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《海洋通报(英文版)》2017,(2)
叶绿素a浓度是浮游植物现存量的表征。本文基于2012年春季渤海湾叶绿素实测数据,下载了相应的遥感数据,利用MODIS数据的OC3M和OC2方法进行叶绿素浓度a反演,利用GOCI数据的波段比值、OC3G以及YOC算法对叶绿素a浓度进行反演,反演结果与实测结果的空间分布趋势一致。由反演精度分析,GOCI的波段比值法与MODIS的OC3M算法的反演精度相近,GOCI数据的YOC叶绿素浓度算法在渤海湾反演精度比其他反演算法高。 相似文献
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叶绿素a作为最重要的水质参数之一,是评价水体富营养化和初级生产力状况的主要因素。我国海洋一号C（HY-1C）卫星海岸带成像仪（CZI）具有高时空分辨率的观测优势。本文基于东海和南海现场实测数据建立了HY-1C卫星CZI叶绿素a浓度反演模型并在实测水域进行反演,与MODIS叶绿素a浓度反演产品进行了对比验证,应用CZI叶绿素a浓度模型在珠江口、长江口、渤海湾水域进行了叶绿素a浓度反演示例试验。结果表明,叶绿素a浓度模型估算浓度与实测浓度相关系数为0.774 3,平均相对误差为24.58%,利用实测叶绿素a浓度对模型进行精度验证,相关系数达到0.993 9,平均相对误差为18.49%。模型在实测水域反演得到的叶绿素a浓度分布与MODIS叶绿素a浓度产品分布大体一致。在珠江口水域反演得到叶绿素a浓度空间分布为由西北向东南逐级递减,峰值出现在珠江口西沿岸。在长江口、渤海湾反演叶绿素a浓度空间分布均符合地理实情。研究表明HY-1C卫星CZI数据可应用于中国近海水色定量化研究。 相似文献
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为提高我国海洋水色遥感技术和海水环境监测水平,文章根据北海区海水遥感现场监测数据,基于经验算法和荧光基线高度法的回归分析,开展海水表层叶绿素a浓度的遥感定量反演,并选取北黄海近岸海域样本数据进行算法检验。研究结果表明:辽东湾等9个北海区典型海域具有相同或相似海水表层光学特性,适宜建立海水表层叶绿素a浓度遥感定量反演模型;典型海域海水表层叶绿素a浓度与遥感反射率之间的相关关系较强,模型均为简单波段比值模型;二类海水研究区域海水表层叶绿素a浓度与荧光基线高度之间的相关关系不明显;北黄海近岸海域海水表层叶绿素a浓度的最优模型遥感定量反演值的相对误差的平均值为0.669μg/L。 相似文献
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珠江口水体叶绿素荧光特性研究 总被引：3，自引：0，他引：3
利用2003年1月和2004年1月珠江口实测的遥感反射率和叶绿素浓度,建立了基于实测1nm带宽及其模拟MERIS遥感反射率数据的叶绿素荧光特征与叶绿素浓度之间的拟合关系。基于实测1nm带宽遥感反射率光谱,叶绿素荧光峰的位置和高度分别与叶绿素浓度之间存在良好的线性关系和指数关系;基于模拟MERIS遥感反射率数据,叶绿素荧光峰的高度与叶绿素浓度之间存在良好的线性关系,叶绿素荧光峰位置与叶绿素浓度之间不存在明显的相关关系,但可作为叶绿素浓度数量级的有效探针。利用2006年5月和8月的珠江口实测遥感反射率和叶绿素浓度对拟合结果进行了检验,结果表明其精度较高,说明叶绿素荧光特征在探测叶绿素浓度时效果良好且MERIS数据在近岸二类水体叶绿素浓度反演、水质监测等方面有着良好的应用前景。 相似文献
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采用常规最小二乘法(LS)和总体最小二乘法(TLS)对浮游植物色素吸收系数与叶绿素a浓度之间的关系进行了研究。利用2003-2012年6个航次243组实测数据,建立了LS和TLS模型,应用模型估算典型波段的色素吸收系数值,并对两种模型进行了验证。采用平均绝对百分误差和均方根误差两种方法进行模型效果评估,结果显示,两种评估方法均能很好地说明,在400～700 nm光谱范围内,TLS拟合结果优于LS拟合结果。总体最小二乘法在综合考虑了参数误差和测量误差的情况下,拟合结果精度更高,更符合实际情况,估算结果的准确性要优于常规最小二乘法。 相似文献
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HY-1 CCD宽波段水色要素反演算法 总被引：7，自引：4，他引：3
利用2003年春季黄海、东海区现场实测数据,建立了HY1卫星4波段CCD成像仪水色要素反演算法.由于HY1CCD的宽波段特性阻碍了黄色物质的反演,因此反演的水色要素仅包括水体表层的总悬浮物、悬浮泥沙(SS)以及叶绿素a的浓度.现场遥感反射率光谱由ASD地物波谱仪测量,对于叶绿素a的浓度利用现场萃取荧光法测量,总悬浮物、悬浮泥沙由实验室滤膜称重法获得.反演算法的拟合相关系数均大于0.88,平均相对误差在40%以下.对反演算法进行了误差灵敏度分析,结果表明对于总悬浮物、悬浮泥沙和低浊度水体中的叶绿素a的浓度反演算法能够满足日常的业务运行要求,但是对于高浊度水体中叶绿素a的浓度反演算法对某个波段组合比较敏感,仍需要进一步探讨. 相似文献
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南海叶绿素a浓度垂直分布的统计估算 总被引：2，自引：0，他引：2
分析整理了1993—2006年近10 a南海北部海域、南沙海域和南海其他海域的叶绿素a浓度历史航次调查资料,基于前人提出的全球叶绿素浓度垂直分布的统计分析模式,根据南海表层叶绿素a浓度大小的不同分级,对南海叶绿素a浓度进行了参数化处理,拟合估算了南海各水层剖面的叶绿素a浓度分布值,并结合不同海区的环境特征,分析了南海叶绿素a浓度垂直分布与其海水物理环境的关系。初步分析结果表明,叶绿素a浓度随深度垂直变化的拟合曲线呈一定倾斜的正态分布特征,当表层叶绿素a浓度较低时,作为南海深水海盆区的代表,拟合值更接近实测平均值的分布,叶绿素a浓度高值集中在次表层剖面上;当表层叶绿素a浓度较高时,作为近岸区和河口区的代表,高值多集中在表层海水,拟合误差偏大。该统计估算模式对于揭示南海叶绿素a浓度垂直分布结构进行了有益的尝试,为发展适合不同海区特点的模式以及校正参数奠定了基础。利用该模式与海洋水色卫星遥感数据有效结合,将对南海叶绿素a浓度时空分布格局的研究具有重要的意义。 相似文献
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利用高光谱监测数据反演浮游植物种群组成是当前海洋光学和水色遥感的研究热点。文章采用大西洋经向断面航次中走航式观测系统测量的海水总颗粒物吸收光谱数据, 尝试建立了两种模型对浮游植物粒级结构(Phytoplankton size class, 简称PSC)进行反演和比较讨论。一类模型是基于总颗粒物吸收光谱高斯分解获得的典型波段高斯带强度与色素浓度之间的关系, 建立了偏最小二乘回归模型(Partial Least Squares regression model, 简称PLS回归模型); 另一类模型是采用长波波段吸收基线高度推算海水总叶绿素a浓度, 进而根据Brewin等(2010) 生物量算法推算PSC的三组分模型(简称三组分模型)。模型比较验证结果显示, 两类模型对海水总叶绿素浓度的反演都有较高的精度, 相对偏差ME在15%左右; 对于三个粒级浮游植物对应的叶绿素浓度(Pico级Cp, Nano级Cn, Micro级Cm)的反演效果也相当, PLS回归模型反演的ME分别为28.4%、31.9%和41%, 三组分模型反演的ME分别为31%、35.9%、37.7%。研究结果初步表明了采用高光谱吸收系数反演浮游植物种群结构的潜在优势, 可为不同海域走航式高光谱观测系统的推广应用提供思路。 相似文献
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The spherical interpolation method of source localization 总被引：1，自引：0，他引：1
