Bio-optical observations of the Baltic Sea and coastal areas, 2008-2012

This a dataset of optical-biogeochemical measurement results was collected during 2008-2012 as part of spring and summer cruises with R/V Aranda as well as from flow-through water samples taken with the Ferrybox system on M/S Finnmaid. The majority of observations were made in the Gulf of Finland, Baltic Proper, Archipelago Sea, and Gulf of Bothnia in the Baltic Sea. A number of riverine and inshore observations are also included. The data collection is owned by the Finnish Environment Institute SYKE and made available under a CC-BY-NC licence. Detail on methods and protocols are provided in the following papers Simis, Stefan GH; Ylöstalo, Pasi; Kallio, Kari Y; Spilling, Kristian; Kutser, Tiitt. 2017. Contrasting seasonality in optical-biogeochemical properties of the Baltic Sea. PLoS One 12(4), e0173357. https://doi.org/10.1371/journal.pone.0173357 Ylöstalo, Pasi; Seppälä, Jukka; Kaitala, Seppo; Maunula, Petri; Simis, Stefan. 2016. Loadings of dissolved organic matter and nutrients from the Neva River into the Gulf of Finland–Biogeochemical composition and spatial distribution within the salinity gradient. Marine Chemistry 186, 58-71. https://doi.org/10.1016/j.marchem.2016.07.004 A large number of individuals took part in these bio-optical research cruises over the years. The authors of this dataset are particularly grateful to the contributions by international visitors, students and volunteers taking part in one or more cruises, as well as crew and support staff operating the research vessel and ship-of-opportunity. Variables included in the dataset include: Column name unit/format Description Secchi m Secchi disk depth AirTemp(38) °C, 01H Air temperature from ship weather channel 38, 1-h average SeaTemp(42) °C, 01H Sea temperature from ship weather channel 42, 1-h average WindSpeed(92) m/s, 10M Wind speed from ship weather channel 92, 10-min average WindDir(96) °, 10M Wind direction from ship weather channel 96, 10-min average Salinity(104) PSU, 01H Salinity from ship weather channel 104, 1-h average Rel.humid(54) %, 01H Relative humidity from ship weather channel 54, 1-h average Chla mg/m3 Chlorophyll-a concentration (cold ethanol extraction and calibrated fluorescence) TSM_avg mg/L Total Suspended Matter Dry Weight, Average OSM_avg mg/L Dry weight of Organic fraction of TSM, Average ISM_avg mg/L Dry weight of Inorganic fraction of TSM, Average DOC_avg µM Dissolved Organic Carbon concentration, Average TDN_avg µM Total Dissolved Nitrogen concentration, Average NH4 µM Ammonium concentration NO32 µM Nitrate-Nitrate concentration NO2 µM Nitrite concentration PO4 µM Phosphate concentration SiO4 µM Silicate concentration TN µM Total nitrogen concentration TP µM Total phosphorous concentration pH pH pH value Temp_CTD °C Water temperature measured by Seabird CTD on sampling rosette Salinity_CTD SSU Salinity measured by Seabird CTD on sampling rosette POC µM Particulate Organic Carbon concentration, Average PON µM Particulate Organic Nitrogen concentration, Average POP µM Particulate Organic Phosphorus concentration, Average (30.973762 g/Mol) Turbidity PSU Turbidity aCDOM m^-1 spectral absorption coefficient of coloured dissolved organic matter CloudCover 0-1 Fraction (0-1) of cloud cover assesed from photos taken in the field. Kd m^-1 spectral Vertical diffuse downwelling irradiance coefficient a_nap m^-1 spectral absorption coefficient by non-pigmented fraction of suspended matter a_tsm m^-1 spectral absorption coefficient by suspened matter R0 - spectral Subsurface Irradiance Reflectance pigments mg/m3 Chlorophyll and other pigments extracted and quantified using a combination of calibrated fluorometry and HPLC