海水中锶与硼均具有良好保守性质;湾内海水中的硼和锶主要来自湾外潮汐输入。湾东北沿岸海水高的Ｂ／Ｃｌ比值,暗示着此处有含硼工业废水排入湾内,认为Ｂ／Ｃｌ 比可作为近岸河口海水硼污染的一种指标。杭州湾海水中未检测到硼有机络合物。     

Residual currents in plume front zone of the Hangzhou Bay

It is of some limitations to analyse residual currents by means of the 25 h anchored current measurements. On the basis of the drift tracking and the mooring system data, here, analyses have been done aiming at the structural characteristics and the dynamical mechanisms of the frontal residual current field of the Hangzhou Bay. Especially a theoritical model is given focusing on the frontal density-driven currents. The results indicate that there exists obviously the upper-layer front-driven flow along the orientation of the front during neap tides in the research area of the Hangzhou Bay. But the flow is restrained by the strong vortical viscosity during spring tides. In the lower layer, the effect of the front is little and the subtidal movements are dominated by the tide-induced residual currents. In addition, the influences of wind forcing to the residual current field are also suggested to be important.