Assessment of the impact of black carbon emissions on the radiation balance and other climatic variables for the territory of Russia.

The INMCM6 Earth system model is used to study the climate system response to black carbon (BC) emissions into the atmosphere for the period 2010-2021 for the territory of Russia. This model includes an aerosol block that describes the evolution of black carbon in the atmosphere and continental snow, including transport-diffusion, microphysical processes of "aging", sedimentation, washing out of aerosol particles by precipitation from the atmosphere and melt water from snow. The direct radiative impact of aerosol particles in the atmosphere is estimated based on their prescribed optical properties, and in snow - based on the calculation of the snow albedo, parameterized depending on the properties of the snow and the concentration of BC particles contained in it. The model does not take into account the indirect impact of BC aerosol particles on clouds. Global CEDS (anthropogenic source) and GFED4 (source from biomass burning) data are used as BC emissions into the atmosphere. 

The results of the model experiments were verified for the average global and spatial characteristics of BC based on the data of the AEROCOM3 multi-model experiment, CAMS and MERRA reanalyses, as well as EBAS observational data on the aerosol absorption coefficient at stations located in the Arctic and vertical BC profiles obtained during aircraft sounding of the atmosphere during the HIPPO campaign. Using this model, data were obtained and analyzed for the territory of Russia for the integral transboundary transport of BC, the radiative impact from BC contained in the atmosphere and snow, and other parameters. The average annual radiation balance at the top of the atmosphere over the territory of Russia increased by 0.28 W/m2 due to the BC contained in the air. The average annual radiation balance on the land increased by 2.3 W/m2 when taking into account the BC contained in snow. This value of radiative forcing is consistent with the work (Flanner et al., 2007) which provides an estimate for radiative forcing from snow darkening due to black carbon and mineral dust for Eurasia in the spring period of 3.9 W/m2.

These changes in the radiation balance lead to additional heating of the surface and an increase in the rate of snow melting. Based on the data of model experiments, an estimate of the climatic response from anthropogenic and natural emissions of BC into the atmosphere was made separately. For this purpose, the results of the corresponding experiments with emissions from a specific source were subtracted from the results of the experiment with total emissions. In particular, it was found that anthropogenic and natural emissions of BC make approximately the same contribution to the increase in the average annual surface air temperature, about 0.2 °C. The maximum temperature response to BC emissions is observed in January and is 0.7 and 1 °C for anthropogenic and natural emissions, respectively. In April, the snow albedo decreases by 0.03, and the snowmelt rate increases by 20% of its average annual value for the case of anthropogenic emissions. These changes in values ​​are consistent with the results obtained by other authors (Bellouin, Boucher, 2010).

The study was carried out within the framework of the Order of the Government of the Russian Federation dated October 29, 2022 No. 3240-r "On approval of the innovative project "Unified national system for monitoring climate-active substances"