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The characteristics of acoustic-gravity waves (waveforms, time durations, amplitudes, azimuths and horizontal phase speeds) from the eruption of the Hunga-Tonga-Hunga-Hapai volcano detected at different infrasound stations of the Infrasound Monitoring System and at a network of low-frequency microbarographs in the Moscow region are studied. Using the correlation analysis of the signals at different locations, six arrivals of signals from the volcano, which made up to two revolutions around the Earth, were detected. The Lamb mode of acoustic gravity waves from the volcano eruption is identified and the effect of this mode on generation of tsunami waves and variation of aerosol concentration is studied. The energy released from an underwater volcano into the atmosphere is estimated from the parameters of the Lamb wave and compared with the energy released from the most powerful nuclear bomb of 58 Mt TNT.

Seasonal variations of the near‐surface NOX (= NO + NO2) and ozone (O3) mixing ratios at Zotino Tall Tower (ZOTTO), a remote site in central Siberia, are described for years 2007–2014. Conditional probability function analysis and back trajectories are used to determine the origins of clean (continental baseline, CB) and regional emissions‐influenced air. High NOX levels at the site are observed for air from industrial regions of western Siberia and Ural Mountains, whereas CB air originates from remote areas of North Eurasia within 55°–70°N. The estimated annual means of daytime O3 and NOX mixing ratios for CB air are 27.0 and 0.44 ppbv, correspondingly, versus the similar quantities of 27.9 and 0.79 ppbv for all data. Monthly ozone for CB air shows a distinct maximum in April, as is the case for Northern Hemisphere midlatitude baseline (NHMLB) air at the European inflow boundary according to the surface ozone data for Mace Head and Norwegian monitoring sites, and a minimum in late summer–early autumn reflecting a weak continental‐scale ozone production from biogenic sources of ozone precursors and wildfire emissions throughout the warm season. During spring and early summer under hot weather conditions, regional anthropogenic and wildfire emissions are an important source for ozone in the continental boundary layer over southern and central Siberia, resulting in surface ozone levels compared to or larger than those observed in NHMLB air. Throughout the remaining part of year, the central North Eurasia represents a sink for tropospheric ozone on a hemispheric scale. Key Points Seasonal variations of NOX and O3 at ZOTTO in Siberia show a signature of weakly polluted air due to the regional pollution Origins of clean and polluted air for the site are identified; seasonal cycle of the baseline ozone for central North Eurasia is estimated In spring‐summer, anthropogenic and fire emissions in Siberia provide a net source for tropospheric ozone in the NH midlatitudes

Contributions of climatically significant natural and anthropogenic emission sources in northern Eurasia to seasonal carbon monoxide (CO) variations observed at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia in 2007–2011 have quantitatively been estimated using the GEOS-Chem chemical transport model. It is shown that the formation of a stable continental pollution plume from sources in Western Europe, European Russia and southern Siberia during winter plays an important role in the regional balance of surface CO and allows one to explain 55–80% of the amplitude of the CO annual cycle observed at the ZOTTO station (~70–90 ppbv). During the warm period, the effect of the anthropogenic factor is weakly pronounced, and the background concentration of CO is regulated, first and foremost, by the oxidation of biogenic volatile organic compounds and fire activity in the region.

The results of the 2002–2012 continuous once-a-minute measurements of the composition of the surface air over Moscow, which were taken at the joint ecological station of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, and the Geographic Faculty of Moscow State University, are discussed. It is shown that the annual increase (on the order of 1%) in the content of surface ozone is stable and the decrease in the content of nitric oxide is statistically significant, while the content of nitric dioxide remains almost unchanged. Reliable regularities in both diurnal and annual variations in the contents of the five trace gases O 3 , NO, NO 2 , CO, and SO 2 have been studied in detail. Statistical relations of the content of sulfur dioxide with the amount of reserve fuel (black oil) used in city heating (this relation is the strongest one), wind velocity in an atmospheric layer up to a height of 200 m, and air temperature have been analyzed. The influence that wind velocity has on the surface contents of trace gases and carbon dioxide has been studied for the first time on the basis of long-term ‘MODOS’ sodar data. It is shown that, with an increase in wind velocity, the contents of nitric and carbon oxides generally decrease, the content of ozone increases, and the content of sulfur dioxide decreases starting from an intermediate value of 1–2 m/s due to the prevalence of high sources of this gas. An additional maximum found in the content of carbon dioxide at high wind velocities may be associated with the long-range transport of CO 2 .

