Evolution and variation of atmospheric carbon dioxide concentration over terrestrial ecosystems as derived from eddy covariance measurements

Abstract

h i g h l i g h t sAtmospheric CO 2 concentration over terrestrial ecosystems (ACTE) was analyzed. ACTE was higher by 9.0 ppm in winter and lower 2.1 ppm in summer than global means. Annual mean and seasonal amplitude of ACTE increased with 2.04 and 0.60 ppm yr À1 . The annual CO 2 concentration showed large variation among ecosystems. a r t i c l e i n f o (CO 2 ) is the most important anthropogenic greenhouse gas contributing to global climate change. Understanding the temporal and spatial variations of CO 2 concentration over terrestrial ecosystems provides additional insight into global atmospheric variability of CO 2 concentration. Using 355 site-years of CO 2 concentration observations at 104 eddy-covariance flux tower sites in Northern Hemisphere, we presented a comprehensive analysis of evolution and variation of atmospheric CO 2 concentration over terrestrial ecosystem (ACTE) for the period of 1997e2006. Our results showed that ACTE exhibited a strong seasonal variations, with an average seaonsal amplitude (peak-trough difference) of 14.8 ppm, which was approximately threefold that global mean CO 2 observed in Mauna Loa in the United States (MLO). The seasonal variation of CO 2 were mostly dominant by terrestrial carbon fluxes, i.e., net ecosystem procution (NEP) and gross primary produciton (GPP), with correlation coefficient(r) were À0.55 and À0.60 for NEP and GPP, respectively. However, the influence of carbon fluxes on CO 2 were not significant at interannual scale, which implyed that the inter-annual changing trends of atmospheric CO 2 in Northern Hemisphere were likely to depend more on anthropogenic CO 2 emissions sources than on ecosystem change. It was estimated, by fitting a harmonic model to monthly-mean ACTE, that both annual mean and seasonal amplitude of ACTE increased over the 10-year period at rates of 2.04 and 0.60 ppm yr À1 , respectively. The uptrend of annual ACTE could be attributed to the dramatic global increase of CO 2 emissions during the study period, whereas the increasing amplitude could be related to the increases in Northern Hemisphere biospheric activity. This study also found that the annual CO 2 concentration showed large variation among ecosystems, with the high value appeared in deciduous broadleaf forest, evergreen broadleaf forest and cropland. We attribute these discrepancies to both differential local anthropogenic impacts and carbon sequestration abilities across ecosystem types.

Trend analysis of CO2 and CH4 recorded at a semi-natural site in the northern plateau of the Iberian Peninsula

“…Moreover, Arctic Oscillation led to an early spring and to higher winter temperatures, resulting in increased seasonal amplitudes. Liu et al (2015) presented CO 2 evolution over nine ecosystems in the period 1997e2006. They used only one harmonic with a variable amplitude.…”

Analysis of the airflow at the centre of the upper plateau on the Iberian Peninsula and its link to CO2 and CH4 concentrations

“…Various expressions have been used to explain CO 2 evolution, with the exponential and fourth-order polynomial being among the most complex (Inoue et al, 2006;Artuso et al, 2009), and the linear among the simplest (Liu et al, 2015). In this analysis, hourly concentrations of both gases were detrended by fitting this last equation…”

Features of the annual evolution of CO 2 and CH 4 in the atmosphere of a Mediterranean climate site studied using a nonparametric and a harmonic function

“…This is a specific feature of the present research, since studies exclusively devoted to analysing annual evolution remain infrequent and normally appear together with research into the temporal trend (Artuso et al, 2007;Liu et al, 2015;Zhu and Yoshikawa-Inoue, 2015). When trend values are much lower than the annual range, analysis may exclude the trend and focus on the annual evolution.…”