Temporal patterns of CO2and CH4in 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 CO2and CH4in terms of monthly trends, growth rate and seasonal variations in the lower atmosphere. Dry continuous measurements of CO2and the CH4mixing 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. CO2showed an accelerating trend in autumn, whereas CH4trends were higher during the winter. Increasing growth rates were reported for CO2and CH4over the whole study period. Nocturnal CO2amplitudes are higher than diurnal ones except in winter for both gases, and also in the autumn for CH4.
Department of Applied Physics, Faculty of Sciences, University of Valladolid, Paseo de Belén, 7, 47011 Valladolid, Spain.
Beatriz
B
Fernández-Duque
Department of Applied Physics, Faculty of Sciences, University of Valladolid, Paseo de Belén, 7, 47011 Valladolid, Spain. Electronic address: iaperez@fa1.uva.es.
Isidro A
IA
Pérez
Department of Applied Physics, Faculty of Sciences, University of Valladolid, Paseo de Belén, 7, 47011 Valladolid, Spain.
M Luisa
ML
Sánchez
Department of Applied Physics, Faculty of Sciences, University of Valladolid, Paseo de Belén, 7, 47011 Valladolid, Spain.
M Ángeles
MÁ
García
Department of Applied Physics, Faculty of Sciences, University of Valladolid, Paseo de Belén, 7, 47011 Valladolid, Spain.
Nuria
N
Pardo
Daytime; Greenhouse gases; Night-time; Series of harmonics; Upper Spanish plateau