南海珊瑚礁光学浅水海域多光谱遥感水深反演

海洋水深信息对研究珊瑚礁海域资源与环境具有重要作用。南海珊瑚礁海域测深数据受多种条件限制施测困难,在时间与空间方面数量非常有限。文章针对南海岛礁海域以I类水体为主导的海水光学特性,以南沙群岛库归沙洲海域为例,使用Sentinel-2多光谱卫星遥感影像和同期过境的MODIS卫星数据,构建底质光谱,采用半分析半经验模型计算海水表面遥感反射率与海水叶绿素浓度,通过对数比值模型进行该地区光学浅水海域遥感水深反演分析,并进一步通过多时相反演水深融合提升精度。经与多波束实测水深数据验证,研究区域反演水深总体均方根误差和平均相对误差分别为2.68 m 和9.99%。该方法通过叶绿素浓度推演部分海水光学特性,可以从多光谱卫星影像中快速获取南海岛礁光学浅水海域初步水深信息,供相关海洋领域分析与应用。     

利用遥感光谱特征提取岩性信息的基础和技术研究

地物光谱特征的研究是遥感技术的基础研究工作之一．从光谱遥感发展与地质应用的趋势出发。从光谱遥感岩矿识别基础与识别技术方法两方面阐述了光谱遥感的研究进展．在技术方法方面，主要从多光谱与成像光谱以及遥感与航空放射性信息集成3个层次上，分析利用光谱特征进行岩石矿物识别的研究进展及其潜力与可行性，并简单阐述了遥感与航空放射性信息的复合这一遥感岩性信息识别研究的发展趋势．     

南沙道明群礁珊瑚礁地貌

珊瑚礁支持了对全球气候变化响应最敏感的生态系统之一,其部分特征地貌是海面变化记录的重要载体.目前,无论是对珊瑚礁现代地貌还是埋藏古地貌的研究多以定性为主,定量研究相对匮乏.基于2017年8～9月采集的浅层地震剖面数据,结合遥感影像研究显示,道明群礁目前是发育有1个岛、4个沙洲、7个干出礁和若干座暗礁的典型珊瑚群礁,其形...     

高光谱遥感水文地质应用新进展

高光谱遥感是一种利用成像光谱仪同时获取地物目标辐射、光谱和空间等多重信息遥感的技术,水文地质是高光谱遥感重要的应用领域之一,通过高光谱遥感图像分析,能够提取大区域包气带及含水系统的水文地质信息,可为水文地质环境的识别及实时监测、地下水资源高效管理、地下水数值模型构建等提供科学数据。通过调研凝练了高光谱遥感基本原理方法及其在水文地质方面的应用研究,重点总结了地下水环境污染和水文信息反演方面的高光谱遥感应用研究进展,分析了高光谱遥感水文地质应用所面临的挑战,并展望了高光谱遥感水文地质应用研究的发展趋势,主要包括:通过土壤和植被的光谱信息实现对研究区包气带土壤重金属污染状况的大面积、短周期连续快速监测;在高光谱图像中提取构造、地层岩性等地质和水文地质特征,以环境指示因子（如植被）为有效补充,获取饱和带地下水环境信息;通过高光谱图像识别植被类型、计算植被覆盖度、分析叶片反射光谱特征并建立模型反演土壤含水量和地下水位,为研究和保护缺水地区生态环境提供数据支撑。     

盐湖遥感研究的进展与展望

盐湖遥感因其研究对象的独特性和重要性而具有重要的理论和实际应用意义。从盐湖水体的光谱特征,盐湖水体、盐分的敏感特征波段,盐湖盐量、水深的估测模型,以及盐湖地质演化的解译,盐湖水面、晶间卤水的变化监测、生态环境的变化等方面,详述了国内外最新的研究进展。指出随着遥感从低分辨率到高分辨率,多光谱到高光谱,可见光到微波方向的发展,应在盐湖信息识别、盐湖成分定量估测的基础上,注重盐湖盐分物化参数的高光谱反演、晶间卤水的雷达遥感监测等,从遥感角度探求生态系统和气候、盐度等因素的深层次相互关系,此外还应在盐湖生物、盐湖灾害等领域拓展研究。     

