Methane Concentration in the Atmosphere over Seas of the Western Sector of Russian Arctic in the Late Autumn Season in 2023

Arctic temperatures have in recent decades risen faster than the global average, threatening the large carbon pools locked in the Arctic permafrost. Monitoring of the environment has become one of priority tasks in risk assessment for extremely attackable Arctic ecosystems, but carrying out measurements of the atmosphere composition in such remote regions, especially over the basin of Arctic seas, is extremely difficult. They are limited by the duration of the navigation season, logistical difficulties of sampling, and the instrumental base necessary for precision measurements of the atmospheric air composition. In the course of this study, atmospheric CH4 concentration was measured from November 9 to December 6, 2023. The Barents Sea and the southern basin of the Kara Sea were the main areas of the study. During the study period, CH4 concentration in the atmosphere ranged from 2.018 to 2.127 ppm, with an average value of 2.040 ± 0.014 ppm. Variations in atmospheric CH4 in the surface layer were caused mainly by meteorological conditions, as well as the geographical location of the vessel and the time of measurements. For example, on the regional scale, the transport of air masses from the land led to a higher concentration of CH4; the carryover from northern regions, to a lower concentration. Local sources determined short-periodic fluctuations of CH4 concentrations in the surface air. Joint high-resolution measurements of marine and atmospheric CH4 data are critically important for understanding the scale of methane emission at the hydrosphere–atmosphere interface, especially in winter when the mixing layer thickness increases, convection intensifies, and a large amount of methane from the water column can enter the atmosphere. In addition, our data can be used as input parameters for climate models.