VIIRS与MODIS海表面温度产品观测能力对比分析

以2015—2016年白天和夜间的VIIRS,MODIS-Terra和MODIS-Aqua三个红外SST产品为研究对象,探讨了3个红外SST的全球覆盖情况,包括统计全年有效观测天数和每日全球海洋覆盖率,将3个红外SST与Argo浮标在全球范围以及大西洋、印度洋、太平洋进行匹配统计分析,同时对匹配点平均偏差与标准偏差随纬度的变化进行研究,最后将3个红外SST进行交叉比对。结果表明:VIIRS在白天和夜间全年观测到的最大有效观测天数高于MODIS-Terra和MODIS-Aqua,该数据白天观测到的范围最大、全球海洋覆盖率也最高,夜间3个红外SST观测范围和覆盖率差别不大;VIIRS SST产品在全球以及3个大洋统计中数据质量较MODIS-Terra和MODIS-Aqua更接近Argo浮标;3个数据白天的SST平均偏差和标准差随纬度变化除了南北高纬度地区,整体浮动相差不大,VIIRS整体偏差在0℃附近,MODIS-Aqua次之,MODIS-Terra大部分都在0℃以下。夜间偏差与标准差随纬度变化平缓,在南北半球高纬度地区波动也小于白天。VIIRS白天和夜间SST值都高于其他2个红外SST。白天,VIIRS与MODIS-Aqua的温度值接近;夜间,则与MODIS-Terra的温度值接近。     

多源星载辐射计SST数据对比分析

基于2018年4种红外辐射计(MODIS-Aqua,MODIS-Terra,VIIRS和AVHRR)的SST数据和3种微波辐射计(GMI,WindSat和AMSR2)的SST数据,分析了7种星载辐射计SST数据的全球覆盖情况,利用Argo数据对7种辐射计SST数据进行了真实性检验,并开展了微波产品、红外产品和Argo的...     

北极星载微波辐射计海表温度遥感观测能力分析

本文利用2016年的AMSR2、GMI、WindSat和HY-2A RM等星载微波辐射计海表温度（SST）数据,分析了北极卫星遥感SST数据的时空覆盖和产品精度情况。结果表明:北极星载微波辐射计SST冬季覆盖率和有效覆盖天数要低于夏季,GMI的SST有效覆盖率较低,AMSR2较高,联合使用AMSR2、GMI、WindSat和HY-2A RM星载微波辐射计SST数据,2月份覆盖率在12%~15%之间,有效观测天数优于26 d,8月份覆盖率全月高于26%,有效观测天数优于29 d。北极地区星载微波辐射计SST数据的误差均要大于全球平均水平,AMSR2数据精度较好,WindSat与AMSR2的精度相当,GMI的均方根误差约是AMSR2的2倍,HY-2A RM数据精度低于其他星载微波辐射计水平。     

2012—2016年可见光红外成像辐射仪（VIIRS）海表面温度产品精度检验分析

本研究以2012—2016年5 a间的可见光红外成像辐射仪（VIIRS）海表面温度（SST）产品为研究对象,利用Argo浮标为主要验证数据、MODIS Terra和MODIS Aqua SST为辅助验证数据,从时间尺度和空间尺度进行检验对比分析,结果表明：VIIRS SST与Argo浮标白天的平均偏差为-0.015 5℃,标准偏差为0.514 0℃;夜间平均偏差是-0.221 4℃,标准偏差是0.418 9℃,白天平均偏差较夜间更接近Argo浮标的观测结果;VIIRS SST在白天和夜间偏差均是夏季大于冬季;白天VIIRS SST在近赤道太平洋海域、近赤道印度洋海域要高于浮标观测的海温,夜间这些地区总体要低于浮标值,白天和夜间标准偏差空间分布差异较小;与MODIS Terra和MODIS Aqua SST月平均偏差对比显示,夏季在南半球VIIRS较MODIS Terra SST偏暖强度减弱,冬季VIIRS较MODIS Terra SST在北半球中高纬度海域偏冷;夏季部分海域VIIRS SST较MODIS Aqua偏低,冬季则是大部分海域VIIRS 低于MODIS Aqua SST。     

