Pepe M, Giardino C, Borsani G, Cardoso A C, Chiaudani G, Premazzi G, Rodari E, Zilioli E
Remote Sensing Department, IRRS-CNR, Milan, Italy.
Sci Total Environ. 2001 Mar 14;268(1-3):31-45. doi: 10.1016/s0048-9697(00)00691-4.
The aim of the present study was the evaluation of methods for estimating the content of bio-physical parameters in lake water on the basis of spectral reflectance measured above water surface, in particular the estimation of chlorophyll-a (chl-a) concentrations. Data sets considered refer to some sampling point located in the sub-alpine meso-eutrophic Lake Iseo, surveyed six times over the period March-July and once in November 1998, as these months were very important for the characterization of the springtime algal bloom, which affect the lake waters yearly. At each point station, limnological observations (chlorophyll, total suspended solids, Secchi disk depth) were conducted simultaneously with optical measurements. The latter consisted of water leaving radiance measured by means of a spectroradiometer above the water surface; moreover, a standard reflector radiance was also measured to obtain the water reflectance. Reflectance spectra were transformed according to two well-documented models and correlated to water quality parameters, to investigate their performances as retrieval algorithms under different conditions and referring to different analytical methods. Results outline the sensitivity of the models to chl-a concentrations, different phytoplankton composition, and the sampling depth.
本研究的目的是评估基于水面以上测量的光谱反射率来估算湖水中生物物理参数含量的方法，特别是叶绿素a（chl-a）浓度的估算。所考虑的数据集涉及位于亚高山中富营养化的伊塞奥湖的一些采样点，在1998年3月至7月期间进行了六次调查，11月进行了一次调查，因为这些月份对于每年影响湖水的春季藻类大量繁殖的特征描述非常重要。在每个站点，同时进行了湖沼学观测（叶绿素、总悬浮固体、塞氏盘深度）和光学测量。光学测量包括通过光谱辐射计在水面上方测量的水体离水辐射率；此外，还测量了标准反射器辐射率以获得水体反射率。根据两个记录完善的模型对反射光谱进行变换，并将其与水质参数相关联，以研究它们在不同条件下作为反演算法以及参考不同分析方法时的性能。结果概述了模型对chl-a浓度、不同浮游植物组成和采样深度的敏感性。
