Preliminary study on the orbit cross-calibration of CMODIS by Sea WiFS

China launched its third spaceship SZ-3 in March, 2002 on which the main remote sensor is the Chinese moderate imaging spectra radiometer (CMODIS). In this paper the properties of CMODIS are firstly introduced briefly. Then, the theory and algorithm of cross-calibration for CMODIS ocean color channels by the sea-viewing wide field-of-view sensor (SeaWiFS) data are discussed in detail. The total radiance (TOA) of four quasi-synchronized crossing ocean areas simulated by SeaWiFS and measured by CMODIS are compared and the calibration coefficients are derived from the relationship between them. Finally, the in-situ water leaving radiance data are used to validate the calibration results. The results show that the cross-calibration method could provide reasonable precision for ocean color measurement.     

Preliminary study on the orbit cross-calibration of CMODIS by SeaWiFS

MostareasofChinaSeasbelongtocase 2water ,andthealgorithmbasedontheratioofgreentoblueisnotsuitabletothoseareas[1] becausetwoormoresubstanceswithdifferentopticalpropertiesarepre sentedwhichdonotco varywithchlorophyllacon centration .Thesemightbewaterwithexceptionalplanktonblooms (suchasredtides) ,discoloredbyretainedandorganicsuspendedmaterialsandthedis solvedorganismmaterial (DOM ) ,suchasacids .Itis,therefore ,essentialtodevelopmorechannelswithmoresensitivesensorsforChinesecoastalwaterdetec …     

我国海洋水色卫星发展概述

目前国外拥有海洋水色卫星的国家和地区有美国、欧洲欧空局、日本、韩国和印度。我国先后成功发射有HY-1A卫星和HY-1B卫星,其中HY-1A卫星为试验型业务卫星;HY-1B卫星在HY-1A卫星基础上研制而成,其技术指标和性能均优于HY-1A卫星。我国常用的海洋水色遥感数据是SeaWiFS数据和M OD IS数据。我国海洋水色卫星主要应用在海洋资源开发利用、海洋灾害监测应用、海洋权益维护、全球气候变化研究、国际交流与合作等方面。我国的海洋水色卫星研究起步较晚,应用水平还不够高,大力发展海洋水色卫星对维护我国海洋权益,加强海洋综合管理,促进海洋资源合理开发利用和海洋环境保护等方面都有非常重要的作用。     

Study on Marine Application Potentiality of CMODIS／SZ-3

The third spaceship SZ-3 of China was launched in March 2002, in which the payload is Chinese moderate imaging spectra radiometer (CMODIS) . In this paper, first, the properties and characteristics of CMODIS are briefly introduced; second, the quality and availahility are evaluated by means of the Complex signal noise ratio (CSNR) which is simulated theoretically； third, the received CMODIS data are compared with the Sea wide field-of-view sensor (SeaWiFS) / SeaSTAR data to understand the accuracy of radiance measurement by CMODIS;finally, the remote sensing products of ocean color and temperature are mapped by CMODIS to study its marine application potentiality. The results show that CMODIS has its latent capability for the application of marine environment detection, the management and protection of marine resources, and the national rights and interests. Meanwhile some suggestions are proposed to modify the next generation sensor on the Chinese spaceship.     

Precise orbit determination of Haiyang-2 using satellite laser ranging

With the successful launch and official commissioning of China’s first dynamic ocean environment satellite Haiyang-2(HY-2),China’s capabilities for oceanic environment monitoring and oceanic resource detecting have been further improved and enhanced.Precise tracking and orbit determination are not only key technical concerns in the ocean dynamic environment satellite project but also necessary conditions for carrying out related oceanic science research using observational data obtained using spaceborne instruments including radar altimeter.In this study,the current available status of international satellite laser ranging(SLR) monitoring on HY-2 was introduced.Six-months of SLR data from HY-2 were processed to obtain precise satellite orbit information using the dynamic orbit determination method.We carried out a detailed assessment of the SLR orbit accuracy by internal evaluation,comparisons with the orbit derived by the French Doppler orbitography and radio-positioning integrated by satellite(DORIS) system,and station-satellite distance validation.These assessments indicate that the three-dimensional orbital accuracy of HY-2 is about 12.5 cm,and the radial accuracy is better than 3 cm.It provides a good example of the application of international SLR monitoring and precise orbit determination in China’s earth observation satellite project.     

利用SeaWiFS数据估算珠江口海域表层叶绿素浓度的研究

介绍了SeaWiFS资料的基本处理方法和海水叶绿素浓度提取方法,针对目前SeaWiFS资料沿岸二类水域的数据失效问题,提出了解决方法.并以珠江口为例,将经改进算法处理后的SeaWiFS数据用于叶绿素信息提取,经与实测数据对比,平均误差为29.6%.     