东南亚海域HY-1C SST数据评估与校正

海洋一号C卫星（HY-1C）是服务于海洋水色水温、海岸带和海洋灾害与环境监测的业务化应用卫星,是海洋遥感数据的重要来源,对中国HY-1C卫星红外辐射计在东南亚海域的SST观测数据开展评估与校正工作具有重要意义。本研究基于多源卫星SST数据和ARGO浮标测量温度数据,对中国HY-1C卫星在东南亚海域的SST数据进行了质量评估和改进工作。HY-1C SST数据的质量评估结果表明：HY-1C白天的平均偏差、标准差和均方根误差分别为–0.73℃、1.38℃和1.56℃,夜晚数据偏差分别为–0.95℃、1.57℃和1.83℃。与其他同类红外辐射计的数据质量对比发现HY-1CSST数据精度低于其他红外辐射计。采用月平均差值校正、SST分区域差值校正、SST分段校正3种校正方法对HY-1C SST数据质量进行改进,其中HY-1C SST分区域校正的质量提升最明显,标准差、均方根误差接近1℃,夜晚均方根误差比校正前降低了约0.8℃,白天和晚上均方根误差分别降低了32.52%和42.04%。     

SST融合产品在渤黄海的质量评估与修正研究

为获取高空间分辨率与空间覆盖率的海表面温度(Sea Surface Temperature,SST)产品,基于最优插值方法,对微波辐射计Wind Sat、AMSR-E、ASMR2、HY-2 RM和红外辐射计MODIS、AVHRR的SST观测数据进行融合,生成了一种0.1°空间分辨率的每日SST融合产品,利用浮标数据在渤黄海区域进行了精度评估和修正,并分析了该区域的SST时空分布特征。结果表明:SST融合产品的在中国近海的精度为1.1℃,利用浮标数据修正后的精度略有改善;利用修正的SST产品对渤黄海区域SST分布特征进行了分析,分析结果显示,渤黄海海域冬季海温最为均匀,春季在海水升温过程中海温不均匀性明显。     

基于最优插值和贝叶斯最大熵的海表温度融合方法研究

海表温度(sea surface temperature,SST)是影响全球气候的重要因素,在海洋科学研究中占有关键位置。论文基于MODIS红外、AMSR-2和HY-2A微波辐射计数据,分别利用最优插值和贝叶斯最大熵方法对SST数据进行融合,并用i Quam实测数据和Argo浮标数据对2015年SST融合数据进行检验。MODIS、AMSR-2、HY-2A辐射计SST的年平均空间覆盖率分别为15.0%,21.6%,22.0%,最优插值和贝叶斯最大熵融合SST产品的年平均空间覆盖率提高到98.6%和99.4%,融合产品空间覆盖率明显提高。与i Quam实测数据对比,最优插值和贝叶斯最大熵融合产品年平均偏差分别为0.07℃,0.04℃,均方根误差皆为0.78℃,其中3-7月最优插值融合产品的精度略优于贝叶斯最大熵融合产品,其它月份则相反;与Argo浮标数据对比,两种融合产品的均值偏差分别为0.06℃,0.01℃,均方根误差分别为0.77℃,0.75℃。整体上,贝叶斯最大熵融合产品的精度略优于最优插值融合产品,但计算成本较高。     

西北太平洋红外辐射计海表温度数据交叉比对分析

本文将西北太平洋海域作为研究区域,以2003—2009年的三个海表温度(sea surface temperature,SST)红外产品(AVHRR Pathfinder/NOAA,MODIS/Terra和MODIS/Aqua)为研究对象,分别与Argo浮标数据进行了真实性检验,同时红外产品之间也进行了交叉比对分析。通过评定产品间的差异及使用条件,为融合产品数据源选取和权重分配提供参考依据,用以提高融合产品的数据质量。结果表明,三种红外数据与Argo浮标的平均偏差在±0.2°C之间,均方根误差小于0.8°C,且存在明显的季节性变化,白天的平均偏差均是夏季为正、冬季为负,夜间的平均偏差基本均为负偏差,冬季比夏季的偏差更大,冬季的均方根误差较小;三种红外数据之间的平均偏差在±0.1°C之间,均方根误差小于0.6°C;三个红外产品在空间上均能反映西北太平洋海域的海表温度变化趋势,三个产品之间无明显优劣差异;尽管红外数据的空间覆盖率偏低,但是它提供了高精度和高特征分辨率的数据产品,并弥补了近岸海域缺乏观测数据的不足。     