A closed-form least squares approximate maximum likelihood method for localization of broad-band emitters from time-difference-of-arrival (TDOA) measurements, called the spherical interpolation (SI) method, is presented. The localization formula is derived from least squares "equation-error" minimization. Computer simulation results show that the SI method has variance approaching the Cramer-Rap lower bound. 相似文献
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A method of extracting wave parameters from surface displacement measured from a moving platform is presented. The article first presents a method for accurately measuring surface displacement using a single beam altimeter and heave sensor. A least squares approach is presented to estimate wave parameters using vessel velocity and perceived wave frequency that eliminates Doppler due to vessel motion. Two techniques for estimating wave frequency are presented: a block data method using MUSIC and a real-time method using demodulation. Sea trial results demonstrate that this method is as effective as a WaveRider buoy for estimating wave parameters. 相似文献
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This paper reports the development and experimental evaluation of two in situ least squares techniques for estimating the alignment matrix of Doppler sonars commonly used for precision navigation of oceanographic submersibles. Most previously reported methods addressed the problem of single degree-of-freedom heading alignment using bottom-lock Doppler sonar data and global positioning system (GPS) navigation data. This paper reports and evaluates two techniques for three degree-of-freedom calibration of attitude and Doppler sonar sensors using sensor data available to vehicles at full ocean depth. The first technique provides a general linear least squares estimate of the alignment matrix. The second technique results in a least squares alignment matrix estimate constrained to the group of rotation matrices. The performance of these estimates is evaluated with a laboratory remotely operated vehicle (ROV) and a field-deployed autonomous underwater vehicle (AUV). Experimental results are reported which demonstrate that Doppler navigation employing the reported alignment calibration techniques significantly improves navigation precision. The experiments show that the latter technique provides calibration estimates that improve Doppler navigation precision not only on the calibration data set itself, but also provide improved precision over a wide variety of vehicle trajectories other than the calibration data set. 相似文献
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Combining Lidar Elevation Data and IKONOS Multispectral Imagery for Coastal Classification Mapping 总被引：1，自引：0，他引：1
This article studies the effect of airborne lidar (surface) elevation data on the classification of multispectral IKONOS images over a coastal area. The lidar data and IKONOS images are treated as independent multiple bands to conduct the classification. To do so, the lidar elevation data is first resampled to the same ground spacing interval and stretched to the same radiometric range as the IKONOS images. An unsupervised classification based on the ISODATA algorithm is then used to determine a class schema of six classes: road, water, marsh, roof, tree, and sand. Training sites and checking sites are selected over the lidar-IKONOS merged data set for the subsequent supervised classification and quality evaluation. The complete confusion matrices and average