中国海洋卫星及应用进展

中国十分重视海洋遥感及其监测技术的发展,初步形成了具有优势互补的海洋遥感观测体系,并发挥了显著的经济和社会效益。其中,海洋一号(HY-1A/B)卫星已经广泛应用于中国海温预报业务系统、冬季海冰业务监测、夏季赤潮和绿潮监测、海岸带动态变化监测、近岸海水水质监测和渔业遥感监测等方面。海洋二号(HY-2A)卫星不仅填补了中国海洋动力环境卫星遥感的空白,也是目前国际上唯一在轨运行的集主被动微波遥感器于一身的综合型海洋动力环境卫星,具备同时获取风场、有效波高、海面高度和海面温度的能力。通过卫星获得的数据提高了中国海洋环境监测与灾害性海况预报的水平,为国民经济建设和国防建设、海洋科学研究、全球变化研究等提供了可靠的遥感数据,同时还在国际对地观测体系中发挥了重要作用,受到国内外用户的高度认可。海洋一号和海洋二号卫星系列为中国建立完善的海洋环境立体监测体系奠定了坚实基础。根据国家发展和"一带一路"建设的实施,在加快建设海洋强国、维护海洋权益和加快发展海洋经济的进程中对海洋遥感的发展也进一步提出了更高的要求和更紧迫的需求。为此,紧紧围绕国家海洋强国战略需求,在《国家民用空间基础设施中长期发展规划(2015年—2025年)》中专门规划了海洋观测卫星系列,服务于中国的海洋资源开发、环境保护、防灾减灾、权益维护、海域使用管理、海岛海岸带调查和极地大洋考察等方面,同时兼顾陆地和大气观测领域的需求。在充分继承已有HY-1A/B、HY-2A、高分三号(GF-3)和中法海洋卫星(CFOSAT)成功研制经验和应用成果的基础上,发展多种光学和微波遥感技术,建设新一代的海洋水色卫星和海洋动力环境卫星,具备卫星组网观测能力;发展海洋监视监测卫星,构建优势互补的海洋卫星综合观测体系。通过空间基础设施的建设,海洋遥感卫星必将在建设海洋强国的进程中发挥出重要作用。     

广西凭祥盆地深水底流沉积类型及其研究意义

内波、内潮汐沉积和复合流沉积是二十余年来在古代深水环境中新发现的一种具牵引流性质的沉积相类型,由于地层沉积记录十分有限,制约了深水底流沉积的沉积学研究。大比例尺实测地质剖面和精细露头测量表明,底流沉积发育于凭祥盆地深水沉积之中,通过对其沉积构造精细剖析和古水流测量,识别出内波、内潮汐沉积和复合流沉积,其中内波、内潮汐沉积以双向交错层理、单向交错层理、透镜状层理为特征,复合流沉积以复合流层理、丘状交错层理和较陡的爬升波纹层理为特征,进一步表明存在浊流和底流的交互作用,为古代地层中的深水底流沉积提供了又一研究实例。     

Fifteen Years of Ocean Observations with China Argo

For 15 years since the beginning of China Argo project, China has deployed over 350 profiling floats in Pacific and Indian ocean, and constructed China Argo ocean observing network. Moreover, we have setup the Argo data receiving, processing and distributing system, and developed various Argo data products using Argo observations, which has promoted the progress of ocean data sharing in China. The abundant Argo data have become a main data source in oceanic and atmospheric basic researches and operational applications. A batch of important achievements in basic research and operational application have been brought, e.g. in aspects of tropical cyclone (typhoon), ocean circulation, meso-scale eddy, turbulence, heat/salt storage and transport and water mass, as well as in ocean, atmosphere/climate operational forecasting and predicting. With the extension of the international Argo program from “Core Argo” to “Global Argo”, we are faced with great challenges in the long-term maintaining and sustained developing of our Argo ocean observing network. It is suggested that we should take the opportunity to construct China regional Argo ocean observing network as soon as possible in adjacent northwestern Pacific and Indian ocean using Chinese BeiDou profiling floats, which will make us to take responsibility and obligation of a big country for addressing global climate changes and preventing natural disasters.     

