Results of the analysis of wildfires in Russian regions using satellite data for 2000-2021 are presented. The results indicate a predominant increase in the number of intense fires in Russia, which has been especially noticeable in recent years. Using reanalysis data, a significant correlation between wildfires in Russia and atmospheric blocking has been revealed. An integral blockings index, whose value can reach and exceed 10% for fire seasons in Russian regions from April to October, was used to characterize atmospheric blocking. It has been found that an increase in the integral blockings index by 1% corresponds to an increase in the number of forest fires in Russia by 14%. According to the estimates, the contribution to the variance of interannual change in the number of wildfires associated with atmospheric blockings reaches ~40%.

Siberian wildfires and related regional anomalies of atmospheric impurities during the period of 2000-2019 are analyzed. The long-range transport of biomass burning products from Siberian wildfires into the Arctic atmosphere during the period of 2000-2019 is estimated. An analysis of the characteristics of forest fires over the past two decades revealed a significant increase in radiation power of an average Siberian wildfire. A joint analysis of fire activity in Siberian forests, as well as the contents of the black carbon (BC) and carbon monoxide (CO) contents in the Arctic atmosphere, indicates that extreme fire events cause the development of regional anomalies in BC and CO. Correlation between the anomalies of BC (CO) over the Russian segment of the Arctic and the number of Siberian wildfires is found to be statistically significant. Using a linear regression, an estimates of the sensitivity of the total BC content and in the volume mixing ratio of CO to the increase in the number of fires. The results of an analysis of the long-range BC transport into the Arctic It is shown, in particular, that the transport of BC to the Arctic from the Siberian regions with fires in the summer of 2019 was associated with the features of large-scale atmospheric circulation characteristic for atmospheric blocking.

Using satellite data and reanalysis data, the characteristics and mechanisms of the formation of an ozone “mini-hole” in the atmosphere over Siberia in the winter of 2015–2016 have been investigated. The relationship between the regional negative anomaly of the total ozone content (TOC), reaching –140 Dobson units, with atmospheric blocking was established. The TOC anomaly was mainly due to a decrease in the ozone content in the lower stratosphere, reaching 50% near the 70 hPa level. With the key contribution of atmospheric dynamic processes to the formation of the ozone “mini-hole,” the possibility of the contribution of ozone destruction in heterogeneous reactions on the surface of polar stratospheric clouds, due to a strong decrease in temperature in the stratosphere above the blocking region, was noted.

Analysis of satellite and reanalysis data indicates a relationship between pyrogenic NO 2 emissions and atmospheric blocking events. According to the estimates obtained for the period of 2001–2019, total NO 2 emissions into the atmosphere during wildfires in Russia increase by 0.7 Mt with an increase in the integral blocking index by 10%. Against the background of the general decrease in pyrogenic NO 2 emission in 2001–2019, a statistically significant increase in the NO 2 emission density per unit area by 23% has been revealed. At the same time, a decrease in the total NO 2 emission during wildfires is noted in relation to the corresponding emissions of carbon monoxide and fine aerosol.

The features of anomalous Siberian wildfires in 2019 and trends of their changes during 2000–2019 are analyzed on the basis of satellite monitoring data. The average values of wildfire areas; total volumes of CO, CO2, and aerosol PM2.5 emissions; and their density (per area unit) in the Siberian Federal District of Russia and its regions are estimated for a 20-year period, as well as the number, radiative power, and spatial distribution of wildfires on the territory of North Eurasia in 2019. In July 2019, the wildfire area in Irkutsk oblast exceeded the average value for the period of 2001–2019 by more than four times, whereas the related total volumes of emissions of CO, CO2, and PM2.5 aerosol in June 2019 were five times higher than their average values for this period. The regional weather-climate features of summer 2019 were revealed using on-land observations and reanalysis, in particular, atmospheric blocking, which is related to the formation of extreme regimes of wildfires and floods in adjacent territories of Siberia.

Using satellite and reanalysis data, estimates of the significant relationship between the wildfire areas and associated pyrogenic emissions of combustion products with atmospheric blocking events in Russia for the period from 2001 to 2019 were found. It has been established that the contribution to the variance of interannual changes of the wildfire areas and emissions of combustion products into the atmosphere associated with atmospheric blocking can reach and even exceed 40%. The tendency toward an increase in the density of emissions of combustion products into the atmosphere, including carbon dioxide and carbon monoxide, as well as fine aerosol, against the background of a general decrease in the areas of natural fires in the first 20 years of the 21st century, is revealed. At the same time, a decrease in the ratio of pyrogenic emissions of carbon monoxide and fine aerosol was found.