二类水体水色遥感的主要进展与发展前景

Ⅱ类水体水色遥感是海洋水色遥感的难点和热点。针对Ⅱ类水体的光谱特性和海洋现象的特点，综述了水色卫星传感器在光谱波段配置、辐射探测性能和时空分辨率等方面的设计要求与技术进步。从水色遥感资料反演的两大关键技术——大气校正和生物光学算法两个方面，概述了Ⅱ类水体水色反演算法的研究现状和发展方向。根据我国近海的水体特点，提出了我国水色遥感研究需要解决的关键问题。     

热带生物海岸对全球变化的响应

以热带生物海岸现代过程研究成果为基础,结合国内外相关资料,分析我国红树林海岸和珊瑚礁海岸对全球变暖、海平面上升、大气CO2浓度升高和海洋酸化的响应.其中,全球变暖和大气CO2浓度升高总体上有利于红树林生长发育,海平面上升对红树林和珊瑚礁的影响取决于红树林潮滩淤积速率和珊瑚礁礁坪堆积速率与海平面上升速率之间的对比关系.海平面加速上升将威胁部分红树林、珊瑚礁及其后的海岸堤防.全球变暖海表异常高温导致珊瑚白化、海洋酸化导致珊瑚和珊瑚藻钙化率降低将成为21世纪珊瑚礁的重大威胁.全球变化的不确定性和生态系统响应机制仍然有待进一步研究.主要是人类不合理开发活动导致目前红树林和珊瑚礁的广泛严重破坏,加强海岸带综合管理和生态环境保护,加强生态系统恢复重建,是有效适应本世纪全球变化影响的重要措施.     

珊瑚礁海岸水动力学问题研究综述

珊瑚礁水动力学是一个涉及生态、环境、地质和工程学的交叉课题,其水动力学研究不仅为珊瑚礁海域生态系统的维护和海岸线的演变提供一定的理论参考,还能为海岸的防灾减灾以及岛礁工程的建设提供一定的决策依据。回顾了国内外珊瑚礁海岸水动力问题的研究与进展,从现场观测、理论模型、物理模型试验和数值模型4个方面对当前该领域的研究进展进行了综述,并提出今后现场观测研究对象可关注南中国海的珊瑚岛礁,理论分析方法可侧重考虑非线性波浪理论,物理模型试验可采用大型波浪水槽和港池来复演现场尺度的水动力问题,数值模型可采用计算流体力学（Computational Fluid Dynamics,CFD）方法对波浪与珊瑚礁相互作用进行精细化模拟,本文旨在为今后国内珊瑚礁水动力学方面的相关研究提供一定的借鉴和参考。     

广东两类花岗岩的反射光谱特征及其遥感意义

地物波谱信息是多光谱遥感的基础、光谱信息所具有的特征反映了地物本身的存在、变化和差异。作为花岗岩岩石物理特性研究的一部分，笔者选择了广东早古生代两类花岗岩为研究对象测定并分析了两类花岗石及其围岩的反射光谱特征，并且依据它们光谱特性的差异。确定了遥感图象处理的技术和方法，为下一步该地区遥感图象识别花岗岩奠定了基础。     

高光谱分辨率遥感在地质应用中的关键技术及前景

遥感技术应用于地质中的目的之一是分辨和识别出不同的岩石和矿物等地质体。宽波段遥感只能分辨不同岩石类型，而难以识别含不同成分的岩石和矿物。高光谱分辨率遥感则可通过诊断性光谱特征对岩石或矿物成分及结构进行识别。通过对高光谱分辨率遥感应用于地质中的关键技术进行分析，对未来高光谱分辨率遥感在地质中的应用进行了预测。     

Determination of the separability of coastal community assemblages of the Al Wajh Barrier Reef, Red Sea, from hyperspectral data

Remote sensing provides a practical means by which coral reefs and their associated communities are commonly mapped. The availability of spectral information is a key determinant of the detail discernable in the mapping process and consequent detail presented in output maps. Testament to this is the increasing utility of hyperspectral sensors, which typically yield datasets of higher resolution, spectrally continuous wavebands. Image classification algorithms distinguish between the different and unique reflectance characteristics of target features. While the availability of more wavebands provides the opportunity to apply analysis techniques that treat the data as spectrally continuous, such a large number of data dimensions also present a considerable computing burden. Through multiple discriminant function analysis, this paper identifies an optimal subset of wavelengths for resolving the reflectance of key terrestrial and marine coverages at the Al Wajh Barrier reef system, Saudi Arabia, Red Sea. The goal of such analysis is to facilitate the processing of high resolution, spectrally continuous remote sensing data of coastal landscapes.     

