Satellite observations, autonomous in situ sensors and ecological modelling: a case study in Lake Trasimeno.

Regular observations of water quality in lakes provide essential information for resource management. To the aim, integration of satellite remote sensing, in situ monitoring from optical sensors and ecological modeling might provide multi scale and multi-frequency data. These data might be also combined to ecological modeling to forecast water conditions to alert for example for cyanobacterial blooms. This study presents the application of a such integrated approach, as part of the European EOMORES project, developed in lake Trasimeno, a turbid shallow lake located in central Italy. Satellite images acquired from OLCI on Sentinel-3 (S3, both A and B) and from MSI on Sentinel-2 (S2, both A and B) are converted into remote sensing reflectance and water quality parameters, such as chlorophyll-a concentrations. The satellite-products are evaluated based on field data and then analysed to capture phytoplankton phenology or to assess how comparable are OLCI and MSI products when obtained from synchronous S2 and S3 overpasses. Satellite data analysis from 2015 to 2018 is also integrated with in situ observations acquired from a WISPStation (an operational station based on a WISP-3 spectroradiometer) that, since April 2018, is autonomously gathering and serving data to evaluate inter- and intra- day changing of remote sensing reflectance. Finally, the setting of the Algae Radar model is presented as a further instrument to support the Lake Trasimeno monitoring