Abstract

The diffuse attenuation coefficient of photosynthetically active radiation is an importantinherent optical property of the subaquatic light field. This parameter, as a measure of the trans-parency of the medium, is a good indicator of water quality. Degradation of the optical propertiesof water due to anthropogenic disturbances is a common phenomenon in freshwater ecosystems.In this study, we used four algorithm-based Landsat 8 OLI and Sentinel-2A/B MSI images to es-timate the diffuse attenuation coefficient of photosynthetically active radiation in Lake Villarricalocated in south-central Chile. The algorithms’ estimated data from the ACOLITE module werevalidated with in situ measurements from six sampling stations. Seasonal and intralake variationsof the light attenuation coefficient were studied. The relationship between the diffuse attenuationcoefficient of photosynthetically active radiation, meteorological parameters, and an optical classifi-cation was also explored. The best results were obtained with QAA v6 KdPAR Nechad (R2 = 0.931,MBE = 0.023 m−1, RMSE = 0.088 m−1, and MAPE = 35.9%) for spring and QAA v5 Kd490 algorithms(R2 = 0.919, MBE = −0.064 m−1, RMSE = −0.09 m−1, and MAPE = 30.3%) for summer. High KdPARvalues are associated with the strong wind and precipitation events suggest they are caused bysediment resuspension. Finally, an optical classification of freshwater ecosystems was proposedfor this lake. The promising results of this study suggest that the combination of in situ data andobservation satellites can be useful for assessing the bio-optical state of water and water qualitydynamics in Chilean aquatic systems