Current carbon dioxide content in the near-surface layer of the Earth’s atmosphere: long-term trends and intra-annual variability
The series of monthly mean concentrations of carbon dioxide (CO2) in the near-surface layer of the atmosphere over the past 50 years have been analyzed. The series are presented on two publicly accessible Internet resources, namely, the websites of the World Greenhouse Gas Data Center (Global Atmosphere Watch, World Meteorological Organization) and of the Earth System Research Laboratory (National Oceanic and Atmospheric Administration, USA). The series from 80 stations are considered, of which 27 are from global (background) stations and the rest are from regional stations. Long-term changes are characterized by the series of twelve-month running averages, while intraannual (inter-monthly) variability is described by the difference of the initial series and the series characterizing long-term changes. Consideration of systematic differences showed that the highest levels of CO2 are characteristic of the regions with developed economies located in North America, Western and Central Europe, and Southeast Asia. Long-term changes (trends) at all stations are practically identical to those at the global (background) stations. Intra-annual variability is regular (seasonal). Seasonal deviations from the line of long-term trends at different points of geographical space demonstrate high correlative similarity after respective seasonal time shifts have been applied. Such similarity is manifested even at the long distance between the stations. The root-mean-square values of the series of intra-annual deviations are maximum in the regions with developed economies located in North America and Western and Central Europe. They are smaller in the high latitudes of the Northern Hemisphere, while in the Southern Hemisphere they are noticeably smaller and decrease with latitude.