Institutional Repository of South China Sea Institute of Oceanology, CAS
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Next-generation sequencing yields the complete mitogenome of stony coral (Favites abdita)
No full textIn this study, the complete mitogenome sequence of stony coral, Favites abdita (Scleractinia), has been decoded for the first time by next-generation sequencing and genome assembly. The assembled mitogenome, consisting of 17,825 bp, has unique 13 protein-coding genes (PCGs), 2 transfer RNAs and 3 ribosomal RNAs genes. The complete mitogenome provides essential and important DNA molecular data for further phylogenetic and evolutionary analysis for stony coral phylogeny
On the precipitation susceptibility of monsoon clouds to aerosols using high-altitude ground-based observations over Western Ghats, India
No full textPrecipitation susceptibility of monsoon clouds to changes in aerosols has been studied initially by utilizing ground based observations from a High Altitude Cloud Physics Laboratory (HACPL), Mahabaleshwar, India collected during monsoon seasons and later compared with the results obtained from satellite observations. Cloud condensation nuclei (CCN) concentration, rain intensity and integrated liquid have been taken from ground based observations for calculating precipitation susceptibility. As a first step, we have analyzed the temporal variation of CCN concentration, rain intensity and integrated liquid water during monsoon season. It is observed that all three parameters exhibit strong diurnal variation with two peaks i.e. in morning and afternoon. CCN showed strong morning peak whereas other two showed during afternoon hours. Later precipitation susceptibility has been estimated using CCN as aerosol proxy and it is higher similar to 0.65 for the integrated liquid water ranging from 0.6 to 0.8 mm. Secondly, we have compared ground based observation with satellite observations carried out using aerosol optical depth (AOD), rain rate and liquid water path. Satellite observations showed that precipitation susceptibility, S-0, using AOD as aerosol proxy is higher (S-0 = 0.98) for liquid water path ranging from 800 to 1000 gm(-2). It is also seen that the results are in agreement with the earlier reported results especially with the report from tropical region. Present analysis also showed that the precipitation is getting suppressed at medium range of integrated liquid/liquid water path. This is the first such study from Indian region explicitly using ground-based observations
Effect of temperature on the accumulation of marine biogenic gels in the surface microlayer near the outlet of nuclear power plants and adjacent areas in the Daya Bay, China
No full textThe surface microlayer (SML) in marine systems is often characterized by an enrichment of biogenic, gel-like particles, such as the polysaccharide-containing transparent exopolymer particles (TEP) and the protein-containing Coomassie stainable particles (CSP). This study investigated the distribution of TEP and CSP, in the SML and underlying water, as well as their bio-physical controlling factors in Daya Bay, an area impacted by warm discharge from two Nuclear power plants (Npp's) and aquaculture during a research cruise in July 2014. The SML had higher proportions of cyanobacteria and of pico-size Chl a contrast to the underlayer water, particularly at the nearest outlet station characterized by higher temperature. Diatoms, dinoflagellates