琼东北浪控海岸的发育

根据波浪能量与潮汐能量的强弱关系,琼东北海岸属浪控海岸,其形态以岬湾螺线海岸、岬湾弧形海岸和障壁海岸为特征.文章对以上几种海岸的发育机制、形成演变过程、地貌特征、沉积物分布和运移趋势进行了分析讨论;同时对海岸的稳定性问题进行了某些探讨,其中着重对南渡江三角洲前缘的侵蚀和铺前湾及海口湾的演变关系进行了预测.     

北戴河海滩养护中的原滩环境调查

从海岸演变、沉积过程、动力条件、泥沙运移等多角度阐述了北戴河海滩养护区域自然环境条件.北戴河海岸属于岬湾沙质海岸,具备岬湾养滩的天然条件,发育多条断续分布的水下沙坝,原滩剖面为侵蚀性剖面;西海滩蚀退速率＞2 m/a,属于严重侵蚀岸段;波浪的强浪向NNE和ENE,常浪向S,潮流为NE —SW向的往复流,沿岸泥沙净输沙方向为NE— SW向.洋河浅海泥沙中值粒径为0.31～0.58 mm,物化性质均符合养滩需求,为理想沙源.通过构建合适的人工岬头和离岸潜堤配合人工养滩可以恢复受蚀的海滩.     

华南岬湾海滩冲淤演变特征及其机制分析—以南澳岛前江湾为例

岬湾海滩在华南地区普遍分布,众多海滩面临侵蚀退化问题,对其海滩冲淤演变特征及机制的研究具有重要的现实意义。本文以粤东重要的旅游海岛南澳岛南部的前江湾为研究区,利用滩面调查、遥感影像数据与历史海图和实测水深数据,研究1970—2022 年海滩冲淤特征,并从水动力、沿岸输沙、稳定岸线形态等方面,探讨人类活动对海滩冲淤演变的影响机制。结果表明：前江湾海滩蚀淤演变在东南沿岸码头防波堤海岸工程建设前后呈现不同的空间变化特征,切线岸段前期侵蚀、后期侵蚀加剧,弧形岸段前期淤积、后期侵蚀;人类海岸工程造成的岬角位置变化和沿岸输沙受阻是影响海滩蚀淤演变的主要机制,导致岬湾岸线平面形态变为不稳定状态,区域沉积物的亏损也加剧了海岸失衡;自东向西的沿岸输沙的不均衡对其海岸线演变的空间特征起控制作用。     

基于原位观测的胶州湾沉积物侵蚀再悬浮过程研究

海洋动力作用下,河口海岸地区海床通常处于动态变化之中。作为地质环境的控制因素,海床沉积物侵蚀再悬浮过程的研究具有重要意义。为阐明胶州湾海域水动力条件对海床侵蚀再悬浮的作用,本文利用海底原位观测三脚架进行了现场观测。观测结果显示：通常条件下,潮流导致的最大海床剪应力可达0.35 N/m²,高于波浪引起的剪应力。涨潮期间,海床发生侵蚀;退潮期间,海床发生淤积。风速达到5 m/s时,波浪引起的剪应力近似等于流致剪应力。风速达到7 m/s时,有效波高为26 cm,波浪对海床侵蚀再悬浮过程起主要作用;此时也会导致海水浊度显著上升,高于通常条件下的2-8倍。分析表明：通常条件下,周期性海流影响海床侵蚀再悬浮过程;而大幅度沉积物再悬浮过程由偶发的波浪事件控制。针对胶州湾沉积物动力学机制的深入研究仍待进一步开展。     

粤东靖海湾海岸地貌动力演变及其工程影响

受人为工程的影响,相对稳定的岬湾海岸地貌常经历显著的动态调整。本文以粤东靖海湾典型岬湾海岸为例,运用Mc Laren模型、波浪动力场数值模拟、等深线对比、冲淤计算等多种方法,从海岸地貌动力学角度,对人为岬角工程前后岬湾海岸地貌动力过程和冲淤演变进行综合分析。结果表明:1)海岸地貌动力系统内常存在负反馈机制以维持系统的稳定。岬角工程后上岬角防波堤沿SSW延伸,ESE和E向浪经过防波堤时发生绕射,波能削减,湾顶动力减弱,海滩沉积物从下岬角向湾顶反向运移;2)海滩的蚀积状态在工程前后发生了转换,工程前遮蔽段侵蚀、开敞段堆积;工程后遮蔽段堆积、开敞段侵蚀;3)海湾水下地形对岬角工程的响应敏感,工程后海湾水下地形冲淤剧烈。     

