Sailboat search and rescue experiment

An experiment to evaluate one satellite search and rescue concept was conducted for one month around the islands of Bahama, aboard a 33-ft sailboat. The sailboat was equipped with satellite data collection equipment which provided vessel communication with an earth station by means of a simple push-button distress alarm keyer. This low-power equipment transmitted boat identification, weather data, location, and simulated other vital distress information and required emergency assistance by means of the NASA NIMBUS 6 data collection satellite at UHF. In addition, the experiment evaluated the NIMBUS Doppler positioning technique for distress application by providing 114 positions derived from the satellite, and 75 percent of these were within 2 nmi of actual locations. Experiment coordination was accomplished by voice link through ATS-3. The experiment demonstrated the potential ability of satellite systems to provide reliable distress alert and position.     

国际海上救援效率比较研究 ——以东海特定水域为例

为研究东海海域海上救援效率和国际协作的协调性,以国际救援为视角,基于ArcGIS构建了海事救援效率评价模型。根据巡逻船舶密度数据确定了救援船舶的概率分布,得出了救援船舶与遇险船舶的可能距离,同时考虑了风浪影响下遇险船舶的漂移以及巡逻船舶失速的情况,分别计算了常风向和次常风向下中国、日本和韩国在东海特定水域的海上救援效率。结果表明:以各国现有的巡逻船舶配备对研究区内漂移的遇险船舶展开救援时,常风向下先后抵达的顺序为韩国、日本和中国,驰援时间分别为5.14、8.18和9.67 h;次常风向下抵达的顺序为韩国、日本和中国,驰援时间分别为5.45、8.25和10.08 h;为提高我国的救援效率,需要在东海海域部署9～10艘巡逻船舶开展常态化巡逻。本文研究可为我国有关部门科学制定和完善海上救援方案,调整海上救援力量配备,进一步加强国际间的协调与合作提供参考。     

发达国家海上搜救体系对比研究及对我国的启示

提升海上应急搜救能力对保障人民生命安全、维护国家海洋权益、彰显大国责任和担当具有积极作用和深远意义。发达国家海上搜救体系的先进性主要体现在搜救力量专业化、应急响应快捷化、组织协调高效化、搜救业务程序化等方面。文中对美国、英国、澳大利亚、日本4个国家的海上搜救组织构成、搜救力量水平、搜救工作模式等进行了分析,与我国海上搜救体系和机制进行了对比,并从优化搜救组织模式、完善搜救运行机制、健全搜救力量等方面给出了发展我国海上搜救体系的建议。     

Maritime satellite requirements and utilization

The basic purpose of this paper is to identify the potential requirements for maritime satellite communication and position fixing as it relates to both present and future operational systems (e.g., MARISAT, INMARSAT, etc.). Particular emphasis is given to the need for position fixing and ship terminal equipment utilization in national waters, as well as other major aspects. Present MARISAT operation and industry evaluation activities are briefly discussed, highlighting a few major programs and some of the potential benefit area thus far generally identified by the users of MARISAT. A comparison is made between satellite communication and the existing MF/HF system, including direct-printing radio telegraph (marine radio telex). From various standpoints, it appears that maritime satellite systems are more desirable than conventional (nontelex) marine telegraph/telephone. In addition, the improved performance, capability, and potential of satellites could outweigh the slightly lower annual traffic and equipment cost for HF marine telex.     

中国海洋卫星遥感应用进展

我国海洋遥感应用自20世纪70年代起步以来,取得了长足发展,构建了覆盖海洋水色、海洋动力和海洋监视监测的三大系列海洋卫星,并初步形成了具有优势互补的卫星海洋遥感业务化应用体系。本文回顾了我国海洋卫星遥感应用取得的重要进展,重点介绍了卫星遥感在海洋环境与资源监测、海洋灾害监测、海洋权益维护、海洋环境预报与安全保障等方面所构建的典型应用示范系统,以及开展的典型业务化监测应用。最后,文章对我国海洋卫星遥感应用下一步发展进行了展望分析。     

基于多处理板联合SAR成像的分布式计算模拟系统研究

合成孔径雷达(SAR)卫星的探测范围有限,全轨利用率不高,并且单个卫星的计算和存储资源有限,难以完成大量的星载合成孔径雷达数据处理.本文拟采用多处理板联合的数据处理方法,针对星上分布式计算构建一种模拟系统,以提高星上数据处理效率,验证多处理板联合的数据处理方法在高效利用卫星计算与存储资源、提升单个卫星全轨利用率等方面的...     