and chlorophyll a were depleted in the SML. Both CSP and TEP abundance and total area were enriched in the SML relative to the underlying water, with enrichment factors (EFs) of 1.5-3.4 for CSP numbers and 1.32-3.2 for TEP numbers. Although TEP and CSP showed highest concentration in the region where high productivity and high nutrient concertation were observed, EFs of gels and of dissolved organic carbon (DOC) and dissolved acidic polysaccharide (> 1 kDa), exhibited higher values near the outlet of the Npp's than in the adjacent waters. The positive relation between EF's of gels and temperature and the enrichment of cyanobacteria in the SML may be indicative of future conditions in a warmer ocean, suggesting potential effects on adjusting phytoplankton community, biogenic element cycling and air-sea exchange processes
Cases Study of Nonlinear Interaction Between Near-Inertial Waves Induced by Typhoon and Diurnal Tides Near the Xisha Islands
No full textNonlinear interaction between near-inertial waves (NIWs) and diurnal tides (DTs) after nine typhoons near the Xisha Islands of the northwestern South China Sea (SCS) were investigated using three-year in situ mooring observation data. It was found that a harmonic wave (f+D-1, hereafter referred to as fD(1) wave), with a frequency equal to the sum of frequencies of NIWs and DTs (hereafter referred to as f and D-1, respectively), was generated via nonlinear interaction between typhoon-induced NIWs and DTs after each typhoon. The fD(1) wave mainly concentrates in the subsurface layer, and is mainly induced by the first component of the vertical nonlinear momentum term, the product of the vertical velocity of DT and vertical shear of near-inertial current (hereafter referred to as Component 1), in which the vertical shear of the near-inertial current greatly affects the strength of the fD(1) current. The larger the Component 1, the stronger the fD(1) currents. The background preexisting mesoscale anticyclonic eddy near the mooring site may also enhance the vertical velocity of DT and thus Component 1, which subsequently facilitates the nonlinear interaction-induced energy transfer to the fD(1) wave and enhances the fD(1) currents after the passage of a typhoon
Modeling the ecosystem response to summer coastal upwelling in the northern South China Sea
No full textA coupled three-dimensional physical model and a nitrogen-based nutrient, phytoplankton, zooplankton, and detritus (NPZD) ecosystem model were applied to simulate the summer coastal upwelling system over the continental shelf of northern South China Sea (NSCS) and its impact on hydrographic conditions and ecosystem. The simulated results were comprehensively validated against field and satellite measurements. The model results show that the near shore ecosystem of NSCS has significant responses to the summer coastal upwelling system. The Shantou Coast to the Nanri Islands of Fujian province (YD) and the east of the Leizhou Peninsula (QD) are two main regions affected by NSCS summer coast upwelling. During summer, these two coastal areas are characterized by nearshore cold and high salinity upwelling current. Further, the summer coastal upwelling serves as a perfect nutrient pump, which lifts up and advects nutrient-rich current from deep to surface, from inner shelf to about 30 km outer shelf. This nutrient source reaches its maximum in the middle of July and then begins to decrease. However, the maximum phytoplankton and chlorophyll a do not coincide with the maximum nutrients and delay for about 10 days. Because of the intensive seasonal thermocline and the complicated current transporting through Qiongzhou strait, the ecological responding of QD is less pronounced than YD. This study has a better understanding of the physically modulated ecological responses to the NSCS summer coastal upwelling system. (c) 2017 Institute of Oceanology of the Polish Academy of Sciences. Production and hosting by Elsevier Sp. z o.o
