CO2 Monitoring and Background Mole Fraction at Zhongshan Station, Antarctica

Thirty Years of Atmospheric CO2 Observations at the Plateau Rosa Station, Italy

The atmospheric background CO2 concentration is a key quantity for the analysis and evaluation of the ongoing climate change. Long-term CO2 observations have been carried out at the high Plateau Rosa mountain station, in the north-western Alps since 1989. The complete time series covers thirty years, and it is suitable for climatological analysis. The continuous CO2 measurements, collected since 1993, were selected, by means of a BaDS (Background Data Selection) filter, to obtain the hourly background data. The monthly background data series was analysed in order to individuate the parameters that characterise the seasonal cycle and the long-term trend. The growth rate was found to be 2.05 ± 0.03 ppm/year, which is in agreement with the global trend. The increased background CO2 concentration at the Plateau Rosa site is the consequence of global anthropic emissions, whereas the natural variability of the climatic system taken from the SOI (South Oscillation Index) and MEI (Multivariate ENSO Index) signals was detected in the inter-annual changes of the Plateau Rosa growth rate.

Temporal patterns of CO2 and CH4 in a rural area in northern Spain described by a harmonic equation over 2010-2016

The present paper seeks to improve our knowledge concerning the evolution of CO₂ and CH₄ in terms of monthly trends, growth rate and seasonal variations in the lower atmosphere. Dry continuous measurements of CO₂ and the CH₄ mixing ratio were carried out over five and a half years (from 15 October 2010 to 29 February 2016) by multi-point sampling at 1.8, 3.7 and 8.3m, using a Picarro analyzer at a rural site in the Low Atmosphere Research Centre (CIBA), on the upper Spanish plateau. Data were divided into diurnal and nocturnal records. The mathematical equation proposed to analyze the overall data was a harmonic one, comprising a polynomial (trend) and a series of harmonics (seasonal cycle). Amplitude was considered as a constant and variable term over time. Quite different behaviour was found between day and night measurements in both climate forcing agents. CO₂ showed an accelerating trend in autumn, whereas CH₄ trends were higher during the winter. Increasing growth rates were reported for CO₂ and CH₄ over the whole study period. Nocturnal CO₂ amplitudes are higher than diurnal ones except in winter for both gases, and also in the autumn for CH₄.