Monitoring of Greenhouse Gases in the Atmosphere – A Polish Perspective

An overview of systematic observations of the trace-gas composition of the atmosphere over southern Poland is presented, against the background of data available for other greenhouse gas (GHG) monitoring stations in Europe. The results of GHG monitoring for three major greenhouse gases (CO2, CH4, N2O) are discussed. Measurements were performed at two locations of contrasting characteristics, i.e. (i) the high-altitude mountain station of Kasprowy Wierch in the High Tatras, representing atmospheric conditions relatively free of local influences, and (ii) an urban station located in the Krakow agglomeration. The GHG data available for the Kasprowy Wierch station were compared with relevant data available for two marine reference stations (Mace Head, Ireland and Terceira Island, Azores), and two continental stations (Hohenpeissenberg, Germany and Pallas-Sammaltunturi, Finland). The growth rates for the CO2 mole fraction recorded at these five stations reveal only small temporal changes that almost coincide, leading to a quasi-linear increase of the CO2 mixing ratio over the European continent over the past 20 years. While N2O observations also reveal a steady increase over this time period, the mole fraction accounted for by CH4 is increasing again, after a period of stagnation in the years 2001–2007. The impact of continental sources of CH4 and N2O is seen clearly in the Kasprowy Wierch records. The mean departure between the CH4 mixing ratios recorded at Kasprowy Wierch and at the marine reference stations in the period 1994–2014 is of 27.3 ppb, and stems from continental emissions of this gas originating mainly from anthropogenic activities (leaking natural-gas distribution networks, landfills and livestock). For N2O, a departure of 1 ppb was observed for the period 2009–2014. Comparison of quasi-continuous measurements of CO2, CH4 and N2O mixing ratios made in the urban atmosphere of Krakow and at the regional reference site Kasprowy Wierch (located approximately 100 km away), allows for a deeper insight into the mechanisms controlling daily variations in atmospheric mixing ratios of these gases at the two sites. The development of a nocturnal inversion layer in the atmosphere above the city leads to local enhancements of CO2, CH4 and N2O mole fractions in the Krakow atmosphere during the night hours, with these exceeding the baseline level significantly.