| Variation in downwelling diffuse attenuation coefficient in the northern South China Sea |
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| 作者姓名： | 王桂芬 曹文熙 杨顶田 许大志 |
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| 作者单位： | LED Laboratory，South China Sea Institute of Oceanology，Chinese Academy of Sciences，Guangzhou 510301，China，The Graduate School of Chinese Academy of Sciences，Beijing 100039，China |
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| 基金项目： | 中国科学院基金，国家自然科学基金，Project of Knowledge Innovation of South China Sea Institute of Oceanology |
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| 摘 要： | The diffuse attenuation coefficient for downwelling irradiance （Kd（λ）） is an important parameter for ocean studies. Based on the optical profile data measured during three cruises in the northern South China Sea in autumn from 2003 to 2005, variations in the Kd（λ） spectra were analyzed. The variability of Kd（λ） shows much distinct features in both magnitude and spectra pattern, it is much higher in coastal waters than that of open oceanic waters; and the blue-to-green （443/555） ratio of Kd（λ） tends to increase with chlorophyll a concentration （Chl-a]） from open ocean to coastal waters. These characteristics can be explained most by the increase of aw＋p（443）/aw＋p（555） with Chl-a]. In short waveband, the relation between Kd（λ）-Kw（λ） and Chl-a] can be well described by a power law function, indicating the large contribution of phytoplankton to the variations in Kd（λ）. As for the spectral model of the diffuse attenuation coefficient, there are good linear relationships between Kd（490） and Kd（λ） in other wavelengths with own slope and intercept of a linear functions in the spectral range 412-555 nm. Kd（490） is well correlated with the spectral ratio of remote sensing reflectance; and should enough measurement data are given, this empirical algorithm would be used in the Kd（λ） retrieval from ocean color satellite data. The variation in Kd（λ） provides much useful information for us to study the bio-optical property in the northern South China Sea.
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| 关 键 词： | 下降流 衰退系数 叶绿素 生物光学模式 南中国海北部 |
| 收稿时间： | 13 March 2007 |
Variation in downwelling diffuse attenuation coefficient in the northern South China Sea |
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| Guifen?Wang,Wenxi?Cao,Dingtian?Yang,Dazhi?Xu.Variation in downwelling diffuse attenuation coefficient in the northern South China Sea[J].Chinese Journal of Oceanology and Limnology,2008,26(3):323-333. |
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| Authors: | Guifen Wang Wenxi Cao Dingtian Yang Dazhi Xu |
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| Institution: | [1]LED Laboratory, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China [2]The Graduate School of Chinese Academy of Sciences, Beijing 100039, China |
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| Abstract: | The diffuse attenuation coefficient for downwelling irradiance (K
d(λ)) is an important parameter for ocean studies. Based on the optical profile data measured during three cruises in the northern
South China Sea in autumn from 2003 to 2005, variations in the K
d(λ) spectra were analyzed. The variability of K
d(λ) shows much distinct features in both magnitude and spectra pattern, it is much higher in coastal waters than that of open
oceanic waters; and the blue-to-green (443/555) ratio of K
d(λ) tends to increase with chlorophyll a concentration (Chl-a]) from open ocean to coastal waters. These characteristics can be explained most by the increase of a
w+p(443)/a
w+p(555) with Chl-a]. In short waveband, the relation between K
d(λ)-K
w(λ) and Chl-a] can be well described by a power law function, indicating the large contribution of phytoplankton to the variations in K
d(λ). As for the spectral model of the diffuse attenuation coefficient, there are good linear relationships between K
d(490) and K
d(λ) in other wavelengths with own slope and intercept of a linear functions in the spectral range 412–555 nm. K
d(490) is well correlated with the spectral ratio of remote sensing reflectance; and should enough measurement data are given,
this empirical algorithm would be used in the K
d(λ) retrieval from ocean color satellite data. The variation in K
d(λ) provides much useful information for us to study the bio-optical property in the northern South China Sea.
Supported by the Chinese Academy of Sciences (No. KZCX2-YW-215) and the National Natural Science Foundation of China (No.
40476019), and the Project of Knowledge Innovation of South China Sea Institute of Oceanology (No. LYQY200701). |
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| Keywords: | the downwelling diffuse attenuation coefficient chlorophyll a bio-optical model the northern South China Sea |
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