黄河三角洲海岸剖面类型与演变规律

根据1976-2002年黄河三角洲滨海区36个断面的地形实测资料以及利津水文站的水沙资料,运用动力地貌学的方法,对黄河三角洲海岸剖面形态及冲淤演变进行了研究。结果表明,黄河三角洲海岸剖面可分为建设型、破坏型和稳定型三种基本类型。建设型海岸分布于行水河口,等深线向海推进的距离取决于入海泥沙的堆积过程与海洋动力对泥沙的侵蚀过程两者之间的对比;破坏型海岸主要分布于停止行河不久的废弃河口附近,剖面侵蚀深度与海洋动力条件尤其是潮流流速大小密切相关;而稳定型海岸主要分布于长时间不行河的湾湾沟口附近和广利河以南岸段,前者受河海动力因素影响较小,而后者主要与莱州湾潮流流场有关。     

三亚湾海岸动力演变的数值模拟研究

近年来,海岸侵蚀呈现不断加剧的趋势,给沿海地区经济社会的发展造成了极大危害。关于三亚湾海岸侵蚀过程及其动力学研究多停留在定性或半定量阶段。从海岸动力地貌学角度出发,基于沉积物迁移理论,利用数值模拟方法,定量研究了三亚湾海岸在波浪和潮流作用下的动力演变过程。计算结果重现了海水波浪的传播形态及动态特征:涨潮时,波高极值相对较大,水位随之升高,波动现象明显,波动形态复杂;落潮时,波高极值相对减小,水位也随之降低,海面相对较平静,波形态在离岸区域较单一,仅在近岸区域相对多样化。同时,数值模拟结果也很好地显示了三亚湾岸线附近的沉积或侵蚀过程特征:三亚湾西段海洋动力条件较强,沉积或侵蚀现象明显,沉积/侵蚀能力由三亚湾西段逐渐向东段减小。此外,以海洋动力学机制为基础,定量模拟了三亚湾海岸侵蚀与演变物理过程,为该地区海岸开发利用、海岸环境保护提供科学依据。     

华南岬间砂质海岸稳定性研究

岬间海湾平衡平面形态规律在海岸长期侵蚀演变预测方面有着广泛的应用,已成为国外研究砂质海岸演变与稳定的重要课题。首先回顾了三种比较典型的经验岬湾形态方程,然后运用当前确定岬间海湾静态平衡形态最广泛使用的经验关系—抛物线关系,对华南31个岬间海湾的稳定状况进行了预测、分类。同时,采用数字岸线分析系统,计算了1990~2000年前后华南岬湾海滩的岸线进退速率,进一步分析、探讨了华南岬间海湾岸滩的稳定状况。     

现代黄河三角洲滨浅海区的灾害地质

利用卫星遥感、测深、浅地层剖面及钻孔资料研究了黄河三角洲海岸及近海海洋灾害地质,编制了黄河三角洲海洋灾害地质图。黄河三角洲海岸灾害地质以海岸侵蚀为主,根据1976—2001年海岸的变化速率,可将海岸分为快速侵蚀海岸、中等程度侵蚀海岸、稳定海岸和淤积海岸四类,快速侵蚀海岸和中等程度侵蚀海岸长期以来遭受侵蚀。灾害地质因素有浅层气、灾害地貌、活动断层、海底滑坡、底辟、隆起脊、埋藏冲沟一古河道。浅层气主要分布在老黄河口附近渤海海底,近岸少见。浅层灾害地貌主要分布在三角洲前缘斜坡上的扰动区。扰动区位置在整个三角洲上变动明显,有向岸移动的趋势,斜坡坡度减小,扰动强度减弱。底辟除了发生在废弃三角洲侵蚀区外,还发生在三角洲外的渤海海底下部。隆起脊位于黄河口东部渤海海底,沿NE—SW方向发育,顺隆起脊发育活动断层。     

