Temporal changes in the remote sensing reflectance at Lake Vänern

• Published in: Journal of Great Lakes Research
• Main Authors: CAZZANIGA Ilaria, ZIBORDI Giuseppe, ALIKAS Krista, KRATZER Susanne
• Language: English
• Published: ELSEVIER SCI LTD 2023
• Subjects: Aerosol Robotic Network
• Online Access: https://publications.jrc.ec.europa.eu/repository/handle/JRC129860; https://www.sciencedirect.com/science/article/pii/S0380133023000291; https://doi.org/10.1016/j.jglr.2023.01.006

The Aerosol Robotic Network - Ocean Color (AERONET-OC) instrument located at the Pålgrunden site in Lake Vänern provides values of remote sensing reflectance RRS(λ) since 2008. These in situ RRS(λ) indicated a temporal increase from 2015. To investigate the environmental and climate processes responsible for this increase, water color trends in Lake Vänern were analyzed considering in situ limnological and meteo-climatic quantities and satellite data from the Moderate Resolution Imaging Spectroradiometer on board the Aqua platform (MODIS-A). Satellite RRS(λ) data assessed against in situ RRS(λ) showed satisfactory agreement at a number of spectral bands. Comprehensive statistical analysis were performed using MODIS-A RRS(λ). These indicated periodical changes between 2002 and 2021 with minima occurring between 2010 and 2013. The complementary analyses of temporal changes characterizing limological and meteo-climatic quantities, and relationships between these quantities and RRS(λ), indicated the existence of complex and concurrent bio-geochemical processes influencing water color in Lake Vänern. Significant correlations were observed between RRS(λ) and turbidity, and also between RRS(λ) and total biovolume. Additionally, an early warming of Lake Vänern surface waters was identified since spring 2014. This occurrence could potentially affect the vertical mixing and water exchange between turbid coastal and pelagic waters with implications for phytoplankton phenology. JRC.D.2 - Ocean and Water