Partitioning particulate absorption coefficient into contributions of phytoplankton and nonalgal particles: A case study in the northern South China Sea
Partitioning particulate absorption coefficient into contributions of phytoplankton and nonalgal particles: A case study in the northern South China Sea
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DOI：
10.1016/j.ecss.2008.01.013
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发表时间：
2008-07
影响因子：
2.8
通讯作者：
Guifen Wang;W. Cao;Dingtian Yang;Jun Zhao
中科院分区：
文献类型：
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作者：
Guifen Wang;W. Cao;Dingtian Yang;Jun Zhao
在南海北方沿岸沃茨至外海的3个航次中，测量了悬浮颗粒物的吸收系数ap（λ）。采用甲醇提取法测定了浮游植物（aph（λ））和非藻类颗粒物（aNAP（λ））的吸收贡献。基于约360个样品的数据集，我们研究了粒子吸收系数的光谱关系。结果表明：在420- 650 nm波段，ap（λ）光谱与ap（443）光谱具有良好的线性相关性;在蓝绿波段，ap（λ）光谱可以很好地表示为ap（443）的二次二次方程，aNAP（λ）光谱服从一般的指数函数。基于这些光谱关系，提出了一个模型的总颗粒物吸收系数的贡献，浮游植物和非藻类粒子的非线性优化方法进行分区。将计算结果与现场吸收系数进行比较，验证了模型的正确性。在412 nm、443 nm、490 nm和683 nm等波段，相关性较好，均方根误差（RMSE）控制在25%以内，斜率接近1.0。对于来自沿海沃茨的样品，差异有点大，这可能是由于某些脱镁色素的吸收贡献较高。总的来说，这个模型为我们提供了很多深入了解浮游植物吸收反演现场测量和遥感海洋颜色数据。
We measured the absorption coefficients of suspended particles (ap(λ)) during three cruises from coastal waters to open ocean in the northern South China Sea (NSCS). The absorption contributions of phytoplankton (aph(λ)) and nonalgal particles (aNAP(λ)) were determined using the methanol extraction method. Based on the dataset of about 360 samples, we examined the spectral relationships of the particle absorption coefficients. The results show that ap(λ) spectra are well linearly correlated with ap(443) over the wavebands between 420–650nm; aph(λ) could be well expressed as the second-order quadratic equations of aph(443) among the blue-green wavebands, and aNAP(λ) follows the general exponential function. Based on these spectral relationships, a model was proposed for partitioning the total particulate absorption coefficients into the contributions of phytoplankton and nonalgal particles using the nonlinear optimization method. The model was validated by comparing the computed results with in situ absorption coefficients. In some wavebands, such as 412nm, 443nm, 490nm and 683nm, we obtained good correlations with the percentage root mean square error (RMSE) values being controlled within 25% and the slopes being closer to 1.0. For samples from coastal waters, the discrepancy was a little large, which might be due to the higher absorption contributions from certain pheopigments. Overall, this model provides us much insight into phytoplankton absorption retrieval from in situ measurements and remote sensing ocean color data.