Revealing the influence of volcanic plumes on lake water quality parameters derived using remote sensing methods

Satellite-derived observations of inland waters are widely used in environmental monitoring and climate research, often forming the basis of long-term analyses in the absence of continuous in situ measurements. However, the influence of transient atmospheric phenomena, such as volcanic plumes, on these datasets remains insufficiently quantified. In this study, we investigate the extent to which volcanic plumes influence lake surface water temperature (LSWT), turbidity, and chlorophyll-a measurements derived from ESA Climate Change Initiative (CCI) Lakes. Using a multi-sensor approach, we leverage MISR and MODIS observations to analyse plume–lake interactions during the 2011–2012 eruption of Puyehue-Cordón Caulle (PCC), Chile. Results indicate that while standard cloud screening procedures remove a substantial proportion of plume-affected observations, residual impacts remain. Notably, lake observations are influenced not only when plumes directly overlay the lake surface but also when plumes are proximal but not visually detectable over the lake, indicating the influence of diffuse aerosol particles. Analysis of aerosol microphysical properties demonstrates that particle-based classification can achieve approximately 67% accuracy, in identifying plume-affected observations but is limited by temporal variability in volcanic plume composition. In contrast, proximity-based approaches more consistently capture plume influence, suggesting that spatial context is critical for effective data flagging. These findings highlight a previously under-recognised source of uncertainty in satellite-derived inland water quality datasets. They support the implementation of proximity-based quality flags to improve data reliability in regions affected by volcanic activity in situations where consistent particle-based observations are unavailable.