Daily Baltic Sea A-Chlorophyll (Envisat MERIS) 2003-2011/Daily Chlorophyll-a of the Baltic Sea (Envisat MERIS) 2003-2011

**[EN]** satellite images monitor the concentration of chlorophyll a in the Baltic Sea (ug/l) in ice-free and cloud-free areas from April to October. Chlorophyll A makes it possible to estimate the amount of algae in water. It is also a key factor in assessing the level of eutrophication of water. The amount of chlorophyll A was calculated from the 3 rd Reprocessing data of Envisat MERIS (Medium Resolution Imaging Spectrometer) using the FUB (Freie University of Berlin) (Shcroeder et al., 2007). The material consists of daily images for the years 2003-2011. The photographs have a terrain separation capacity of 300 meters. The nearby shallow areas of the coast and islands have been removed from the material. The material is part of SYKE’s open data (CC BY 4.0). Purpose: Monitoring of water quality in the Baltic Sea. *** **[En]** Satellite remote sensing is used to monitor the Chlorophyll-a (ug/l) of surface water in the Baltic Sea during the open water season from April to October. Areas covered by ice or cloud are excluded from the data. Chlorophyll-a (chl-a) represents the quantity of algae in the water but not directly the amount of Cyanobacteria. A daily Chlorophyll-a product has been calculated using Envisat MERIS (Medium Resolution Imaging Spectrometer) 3 rd Reprocessing data. Satellite data have been processed to chl-a concentrations using a neural network-based FUB processor (Freie University of Berlin). The dataset covers years 2003-2011. The spatial resolution is 300 meters. Shadow areas near the coast and island have been excluded from the dataset. Purpose of use: Monitoring of water quality in the Baltic Sea. *** ## References/References Attila, J., Kauppila, P., Alasalmi, H., Kallio, K., Keto, V., Bruun, E., & Koponen, S. (2018). Applicability of Earth Observation Chlorophyll-a data in assessment of water status via MERIS — with implications for the use of OLCI sensors. Remote Sensing of Environment, 212, 273-287. https://doi.org/10.1016/j.rse.2018.02.043 Attila J. (2019). Water quality monitoring and assessment of the Northern Baltic Sea using Earth Observation. Aalto University publication series, 229/2019. 178p. ISBN (pdf) 978-952-60-8867-9, ISSN (pdf) 1799-4942, http://urn.fi/URN:ISBN:978-952-60-8867-9. HELCOM (2015). Eutrophication Assessment Manual, Annex 3A. http://www.helcom.fi/helcom-atwork/projects/eutro-oper/. Last revision 2015. HELCOM (2018): State of the Baltic Sea — Second HELCOM Holistic assessment 2011-2016. Baltic Sea, Environment Proceedings 155, 155p. Schroeder, T., Schaale, M., & Fischer, J. (2007). Retrieval of atmospheric and oceanic properties from MERIS measurements: A new Case-2 water processor for BEAM. International Journal of Remote Sensing, 28(24), 5627-5632. *** **WMS server/WMS service endpoint**: https://geoserver2.ymparisto.fi/geoserver/eo/wms **WMS level/WMS layer**: MER_FSG_L3_rp2017_chla *** **[EN]** Daily a-chlorophyll material consisting of observations from 2003-2011 resulting from remote sensing monitoring. Processing history: chlorophyll A has been interpreted from the 3 rd Reprocessing materials of the Envisat MERIS satellite instrument. The original satellite data has been downloaded from the European Space Agency (ESA) download services. In the heart rate, a chlorophyll readings are calculated using the FUB (Freie University of Berlin) water quality processor. *** **[En]** Chlorophyll-a data from years 2003-2011 for the Baltic Sea. Processing history: The Envisat MERIS 3 rd Reprocessing data have been received from ESA service. The dataset has been processed to Chlorophyll-a values in SYKE using the FUB (Freie University of Berlin), which includes atmospheric correction.