Multi-decadal atmospheric carbon dioxide measurements in Central Europe, Hungary

Abstract. The paper reviews and evaluates a 30-year-long atmospheric CO₂ data series measured at Hegyhátsál tall-tower greenhouse gas monitoring site, a member of WMO GAW, NOAA, and ICOS networks (id. code: HUN). The paper also gives the technical description of the monitoring system, and that of the physical environment of the station. This low elevation (248 m above m.s.l.), mid-continental Central European site shows a 3.90±0.83 µmol mol^‑1 offset relative to the latitudinally representative marine boundary layer reference concentration presumably due to the European net anthropogenic emissions. The long-term trend (2.20 µmol mol^‑1 year^‑1) closely follows the global tendencies. In the concentration growth rate, the ENSO effect is clearly detectable with a 6–7 months lag-time. The summer diurnal concentration amplitude is slightly decreasing due to the faster-than-average increase of the nighttime concentrations, which is related to the warming climate. The warming climate also caused a 0.96±0.41 day year^‑1 advance in the beginning of the summer CO₂-deficit season in the first half of the measurement period, which did not continue later.