Environmental characteristics of tropical coral reef-seagrass dominated lagoons (Lakshadweep,India) and implications to resilience to climate change

Environmental characteristics of the coral reef-seagrass ecosystem of selected Lakshadweep Islands (India) were assessed with a view to understanding the future climate change scenario in the region. Images obtained from the Indian remote sensing satellite (IRS P6) were used to identify the different zones such as the corals, the seagrass and the sandy region. The pH (7.6–8.6) of sediment was relatively high in the coral reef compared to the seagrass area, possibly indicating a climate shift-induced coral bleaching. The water quality and sediment texture generally showed marked intra- and inter-island variations illustrating that these coral reef ecosystems are highly vulnerable to climate change brought about by increased human interventions. Future research should therefore explore the habitat and resource connections, to predict their restoring capabilities for a sustainable exploitation. With an alarming increase in the population and associated developmental activities, the island ecosystems are expected to respond severely to the climate change, which may eventually lead to mass mortality of corals due to bleaching.     

Studies on the Coral Reefs of the South China Sea: From Global Change to Oil-Gas Exploration

Studies on the coral reefs of the South China Sea (SCS) was the theme of the 6th Session of the 3rd Conference on Earth System Science (CESS) in Shanghai, 2014. This session discussed the most recent study developments on the SCS coral reefs, including coral reefs’ responses to global changes, coral reefs’ records on past climatic variations, and the activities about constructions and oil gas explorations in the coral reefs areas of the SCS. Disturbed by intensive anthropogenic activities and global climate warming, coral reefs in the SCS have declined dramatically, reflecting the up to 80% decrease of living coral cover and many areas having less than 20% of living coral cover. Geochemical data of SCS coral skeletons clearly show that since the Industry Revolution, the pollution situation of the SCS have dramatically increased and the seawater pH values have been continuously lowering, i.e. oceanic acidification. All these environmental phenomenon are further stressing the healthy development of the coral reef ecosystem in the SCS. Meanwhile, the poor coral reef ecosystems in the SCS are facing more anthropogenic disturbances such as coastal developments and engineering constructions. Obviously, the SCS coral reefs will be faced with more environmental challenges in the coming future. We therefore suggest that the policy makers should realize the extreme importance and the fragile of the coral reef ecosystems, and scientifically and with great cautions design construction project when in coral reef areas. We initiated the concept of “green engineering” for future developments in coral reef areas. Coral reefs are widely spreading in the whole SCS, and most of them developed since Miocene. Variations in coral reef structures provide good future oil-gas exploration. Because the SCS coral reefs have a long-developing history and a wide spatial distribution, they provide great potential in recording past environmental changes.     

面向对象的喀斯特地区土地利用遥感分类信息提取

传统的面向像元分类方法虽然对光谱差异较为明显的遥感影像信息提取具有较好的效果,但会不可避免地产生“椒盐现象”,同时对纹理和形状信息不能充分应用,造成了大量信息损失。为了提高喀斯特地区土地利用遥感信息提取的精度,本文采用面向对象的分类方法,对贵州省毕节地区开展了土地利用遥感信息自动提取研究。首先对该地区Landsat-5 TM影像进行多尺度分割,形成影像对象层,然后综合应用基于知识决策树分类和基于样本的最邻近分类等技术对喀斯特地区进行遥感解译。结果表明,面向对象分类技术能较好地对喀斯特地区土地利用信息进行提取,同时避免了“椒盐现象”的产生,经野外采集样点数据验证,一级类分类精度为91.7 %,二级类分类精度为89.4 %,表明该方法在贵州省毕节地区应用效果良好。      

Investigation of hydrogen sulphide eruptions along the Namibian coastline using different remote sensing systems

Hydrogen sulphide eruptions with their typical turquoise discolorations at the water surface are a unique phenomenon along the Namibian coastline. The remote sensing techniques of ocean colour sensors and microwave scatterometers were used for the investigation of such events. The studies with ocean colour sensors showed that the turquoise discolorations near the Namibian coast were neither linked to dust deposition into the water column by desert storms nor to the reflection of bright material in shallow water areas. In addition, other coloured marine events like algae blooms and river outflows were differentiable from the hydrogen sulphide eruptions by their special optical properties. Quasi-true colour images and spectral identification methods were utilised to monitor and investigate the spatial and temporal distribution of sulphide events. In the past years, they were sometimes and locally limited discovered. Newest remote sensing observations including our own investigations have established that the occurrence of sulphide events is more frequent and longer lasting. The north-westerly direction of propagation and their velocity between 12 cm s^-1 and 15 cm s¹ were derived from an event on 14 April 2004. Lastly, the microwave scatterometer remote sensing was applied to investigate the relation of sulphide events to oceanographic conditions. The events from May 2004 were clearly related to strong coastal upwelling.     

