# Aquasafe: A Remote Sensing, Web-Based Platform for the Support of Precision Fish Farming
## 2 Materials and Methods
### Data
#### 2.2.1 Satellite and CMEMS Data  
The satellite data used in this study were obtained free of charge from the Copernicus services. Specifically, we utilized data from Sentinels 1, 2, and 3, as well as the Copernicus Marine Environment Monitoring Service (CMEMS). The input data sources and processing levels, as well as the available spatial and temporal resolution, are presented in Table 1.  
Sentinel-1 is a Synthetic Aperture Radar (SAR) mission of the Copernicus program, funded by the European Commission in partnership with the European Space Agency (ESA), which aims to provide data for ocean and land monitoring. The mission provides data regardless of weather and light conditions, as well as cloud coverage. The input data used in this study were Level-1 Ground Range Detected (GRD) products projected onto a ground range using an Earth ellipsoid model. These data were used for the detection of surface oils near fish farming sites. According to previous research, VV polarization offers a better clutter-to-noise ratio and is preferred for the detection of sea surface oils, which are indirectly detected as differences in sea surface roughness [14; 15; 16; 17; 18]. Sentinel-2 mission is mainly designed as a land-monitoring mission but is widely used for coastal waters as well. Sentinel-2 twin satellites (Sentinel-2A and Sentinel-2B) are equipped with a multispectral sensor (Multispectral Imager--MSI, manufacturing led by Airbus Defence and Space, Friedrichshafen, Germany, developed and operated by European Space Agency) with 13 spectral bands at 10, 20, and 60 m of resolution covering the optical, near-infrared, and shortwave infrared part of the spectrum, thus providing high-resolution imagery with global coverage every 5 days ([[https://sentinels.copernicus.e](https://sentinels.copernicus.e)]([https://sentinels.copernicus.e](https://sentinels.copernicus.e)) u/web/sentinel/missions/sentinel-2 (accessed on 20 April 2023)). Sentinel-2 data were \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Provider** & **Copernicus Open Access Hub 1** & **Eumetsat Data Services 2** & **Copernicus Marine Service 3** \\ \hline Platform & Sentinel-1 & Sentinel-2 & Sentinel-3 & CMEMS \\ Sensor & SAR & Multispectral & Thermal & Model \\ Format & Raster & Raster & Raster & Raster \\ Processing Level & 1, 2 & 1, 2 & 2 & 4 \\ Spatial Resolution & 30 m & 10 m, 20 m & 300 m, 1000 m & 1 km, 4 km \\ \hline Output & Biogenic Oil Film & Chlorophyll-a & Sea Surface Temperature & Dissolved Oxygen \\ \hline \hline \end{tabular}  
* [[https://sciub.copernicus.eu](https://sciub.copernicus.eu)]([https://sciub.copernicus.eu](https://sciub.copernicus.eu)) (accessed on 20 March 2023). 2 [[https://data.eumetsat.int](https://data.eumetsat.int)]([https://data.eumetsat.int](https://data.eumetsat.int)) (accessed on 20 March 2023). 3 [[https://marine.copernicus.eu](https://marine.copernicus.eu)]([https://marine.copernicus.eu](https://marine.copernicus.eu)) (accessed on 20 March 2023).  
\end{table} 
Table 1: Input data sources, processing levels, and resolutions are presented below. used for the estimation of chlorophyll-a and dissolved oxygen, as well as for the detection of surface oils near the farms. Both Level-1C and Level-2A data were exploited, and they were georeferenced in WGS84/UTM automatic zone projection. Sentinel-3 imagery was also found to be appropriate for such applications due to its spatial and temporal properties. Sentinel-3 is designed for ocean color applications specializing in estimating various Essential Oceanographic Variables (EOVs) on the surface layer ([[https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-3](https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-3)]([https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-3](https://sentinels.copernicus.eu/web/sentinel/missions/sentinel-3)) (accessed on 20 April 2023)).