Exploration of the wind-induced drift characteristics of typical Chinese offshore fishing vessels

The drift motion of a maritime distress target is the collective result of the balance of forces that comes from wind, currents and waves. The drift properties vary from one type of object to another. The objective of this paper is to explore the leeway drift characteristics of typical Chinese offshore fishing vessels as well as evaluate the leeway drift model. First, a series of field experiments were conducted in South China Sea to provide data source. Next, nine leeway coefficients in AP98 leeway model were derived by the least square fitting based on the experimental data. Furthermore, another drifting dynamics model based on a balance of forces on the drifting vessel due to wind and currents, was also calibrated for comparison. Finally, two cases of drift trajectory and searching areas were simulated by the two different models through Lagrangian particle tracking and Monte Carlo techniques. Results indicate that the AP98 leeway model is in better accordance with the observation compared with the drifting dynamics model. Additionally, the simulation accuracy of AP98 leeway model can be improved to some extent especially when the probability of positive crosswind (POPC) is considered. Considering the large number of the typical offshore fishing vessels in South China Sea, and their high accident rate, the model coefficients for this type of vessels are expected to be implemented into more search and rescue (SAR) models by SAR organizations.     

多模式小卫星SAR机载挂飞试验的飞行路线规划与雷达参数设计

多模式小卫星SAR(synthetic aperture radar,合成孔径雷达)是一种搭载于小卫星平台的新体制雷达系统,它集SAR、散射计、高度计、波谱仪4种遥感器的优势于一身.它可以根据需求分时实现几种工作模式的切换,可兼顾对海洋目标和海洋动力环境的高精度测量.由于卫星发射存在诸多不确定因素,为了在卫星发射前对多...     

一种增强型YOLOv3的合成孔径雷达(SAR)舰船检测方法

近年来,海战场成为现代战争的主要作战区域之一,舰船目标逐渐成为海上重点监测对象,能否快速准确地识别海战场舰船目标的战术意图,给指挥员的决策提供必要的支持,这关系到一场海上战役的成败。随着合成孔径雷达(synthetic aperture radar, SAR)成像技术的不断发展,大量SAR图像可用于舰船目标检测与识别。利用SAR图像进行舰船目标检测与识别,已经成为重要的海洋应用之一。针对传统SAR图像舰船检测方法准确率较低的问题,本文在YOLOv3的基础上,结合感受野(receptive fieldblock,RFB)模块,提出一种增强型的SAR舰船检测方法。该方法在最近公开的SAR图像舰船检测数据集上平均准确率值达到了91.50%,与原YOLOv3相比提高了0.92%。实验结果充分表明本文提出的算法在SAR舰船的检测中具有较好的检测效果。     

观测卫星选择对GPS基线解算质量的影响

研究了观测卫星的选择对基线解算质量的影响，介绍了提高基线解算质量的人工选星的基线处理方法，通过人工干预选择卫星，解算结果得到明显改善。     

Emptying the sea with a spoon? Non-governmental providers of migrants search and rescue in the Mediterranean

In 2015 and 2016, 1,200,000 migrants crossed the Mediterranean into Europe. At least 6000 went missing at sea. In response to states’ failure to provide adequate search and rescue (SAR), several non-governmental organisations (NGOs) have launched their own rescue operations in both the Central Mediterranean and Aegean. This article provides the first empirical analysis of SAR NGOs, outlining their structure and operating models, investigating the reasons underlying their proliferation and assessing their contribution to mitigating the loss of life at sea     

渤海海域搜救困难度研究

为优化海上搜救资源部署、提高救助成功率,结合层次分析法与模糊综合评价法,从海上搜救的自然环境、辖区信息和行动评估3个方面选取11个指标构建海上搜救困难度评价模型,在验证模型可靠性的基础上,首次对渤海海域开展二维搜救困难度评价和研究。使用成功率来表征搜救困难度并进行时空分布特征分析,成功率越低则困难度越高。结果表明：渤海海上搜救成功率全年分布趋势为海岸线周边海域相对较低,渤海中部海域相对较高。整体来看,夏季成功率远高于其他季节,春、秋季次之,冬季最低。冬季辽东湾及秦皇岛沿岸海域成功率为全年和全海域最低。对渤海沿岸港口海域及中部海域各选1个长期观测的站点开展年变化特征分析,发现同一地点的搜救成功率年变化主要受水温影响,证实了冬季是搜救困难度最高的季节。综上所述,冬季渤海沿岸海域,尤其是辽东湾及秦皇岛沿岸海域为高困难度搜救区,需要加大日常巡逻管理,改善搜救系统部署。     

Sea state estimation using multiple ships simultaneously as sailing wave buoys

The article presents initial ideas towards a network-based approach for sea state estimation used for marine operations and other maritime applications. In principle, all available means, ranging from in situ buoys, fleet of ships to remote sensing by satellite and aircraft, could be considered, emphasising that each means and any combinations among may act simultaneously. This study focuses on just one of the means; the use of ships as sailing wave buoys. The article introduces the wave buoy analogy, i.e. ship-as-a-wave-buoy, and it makes a proposal on how to impose (different) weights to the single ship-specific wave spectrum estimates obtained from multiple ships. Moreover, the work includes a discussion about the importance to associate a measure to reflect the (un)certainty of the wave spectrum estimate. The article presents a numerical case study, where multiple ships act simultaneously as wave spectrum-estimators. The case study relies on numerical motion simulations, as appropriate full-scale data is not yet available. In the analysis, it is shown that the use of simultaneous data from multiple ships leads to more accurate wave spectrum estimations.     

