Comparison of Distributions of Atmospheric Gas Admixture Concentrations Measured by Remote and In Situ Instruments over the Russian Sector of the Arctic

As at other remote sites on the globe, it hoped that the problem of monitoring the air composition in the Arctic region could be solved through the development of satellite sensing systems. The overview in [1] suggests that in 2017 there were 15 types of operational spacecraft measuring the aerosol and gas composition of the atmosphere. However, so far the satellite measurements have not been sufficiently accurate [2], requiring perfection of both instrumental and methodological components of this sensing technique [3,4].

Comparisons with data obtained by other methods used to determine the errors of measuring any air admixture from satellites. For instance, comparisons are made against radiosondes for water vapor and against ozone sonde for ozone. Satellite profiles for other gases and aerosol often compared with results from aircraft sensing. These comparative data make it possible to identify the measurement errors and update the method for retrieving the profiles of gases and aerosol or formulate the conditions required to improve the technical characteristics of instruments themselves.

Data from aircraft and satellite sensing at the ocean-land boundary in the region of the Kara Sea in October 2014 are compared, using 11 and 7 profiles, which were synchronously measured over a continental part and ocean, respectively. It was found that the satellite usually overestimates the CH4 and CO2 concentrations in the 0-8-km layer over the continental part of the Arctic region and underestimates them over the ocean. Over continent, the satellite overestimates the methane concentrations by 28 ppb in the boundary layer and by much more in the middle (182 ppb) and upper (113 ppb) troposphere. Over ocean, the satellite measurements are, on average, lower by 37 ppb in the boundary layer, by 73 ppb in the middle troposphere,

and by 71 ppb in the upper troposphere. Over continent, the inequality in CO2 concentrations, measured with different instruments, is, on average, 18.2 ppm in the boundary layer and can vary from 3.2 to 26.5 ppm. In the middle troposphere (4 km), the average differences decrease to 10.8 ppm, with the range of differences even increasing somewhat, to 0.6-25.5 ppm. In the upper troposphere (8 km), the average difference in measurements between the instruments decreases to 2.8 ppm. The underestimation turns out to be greater in amplitude over the ocean. It is noteworthy that the comparison given acceptable results for CO and O3.

This work supported by the Russian Science Foundation (grant no. 17-17-01095).

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