VIIRS和AVHRR海表温度场空间精细度估算

对上层海洋次中尺度过程研究至关重要的卫星海表温度(Sea Surface Temperature,SST)场的空间精细度一直未受到足够重视。由于卫星SST产品反演噪声的影响和实测数据的缺乏等原因,目前对卫星SST场空间精细度的研究受到较大限制。本研究开发了一套估算卫星SST场空间精细度的方法,将Suomi National Polar-orbiting Partnership卫星Visible Infrared Imager Radiometer Suite(Suomi-NPP/VIIRS)和NOAA-15卫星Advanced Very High Resolution Radiometer(NOAA-15/AVHRR)Level-2 SST场的空间能量谱与长时间在同一航线反复观测的高空间分辨率实测海温数据的空间能量谱进行了比较。研究发现VIIRS SST场夜间沿扫描方向在1.5~50 km尺度对海表温度空间能量的分布特征和变化趋势描述准确,日变化导致VIIRS白天场次中尺度空间谱能量相对夜晚有所增加。AVHRR SST场空间谱能量在次中尺度相比VIIRS有较大升高。     

黑潮延伸体海域漂流式海气界面浮标数据分析与评估

漂流式海气界面浮标是创新研制的“小型化、轻质化、免维护”的漂流观测系统,能够测量海面以上3 m气象、水下20 cm海表面温度和波浪参数等11个不同的物理参数,并且已经经过多次观测应用,结果均较好。为实现漂流式海气界面浮标观测数据全球范围的应用,利用2018年黑潮延伸体海域Argo观测的海表面温度(sea surface temperature, SST)、SVP (surface velocity program)浮标观测的海表温度和OISST (optimum interpolation sea surface temperature)数据,通过将其与漂流式海气界面浮标观测数据进行时空匹配以及对比验证,对漂流式海气界面浮标观测的海表面温度进行了系统评估,检验其在黑潮延伸体复杂水文环境下的观测准确性。结果表明,漂流式海气界面浮标观测SST数据与Argo观测SST数据相关系数达到0.9737,均方根误差和平均误差分别为0.5790°C和0.4539°C;与SVP浮标SST数据的相关系数弱于与Argo的相关系数,为0.9285,均方根误差为1.323 0°C,平均误差约为0.979 4°C...     

Microbial Biomass and Organic Nutrients in the Deep-Sea Sediments of the Central Indian Ocean Basin

In order to assess the impact of deep-sea mining on the in situ benthic life, we measured the microbial standing stock and concentration of organic nutrients in the deep-sea sediments of the Central Indian Ocean Basin in the Indian pioneer area. Sediments were collected using box core and grab samples during September 1996. The total bacterial numbers ranged from 10 10 -10 11 cells per g -1 dry weight sediment. There was a marginal decrease in the number of bacteria from surface to 30 cm depth, though the subsurface section registered a higher number than did the surface. The highest numbers were encountered at depths of 4-8 cm. The retrievable number of bacteria were two orders less in comparison with the direct total counts of bacteria. An almost homogeneous distribution of bacteria, total organic carbon, living biomass, and lipids throughout the depth of cores indicates active microbial and benthic processes in the deep sea sediments. On the other hand, a uniform distribution of total counts of bacteria, carbohydrates, and total organic carbon in all the cores indicates their stable nature and suggests that they can serve as useful parameters for long-term monitoring of the area after the benthic disturbance. Further studies on temporal variability in this region would not only verify the observed norms of distribution of these variables but would also help to understand restabilization processes after the simulated benthic disturbance.     