近红外光谱在印刷品颜色检测中的应用

为了对印刷品颜色进行快速、准确检测,应用近红外光谱技术(NIR)并结合偏最小二乘法(PLS)建立印刷品颜色检测模型.对近红外光谱获取的144个样本光谱曲线,应用主成分分析方法进行降维,维数为5.选取的主成分作为光谱优化特征子集以替代原来复杂的光谱数据.随后,将144个样本数据随机分为定标集和预测集,利用偏最小二乘法在103个定标集样本数据基础上建立印刷品颜色预测模型,应用此模型对41个预测集样本颜色进行预测.研究结果表明:利用PLS模型得到样本的实测值和预测值之间的预测决定系数(R~2)为99.74%,预测平均相对误差为0.636%,表明利用近红外光谱技术检测印刷品颜色是可行的.     

海洋卫星微波遥感技术发展现状与展望

 主动式和被动式微波遥感可以得到大量的地球物理参数和上层海洋信息,包括海表温度、海面矢量风、海面高度、海表盐度、海冰等。微波遥感可以穿透云层,全天候不间断观测海况信息。中国计划2011年发射运行的“海洋”2号（HY-2A）卫星有效载荷为3个微波遥感器,主要用来观测海面矢量风、海表温度和海面高度。HY-2A卫星将有效提高全球海洋卫星观测在时间和空间上的采样频率。本文介绍了与HY-2A卫星相关的海洋微波遥感技术现状,对微波遥感的优势和目前业务化运行的海洋微波卫星的局限性进行分析,总结了微波遥感的新技术进展和全球下一代微波遥感卫星的发射计划,最后指出发展中国立体海洋监测和中国“海洋”3号（HY-3）卫星（其主载荷为C频段多极化合成孔径雷达）对于更深入了解大洋和海岸带的必要性。     

利用SeaWiFS资料对二类水体辐射大气校正方法的研究

SeaDAS软件提供的标准大气校正算法中，假设第7和第8通道的离水辐射为0，但测量数据表明，在二类水体的大气校正算法中这种假设不成立．针对中国海区的特点．选取不同的近岸二类水体大气校正方法进行分析和比较，给出了适用于近岸二类水体尤其是近岸高泥沙含量的混浊水体的大气校正方法．     

Association Mechanism Between Propionic Acid and Trioctylamine

IntroductionIn recent years,solvent extraction has receivedmore and more attention for recovery of carboxylicacids from dilute aqueous solutions,especiallywith the hydrophobic tertiary amines dissolved invarious organic diluents[18] . Studies on theextrac…     

面向鄱阳湖洪涝风险分析的HY-1C/D卫星CZI影像水体面积与水位关系研究

海洋一号C星(HY-1C)和海洋一号D星(HY-1D)搭载的海岸带成像仪(coastal zone imager，CZI)广泛应用于海洋、海岛和海岸带监测，同时也是内陆水体动态监测的重要数据源.该文选择水体范围变化剧烈、旱洪灾害频发的鄱阳湖为研究区，以瑞利校正后的CZI反射率数据为基础，利用归一化水体指数(normalized difference water index，NDWI)与归一化植被指数(normalized difference vegetation index，NDVI)联合的水体范围提取方法，相对精度达到96%，并获取了2019年3月至2020年8月鄱阳湖湖泊淹没面积.在此基础上，结合同步的水文站水位测量数据，建立了适用于鄱阳湖的水面积－水位定量关系模型(R＝0.97).分析结果显示，鄱阳湖9月中旬至1月，水体面积最小，水位最低；2月至6月，水体面积逐渐增大，水位逐渐抬升；7月和8月，水体面积和水位达到年内峰值.洪涝风险区主要集中在鄱阳湖的东南部和西部.该研究对星地联合的洪涝风险分析有一定的借鉴意义.     

基于自动识别系统信息相关系数法的阵列幅相误差校准方案

针对高频地波雷达系统的工程应用,提出一种基于自动识别系统(automatic identification system, AIS)信息相关系数法进行阵列幅相误差校准的方法。该方法利用低信噪比的舰船回波信号,可以实现同步校正,不需要专门部署应答器,且成本低,对于不能借助直达波校准的单基地高频地波雷达系统同样适用。分析现场的实测数据结果表明,通过该方法对阵列幅相误差进行校准可以获得稳定的幅度、相位校准值,校准后多信号分类(multiple signal classification, MUSIC)空间谱估计方位角的准确性和分辨率得到大幅度提高,进而显著改善利用MUSIC算法估计海流方位角的高频地波雷达系统海流探测性能。     