The abnormally high temperature and the deficit of precipitation in Siberia in summer 2016 contributed to the development of massive forest fires, which resulted in pyrogenic emission in the atmosphere of various biomass burning products. This paper presents the analysis results of the spatial and temporal variations of black carbon (BC) in the atmosphere over Northern Eurasia during the 2016 Siberian wildfires using the MERRA-2 reanalysis data. The spatiotemporal evolution of BC anomalies is presented, with estimates of the increase in BC mass during wildfire period. The peculiarities of large-scale atmospheric circulation responsible for BC transport from Siberia to Central Europe are discussed. The estimates of spatial scale, effective height and speed of the long-range anomalous (from east to west) transfer of air masses in the atmosphere over Northern Eurasia in July 2016 are obtained. Changes in the optical and microphysical characteristics of biomass-burning aerosol during its long-range transport are also discussed. A comparison of daily variations in surface BC concentrations at the polar observatory Tiksi with those in BC column mass density from MERRA-2 revealed a high correlation between local and integral characteristics of BC during arriving air masses from Siberian wildfires.

Changes in the composition of the atmosphere associated with the atmospheric blocking events were analyzed using the measurements of ozone, water vapor, methane, formaldehyde, carbon monoxide, nitrogen dioxide, as well as aerosol optical characteristics from the satellite instruments OMI, MLS, AIRS, MODIS and MOPITT as well as ground-based, balloon and NCEP/NCAR reanalysis data. The changes in atmospheric composition associated with pyrogenic, biogenic and soil emissions of aerosol and gas constituents as well as the changes due to the regional peculiarities of the large-scale atmospheric dynamics are discussed.

Using the aerosol optical depth (AOD) data from the MODIS satellite instruments, the hazes over Eurasia in July 2016 were analyzed. Total area of the haze blanketing was estimated to be approximately 20 million km2, including the Siberian smoke haze (SSH) with a maximum area of 16 million km2, spreaded over European territory of Russia, Kazakhstan and many European countries. The evolution of AOD in SSH has been analyzed. The total mass of smoke at different stages of the SSH evolution was ranged from 1.6 to 3.7 million tons. When using the aerosol index data from the OMI UV measurements, the essential changes in the qualitative composition of smoke aerosol transported away from the fire places at a distance of 1000-2000 km were detected. The average aerosol radiative forcing at the top of the atmosphere and at the stage of maximum development of the SSH was estimated to be -38 W/m2.

Using maximum aerosol optical depth (MAOD) spatial distribution formation technique the optically dense haze expansion scales in period from 15 to 31 July 2016 over Eurasia are estimated in during great Siberian smoke haze (SSH) with the area 16 mln km2 about, smog over the Northern China Plain (2 mln km2), dust haze in Takla Makan desert (0.8 mln km2) and hazes in India and Pakistan (1 mln km2 approximately). Empirical distribution function (EDF) MAOD is received which is approximated by linear function of MAOD logarithm. Aerosol optical depth (AOD) spatial distribution at wavelength 550 nm in SSH is analyzed. Total smoke aerosol mass assessment in SSH (3.2 mln tons) is evaluated. Smoke aerosol (SA) mass during maximum growth period from 22 July to 26 July 2016 over Siberia (50°-70°, 60°-120 °E) was equal 2 mln tons approximately. Aerosol index (AI) temporal variability is illustrated visually SA composition qualitative change in SSH during long-range transport. It is shown that AI variations are correlated with AOD variations. Aerosol radiative forcing (ARF) at the top and the bottom of the atmosphere over Siberia from 22 July to 26 July 2016 is estimated (average ARF are equal –68 and –98 W/m2). EDF AOD and EDF ARF at the top of the atmosphere are approximated by exponential and power function of AOD correspondingly.

The smoke haze over the European part of Russia (EPR) and Belorus in July 2016 has been studied with the use of aerosol optical thickness (AOT) data measured by MODIS satellite spectrometers. The AOT maximum on the territory limited by coordinates 45°–70° N and 20°–60° E reached 2.95 on July 24, 2016 with an average regional value of 0.48. The total mass of smoke aerosol without the area covered by clouds was 0.73 million tons. Analysis of the wind fields and five-day back trajectories of air mass movement showed that the smoke was transported by the northeast winds to the EPR and Belorus from western Siberia, including the Yamalo-Nenets Autonomous District, which was characterized by large forest fires from July 17 to 23. Simulation of the radiation regime of the smoky atmosphere indicated that the average radiative forcings of smoke aerosol at upper and lower boundaries of the atmosphere for the above-mentioned territory are –29 and –54 W/m2, respectively (the extreme values are –124 and –154 W/m2, respectively). A comparative analysis of the smoke haze characteristics over the EPR in July 2016 and in summer 2010 has been conducted. According to ground-based measurement data, the mass concentration of PM10 during the smoke period from July 24 to 27 in the Moscow region reached 0.25 mg/m3.