日照石臼港人工岬湾海岸设计及稳定性研究

基于日照万平口海区三期水深地形调查资料、水动力及海底沉积物调查数据,研究了日照石臼港海域人工岬湾海滩建设前后波浪场的变化、沉积物在波浪作用下沿岸输运变化及海岸侵蚀冲淤特征,并模拟验证了人工沙滩建设后的平衡岸线,明确了不同长度防波堤建设后海滩的稳定性及其设计的合理性。结果表明:防波堤建设前研究区入射波浪与岸线有一定夹角,导致波浪作用下沉积物有由南向北输移的趋势;人工岬湾的建设可改变近岸波浪场,继而影响沿岸泥沙输运,对岸滩稳定有重要影响;海岸工程、波浪场及泥沙输运三者相互作用,是人工岬湾海岸稳定性的关键因素。     

辽河三角洲地区海平面上升趋势及其影响评估

根据潮位资料分析,辽河三角洲平原和辽东湾东岸近四五十年来相对海平面处于上升趋势,从70年代以来平均每年上升量为5mm左右.考虑到辽河三角洲平原地面下沉以及全球性海平面将加速上升,预计下个世纪内,辽河三角洲平原相对海平面上升的速率将达到8-10mm/a,到2050年相对海平面上升量将达到40～55cm.利用遥感和地理信息系统,对不同的海平面上升量将造成的土地淹没损失进行了预测.如不加防护,相对海平面上升0.5m时,将淹没近4000km2,包括整个营口市区和半个盘锦市区;上升1.0m时,将淹没5000km2.对海平面上升将造成海岸侵蚀、风暴潮和洪涝等灾害加剧等影响也进行了分析.     

Quality evaluation and calibration of the SWIM significant wave height product with buoy data

The significant wave height (SWH) is one of the main parameters that describe wave characteristics and is widely used in wave research fields. Wave parameters measured by radar are influenced by the offshore distance and sea state. Validation and calibration are of great significance for radar data applications. The nadir beam of surface wave investigation and monitoring (SWIM) detects the global-ocean-surface SWH. To determine the product quality of SWIM SWH, this paper carried out time-space matching between SWIM and buoy data. The data qualities were evaluated under different offshore distances and sea states. An improved calibration method was proposed based on sea state segmentation, which considered the distribution of the point collocation numbers in various sea states. The results indicate that (1) the SWIM SWH accuracy at offshore distances greater than 50 km is higher than that at distances less than 50 km, with an root mean squared error (RMSE) of 0.244 4 m, scatter index (SI) of 0.115 6 and relative error (RE) of 9.97% at distances greater than 50 km and those of 0.446 0 m, 0.223 0 and 18.66% at distances less than 50 km. (2) SWIM SWH qualities are better in moderate and rough sea states with RMSEs of 0.284 8 m and 0.316 9 m but are worse in slight and very rough sea states. (3) The effect of the improved calibration method is superior to the traditional method in each sea state and overall data, and the RMSE of SWIM SWH is reduced from the raw 0.313 5 m to 0.285 9 m by the traditional method and 0.198 2 m by the improved method. The influence of spatiotemporal window selection on data quality evaluation was analyzed in this paper. This paper provides references for SWIM SWH product applications.     

2006年夏季琼东、粤西沿岸上升流研究

利用2006年夏季广东、海南、广西近海的海洋水文调查资料和卫星遥感QuikSCAT风场资料分析琼东、粤西沿岸上升流的空间结构特征, 探讨风场、风应力旋度对上升流的影响以及上升流区水温、海流、海平面对上升流的响应。结果表明:琼东、粤西沿岸上升流区并非相互独立, 从10 m层以下已经连成一片。琼东沿岸上升流主要由夏季西南季风驱动而产生, 风应力旋度也有一定贡献。琼东沿岸上升流的强度比粤西强。琼东沿岸海域的上层海水(18 m以浅)以离岸运动为主, 中下层海水以向岸运动为主。上层的离岸流速大于中下层的向岸流速。琼东沿岸的上升流现象是间歇性的, 与沿岸风速强弱有关。琼东沿岸海域海平面的升降与上升流的强弱有良好的关系, 上升流的强弱滞后于海平面的升降约1～2 d。     