一种基于光谱角和光谱距离自动加权融合分类方法

高分辨率遥感影像分类一直是业内研究的热点之一,考虑到影像地物光谱角和光谱距离在分类中具有较好的互补性,提出了一种基于光谱角和光谱距离自动加权融合的分类方法,对传统多分类器分类的融合策略进行改进,能够在训练阶段根据样本自动地调整好各分类器对各类别进行分类的权重系数,使得融合后的分类结果更加科学和准确。QuickBird影像的分类实验表明,方法的分类精度明显优于单纯的光谱角或距离法,可广泛用于各种高分辨率影像的分类识别。     

Aggradation and carbonate accumulation of Holocene Norwegian cold‐water coral reefs

Cold‐water coral ecosystems present common carbonate factories along the Atlantic continental margins, where they can form large reef structures. There is increasing knowledge on their ecology, molecular genetics, environmental controls and threats available. However, information on their carbo‐nate production and accumulation is still very limited, even though this information is essential for their evaluation as carbonate sinks. The aim of this study is to provide high‐resolution reef aggradation and carbonate accumulation rates for Norwegian cold‐water coral reefs from various settings (sunds, inner shelf and shelf margin). Furthermore, it introduces a new approach for the evaluation of the cold‐water coral preservation within cold‐water coral deposits by computed tomography analysis. This approach allows the differentiation of various kinds of cold‐water coral deposits by their macrofossil clast size and orientation signature. The obtained results suggest that preservation of cold‐water coral frameworks in living position is favoured by high reef aggradation rates, while preservation of coral rubble prevails by moderate aggradation rates. A high degree of macrofossil fragmentation indicates condensed intervals or unconformities. The observed aggradation rates with up to 1500 cm kyr^?1 exhibit the highest rates from cold‐water coral reefs so far. Reef aggradation within the studied cores was restricted to the Early and Late Holocene. Available datings of Norwegian cold‐water corals support this age pattern for other fjords while, on the shelf, cold‐water coral ages are reported additionally from the early Middle Holocene. The obtained mean carbonate accumulation rates of up to 103 g cm^?2 kyr^?1 exceed previous estimates of cold‐water coral reefs by a factor of two to three and by almost one order of magnitude to adjacent sedimentary environments (shelf, slope and deep sea). Only fjord basins locally exhibit carbonate accumulation rates in the range of the cold‐water coral reefs. Furthermore, cold‐water coral reef carbonate accumulation rates are in the range of tropical reef carbonate accumulation rates. These results clearly suggest the importance of cold‐water coral reefs as local, maybe regional to global, carbonate sinks.     

Automatic building extraction from very high-resolution image and LiDAR data with SVM algorithm

Recent developments in the field of remote sensing have introduced new sensor technologies in usage of LiDAR, SAR, and high-resolution optical data. Classification performance is expected to increase through combining these various data sources. The purpose of this study is to develop a new approach for automatic extraction of buildings in urbanized and suburbanized areas. For this purpose, multi-feature extraction process including the spatial, spectral, and textural features were conducted on the very high spatial resolution multispectral aerial images and the LiDAR data set. SVM algorithm was trained by using this multi-feature data, and the classification was performed. After the classification of building and non-building, objects were extracted with high accuracy for the test areas. As a result, it has been proven that multi-features derived from combination of optical and LiDAR data can be successfully applied to solve the problem of automatic detection of buildings by using the proposed approach.     

Detecting the water depth of the South China Sea reef area from WorldView-2 satellite imagery

The accurate and efficient detection of the water depth of coral reefs through remote sensing imagery is crucial for navigation, marine engineering, and marine safety, among others. This study proposed a water depth inversion method that is processed using a two-step strategy. First, a log-dual-band ratio transform model is employed by combining blue, yellow, red, and red edge bands. Second, a multivariable linear regression model is constructed to determine water depth. The experimental study is conducted in a reef island in the South China Sea, and the WorldView-2 satellite data is used as the test data. Results demonstrated that the proposed method needs a few parameters in the model, and can effectively and reliably characterize the correlation between the spectral features and water depth.