We have characterized the large-scale smoke pollution of the European territory of Russia (ETR) and adjoining areas in July 2017, caused by long-range transport from forest-fire areas in Siberia, confirmed by calculations of ten-day back trajectories of air mass motion to the ETR urban area, spanning Archangelsk to Rostov-on-Don. The smoke-laden ETR area with an AOD > 0.3 (average value being 0.43 and maximal value being 2.5) on July 25, 2016, covered 5 million km 2 , and the total smoke mass was ~1.2 million tons. It is shown that the daily average mass concentration of aerosol with particle sizes less than 2.5 μm exceeded the corresponding maximum permissible concentration in the Moscow region during the period from July 24 to 27, 2016. The influence of local sources on aerosol and gas pollution of atmospheric air was estimated. The smoke haze in 2016 was found to be deficient in carbon monoxide as compared to smoke pollution in 2010. It is shown that the thermal and wind stratification in the atmospheric boundary layer markedly influenced the pollution level in the smoke-laden urban atmosphere. Smoke aerosol radiative effect was estimated. The average aerosol radiative forcings at the top and bottom of the atmosphere over ETR on July 25, 2016, were–29 and–53 W/m 2 , and extreme forcings reached–112 and–215 W/m 2 , respectively.

On the basis of the detection data on active fires from the MODIS satellite instrument in the 2000–2016 period an analysis of the characteristics of forest fires in the boreal zones of Eurasia and North America was carried out. The total number of the forest fires in the boreal zone is dominated by the fires in Northern Eurasia. At the same time, the intensity of the North American forest fires is higher on average than the intensity of the Eurasian forest fires. Along with some tendency to a reduction of the annual number of boreal fires, there are tendencies towards an increase in the intensity of the average forest fire, which are statistically significant for the North American region and for the boreal zone as a whole. The regional features of the long-term characteristics and the seasonal dependence of forest fires, as well as the regional peculiarities of the interannual variations of the fire level in the boreal forests, were discussed. A comparative analysis of the results of detection of fires by MODIS and VIIRS satellite instruments was carried out.

Using data from the AIRS satellite instrument for the period of 2003–2016, the correlation between the regional anomalies of methane content in the atmosphere and the anomaly of the surface temperature in the northwestern Siberia, in particular, on the Yamal Peninsula in the summer of 2016, is analyzed. Quantitative estimates of the regional anomalies, trends, and sensitivity of variations in the methane content in the atmosphere to variations in the surface temperature at the interdiurnal and interannual scales are obtained. The characteristics of the large-scale atmospheric circulation that contributed to the formation of the anomalous temperature regime over northwestern Siberia and resulted in an increase in methane content in the atmosphere are described.

This paper reports the estimated scales of optically dense haze over Eurasia for the period from July 15 to July 31, 2016, including the Siberian smoky haze (with a smoke area of 16.3 million km2) over Siberia and European Russia, and also many countries of Europe, Kazakhstan, and other countries of Asia, the human-induced smog over the North Chinese Plain (about 2 million km2), dusty haze in the Takla-Makan Desert (about 0.8 million km2), and haze over India and Pakistan (approximately 1 million km2).

An analysis of smoke haze over Europe in July 2016 caused by the wildfires in Siberia has been carried out. Surface air pollution by aerosols in Moscow region during the smoke event was also investigated. It was found that optical and microphysical characteristics of the smoke aerosol in Europe were typical for the boreal forest fires. The aerosol radiative forcing (ARF) variations at the top of the atmosphere (TOA) and the bottom of the atmosphere (BOA) during the smoke haze period were analyzed. The regional mean direct radiative forcing of aerosols at the TOA and BOA on 26 July 2016 were estimated to be -25 and -45 W/m2 respectively. Probability distribution function of ARF values at the TOA was presented.

Using data from the MLS instrument (Aura satellite), the temperature variations at heights from the upper troposphere up to the lower thermosphere over the north of European Russia (60°-70°N, 40°-60°E) in 2010 are analyzed. The vertical structures of the changes in temperature associated with the annual- and semiannual oscillations, sudden stratospheric warming, summer atmospheric blocking event and 24-h thermal solar tides are presented.