Home – Home – Jornals – Atmospheric and Oceanic Optics 2023 number 2

Calculated carbon dioxide broadening coefficients of sulfur dioxide lines at a room temperature are presented. The calculations are performed for the ν₁ + ν₃ band, rotational quantum numbers vary in the ranges of J up to 100 and of K_a up to 20. Based on the experimental data the semi-empirical method parameters are determined; the computed broadening coefficients are in good agreement with the literature data.

Contributions of stable dimers to the water continuum in the 1600 and 8800 cm^-1 bands are examined. They are found as the difference between experimental data and the calculation data within the asymptotic line wing theory taking into account the violation of the longwave approximation for the molecular centers of mass. The stable dimer contribution is close in value to the contribution due to all other pair interactions and decreases with increasing temperature. The estimate of the equilibrium constant of the dimer formation reaction is derived proceeding from the temperature dependence of the classical interaction potential of water molecules describing the temperature behavior of the second virial coefficient.

In 2021, concentrations and elemental chemical composition of the inorganic part of solid snow impurities were studied on the territory of the Norilsk Industrial District. Based on the analysis of these data, a list of priority polluting chemical elements is compiled (Ni, Cu, Cd, Co, Sn, Pb, B, and Zn) and a method for quantifying the contribution of atmospheric emissions from Nadezhda Metallurgical Plant to aerosol pollution of the territory is suggested. In the sub-latitudinal direction, emissions from this plant predominate in dust pollution of the air at a distance of up to 7 km from the source.

In the Arctic, global warming is 2-3 times faster than over other regions of the globe. As a result, noticeable changes are already being recorded in all areas of the environment. However, there is very little data on such changes in the Russian Arctic. Therefore, to fill the gap in the data on the vertical distribution of the gas and aerosol composition of air in this region, an experiment was carried out on the Tu-134 Optical laboratory aircraft in September 2020 to sound the atmosphere and water surface over the water areas of all seas in the Russian Arctic. This paper analyzes the spatial distribution of methane. It is shown that during the experiment its concentration was the highest over the Kara Sea (2090 ppb), the lowest over the Chukchi Sea (2005 ppb). The East Siberian and Bering seas were slightly different from the Chukchi Sea in its content. Average values of CH₄ are characteristic of the Barents (2030 ppb) and the Laptev Seas (2040 ppb). The difference in the concentrations between the level of 200 meters and the free troposphere reached 150 ppb over the Kara Sea, decreased to 91 and 94 ppb over the Barents and Laptev Seas, and further decreased over the East Siberian, Chukchi and Bering Seas to 66, 63 and 74 ppb, respectively. Horizontal heterogeneity in the distribution of methane over the Arctic seas is the greatest over the Laptev Sea, where it reaches 73 ppb. It is 2 times higher than over the Barents and Kara Seas, and 5-7 times higher than over the East Siberian and Bering Seas.

In this work, we present the time series of regular observations of the total ozone content over Tomsk with three independent instruments over the period from 2006 to 2020. The main statistical characteristics of these time series are determined. We carried out the comparative analysis of these time series with each other and, in particular, the analysis of long-term annual average behaviors. The causes for the discrepancies of these measurements are discussed.

The results of numerical simulation of a scanning lidar return for the case of sounding a cloud containing quasi-horizontally oriented plate-like crystals are presented. It is shown that a vertically oriented lidar is "blinded" by the specular component of the scattered radiation, while the scanning lidar return is sensitive to the crystal shape. The results of the numerical calculation confirm a sharp increase in the depolarization ratio in the vicinity of scanning angles of 30°, which was earlier observed in experiments. It is found out that this depolarization ratio enhancement is a marker of the perfect shape of a plate-like crystal and can be used to interpret experimental data.