quality indices are presented to assess and compare the classification results. It is shown that the inclusion of the lidar elevation data benefits the separation of classes that have similar spectral characteristics, such as roof and road, water and marsh. The overall classification errors, especially the false positive errors, are reduced by up to 50%. Moreover, by using the lidar elevation data, the classification results show more realistic and homogeneous distribution of geographic features. This property will benefit the subsequent vectorization of the classification maps and the integration of the vector data into a geographical information system. 相似文献
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This article studies the effect of airborne lidar (surface) elevation data on the classification of multispectral IKONOS images over a coastal area. The lidar data and IKONOS images are treated as independent multiple bands to conduct the classification. To do so, the lidar elevation data is first resampled to the same ground spacing interval and stretched to the same radiometric range as the IKONOS images. An unsupervised classification based on the ISODATA algorithm is then used to determine a class schema of six classes: road, water, marsh, roof, tree, and sand. Training sites and checking sites are selected over the lidar-IKONOS merged data set for the subsequent supervised classification and quality evaluation. The complete confusion matrices and average quality indices are presented to assess and compare the classification results. It is shown that the inclusion of the lidar elevation data benefits the separation of classes that have similar spectral characteristics, such as roof and road, water and marsh. The overall classification errors, especially the false positive errors, are reduced by up to 50%. Moreover, by using the lidar elevation data, the classification results show more realistic and homogeneous distribution of geographic features. This property will benefit the subsequent vectorization of the classification maps and the integration of the vector data into a geographical information system. 相似文献
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溶解氧浓度检测在水产养殖和环境监测中具有重要的意义。本文提出了一种基于快速数字锁相的溶解氧检测优化设计，利用快速数字锁相算法与过采样技术，实现了荧光信号和调制信号的快速相位解调，并得到二者相位差，根据Stern-Volmer方程求出溶解氧浓度值。本文分析了调制频率对测量结果的影响，选择合适的调制频率用于测量，并利用最小二乘法对测量结果进行拟合，拟合后的确定系数R-square为0.999 25。实验数据表明，测量结果相对误差（RE）小于±1.5%，相对标准差（RSD）小于4%，稳定时间小于50 s。本文提出的优化设计不仅具有较高的测量精度，还简化了硬件设计，降低了成本。 相似文献
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An optimal evaluation of adaptive beamforming techniques in a reverberation-limited shallow water environment is presented. A comprehensive simulation, using the sonar simulation toolset (SST) software in conjunction with the generic sonar model (GSRT) software, is used to create realistic beam data complete with target, noise, and reverberation. Adaptive beamforming techniques from the recursive least squares (RLS) family are applied to enhance detection performance via interference rejection. Two techniques are considered: linearly constrained beamforming using the minimum variance distortionless response (MVOR) beamformer and constrained adaptive noise cancelling (ANC) using the joint process least squares lattice (JPLSL) algorithm. Target detection trials, summarized in the form of receiver operator characteristics (ROC), are used to evaluate performance of the two adaptive beamformers. Results demonstrate mixed performance in reverberation-limited shallow water environments 相似文献