海上大直径钢管桩打桩过程中桩周土强度弱化研究

海上大直径钢管桩打桩过程中,桩周土体受到强烈扰动而发生强度弱化,掌握桩周土体强度弱化规律对于准确预测打桩过程、保证工程安全具有重要意义。为研究土体强度弱化规律,开展了环剪试验模拟打桩对桩周土体的扰动,测试土体强度随剪切速率的变化规律,建立了描述土体强度弱化规律的拟合公式,引入到打桩分析软件中。研究结果表明：土体的强度折减程度不仅与土体本身的性质有关还受到土体的埋深和剪切速率的影响,埋深越深土体强度折减程度越低,剪切速率越高土体强度折减越高,在打桩分析中可采用这里推荐的线性折减方法来模拟不同深度处土体强度的折减规律。     

Geoacoustic Inversion via Genetic Algorithm and Its Application to Manganese Sediment Identification

An acoustic inversion method using a wide-band signal and two near field receivers is proposed and applied to multiple layered seabed models including a manganese sediment. The inversion problem can be formulated into a probabilistic model comprised of signals, a forward model, and additive noise. The forward model simulates wide-band signals, such as chirp signals, and is chosen to be the source-waveletconvolution plane wave modeling method. The wavelet matching technique, using weighted least-squares fitting, estimates the sediment sound-speed and thickness on which determination of the possible numerical ranges for a priori uniform distribution is based. The genetic algorithm is applied to a global optimization problem to find a maximum a posteriori solution for determined a priori search space. Here the object function is defined by an L 2 norm of the difference between measured and modeled signals. Not only the marginal pdf but also its statistics are calculated by numerical evaluation of integrals using the samples selected during importance sampling process of the genetic algorithm.     

A Review of Some Environmental Issues Affecting Marine Mining

This article reviews information recently available from existing marine and coastal mining for responses to environmental issues affecting marine mining at different depths. It is particularly but not exclusively concerned with those issues affecting seabed biodiversity impact and recovery. Much information has been gathered in the past 10 years from shallow mining operations for construction aggregate, diamonds, and gold, from coastal mines discharging tailings to shallow and deep water, and from experimental deep mining tests. The responses to issues identified are summarized in a series of eight tables intended to facilitate site-specific consideration. Since impacts can spread widely in the surface mixing layer SML, and can affect the biologically productive euphotic zone, the main issues considered arise from the depth of mining relative to the SML of the sea. Where mining is below the SML, the issue is whether it is environmentally better to bring the extraction products to the surface vessel for processing (and waste discharge), or to process the extraction products as much as possible on the seabed. Responses to the issues need to be sitespecific, and dependent on adequate preoperational environmental impact and recovery prediction. For deep tailings disposal from a surface vessel, there are four important environmental unknowns: (1) the possible growth of "marine snow" (bacterial flocs) utilizing the enormous quantities of fine tailings particles (hundreds or thousands of metric tons per day) as nuclei for growth, (2) the possibility that local keystone plankton and nekton species may migrate diurnally down to and beyond the depth of deep discharge and hence be subjected to tailings impact at depth, (3) the burrow-up capability of deep benthos and their ability to survive high rates of tailings deposition, and (4) the pattern and rate of dispersion of a tailings density current through the deep water column from discharge point to seabed. Actions to obtain relevant information in general and site-specifically are suggested.     

Increased Particle Fluxes at the INDEX Site Attributable to Simulated Benthic Disturbance

Particle fluxes were measured 7 m above the sea bottom during the predisturbance, disturbance, and postdisturbance periods by using time series sediment traps attached to seven deep-sea moorings deployed in the INDEX experiment site in the Central Indian Basin. The predisturbance particle fluxes varied between 22.3 to 55.1 mg m -2 day -1 . Increased and variable particle fluxes were recorded by the sediment traps during the disturbance period. The increase observed was 0.5 to 4 times more than the background predisturbance fluxes. The increases in particle fluxes (~4 times) recorded by the sediment trap located in the southwestern direction (DMS-1) were the greatest, which could be the result of preferential movement of resuspended particles generated during the deep-sea benthic disturbance along the general current direction prevailing in this area during the experimental period. Also, the traps located closer to the disturbance area recorded greater fluxes than did the traps far away, across the Deep Sea Sediment Resuspension System path. This variability in recorded particle fluxes by the traps around the disturbance area clearly indicates that physical characteristics such as grain size and density of the resuspended particles produced during the disturbance had an important effect on particle movement. The postdisturbance measurements during ~5 days showed a reduction in particle fluxes of ~50%, indicating rapid particle settlement.     

