2020
DOI: 10.3390/atmos11070769
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Statistical Analysis of the CO2 and CH4 Annual Cycle on the Northern Plateau of the Iberian Peninsula

Abstract: Outliers are frequent in CO2 and CH4 observations at rural sites. The aim of this paper is to establish a procedure based on the lag-1 autocorrelation to form measurement groups, some of which include outliers, and the rest include regular measurements. Once observations are classified, a second objective is to determine the number of harmonics in order to suitably describe the annual evolution of both gases. Monthly CO2 and CH4 percentiles were calculated over a six-year period. Linear trends for most of the … Show more

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Cited by 6 publications
(5 citation statements)
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“…The measured average concentrations for atmospheric CO 2 ranged from 380 to 440 ppm with a mean of 412 ± 3.1 ppm for the vegetation season; and the maximum concentrations for CO 2 were observed in the heating season, in the range of 410-470 ppm with a mean of about 430 ± 3.8 ppm in winter (Figure 3). Thus, the derived seasonal variation in atmospheric CO 2 concentration reaches up to 25-30 ppm, which is consistent with the majority of previous studies [63][64][65][66].…”
Section: Summary Of the Measured Co 2 Concentrationssupporting
confidence: 92%
“…The measured average concentrations for atmospheric CO 2 ranged from 380 to 440 ppm with a mean of 412 ± 3.1 ppm for the vegetation season; and the maximum concentrations for CO 2 were observed in the heating season, in the range of 410-470 ppm with a mean of about 430 ± 3.8 ppm in winter (Figure 3). Thus, the derived seasonal variation in atmospheric CO 2 concentration reaches up to 25-30 ppm, which is consistent with the majority of previous studies [63][64][65][66].…”
Section: Summary Of the Measured Co 2 Concentrationssupporting
confidence: 92%
“…However, even for the simplest cycles, the one harmonic evolution may be considered as an initial approximation, since a six-month period between the maximum and the minimum is difficult to achieve [48,49]. Pérez et al [19] tried different combinations of four harmonics and recommended using the first and second harmonics as a simple enough and complete enough equation to accurately describe CO 2 and CH 4 annual evolution. Moreover, the CO 2 cycle was already fitted by a two-harmonic function and kernel calculations by Pérez et al [50].…”
Section: Fitting Of Daily and Annual Cyclesmentioning
confidence: 99%
“…Finally, the last part of this analysis considers the daily and annual cycles of CO 2 and CH 4 . Although these cycles have previously been described [18,19], their response to wind speed merits a detailed study. Two procedures, one parametric and another nonparametric, are used to smooth and investigate the two cycles.…”
Section: Introductionmentioning
confidence: 99%
“…Better fits were found for CO2 data as well as for rural data. (Pérez et al, 2020). More specifically, the highest CH4 mixing ratio values reported at the CIBA station are partially due to the greater sensitivity from CH4 emission sources at the monitoring station.…”
Section: Validation Indicators (I II Iii Iv)mentioning
confidence: 89%
“…As regards CO2 and CH4 seasonal behaviour, it should be noted that the lowest mixing ratios for both greenhouse gases were found in the summer season. The minimum mixing ratio values occurred when hemispheric CO2 uptake draws down global CO2 mixing ratios and when CH4 is oxidised by OH radicals through the hemisphere (Cheng et al, 2019;Pérez et al, 2020). Al-Anzi et al (2016) also explained this behaviour because of the higher planetary boundary layer that reinforces pollutant transport and the dispersion process.…”
Section: Co2 and Ch4 Seasonal Evolutionmentioning
confidence: 99%