Analysis of interaction between ship bottom air cavity and boundary layer

The successful designs of hulls for ships employing drag reduction by air bottom cavitation have been based on solutions of inverse problems of the theory of ideal incompressible fluid. However, prediction of the drag reduction ratio, the air demand by ventilated cavities and the cavity impact on the hull–propeller interaction is impossible in the framework of this theory because all mentioned characteristics depend on interaction of air cavities with the ship boundary layers. Because the known CFD tools are not fitted to ventilated cavitation at low Froude numbers, an analysis of this interaction requires a novel flow model. This model includes the incompressible air flow in the ventilated cavity, the compressible flow of a water–air mixture in the boundary layer on cavities and downstream of them and the curl-free incompressible outer water flow. The provided 2D computations employing this model allows for explanations of the earlier observed effects and for prediction of the air demand by ventilated cavities. The computed velocity profiles downstream of cavities are in the accordance with the available experimental data.     

Spatial distribution of crustaceans associated with shallow soft‐bottom habitats in a coral reef lagoon

The ecology and diversity of the shallow soft‐bottom areas adjacent to coral reefs are still poorly known. To date, the few studies conducted in these habitats dealing with macroinvertebrate fauna have focused on their abundance spatial patterns at high taxonomic levels. Thus, some aspects important to evaluate the importance and vulnerability of these habitats, such as species diversity or the degree of habitat specialization, have often been overlooked. In this study we compared the crustacean assemblages present in four different habitats at Magoodhoo Island coral reef lagoon (Maldives): coral rubble, sandy areas and two different seagrass species (Thalassia hemprichii and Cymodocea sp.). Forty‐two different crustacean species belonging to 30 families and four orders were found. ‘Site’ was a significant factor in all of the statistical analyses, indicating that tropical soft‐bottom habitats can be highly heterogeneous, even at a spatial scale between tens and hundreds of meters. Although traditionally it has been considered that seagrass beds host greater species diversity and abundance of organisms than adjacent unvegetated habitats, no differences in the univariate measures of fauna (abundance of organisms, number of species and Shannon diversity) were observed among habitats. However, sandy areas, coral rubble and seagrass beds exhibited different species composition of crustacean communities. The percentage of taxa considered as potential habitat specialists was 27% and the number of species exclusively occurring in one habitat was especially high in seagrass beds. Thus, degradation of this vegetated habitat would result in a great loss of biodiversity in tropical shallow soft‐bottom habitats.     

基于长期观测的辽东湾口东部海域水动力特征研究

辽东湾口东部海域是辽东湾与渤海中部进行物质和能量交换的主要通道之一。本文利用坐底式海床基平台获取的近8个月的水动力连续观测资料,通过谱分析和调和分析方法对该海域的潮汐、潮流特征进行分析,并讨论了余流及底层温度的季节变化规律。研究结果表明:该海域潮汐属于不规则半日潮,平均潮差为0.95 m,最大可能潮差为2.27 m。潮流属于不规则半日潮流,M₂分潮流为其优势分潮流。主要分潮流运动形式为往复流,最大流速方向为西南-东北向。余流的季节性特征较为明显:秋季,余流流速在中层达到最大,流向以西南向为主;冬季,余流流速垂向变化较小,并呈西南偏西向流动;春季,流速随深度增加而减小,流向从表层至底层呈现逆时针旋转的特征。受底层潮流、水平温度梯度及海面温度日变化的影响,底层温度表现出短期的高频变化特征:秋季,短期振荡以半日周期信号为主;冬季,全日周期信号较为显著;春季,短期振荡的现象较弱。     

孟加拉湾海表盐度变化特征的卫星遥感应用研究

本文利用2011年8月至2014年3月Aquarius卫星盐度产品结合Argo等实测盐度资料,探讨了孟加拉湾海表盐度的季节及年际变化特征。结果显示,Aquarius与Argo盐度呈显著线性正相关,总体较Argo盐度值低,偏差为-0.13,其中在孟加拉湾北部海域负偏差值比南部海域更大,分别为-0.28和-0.10。Aquarius卫星与Argo浮标在表层盐度观测深度上的差别是造成此系统偏差的主因。Aquarius盐度资料清晰显示了孟加拉湾海表盐度具有明显的季节变化特征,包括阿拉伯海高盐水的入侵引起湾南部海域盐度的变化以及湾北部淡水羽分布范围的季节性迁移等主要特征。此外,分析还揭示了2011(2012)年春季整个湾内出现异常高盐(低盐)现象。研究表明,2010(2011)年湾北部夏季降雨减少(增加)导致该海域海水盐度偏高(偏低),并通过表层环流向南输运引起次年春季湾内表层盐度出现异常高盐(低盐)现象,春季风应力旋度正(负)距平通过影响盐度垂直混合过程对同期表层盐度异常高盐(低盐)变化也有影响。     

