Spatial and temporal variations of carbon dioxide flux to the atmosphere in Krakow, Poland: four years of eddy covariance measurements

As the European Union policy on reducing fossil fuel consumption progresses, increasing interest is focused on the main emitters of greenhouse gases. Cities are unequivocally considered a net source of CO₂: it is estimated that more than 70% of global anthropogenic emissions originate in urban areas. On the other hand, the abundance of sources, each with its own dynamically changing emission rate combined with a highly heterogenic source area, is a known source of uncertainty for quantifying net CO₂ flux to the atmosphere. Krakow is the second largest city in Poland, located in a river valley in the southern part of the country. The Eddy covariance measurement site has been established at AGH University of Krakow in 2021 as a complementary method for long-term atmospheric monitoring including the concentration of various gases, stable isotopes, vertical profiles and other types of measurements. Since then, CO₂ and heat fluxes have been continuously measured at 40 m above ground. Significant green coverage in the source area (60%) resulted in observation of short-term net CO₂ assimilation under favourable conditions, however, the overall balance remained positive. Traffic proved to be a secondary source of anthropogenic CO₂ in the area, with the emissions of the neighbouring tenement houses exceeding the flux values recorded in the direction of a busy street. Krakow four-year data record will be presented. An attempt will be made to find connections of local CO₂ emission rates with typical synoptic weather patterns that occur in the region.

This project has been partially supported by the PAUL Horizon 2020 research and innovation programme of the European Union under grant agreement No. 101037319, the "Excellence Initiative - Research University" programme at AGH University of Krakow, and the subsidy from the Ministry of Science and Higher Education.