Abstract:

The long-term baseline trends of the atmospheric greenhouse gases (GHGs) CO₂ (including δ¹³C-CO₂and δ¹⁸O-CO₂ abundances), CH₄, and N₂O in Antarctica were compared with those from other latitudinal bands. The results suggest that global concentrations of GHGs increase with latitude from south to north, with the lowest (highest) abundance in Antarctica. The overall long-term trends and annual growth rates of GHGs in Antarctica are consistent with the global values, although the trends or growth rates of a concrete gas in Antarctica may quantitatively differentiate from the global values.  During 1958–2014, the average growth rate of CO₂ concentration in Antarctica (1.43 ± 0.59) mg·L^–1·a^–1 was lower than that in the tropics (1.51 ± 0.72) mg·L^–1·a^–1. Conversely, the average growth rate of CO₂ concentration in Antarctica during the periods 1980–2014 and 2000–2014 were higher than that in the Southern Hemisphere Middle (SHM) latitudinal band but lower than that in the Northern Hemisphere (NH). The trends of δ¹³C-CO₂ and δ¹⁸O-CO₂ abundance reflect the effects of fossil fuel combustion and global-scale processes on global CO₂  variations. During 1983–2014, the overall growth rate of CH₄ concentration in Antarctica (1.43 ± 0.59) µg·L^–1·a^–1 was lower than that in the NH (6.5 ± 5.6) µg·L^–1·a^–1, but higher than that in the tropics (5.6 ± 5.3) µg·L^–1·a^–1 and the SHM (6.1 ± 4.9) µg·L^–1·a^–1. This confirmed the NH as the largest source of CH₄, and the tropics and SHM as substantial CH₄ sinks via OH oxidation. The overall average growth rate of atmospheric N₂O in Antarctica was (0.87 ± 0.15) µg·L^–1·a^–1 during 2005–2013; lower (higher) than that in the NH (tropics) and very close to that in the SHM. The difference in the growth rate reflects anthropogenic emissions and the latitude-dependence of the vertical structure of the surface boundary layer, which has obvious influence on surface-level behavior of N₂O.

Key words: Antarctica, greenhouse gases (GHGs, CO₂, CH₄, N₂O), annual growth rate, comparison analysis