Determination of In Situ Sediment Shear Strength from Advanced Piston Corer Pullout Forces

The advanced piston corer (APC) has been used by the Ocean Drilling Program since 1985 for recovering soft sediments from the ocean floor. The pullout force measured on extracting the core barrel from the sediment is shown to correlate with the average shear strength of the sediment core measured in the ship's laboratory. A simple rule of thumb is derived relating the shear strength of the sediment to the pullout force. Multiple APC holes at individual sites allow the consistency of the pullout measurements to be assessed. The effects of different operational procedures during APC coring are also explored. Although generally applicable, the correlation between pullout force and laboratory measurements of shear strength breaks down for some APC holes, possibly because of the disturbance of some sediment types during the APC coring process. A better understanding of the physical process of APC coring, and its effect on the properties of the sediment both inside and immediately outside the core barrel, would indicate what confidence can be put on the measurement of pullout force as a way of evaluating the in situ shear strength of deep sea sediments.     

Phylogenetic diversity and phenotypic characterization of cultivable bacterioplankton isolated from polar oceans

A set of 27 marine planktonic bacteria isolated from the polar regions was characterized by 16S rDNA sequencing and physiological and biochemical testing. More than half of these bacteria were positive for caseinase, gelatinase and 13-glucosidase, and could utilize glucose, maltose or malic acid as carbon source for cell growth. Twelve isolates expressed nitrate reduction activities. Except for one antarctic isolate BSwlO175 belonging to Actinobacteria phylum, these isolates were classified as γ-Proteobacteria, suggesting that γ-Proteobacteria dominated in cultivable marine bacterioplankton at both poles. Genus Pseudoalteromonas was the predominant group in the Chukchi Sea and the Bering Sea, and genus ShewaneUa dominated in cultivable bacterioplankton in the Prydz Bay. With sequence similarities above 97%, genus Psychrobacter was found at both poles. These 27 isolates were psychrotolerant, and significant 16S rDNA sequence similarities were found not only between arctic and antarctic marine bacteria （ 〉 99% ）, but also between polar marine bacteria and bacteria from other aquatic environments （ ≥ 98.8% ）, including temperate ocean, deep sea, pond and lake, suggesting that in the polar oceans less temperature-sensitive bacteria may be cosmopolitan and have a bipolar, even global, distribution at the species level.     

Deep-Sea Sediment Compression Curves: Some Controlling Factors, Spurious Overconsolidation, Predictions, and Geophysical Reproduction

Oedometer tests have been carried out on 70 undisturbed surficial clays (at approximately 250 mm below the mudline), mostly collected by free-fall corers from sites widely scattered throughout the deep-sea North Atlantic. Acoustic measurements were also made, initially on contiguous samples and ultimately on the same sample using a geophysically instrumented oedometer which also collected electrical resistivity data. Apart from those quiescent areas below the carbonate compensation depth, such as north of the West Indies where very fine clays exist, most of the samples are silty clays whose geotechnical-geophysical properties are dependent on the type of clay minerals present (and their ability to take in moisture), the sand-size fraction, and the quantity of carbonate present. Thus the pure clays have high compressibilities which decrease on the addition of coarse particles, while the converse is true for the acoustic parameters, these increasing with the sand fraction. Using the notion of the intrinsic compression line for all samples, and comparison to it of the measured compression curves, it is clear that, contrary to some previously held ideas, most deep-sea clays are normally consolidated; the addition of carbonate has the effect of creating an open, stronger sediment skeleton. Interestingly, where information is available, the variation with depth of a sample's acoustic velocity follows the void ratio pressure relationship of the compression curve. This allows the construction of an in-situ sediment compression curve using the in-situ geophysical observations.