基于WOA13数据的海区位置对北大西洋声波导影响分析

应用WOA13季节平均数据和BELLHOP模型,在季节、声源频率等因素确定的情况下,分10 m表面声源和250 m水下声源,分析北大西洋冬季东、西部海区的声波导情况。在给出不同海区位置的声速场和声波导具体信息的基础上,研究其规律:最小声速值和声道轴深度由直布罗陀海峡向外递减扩散,表层声速值和声速梯度由南向北递减,声跃层存在于低纬度海区,混合层在低纬度通常在100 m以内,在高纬度增加至100 m以上。10 m深度表面声源的汇聚区反转深度随纬度增加逐渐减少,西部海区深于东部海区;西部海区的汇聚区跨度大于东部海区,东西部跨度最大值出现在25°N和15°N,传播损失基本一致。250 m水下声源的汇聚区反转深度浅于10 m深度表面声源时,同样是西部海区大于东部海区,汇聚区跨度呈低-高-低规律,东西部跨度最大值出现在35°N和25°N;东部海区25°N以南、西部海区15°N以南,不同接收深度上的传播损失差异较大,以北差异较小。同时简要叙述了声影区对目标探测的影响。     

2021年春季海洋天气评述

2021年春季(3—5月)的大气环流特征为:北半球极涡为偶极型分布,极涡较常年平均值偏强,中高纬度西风带呈现4波型。3月,南下冷空气活动偏弱,月内海雾过程频发。4月,北部海域受高压影响,低层形势场稳定,冷空气活动减弱。5月,我国近海受温带气旋影响出现大风天气。春季我国近海出现了5次8级以上大风过程,其中冷空气大风过程2次,冷空气和温带气旋共同影响的大风过程1次,温带气旋影响的大风过程2次。春季共有8次海雾过程,3月3次,4月2次,5月3次。近海浪高在2 m以上的海浪过程有8次,大浪日数偏少。西北太平洋和南海共生成2个台风。我国近海的海面温度整体呈上升趋势,东部和南部海域升温明显,南部和北部海域海面温度梯度增加。     

东海南部与台湾以东海域浮游介形类的群落结构

分析东海南部与台湾以东海域浮游介形类的物种和生态类群多样性,并阐述其季节差异与区域差异,同时指出本海区存在4种生态类群,但以高温高盐类群起支配作用.此外,夏、冬两季浮游介形类的丰度有显着的差别,7和12月的均值分别为0.63个/m3和1.22个/m3,而就丰度的水平分布而言,表现出东海南部大于台湾以东海域的分布格局,并在海区的东北部形成数量密集区.同时,还着重阐述本海区的群落结构,本区虽存在3种生态群落,但以外海群落占据绝大部分海域,尤其应指出的是,钓鱼岛邻近海域与台湾北部和东部水域同属于外海群落.最后,分析了由于海域环境因子的变化导致群落生境地理位置的季节性迁移.     

A relict ice-scoured erosion surface in the central North Sea

The interpretation of shallow seismic records from the central North Sea has revealed the existence of an irregular erosion surface within late Pleistocene sediments. A morphological study of this surface has identified two main types of relief: (1) an irregular, rough topography with depressions varying in depth from 1 to 6 m, and in width from 25 to 300 m; and (2) a much smoother topography with relatively few depressions. On a palaeobathymetric map the rough topography extends from ca. 110 to 160 m below sea level (OD), while the smoother topography extends beyond the 160 m below OD contour. This surface is interpreted as an ice-scoured erosional feature formed by the grounding of sea ice in a shallow shelf environment. The stratigraphic position of the ice-scoured surface shows it to be a relict late Weichselian feature formed at ca. 17,000–18,000 B.P.     

Issues of the Holocene transgression on the southern plain of the Changjiang Delta

The paper deals with the question of Holocene transgression on the southern plain of the Changjiang Delta.At the beginning of the transgression, the paleovalleys of the Changjiang and Qiantang Rivers were covered by sea water at first.The shoreline of 8000-7500 yr BP coincided with the -7m isobath of paleotopography. Sea level had already been the present level about 7000-6500 years ago, and the Holocene transgression reached its maximum extent. During the period, the Changjiang and Qiantang Rivers and the Dongtiaoxi valley were turned into estuaries; the eastern area of Shanghai became a shallow sea; some of the bays and lagoons were distributed on the Hang-Jia-Hu and Tao-Ge Plain; the hilly region around the Taihu Lake was coastal marsh and freshwater swamp. Gangshen on the west of Shanghai was formed 7000-4000 yr BP, and during the last 4000 years, the eastern coastal plain of Shanghai advanced quickly toward the sea, and partial clear land of the western Taihu Lake was enclosed and charged into a fre     

