| Fu Dongyang,Huang Yuye,Liu Dazhao,Liao Shan,Yu Guo,Zhang Xiaolong. 2020. Analysis of the regional spectral properties in northwestern South China Sea based on an empirical orthogonal function. Acta Oceanologica Sinica, 39(7):107－114 |
| Analysis of the regional spectral properties in northwestern South China Sea based on an empirical orthogonal function |
| 基于EOF分析对南海西北海域水体光谱特性的研究 |
| Received:August 30, 2019 |
| DOI：10.1007/s13131-020-1625-x |
| Key words:northwestern South China Sea remote sensing reflectance empirical orthogonal function analysis ocean color control factors |
| 中文关键词: 南海西北部海域 遥感反射率 经验正交函数分析 水色控制因子 |
| 基金项目:The Key Projects of the Guangdong Education Department under contract No. 2019KZDXM019; the Fund of Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang) under contract No. ZJW-2019-08; High-Level Marine Discipline Team Project of Guangdong Ocean University under contract No. 002026002009; the Guangdong Graduate Academic Forum Project under contract No.230420003; the "First Class" discipline construction platform project in 2019 of Guangdong Ocean University under contract No. 231419026. |
| Author Name | Affiliation | E-mail | | Fu Dongyang | College of Electronic and Information Engineering, Guangdong Ocean University, Zhanjiang 524088, China | | | Huang Yuye | State Key Laboratory of Tropical Oceanography, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
University of Chinese Academy of Sciences, Beijing 100049, China | hyuye0626@163.com | | Liu Dazhao | College of Electronic and Information Engineering, Guangdong Ocean University, Zhanjiang 524088, China | | | Liao Shan | College of Electronic and Information Engineering, Guangdong Ocean University, Zhanjiang 524088, China | | | Yu Guo | College of Electronic and Information Engineering, Guangdong Ocean University, Zhanjiang 524088, China | | | Zhang Xiaolong | College of Electronic and Information Engineering, Guangdong Ocean University, Zhanjiang 524088, China | |
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| Abstract: |
| This study presents an analysis of the spectral characteristics of remote sensing reflectance (Rrs) in northwestern South China Sea based on the in situ optical and water quality data for August 2018. Rrs was initially divided into four classes, classes A to D, using the max-classification algorithm, and the spectral properties of whole Rrs were characterized using the empirical orthogonal function (EOF) analysis. Subsequently, the dominant factors in each EOF mode were determined.The results indicated that more than 95% of the variances of Rrs are partly driven by the back-scattering characteristics of the suspended matter. The initial two EOF modes were well correlated with the total suspended matter and back–scattering coefficient. Furthermore, the first EOF modes of the four classes of Rrs (A-D Rrs-EOF1) significantly contributed to the total variances of each Rrs class. In addition, the correlation coefficients between the amplitude factors of class A-D Rrs-EOF1 and the variances of the relevant water quality and optical parameters were better than those of the unclassified ones. The spectral shape of class A Rrs-EOF1 was governed by the absorption characteristic of chlorophyll a and colored dissolved organic matter (CDOM). The spectral shape of class B Rrs-EOF1 was governed by the absorption characteristic of CDOM since it exhibited a high correlation with the absorption coefficient of CDOM (ag (λ)), whereas the spectral shape of class C Rrs-EOF1 was governed by the back-scattering characteristics but not affected by the suspended matter. The spectral shape of class D Rrs-EOF1 exhibited a relatively good correlation with all the water quality parameters, which played a significant role in deciding its spectral shape. |
| 中文摘要: |
| 分析遥感反射率(Rrs)的光谱特性是研究水色遥感的基础之一。基于2018年8月在南海西北部近海实测的遥感反射率(Rrs)和水质参数，以最大值分类法将Rrs分为四类(Class A-D)。利用经验正交函数(EOF)分解分类前后Rrs的谱型结构，探讨Rrs正交模态的谱型特性及其与水质参数的相关性，判定控制Rrs-EOF模态的主导因子。结果表明95%的Rrs变化特性受悬浮颗粒物后向散射的影响，总Rrs EOF分析的前两个模态与悬浮物(TSM)及后向散射系数(bb(λ))的相关性均比较好。此外，Class A-D Rrs EOF分析的第一模态(Rrs-EOF1)与水质参数的相关性均优于分类前。Class A Rrs-EOF1的谱型变化受黄色物质(CDOM)和叶绿素a (Chl-a)吸收特性的共同影响；由于Class B Rrs-EOF1与CDOM的吸收系数(ag(λ))相关性很好，因此其谱型变化主要受黄色物质吸收特性的主导；Class C Rrs-EOF1的谱型变化受后向散射的影响，但不是由悬浮颗粒物引起的；Class D Rrs-EOF1与各水质参数的相关性均比较好，其谱型变化受到多种因子的共同影响。 |
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