Home – Home – Jornals – Atmospheric and Oceanic Optics 2023 number 11

Simple isotopic relations relating the energy levels of the isotopologues ³²S¹⁶O₂, ³³S¹⁶O₂, and ³⁴S¹⁶O₂ with the levels of other isotopic variants are applied to calculations of vibrational-rotational energy leveles. To estimate the accuracy of the isotopic ratio, we calculated and compared with the measured line centers of the microwave spectrum of the ³⁶S¹⁶O₂ isotopologue. Comparison showed their quite satisfactory agreement at a level of 10^-3 cm^-1. Vibrational-rotational energy levels of sulfur dioxide isotopologues X S¹⁶O₂, X = 35-38, up to J = 9 for five lower vibrational states are presented.

The chemical composition of aerosol in the atmosphere of the research station „Cape Baranov Ice Base“ (Severnaya Zemlya archipelago) collected in 2017-2022 is studied. The interannual and seasonal dynamics of ions and trace elements in the aerosol composition is analyzed in detail. A 1.5-fold increase in the annual mean concentrations of the sum of ions is traced. The growth of the sum of ions was mainly due to the concentrations of ions of marine origin Na⁺ and Cl^-, the content of which is minimal in summer and maximal in winter. The variability of concentrations of non-marine ions NH₄⁺, K⁺, Ca²⁺, F^-, NO₂^- i NO₃^-differed from the seasonal course of concentrations of Na⁺ and Cl^- and consisted in a decrease during the transition from winter to spring season and an increase in the summer period with a subsequent decrease in autumn against the background of an increase in the sum of ions at the expense of ions of marine origin. Formation of aerosol ion composition is affected by the marine factor, air mass transport, underlying surface, and wildfires. Among trace elements, Fe, Al, Zn, Mn, Sn, Cr, and Cu dominated with high concentrations in the fall and winter periods. Based on enrichment factors, elements of terrigenous (Al, Ti, Mn, Fe, Th, U), mixed terrigenous and non-terrigenous (Li, Be, V, Co, Sr, Ba), and non-terrigenous origin (Ni, Cu, Zn, Cr, Mo, Mo, W, Ag, Tl, Pb, As, Se, Cd, Sn, Sb) are identified. In winter and autumn periods, Fe and Mn have the highest contribution to the total level of air pollution, while in spring and summer, Fe and Be. Among non-terrigenic elements, Cu, Sn, Zn, Se and Ni had increased contribution in all seasons. The level of atmospheric pollution by trace elements at the station „Cape Baranov Ice Base“ is assessed as low.

Measurements of polarization scattering phase functions and spectral extinction coefficients were carried out in smoke aerosols formed as a result of thermal decomposition of pine wood in the mode of low-temperature pyrolysis in the Big Aerosol Chamber (BAC) of IAO SB RAS. Using the developed algorithm for inverting optical measurements, the microstructure and complex refractive index of pyrolysis smoke are retrieved. The volume concentration and the mean radius of particles are analyzed microstructure parameters, with division into fine and coarse fractions. The temporal variability of the microphysical parameters of smoke aerosol is studied for 65 hours. It has been established that the real part of the refractive index is in the vicinity of n = 1.55, and the imaginary part is in the range 0.007 < k < 0.009. The mean radius of fine particles varies in the narrow range 0.137-0.146 mm. During smoke aging, the mean particle radius of the total ensemble monotonically increased from 0.19 to 0.6 mm, mainly due to a relative increase in the content of coarse aerosol. Results of this work are important for estimation of the radiative forcing of aerosol, improvement of climate models and algorithms of remote optical sounding.

Based on the results of a comprehensive experiment conducted in September 2020, the spatial distribution of the following trace gases over the seas of the Russian Arctic are analyzed: carbon monoxide (CO), ozone (O₃), nitrogen oxide and dioxide (NO and NO₂), and sulfur dioxide (SO₂). It is shown that the gas concentrations in the surface air layer over the seas (at a height of 200 m) vary in the range 18-36 ppb for O₃, 60-130 ppb for CO, 0.005-0.12 ppb for NO, 0.10-1.00 ppb for NO₂, and 0.06-0.80 ppb for SO₂. Over most seas, the distribution of the gases across the water area is heterogeneous, which most likely reflects differences in their uptake by the ocean and peculiarities of transport from the continent.

Behavior of ozone in the Arctic is of major concern. Ozone anomalies occur every five years on the average. The last, record strong decrease of the ozone level in the stratosphere of the Arctic took place in March-April 2020. In February 2022, ozone destruction developed by the scenario very similar to the anomaly of 2020. Like in 2020, the ClO mixing ratio, which can be considered a reliable indicator of ozone destruction, strongly increased after the end of the polar night in Arctic latitudes in 2022, but the subsequent ozone depletion process was halted by a sudden major stratospheric warming on March 20, 2022. In this work, we analyze ozone destruction in 2020-2022 based on measurements of the total ozone content over 2003-2022 from the TEMIS service, profiles of the air temperature and ozone mixing ratio for 2005-2022 and of ClO mixing ratio for 2020-2022 from Aura MLS observations. The following sites are considered: Eureka, Canada; Ny-Ålesund, Norway; Thule, Greenland; and Resolute, Canada. A relationship is revealed between ozone and chlorine oxide contents. High coefficients of correlations between oscillations of the above parameters at close altitudes of their recording, as well as between the total O₃ and ClO contents calculated from their profiles, indicates their close interrelation. Hence, the ClO concentration and total content can be used as indicators of ozone destruction in the Arctic stratosphere.