Characteristics of coastal trapped waves along the southern and eastern coasts of Australia

The spatial structures and propagation characteristics of coastal trapped waves (CTWs) along the southern and eastern coasts of Australia are investigated using observed daily mean sea level data and results from a high-resolution ocean general circulation model (OGCM), and by conducting sensitivity studies with idealized numerical models. The results obtained from the sea level observations show that shortterm variations, with a typical period of 1 to 2 weeks, dominate the sea level variability in the southern half of Australia. The signal propagates anticlockwise around Australia with a propagation speed of 4.5 m/s or faster in the western and southern coasts and 2.1 to 3.6 m/s in the eastern coast. Strong seasonality of the wave activity, with large amplitude during austral winter, is also observed. It turns out that the waves are mainly generated by synoptic weather disturbances in the southwestern and southeastern regions. The numerical experiment with idealized wind forcing and realistic topography confirms that the propagating signals have characteristics of the CTW both in the southern and eastern coasts. Sensitivity experiments demonstrate that the difference in the phase speed between the coasts and reduction of the amplitude of the waves in the eastern coast are attributed to the different shape of the continental shelf in each region. The structures and the propagation characteristics of the CTWs around Australia are well reproduced in OFES (OGCM for the Earth Simulator) with dominant contribution from the first mode, although meso-scale eddies may modify the structure of the CTWs in the eastern coast. It is also found that generation or reinforcement of the waves by the wind forcing in the southern part of the eastern coast is necessary to obtain realistically large amplitude of the CTWs in the eastern coast.     

Long-Term and Short-Term Variations of Sea Level in Eastern Canada: A Review

This is a review of sea level data performed at three selected stations (Québec-Lauzon, Harrington Harbour,and Halifax) in eastern Canada in order to investigate the seasonal trends and other long-term and short-term changes which occurred since the beginning of the 20th century. Stations situated in riverine or estuarine regions (e.g., Québec-Lauzon) are significantly affected by freshwater flow in their annual cycle of sea level changes and exhibit a definite maximum in spring and minimum in autumn-winter. Other stations situated in the eastern half of the Gulf of St. Lawrence (e.g., Harrington Harbour) or near the open Atlantic coast (Halifax) mainly follow the general cycle of subarctic regions, with lows in spring-summer and highs in autumn-winter. Such seasonal variations appear to be related to the atmospheric pressure and baroclinic current variations. Secular trends in mean sea level in eastern Canadian waterbodies show a mean rise of about 2.56 mm/yr -1 due to tectonic motions, that is, land subsidence. At several stations in eastern Canada, evidence is found for the influence of the nodal tide (18.6 years), the sunspot cycle (10.8 years), the lunar perigee (8.47 years), the pole tide (14.5 months), the annual cycle (12 months), and semiannual tidal cycle (6 months) in sea level records. Beside long-term oscillations with periods of more than one year, evidence is found for high energetic semidiurnal and diurnal tides where they contribute largely (from 90-95%) to short term variability of sea level. In the residual signal (variations of sea level--tidal variations), short-term variations between 2 to 30 days can be attributed to meterological forcing (atmospheric pressure and winds), longitudinal seiches (2-10 h), atmospheric tides (12 h and 24 h) and inertial oscillations (16-18 h). A regressive model showed that the water discharge from the St. Lawrence River contributes 29% to the monthly residual sea level at Québec-Lauzon. The atmospheric pressure and winds contribute respectively 8.1% and 8.9% at this station. They contribute 52.1% and 7.7% at Harrington Harbour and 41.8% and 14.3% at Halifax. The regression coefficients of residual sea level on atmospheric pressure are respectively estimated to be -1.507 cm. ( hPa ) -1 ( - 0.345 cm. ( hPa ) -1 ), -0.776 cm. ( hPa ) -1 ( - 0.112 cm. ( hPa ) -1 ) and -0.825 cm. ( hPa ) -1 ( - 0.008 cm. ( hPa ) -1 ) at the three stations. Compared to the coefficient of the inverted barometer, estimated to be -1 cm. ( hPa ) -1 , these effects of the atmospheric pressure on sea level variations seem to be amplified at Que´bec-Lauzon by the wind effects (and water discharge) while they are reduced at Harrington Harbour and Halifax.