中国近海以及邻近海域海洋再分析产品(CORA)中季节内变化的评估

A regional reanalysis product—China Ocean Reanalysis(CORA)—has been developed for the China's seas and the adjacent areas. In this study, the intraseasonal variabilities(ISVs) in CORA are assessed by comparing with observations and two other reanalysis products(ECCO2 and SODA). CORA shows a better performance in capturing the intraseasonal sea surface temperatures(SSTs) and the intraseasonal sea surface heights(SSHs) than ECCO2 and SODA do, probably due to its high resolution, stronger response to the intraseasonal forcing in the atmosphere(especially the Madden-Julian Oscillation), and more available regional data for assimilation. But at the subsurface, the ISVs in CORA are likely to be weaker than reality, which is probably attributed to rare observational data for assimilation and weak diapycnal eddy diffusivity in the CORA model. According to the comparison results, CORA is a good choice for the study related to variabilities at the surface, but cares have to be taken for the study focusing on the subsurface processes.     

南海中尺度涡强度的季节和年际变化分析

为了研究南海中尺度涡强度的季节和年际变化规律,利用Matlab提取50 a(1958~2007年)简单海洋资料同化(Simple Ocean Data Assimilation,SODA)月平均数据集中流场和海表面高度场数据,应用一个涡旋自动探测算法对南海中尺度涡初始生成位置进行分析,并分析了海表面高度异常均方根值的季节变化和年际变化。结果表明:50 a里南海中尺度涡主要分布在吕宋岛西北海域、吕宋岛西南海域和越南以东广大海域,秋、冬季中尺度涡能量较高,春季中尺度涡最弱,中尺度涡强度高值区年际变化明显。从季节变化上看,海面高度异常均方根春、夏季最小,秋冬季最大;从年际变化上看,与同时期Nino3指数有显著负相关,周期大约为3 a。     

Early Mesozoic Southward Subduction of the Eastern Mongol–Okhotsk Oceanic Plate: Evidence from Zircon U–Pb–Hf Isotopes and Whole‐rock Geochemistry of Triassic Granitic Rocks in the Mohe Area,NE China

In this paper, we present new U–Pb zircon ages, Hf isotope data and major and trace elements for Early Mesozoic granitic rocks in Mohe area in the Erguna Massif of northeast China to elucidate the southward subduction of the eastern Mongol–Okhotsk Oceanic plate in Early Mesozoic. Zircons from two representative intrusions, syenogranites and monzogranites, in the Mohe area are euhedral–subhedral in shape, display oscillatory growth zoning in cathodoluminescence (CL) images, and have Th/U ratios of 0.10–0.72, and in combination these features indicating that the zircons are of igneous origin. U–Pb zircon dating results demonstrate that the syenogranites formed at 245.1 ± 1.4 Ma and monzogranites formed at 212.2 ± 1.7 Ma. These granitic rocks are characterized by high SiO₂, Al₂O₃ and (Na₂O + K₂O), low TFeO, MgO, TiO₂ and P₂O₅ concentrations, belonging to the high‐K calc‐alkaline series. They are enriched in LREE and large ion lithophile elements (e.g., Rb, K, and Sr), depleted in HREE and high field strength elements (e.g., Nb, Ta, Th, and Ti), as well as very weak negative Eu anomalies (Eu/Eu* = 0.48 ~ 1.01). Their zircon εHf(t) values range from −7.9 to −2.0 and range from 0.20 to 0.49, in response to their two‐stage Hf model ages (T_DM2) range from 1.40 Ga to 1.77 Ga range from 0.94 Ga to 1.24 Ga, respectively, indicating that primary magmas of syenogranites were derived from partial melting of newly accreted juvenile crustal material that formed from the enriched mantle during the Mesoproterozoic, monzogranites are generated by partial melting of newly accreted juvenile crustal material that formed from the depleted mantle during the Meso‐ to Neoproterozoic. We conclude, therefore, that the early Mesozoic granitic rocks of the Mohe area are associated with the continuous southward subduction of the Mongol–Okhotsk oceanic plate rather than the Paleo‐Asian and circum‐Pacific tectonic regimes.