Pleistocene climate change inferred from multi-proxy analyses of a loess-paleosol sequence in China
No full textThe aeolian loess blanketing the Chinese Loess Plateau (CLP) is sensitive to climate change in monsoonal East Asia. Here, we present a multi-proxy climatic record from a Pleistocene loess-paleosol sequence from the Lantian Basin on the southern margin of the CLP. The measurements include magnetic susceptibility and related magnetic properties, bulk median grain-size, color reflectance, and the color-inferred hematite versus goethite ratio (Hm/Gt). A long-term aridification and cooling trend during the interval from ca 2.22-0.43 Ma is indicated by two magnetic grain-size proxies, corresponding to the global climatic cooling of the late Cenozoic. In addition, at least four intervals of climatic extremes are evident in the record of Hm/Gt ratio: at 1.71-1.65 Ma, 1.26-1.24 Ma, 0.94-0.86 Ma, and 0.62-0.48 Ma. These intervals are characterized by distinct regional climates, which contrast with the global climatic conditions represented in marine sediments. For example, a relatively arid climate is documented from 1.71 to 1.65 Ma, which was rapidly succeeded by a relatively humid climate which is associated with the earliest hominin (with an age of ca 1.63 Ma) in the Lantian Basin
琼东南盆地深水区叠前深度偏移连片处理关键技术
No full text随着琼东南盆地深水区油气勘探不断深入,过去单块地震资料因采集、处理技术不同造成各块资料品质差异,无法满足勘探整体评价的要求。针对上述问题,从炮集资料出发,采用统一的技术流程,使用组合多次波衰减技术压制深水多次波,进行全区连片匹配处理,统一资料品质,改善中深层信噪比。在较高信噪比基础上,基于深水沉积结构、地层速度规律等约束条件建立叠前深度偏移(PSDM)初始速度模型,运用高精度网格层析速度反演技术更新速度场,最终得到合理、高精度的PSDM速度场,有效改善了叠前深度偏移成像质量。该技术有效解决了深水区三维资料品质不统一的问题,改善了中深层成像效果,并在生产实践中取得了显著的应用效果
东印度洋-南海表层现代放射虫的群落结构及其区域差异
No full text现生放射虫的群落结构与海水温度、盐度、叶绿素和海流等环境要素密切相关,具有很强的区域性特征。而东印度洋—南海是亚洲夏季风爆发和发展的关键海区,该低纬度海区具有最为丰富的现生放射虫群落。本项研究通过24小时不间断连续过滤大量表层水的方式,获取了东印度洋—安达曼海—马六甲海峡—南海连续表层水春季3-5月样品,采用虎红染色方法区分出放射虫活体和死的残骸;通过定量研究,率先获取了研究区域的现生放射虫属种组成及其多样性等第一手数据资料及其区域性差异;此外,获取了一些典型特征种在不同发育阶段的形态特征变化过程,这对于沉积物中放射虫化石根据其骨骼形态进行属种的准确鉴定具有重要的应用价值
面向GF-5卫星高光谱传感器的浑浊水体叶绿素a浓度反演算法研究——以鄱阳湖为例
No full text为了分析即将发射的高分5号卫星(GF-5)的高光谱数据在内陆水体水色遥感中的应用潜力,以鄱阳湖为研究区域,利用2009年、2011年和2016年共134组现场实测光谱及其对应的叶绿素a、总悬浮物浓度数据,考虑高浑浊水体引起的叶绿素a浓度变化的光谱响应差异,在进行水体光学分区基础上通过光谱模拟与差分处理开展了叶绿素a浓度跨阶分高光谱反演研究.结果表明:1)进行光学分区有利于提高反演精度,非高浑浊水体(NDCI≥0.06)区域,反演模型判定系数R2达到0.82,均方根误差RMSE为1.12,平均相对误差MRE为0.32,而不进行光学分区的全湖区反演建模R2仅为0.37;2)相较于鄱阳湖前期研究得到的最优多波段反演模型(R2=0.76),利用495、591、675、679、684、688、692和696nm等波长的原始光谱以及差分光谱(一阶差分、二阶差分)建立的跨阶分多波段组合模型可以更有效地反演非高浑浊水体叶绿素a浓度(R2=0.82),但对于高浑浊水体(NDCI<0.06),叶绿素a浓度的高光谱反演能力还需要进一步挖掘
南海巴士海峡三维OBS探测的异常数据恢复
No full text为了探明南海东北部马尼拉俯冲带北段的地壳结构属性,2016年4—6月,"实验2"号科考船执行基金委共享航次,在巴士海峡区域实施三维海底地震仪(OBS)深地震探测实验.实验总共投放48台国产便携式OBS,最终回收41台,放炮测线长2300km,有效放炮10800次,获得了宝贵的第一手数据资料.但初步处理显示,新研发的25台OBS数据异常,未能识别有效震相,给后续计算模拟带来极大困难.为此,本文对异常数据进行了深入分析,通过数据格式检查、导航放炮时间查对、相邻台站信号对比、外部时间和内部时间分析等手段,发现数据异常的原因是采样间隔发生了变化,由设置的4.0ms变为实际的4.5ms,导致内部时间出错,无法正确裁截和对齐震相.新版仪器为节能优化,调低了CPU主频,导致在较高采样率情况下,实际采样间隔比预设要长,这是造成数据异常的主要原因.通过修正采样间隔和数据重采样的方法,我们成功恢复了异常数据,获得了清晰的地震剖面.此项研究不仅挽救了宝贵的地震数据,为下一步地壳结构研究提供数据基础,而且提升了国家基金委共享航次的科学意义,可为今后国产仪器的研发和使用提供重要参考