Analyzed are the results of meteorological and environmental measurements performed over the 60-year period (1954–2013) at the Meteorological Observatory of Lomonosov Moscow State University. The significant positive temperature trend (0.04°C/year for 1954–2013) was obtained; it increased up to 0.07°C/year in 1976–2012. Considered are the features of seasonal variations of different atmospheric characteristics. Discussed are the type and causes of low-frequency changes in meteorological parameters, radiation balance components, radiation in different spectral ranges, and chemical composition of precipitation. Demonstrated are possible mechanisms of the more significant increase observed in air temperature in Moscow as compared with that in Central Federal District and their connection with the greenhouse effect in the urban atmosphere.

During the transcontinental studies of the state of the atmosphere above Russia in 1995-2010 using the train based laboratory (the TROICA experiment Transcontinental Observations Into the Chemistry of the Atmosphere), the territory of Moscow megapolis and Moscow region has been repeatedly crossed in various directions and in different seasons. The present work analyzes the characteristic peculiarities of spatial and temporal temperature changes and the content of primary gases (CO, O3, NOx = NO + NO2), defining the air quality, in the near surface air.

In the summer of 2010, the Moscow megacity during two months was within the zone of action of a blocking anticyclone. The accumulation of pollutants in a closed air mass sharply changed the surface air quality. At the end of July-the first half of August, the extreme situation became even more complicated, because the air from regions of turf and grass fires came into Moscow. According to measurement data of the Moscow IAP RAS station, the maximal hourly mean concentrations of chemically active gases NO, NO 2 , CO, O 3 , and SO 2 were 175.9, 217.4, 15.8, 134.2, and 15.2 ppb, respectively. For NO 2 and CO, these values are largest over the entire decadal period of observations at the station and many times exceed the MPC level (see table). The concentrations of greenhouse gases CO 2 , CH 4 , and nonmethane hydrocarbons also sharply increased. Analysis of the variability of gas contents in the surface air and in the atmospheric boundary layer showed a close relation between extreme changes in the atmospheric composition and its vertical stratification.

The paper presents results of experimental study of the physicochemical properties of surface aerosols in the Moscow region in the summer of 2019. Microphysical parameters, mass concentration and elemental composition of submicron and micron aerosol particles are considered, and their morphological structure is described. The features of variability of aerosol characteristics under atypical weather conditions prevailing in June-July 2019 are shown. The spatial distribution of the elemental composition of aerosols is established, a significant degree of their enrichment with heavy metals and metalloids is revealed. Geochemical analysis of aerosols and soils in Moscow was performed, and the coefficients of local aerosol concentration were calculated. The obtained experimental data will be useful for the refinement and verification of climate models.

Results of the analysis of interannual, seasonal, and diurnal variations in the ratios of the mixture of CH 4 , CO 2 , CO, benzene, and δ13C–CH 4 in the surface air of Moscow based on the measurements at the station of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS), in 2018–2020 are presented. The annual maximum concentration of CH 4 , CO 2 , and CO (>2.2, 430, and 0.20 ppm, respectively) occurs in the winter months due to the seasonal increase in the anthropogenic load from the main sources of urban pollution: motor transport and thermal power plants and a decrease in the role of vertical air mixing. The greatest contribution of local and remote microbial sources to the CH 4 concentration is noted in the summer months against the background of low δ13C–CH 4 values (–50 to –60‰). In all seasons, CH 4 , CO 2 , and CO ground level peaks lasting up to several hours are due to the transport from industrial sites in the E–SE sector. The calculated mean emission ratios in urban air were CH 4 /benzene = 0.52–0.54 ppm/ppb, CH 4 /СО = 0.56–0.75 ppm/ppm, CO 2 /benzene = 77–93 ppm/ppb, CO 2 /СО = 81–131 ppm/ppm, and CO/benzene = 0.65–1.11 ppm/ppb. These ratios characterize the predominant contribution of emissions from motor transport and the heat and power equipment and can be used to refine the absolute values of emissions, including those on the basis of existing inventories of sources of anthropogenic air pollution.

This paper reports a study of the April 2010 Eyjafjallajökull eruption on the atmosphere composition in Moscow. Concentrations of some gases, including sulfur dioxide, were measured at a station operated by Moscow University and the Institute of Atmospheric Physics. The impact of this eruption was felt, not only in the composition of the gaseous medium, but also in that of atmospheric precipitation as sampled and analyzed at the Meteorological Observatory of Moscow University. The NOAA hysplit model was used to carry out forward and backward trajectory analyses. It is shown that the descent of air masses during an anticyclone is a necessary condition for reliable recording of volcanic admixtures by ground-based stations.