Forest are among the main places on Earth where carbon is collected and accumulated. However, quantitative instrumental assessment of carbon fluxes is possible only for small-scale areas. When solving the scaling problem, we use machine learning methods, which can transform the values of the intensity of the Earth’s surface reflectance in different spectral intervals into ground-based in situ observations. The assessments of carbon fluxes by a regression neural network model of the multilayer perceptron type trained on FLUXNET network data for a station located in a boreal coniferous forest (56.4615°N, 32.9221°E) are presented. Using vegetation indicies NDVI and EVI measured by MODIS Aqua, air temperature at an altitude of 2 m, and total precipitation as input data, the model estimates of gross primary production (GPP), net ecosystem exchange (NEE), ecosystem respiration (TER), and some other parameters describing water and energy fluxes are calculated. Statistical estimation provides high values of the correlation coefficient and Nash-Sutcliffe coefficient on test dataset: R ≥ 0.9 and NSE ≥ 0.87 for GPP and TER; R = 0.4 and NSE = 0.15 for NEE.

A computational technology for studying aerosol-radiation interactions and calculating regional estimates of the direct and semi-direct radiative effects of biomass burning (BB) aerosol based on calculations with the CHIMERE chemistry-transport model coupled to the WRF meteorological model is described. The technology was applied to the numerical study of the radiative effects of Siberian BB aerosol in the eastern Arctic in the period of July 16-31, 2016. The simulation results show that Siberian BB aerosol had a significant cooling effect on the atmosphere in the eastern Arctic in that period due to the direct radiative effect (DRE), the value of which at top of the atmosphere was, on average, -6.0 W × m^-2, being minimal over the snow-ice cover of the ocean (-1.2 W × m^-2). At the same time, it is found that the contribution of the Siberian BB aerosol DRE to the radiative balance of the Arctic atmosphere is compensated to a certain extent by the semi-direct radiative effect (SDRE), which is positive on average (2.0 W × m^-2). The SDRE is formed as a result of the aerosol feedback on meteorology during many hours of the evolution of the atmosphere and plays the most important role over the snow-ice cover, where it exceeds the DRE in absolute value. It has been shown that the SDRE of Siberian BB aerosol in the performed numerical experiments is mainly due to the process of scattering (rather than absorption) of radiation by aerosol particles.

The results of the analysis of atmospheric blockings in the regions of the Northern Hemisphere (NH) under general warming during recent decades are presented. In particular, estimates of the total increase in the duration of summer atmospheric blockings in the NH with an increase in the hemispheric surface air temperature for the period 1969-2022 are obtained using observations and reanalysis data. Significant coherence of the most long-term changes of the integral index of summer atmospheric blocking activity for the Russian regions and for the NH as a whole is noted. A statistically significant correlation of the duration of atmospheric blockings of the area of wildfires in the Russian regions with related gas and aerosol emissions into the atmosphere is estimated based on satellite and reanalysis data. Estimates of the correlation of the Siberian fires with anomalies in the content of atmospheric impurities, including black carbon, in the Arctic regions are presented.

We consider data from laboratory simulation of the dynamics of sulfate origination in atmospheric haze particles during oxidation of SO₂ captured from the gas phase in the presence of Mn/Fe ions. The rates of sulfate origination under dark conditions of these experiments (tens of micrograms m^-3 × h^-1) have been found to correspond to a previously unknown mode of catalytic reaction. Its key element is the branching of chains involving the intermediate HSO₅^- ( Caro’s acid) and Mn²⁺ ions. Estimates are given for the rate constant of this aqueous-phase reaction, and a criterion for separation the slow and degenerate-branched (fast) modes of SO₂ oxidation is considered. The observed rate constant of sulfate origination in particles k^*_obs = 1.4 L × mol^-1 × s^-1 ( T = 298 K). The calculations of the dynamics of sulfate origination agree with data of laboratory experiments (smog chamber data). Their results also do not contradict the monitoring data on sulfate content in the haze over Beijing (December 2016).

The experimental setup and the technique are suggested for sequential feeding of controlled doses of Hg, benzene, and toluene vapors into the measuring cell of a DOG-07 analyzer with a mercury capillary lamp based on the transverse Zeeman effect as a radiation source. It is shown that when benzene or toluene vapors with concentrations of up to 10 mg/m³ are added to the measuring cell with mercury vapors in a concentration of more than 30 ng/m³, there is no error in the measured Hg concentration. With the introduction of a higher concentration of benzene vapors, an increase in the measured concentration of Hg is observed. The introduction of a higher concentration of toluene vapor into the measuring cell leads to a decrease in the measured concentration of Hg.