Evaluating Sentinel-2 for Lakeshore Habitat Mapping Based on Airborne Hyperspectral Data.

Monitoring of lakeshore ecosystems requires fine-scale information to account for the high biodiversity typically encountered in the land-water ecotone. Sentinel-2 is a satellite with high spatial and spectral resolution and improved revisiting frequency and is expected to have significant potential for habitat mapping and classification of complex lakeshore ecosystems. In this context, investigations of the capabilities of Sentinel-2 in regard to the spatial and spectral dimensions are needed to assess its potential and the quality of the expected output. This study presents the first simulation of the high spatial resolution (i.e., 10 m and 20 m) bands of Sentinel-2 for lakeshore mapping, based on the satellite's Spectral Response Function and hyperspectral airborne data collected over Lake Balaton, Hungary in August 2010. A comparison of supervised classifications of the simulated products is presented and the information loss from spectral aggregation and spatial upscaling in the context of lakeshore vegetation classification is discussed. We conclude that Sentinel-2 imagery has a strong potential for monitoring fine-scale habitats, such as reed beds.

Estimations of 137Cs activity concentrations using marine parameters issued from MODIS and Copernicus Marine Environment Monitoring Services (CMEMS) data in Souda Bay (Crete, Greece) for the period 2011-2019.

Cesium-137, as the main fission product, is of special interest in the marine environment because of its solubility, which results to very low sinking time. Nevertheless, the conservative form of the main percentage of 137Cs introduced in the marine environment (70%) makes 137Cs to be included in the salinity of sea water. Based on this property, in this study, we examine potential relations between 137Cs activity concentrations and marine parameters issued from Earth Observation (EO) data products in the Southern Aegean Sea, in order to investigate the possibility of 137Cs to be recorded by satellite data. In particular, measurements of physical and biological marine parameters issued from the Copernicus Marine Environment Monitoring Service (CMEMS) database and MODIS ocean products are retrieved for the dates of 137Cs field measurements. Single and multiple regression analyses are performed between the marine parameters and 137Cs activity concentration measurements for three distinctive time periods (total, cold, and warm period). The best results are obtained from multiple regressions, one for each time period (r2 > 0.70). The models show that during cold period, 137Cs activity concentrations are highly correlated to both chlorophyll and nutrients (phosphates) while during warm and the total period, they seem to be mainly correlated to the photosynthetic available incident solar radiation on the sea surface. For each period, we propose a multiparameter model linear in its parameters. Although the results of this study must be considered preliminary due to the limited size of the datasets, for the first time, we show that estimations of 137Cs activity concentrations from EO measurements and CMEMS environmental models are feasible, and they can be used as a marine radiological assessment tool for a closed Mediterranean bay such as Souda Bay in Greece.