Daily averaged Earth observation data from Sentinel-3 OLCI of the North and Baltic Sea region at the top-of-atmosphere and for cloud-free water areas after atmospheric correction for water constituents.
Sentinel-3 OLCI images processed with the Atmospheric Correction for Optical Water Types, A4O [Hieronymi et al. in prep & 2023], and the water algorithm OLCI Neural Network Swarm, ONNS [Hieronymi et al., 2017]. ONNS derives inherent optical properties (IOPs) from which the concentrations of water constituents are estimated. In addition, the results of an Optical Water Type (OWT) classification based on A4O reflectances are provided [Bi and Hieronymi, 2024]. All available satellite data of a day for the North and Baltic Sea region are merged in a common grid at approximately original resolution.
The following remote sensing products are available in the dataset.
Parameters from the original OLCI Level-1 data:
- L1_land: Level_1 land mask (thus implicitly water area)
- L1_Wind_speed: Wind speed (omnidirectional) from Level-1
Parameters from the atmospheric correction A4O:
- A4O_R_toa_400 – 1020: Reflectance at the Top-of-Atmosphere
- A4O_Rrs_n_400 - 1020: Normalized Remote-sensing reflectance Rrs_n
- A4O_SST: Monthly average of the Sea Surface Temperature from climatology
- A4O_SSS: Annual average of the Sea Surface Salinity from climatology
- A4O_A_wc: Percentage whitecap fraction of water areas based on wind speed and sea surface temperature
Parameter from the Optical Water Type classification [Bi and Hieronymi, 2024]:
- OWT_AVW: Apparent Visible Wavelength based on A4O_Rrs_n between 400 and 800 nm
- OWT_Area: Trapezoidal Area at Red, Green, and Blue (RGB) bands based on A4O_Rrs_n
- OWT_NDI: Normalized Difference Index at Green and Red based on A4O_Rrs_n
- OWT_index: Optical Water Type index or class based on A4O_Rrs_n
- OWT_U_tot: Total membership values in the OWT framework
Parameters from the ONNS water algorithm [Hieronymi et al., 2017]:
- ONNS_a_g_440: CDOM absorption coefficient at 440 nm (from IOP nets)
- ONNS_a_p_440: Absorption coefficient of phytoplankton particles at 440 nm
- ONNS_a_m_440: Absorption coefficient of minerals at 440 nm
- ONNS_a_tot_440: Total absorption coefficient at 440 nm, including CDOM, phytoplankton, minerals, and water
- ONNS_b_p_440: Scattering coefficient of phytoplankton particles at 440 nm
- ONNS_b_m_440: Scattering coefficient of minerals at 440 nm
- ONNS_b_tot_440: Total scattering coefficient at 440 nm, including phytoplankton, minerals, and water
- ONNS_a_dg_412: Absorption coefficient of detritus plus CDOM at 412 nm
- ONNS_b_bp_510: Total back-scattering coefficient of all particles at 510 nm
- ONNS_FU: Forel-Ule colour index
- ONNS_K_d_490: Downwelling diffuse attenuation coefficient at 490 nm
- ONNS_K_u_490: Upwelling diffuse attenuation coefficient at 490 nm
Parameters for concentrations of water constituents based on inherent optical properties:
- IOP_Chl: Chlorophyll concentration estimated from total particulate absorption coefficient at 440 nm based on Hereon measurements
- IOP_TSM: Total Suspended Matter concentration estimated from total particulate scattering coefficient at 440 nm based on Hereon measurements
- IOP_POC: Total particulate organic carbon (POC) concentration based on Hereon measurements of inherent optical properties of phytoplankton and TSM
- IOP_DOC: Concentration of dissolved organic carbon (DOC) related to CDOM absorption at 440 nm [Juhls et al., 2019]
Available flags from the atmospheric correction and water algorithm
- A4O_flag_cloud: Cloud mask from A4O
- A4O_flag_cloud_risk: High risk of clouds, which can strongly influence the quality of the retrieval
- A4O_flag_adjacency: Pixel near land or clouds with high risk of retrieval influence, e.g. through sub-pixel contamination of land, optically shallow water, aquatic plants or clouds
- A4O_flag_bright: Level_2 bright mask, that includes possible clouds and sea ice
- A4O_flag_suspect_pixel: Level_2 flag for possibly implausible AC output
- A4O_flag_floating: Level_2 flag for very high biomass and possibly floating algae
- A4O_flag_glint_risk: Level_2 flag for sun glint risk
- ONNS_limited_valid: Esimated concentration values are likely invalid