Impact of Temperature on Absorption Coefficient of Pure Seawater in the Blue Wavelengths Inferred from Satellite and In Situ Measurements
Impact of Temperature on Absorption Coefficient of Pure Seawater in the Blue Wavelengths Inferred from Satellite and In Situ Measurements
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DOI：
10.34133/2021/9842702
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发表时间：
2021-07
影响因子：
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通讯作者：
G. Wei;Z. Lee;Xiuling Wu;Xiaolong Yu;S. Shang;Ricardo M Letelier
中科院分区：
文献类型：
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作者：
G. Wei;Z. Lee;Xiuling Wu;Xiaolong Yu;S. Shang;Ricardo M Letelier
关于“纯”淡水（afwλ）和“纯”海水（aswλ）的吸收系数如何（如果）随温度（T）变化的研究由来已久，但文献中报道的T的影响在蓝色区域中显著不同。与以往基于实验室测量的研究不同，我们采用了一种基于~18年（2002-2020年）贫营养海洋MODIS海洋颜色和温度测量的方法，沿着，结合现场测量的叶绿素浓度和浮游植物吸收系数，研究了T与412和443 nm处总吸收系数（aλ）之间的关系。我们发现，在夏季，a412和a443的值在观测到的~19-27 °C的T范围内几乎是平坦的（略有下降）。由于在此期间没有可检测到的叶绿素变化，结果表明，T在此T范围内对asw 412和asw 443的影响可以忽略不计。作为补充，还使用aswλ和afwλ的三次独立测定来评估盐度对afwλ的影响，其中从这些观察中发现了良好的一致性。
There has been a long history of interest on how (if) the absorption coefficient of “pure” fresh water (afwλ) and “pure” seawater (aswλ) changes with temperature (T), yet the impact of T reported in the literature differs significantly in the blue domain. Unlike the previous studies based on laboratory measurements, we took an approach based on ~18 years (2002–2020) of MODIS ocean color and temperature measurements in the oligotrophic oceans, along with field measured chlorophyll concentration and phytoplankton absorption coefficient, to examine the relationship between T and the total absorption coefficient (aλ) at 412 and 443 nm. We found that the values of a412 and a443 in the summer are nearly flat (slightly decreasing) for the observed T range of ~19–27 °C. Since there are no detectable changes of chlorophyll during this period, the results suggest that T has a negligible impact on asw412 and asw443 in this T range. As a complement, the impact of salinity on afwλ was also evaluated using three independent determinations of aswλ and afwλ, where good agreements were found from these observations.