海洋遥感卫星发展历程与趋势展望

海洋是对地观测卫星的重要领域,在对地观测卫星中就具有专门用于海洋观测的海洋遥感卫星。海洋遥感卫星是一种利用所搭载的遥感器对海面进行光学或微波探测来获取有关海洋水色和海洋动力环境信息的卫星。海洋卫星有效弥补了传统海洋观测手段的不足,基于多种遥感器连续对海洋的观测,使人类极大的加深了对海洋的认识,在海洋灾害的防灾减灾、资源开发、海洋维权、海洋生态和环境保护等诸多领域发挥着重要作用。本文在详细梳理西方主要航天大国海洋遥感卫星(包括了对地观测卫星中具有海洋观测功能的卫星)的发展历程,在此基础上对未来海洋遥感卫星的发展趋势进行了论述,可为我国海洋遥感卫星的发展提供技术发展参考。     

一种快速非局部平均合成孔径雷达海洋图像斑点噪声抑制方法

合成孔径雷达在海洋环境监测和海洋研究中扮演着越来越重要的角色。受其成像机制的影响,合成孔径雷达图像总是受到斑点噪声的污染。斑点噪声的存在会增大目标识别、跟踪和分类的难度,也会降低雷达信号的信噪比。合成孔径雷达海洋图像具有一些特殊的性质：海洋现象在雷达图像中主要呈现为条带状或斑块状的结构。这些条带状或斑块状的结构呈现出高度的自相似性或信息冗余。非局部平均方法能够衡量图像中不同图像块之间纹理结构的相似性,并利用图像的自相似性对图像进行去噪。但非局部平均去燥方法存在计算量巨大、计算耗时长的缺点,这几乎限制了其实际应用。本文采用一种自适应方法将雷达图像中的像素点区分为纹理区像素点和平坦区像素点。对纹理区像素点,采用较大的相似窗和搜索窗,对平坦区像素点,采用较小的相似窗和搜索窗,从而提高计算速度。进一步,本文基于计算统一设备并行架构（CUDA）技术,利用计算机图形处理器（GPU）对前述算法进行并行加速。与经典非局部平均算法相比,加速后算法的计算效率提高了200倍。     

高分3号星载合成孔径雷达极地海冰自动检测方法研究

随着全球变暖等一系列气候变化的发生,极地海冰成为人们日益关注的焦点。由于不受光线和云雨影响,合成孔径雷达（SAR）可以进行全天时全天候的观测。高分3号是我国高分系列卫星中的一颗星载合成孔径雷达成像卫星,具有多种成像模式,可以在全球获取SAR数据。全天时全天候的工作特性和高空间分辨率的优势,使得高分3号星载SAR在极地海冰遥感监测中发挥重要的作用。本文基于高分3号水平-垂直（Horizontal-Vertical,HV）极化数据,提出了一种基于支持向量机的无需人工干预的海冰检测方法,实现海水和海冰的自动分离。利用该方法得到的海冰和海水分离结果同辅以人工解译的半监督分类结果相比较为吻合,为高分3号服务于极区海冰监测奠定了良好的基础。     

针对C波段组网SAR卫星的风场优化反演方法研究

地球物理模型函数是一种常被用于同极化合成孔径雷达(synthetic aperture radar,SAR)的风场反演方法.在使用该方法提取SAR数据的风速时,需要将风向作为输入信息,这导致反演风速的精度受风向精度的影响,且使SAR风场反演无法独立完成.为了解决这些问题,通过数值模拟获取仿真的组网SAR卫星数据,3颗S...     

一个基于MOM的全球海洋数值同化预报系统

随着国家战略利益的拓展,国家对全球海洋环境预报保障的需求日益凸显。近年来,国家海洋环境预报中心研发并建立我国首个涵盖全球大洋的"全球海洋数值预报系统",该预报系统由MOM4全球海洋环流模式及三维变分同化系统组成。该系统的建立,实现了全球范围海洋环流预报业务全覆盖,为我国探索深海大洋环境的迫切需求提供有力保障,明显提升了我国海洋环境预报能力,体现了我国海洋数值预报技术的发展和进步。该系统的历史回报试验和业务化试运行结果表明其对全球海洋环境要素具有较好的预报能力,其预测结果已经在实际业务中得到了应用,在"雪龙号"极地遇险脱困、马航MH370失联飞机搜救等重大事件的预报保障任务中发挥了重要作用,为我国实施海洋强国战略,推进实施"21世纪海上丝绸之路"的战略构想,应对海上突发事件、维护国家海洋权益等各个方面提供有力的科技支撑和保障,并成为我国全球海洋预报业务的重要参考依据。