A regional pCO2 climatology of the Baltic Sea

Based on direct surface pCO2 observation and a model-based extrapolation technique, we established a regional pCO2 climatology of the Baltic Sea. Observations from June 2003 to Dec. 2021 are obtained from the SOCAT version 2022 data collection and largely based on ICOS DE-SOOP Finnmaid data. The extrapolation technique uses model-based patters of variability to create observational data-constrained, gap- and discontinuity-free mapped fields including local error estimates without the need for or dependence on ancillary data (like, e.g., satellite sea surface temperature maps). Details on the pCO2 climatology and the model-based extrapolation technique are found in Bittig et al. (2023). Here we make the corresponding dataset available with monthly climatological pCO2 value as well as a linear pCO2 time trend for the Baltic Sea domain. Both value and trend are provided with their error estimate and are centered on the 15th of each month. Besides, the long-term trend 2003-2021 in pCO2 as well as its error estimate is given.