纯水吸收系数在近红外波段随温度变化的实验评估

Experimental Evaluation of Temperature Dependence of Pure Water Absorption Coefficient in Near-Infrared Domain

关于温度(T)对纯水吸收系数[a_(w)(λ)]的影响,文献中有许多报道,其中有些报道并不一致。在这项研究中,通过对温度从7℃到51℃变化的高浑浊水体的遥感反射比[R_(rs)(λ)]的测量,分析了R_(rs)光谱在740~850 nm波段的形状变化,特别是R_(rs)与最近Rottgers等在实验室测量所揭示的由温度变化引起的a_(w)(λ)光谱形状变化的关系。分析发现R_(rs)光谱在740~850 nm波段的形状扭曲可以很好地由温度变化引起的a_(w)(λ)光谱的形状扭曲来解释。由于在近红外(NIR)波段R_(rs)光谱的形状主要由a_(w)(λ)光谱来决定,因此该结果的一致性提供了对从实验室测量获得的740~850 nm波段a_(w)(λ)数值与温度呈相反依赖性的独立验证。

There are many reports regarding the impact of temperature(T)on the absorption coefficient of pure water[a_(w)(λ)]in the literature,and some of them are not consistent.In this study,using well-controlled measurements of remotesensing reflectance[R_(rs)(λ)]of highly turbid waters where the temperature varied from 7 to 51℃,we analyzed the changes in the shape of R_(rs) in the 740-850 nm domain,especially the relationship between this change in R_(rs) spectral shape and the change of spectral shape in a_(w)(λ)caused by temperature variations indicated by the latest laboratory measurements from Rottgers et al.We found that the twist of R_(rs) spectral shape in the 740-850 nm domain can be well explained by the twist of spectral shape in a_(w)(λ)caused by changes in temperature.Since the spectral shape of R_(rs) in the near infrared(NIR)is mainly driven by the spectral variation of a_(w)(λ),the consistency provides an independent verification of the spectrallyopposite temperature dependence of a_(w)(λ)for bands in the 740-850 nm domain that was obtained from laboratory settings.