Study of trends of total CO and CH 4 contents over Eurasia through analysis of ground-based and satellite spectroscopic measurements

Trends of total CO and CH4 contents are estimated from satellite AIRS spectrometer data for the Eurasian domain (0–180° E, 0–85° N) for different time periods and seasons. The results are compared with similar estimates, obtained from ground-based spectroscopic measurements at seven stations of the European Network for the Detection of Atmospheric Composition Change (NDACC) and at measurement sites of the Institute of Atmospheric Physics, Russian Academy of Sciences (Zvenigorod Scientific Station (ZSS), Zotto, and Beijing) and St. Petersburg University (Peterhof), located in the study domain. Overall, the total CO decreased over northern Eurasia during the period of 2003–2015 at a rate of 0.05–1.5%/yr, depending on the region; while the total CH4 increased at a rate of 0.16–0.65%/yr. Since 2007, the total CO has been increased during summer and autumn months in most mid- and high-latitude Eurasian background regions, and the total CH4 growth has been accelerated. Changes in the global photochemical system, proceeding against the background of global climate change and, in particular, changes in the “sources/sinks” ratio for minor atmospheric admixtures are suggested as possible causes of this dynamic of trends of the atmospheric CO and CH4 contents.