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This work is part of a study on the impact of black carbon (BC) transfer from various sources to the Arctic on climate change in the region. The main objectives are to develop software for analyzing the Lagrangian transport of air particles; assessing the deposition of aerosol particles by precipitation and the concentration of particles in the atmosphere; and obtaining, for specific conditions of atmospheric circulation during severe fires in the years of maximum reduction in the Arctic sea ice area, estimates of the relative residence time of air particles emitted by these fires over the Arctic Basin (AB), as well as the proportion of BC deposited in the AB from fires. This software package contains a module for calculating Lagrangian trajectories from a 4-dimensional wind array (u, v, ω, t), which contains horizontal wind components and an analog of vertical speed available from reanalysis, as well as modules for the postprocessing of the found trajectories, which allow us to obtain in a given area the residence time estimates, 3-dimensional BC concentration, and BC deposition on the surface, also using reanalysis data and some empirical constants. Since the main decrease in the Arctic sea ice area occurred in 2 years, 2007 and 2012, it was supposed to analyze the fires of these years; however, in 2007, there were no great fires, and in 2012 one fire was much larger than the others (K-217, March–June). This fire was chosen for the experiments: several sets of trajectories were obtained for it, corresponding to various options for choosing the initial conditions, and estimates were obtained for the fraction of trajectories that passed over the Arctic basin, the time spent there, and the fraction of BC deposited in the AB. Together, these estimates led to the conclusion that Siberian fires can hardly be the leading cause of the accelerated melting of Arctic sea ice. [ABSTRACT FROM AUTHOR]

The circum-Arctic region experienced serious fires in 2019 and 2020. Biomass burning is considered a primary source of black carbon (BC) aerosols. BC contributes to Arctic warming and impacts snow/ice melting. However, the impacts of biomass burning on BC in the Arctic during these recent serious fires have not been quantified in detail. In this study, based on numerical simulations using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem), we calculated the contribution ratios of biomass burning to Arctic BC and revealed its transport pathways. Affected by biomass burning emissions, the near-surface BC concentrations over the terrestrial areas within the Arctic Circle were highest in summer, and declined in spring and autumn. Spatially, high-concentration levels of BC were distributed in the Russian central and eastern areas. Biomass burning accounted for 63.72% and 45.18% of the summer BC in the Arctic near-surface and middle troposphere, respectively. In the near-surface, the contributions from local Arctic sources were comparable to those from sources outside the Arctic Circle in summer. In the middle troposphere, contributions from sources outside the Arctic Circle were dominant. In summer, BC originating from biomass burning in Siberia was transported a short distance by southwesterly winds to the central Arctic near-surface, while the enhanced southwesterly winds in the middle troposphere transported BC from Siberia, Alaska and northern Canada to the central Arctic and Greenland. In spring and autumn, most BC originating from biomass burning in the near-surface of Eurasia was transported eastward by westerly winds and then transported northward over the North Pacific Ocean, and the long distance may have resulted in fewer effects on the Arctic. These results highlight the important role of biomass burning in the Arctic environment under a warming climate. [Display omitted] • Affected by biomass burning, the near-surface BC concentrations over the terrestrial areas within the Arctic Circle were highest in summer. • The biomass burning contributions from local sources to Arctic BC in the near-surface in summer were obvious. • BC from biomass burning in the near-surface of Siberia were transported by southwesterly winds to the central Arctic. • The enhanced southwesterly winds in the middle troposphere transported BC from Siberia, Alaska, and northern Canada to the central Arctic and Greenland. [ABSTRACT FROM AUTHOR]