CO2 ecosystem-atmosphere exchange in Krakow, Poland – preliminary results from a new European Fluxes Database Cluster EC urban station

Urban areas, being a considerate source of CO₂, at the same time are one of the most complicated ecosystems, with some uncertain components still present in the local carbon cycle. Complications with CO₂ dynamics monitoring arise from high heterogeneity of the area and the presence of various sources, but also from a not entirely explored impact of urbanization on the local biosphere. There is a growing need for experimental data to verify existing CO₂ emission inventories and to serve as a reliable input to climate models.

In February 2021, an eddy covariance site was established in Krakow, southern Poland, to investigate CO₂ exchange in its urban ecosystem. The neighborhood of the site is highly heterogeneous, including various anthropogenic sources such as traffic, household heating, and humans themselves; however, a considerable part of the source area is covered with green, including home gardens, a soccer stadium, and a municipal park.

We present a first sight of the CO₂ eddy covariance flux results that were obtained since the site was established. The city is undoubtedly a net CO₂ source. A significant diurnal variation in the CO₂ flux amplitude was observed in the warm season as compared to winter, with the highest positive values during the night and negative values during the day, indicating effective CO₂ photosynthetic uptake. Morning and afternoon traffic peaks were not clearly pronounced: the area is highly heterogeneous and includes other sources as well that may have their own diurnal variability overlapping the traffic signal.

This project has been partially supported by the European Union’s Horizon 2020 research and innovation programme under grant agreement No 958927, and the subsidy of the Ministry of Education and Science.