基于模极大值与希尔伯特结合的TOA估计

传统的TOA(time of arrival)算法仅在高信噪比情况下才能获得较高精度的估计,为弥补现有估计算法的不足,提出了一种新的基于模极大值与包络提取结合的TOA估计算法。该算法首先利用小波模极大值对多径信号去噪,然后运用希尔伯特变换,对去噪后信号进行包络提取,选取第一个包络的峰值作为TOA估计值。仿真结果显示,与小波阈值相比,小波模极大值与希尔伯特结合的TOA估计误差更小。算法简单有效,实现了低信噪比下的高精度估计。     

Simulation and evaluation of the quality and availability of typical GLI ocean image

ADEOS-II satellite will be launched in the near future. It collocates many remote sensing instruments in the same platform. Among them, Global Image (GLI) is considered to be a main sensor which will play a key role. In order to understand the characteristics of future GLI ocean color images, a simulation and evaluation of the quality and availability of GLI typical ocean image has been done. In the paper, we first introduce the simulation models briefly, and simulate typical cases of radiance images at visible channels, in which the radiance distribution is based on geographic location, the satellite orbital parameters and sensor properties. A method, complex signal noise ratio (CSNR) to evaluate the image quality and availability, is developed according to the characteristics of image. Meanwhile, a series of CSNR images are generated from the simulated radiance components for different cases, which can be used to evaluate the quality and availability of GLI images before the ADEOS-II is placed in orbit. Finally, the quality and availability of GLI images are quantitatively analyzed by the simulated CSNR data. The results will be beneficial to the people who are in charge of GLI mission or plan to use the data from GLI.     

高频地波雷达的阵列互耦校正

针对分布式高频地波雷达（HFSWR）的工程应用,研究了基于自适应混合算法（AHA）的阵列无源校正方法.该方法将阵列误差估计问题转化为多元参数的联合估计问题,利用改进的混合算法得到了该优化问题的最优解估计.利用海洋回波校正了分布式高频地波雷达阵列幅相误差之后,将该方法应用到雷达系统的阵列互耦误差校正.仿真和现场实验实测数据的分析表明,该方法对空间谱算法性能的改善十分明显,验证了其有效性.     

东中国海域上空modis与seawifs两颗卫星反演气溶胶的比较

通过与地基气溶胶观测数据的对比,确认了MODIS,Sea WiFS气溶胶光学厚度产品用于研究中国海域气溶胶分布和变化特征的有效性.在此基础上,交叉比较了MODIS和Sea WiFS的气溶胶三级产品,发现他们在空间变化趋势上是一致的,在中国海域的气溶胶光学厚度都是随着离岸越远,气溶胶的光学厚度越来越小,在北纬30°-35°有高值区,在靠近大陆的沿岸地带也是气溶胶的光学厚度的高值区.Sea WiFS反演的气溶胶光学厚度整体比MODIS反演的气溶胶光学厚度偏高,两者的年平均气溶胶光学厚度有明显的区别.     

农药残留检测系统图像采集标定方法研究

利用农药残留检测试纸显色区域的颜色值进行农药残留度测量,需对测量系统中的彩色CCD图像传感器进行标定,消除图像颜色失真.采用在拍摄环境中放置灰度块的方法,利用灰度块的RGB分量平衡性与灰度线性渐变性,同时对彩色CCD图像传感器进行白平衡和非线性校正.实验表明,该标定方法能够很好地还原颜色值,有利于农药残留检测的后续工作.     

桅杆结构数据采集软件

文章介绍了桅杆结构数据采集软件的编制 ,并基于HY -8021多功能数据采集板与光电位置传感器的特性 ,使得该软件可满足以低频振动为主的建筑工程结构数据采集的要求。     

Retrieval of ocean surface wind stress and drag coefficient from spaceborne SAR

A model for retrieval of wind stress and drag coefficient on the sea surface with the data measured by spacebome synthetic aperture radar (SAR) has been developed based on the SAR imaging mechanisms of ocean surface capillary waves and short gravity waves. This model consists of radiometric calibration, wind speed retrieval and wind stress and drag coefficient calculation. A Radarsat SAR image has been used to calculate wind stress and drag coeffi cient. Good results have been achieved.     

应用水色卫星对海水油及COD的遥感探测

应用水色卫星（ＳｅａＷｉＦＳ,１９９７年由美国发射）近海监测海水ＣＯＤ及油污染状况及其分布,在广东珠江口、大亚湾等近海海域,进行了水体波谱测试与分析,建立了与水色卫星相应波段的ＣＯＤ及油的质量浓度信息提取模型,并用此模型处理了１９９８年６月３０日过境的水色卫星图像,得到了珠江口、大亚湾近岸水域ＣＯＤ及油分布的专题图