Radiation budget at the Baltic Sea surface in 2010 – 2023 from SatBałtyk System

Global climate change, which causes, among other things, an accumulation of energy in the oceans, may cause irreversible changes to their ecosystems. This can be particularly quickly apparent in bodies of water that are shallow and small in relation to the Oceans, such as the Baltic Sea. In the SatBałtyk System (http://www.satbaltyk.pl), which aims to observe the state of the Baltic Sea environment based on satellite data, maps of the distributions of values of a number of physical biological and chemical parameters of the sea are collected and made available. Within the framework of this System, the SBRB (SatBałtyk Radiation Budget) model was launched, determining data on radiation budget (NET) at the sea surface. Daily maps of the spatial distribution of the radiation budget  and its components at the Baltic Sea surface are created based on data from SEVIRI, AVHRR, MODIS, SBUV/2, TOVS radiometers, and forecast auxiliary models. The component algorithms of this model were developed and validated against empirical data measured directly in the Baltic Sea (Zapadka et al. 2020). The uncertainties in the estimation of the radiation budget for the monthly averages are: RMSD 4 Wm-2 and BIAS -0.5 Wm-2. The individual downward and upward shortwave radiation fluxes are determined with an accuracy of RMSD 3 Wm-2, 1 Wm-2, BIAS 3 Wm-2, 0.1 Wm-2 respectively, and downward and upward longwave radiation fluxes are RMSD 4.5 Wm-2, 3.7 Wm-2, BIAS -0.8 Wm-2, 2.6 Wm-2 respectively. The uniform methodology used since 2010 has enabled an analysis of the variability of the radiation budget and its components at the surface of the Baltic Sea covering 14 years. Despite the natural variation in NET values and its components year-on-year, the analyses showed an annual growth trend of c. 0.7 Wm-2. Interestingly, the increasing trend applies to all NET components. An analysis of the possible causes of the trend observed in recent years may confirm the role of the anthropological factor in these changes.