Atmospheric waves are of increased interest in connection with exchange processes occurring in the atmospheric boundary layer. Experimental results of sounding mesoscale Kelvin-Helmholtz waves by turbulent lidars in a stably stratified boundary layer of the atmosphere are presented. This paper presents the data of measurements by BSE-4 lidar (532 nm), which has been working over forest-steppe for a long time. Atmospheric waves in most cases were observed in the evening and at night in the range of heights from the land to 600 m, when the Richardson number in the surface air layer did not exceed a critical value of +1/4. Fourier analysis of the time series of the structural characteristic of the refractive index Cn² showed that the spectrum of the wave process in the atmospheric boundary layer consists of a set of monochromatic waves with different oscillation frequencies. During the observations, the period of the waves varied from 1 to 11 min, and their amplitude changed from 20 to 300 m. It is found that monochromatic waves exist from half an hour to two hours. The disappearance of some monochromatic waves is compensated by the appearance of new ones. The process of generating small-scale turbulence runs throughout the life cycle of a Kelvin-Helmholtz wave. The results indicate that the turbulent lidar ensures remote detection and observation of atmospheric waves.

The article studies a single thundercloud that developed at night near the coast of the Gulf of Finland. Using three meteorological radars, two lightning detection systems, and a 3D numerical model, the physical processes that caused its electrification are analyzed. It is shown that the first lightning occurred during the period when there was a small area containing graupel particles in the upper part of the cloud. Updrafts played an important role in the formation of this area and the microstructure of the cloud, as shown both by radar observations and numerical simulation. Further intensification of thunderstorm activity is associated with an increase in the cloud volume with graupel and hail. Analysis of the charge values of individual cloud fractions based on the results of numerical simulation showed that hailstones are the main carriers of the negative charge.

The paper is devoted to the study of the effect of relative air humidity on the color of diffuse plasma jets (DPJs) initiated by a capacitive discharge at pressures of 0.03-1 torr, which are analogues of columnar sprites. Photographs and emission spectra of DPJs are given, as well as a photograph of a sprite. The results of the study showed that a decrease in the relative air humidity at pressures less than 0.1 torr contributes to the preservation of the red color of DPJs. Quantifying the average number of red and blue pixels in the photographs confirms this result. It has been established that an increase in the reduced electric field leads to a change in the color and spectrum of the periodic domain structure due to an increase in the intensity of the emission of the bands of the first negative nitrogen system.

In order to study temporal variations in the mixing ratios of greenhouse carbon-containing gases and factors influencing them, local measurements of CO₂, CH₄ (January 2013 - January 2020), and CO (January 2013 - January 2019) mixing ratios in atmospheric air at the St. Petersburg State University station are analyzed. For this analysis, the trend and seasonal oscillations are taken into account. Linear trends for CO₂, CH₄, and CO, which are 2.42 ppm/year (0.60%), 8.6 ppb/year (0.49%), and -3.8 ppb/year (-2.2%), respectively, are in a good agreement with independent estimates for both global/background changes and changes in urban area. The analysis of the CO/CO₂ emission ratio confirmed that motor vehicles are the dominant anthropogenic source affecting the composition of atmospheric air in the area of the St. Petersburg State University monitoring station. The results presented in this work can be used for validation of atmospheric models, as well as for independent estimations of greenhouse gas fluxes.

The polar vortices play a significant role in the distribution of stratospheric ozone, the movement of air masses in the polar and subpolar stratosphere, and temperature changes over the polar region. The Antarctic polar vortex forms in autumn and reaches its peak intensity in early spring. In late spring, when this vortex weakens, the influence of the lower subtropical stratosphere increases. We consider the effect of temperature changes in the lower subtropical stratosphere on the Antarctic polar vortex strengthening. Using correlation analysis and ARA5 reanalysis data, we show a significant increase in the effect of minor temperature changes in the lower subtropical stratosphere on the Antarctic polar vortex dynamics in the second half of November.

This work continues the series of experimental studies of fluctuations of the parameters of optical waves along extended paths. In this part, we study possibilities of using an adaptive optics system for focusing laser radiation along long paths in the atmosphere. The adaptive optics system is described, which is part of a hybrid system that provides focusing of a laser radiation beam along an extended atmospheric path. A focusing system, which uses a Shack-Hartmann wavefront sensor, a deformable controllable mirror, and a wavefront tilt corrector implements a phase conjugation algorithm based on a signal from a point reference source. To accompany the experiment, optical and acoustic meters of the level of turbulence and wind speed were used. The results show both opportunities and limitations for the efficient operation of the system on a long turbulent path.

An original technique for pumping a pulsed CO₂ laser with a longitudinal discharge in an alternating magnetic field is proposed and implemented. Based on this technique proposed technique, a small CO₂ laser with an active medium length of ~ 200 mm, a pulse energy of ~ 30 mJ, and an efficiency of 3.4% is designed. It is revealed that the main factor which limits the generation energy of small lasers is the development of current instabilities in a longitudinal discharge across a cross section of the discharge tube. It is noted that the growth of instabilities accelerates with increasing pressure of a CO₂ : N₂ : H₂ : He gas mixture to more than 0.1 atm and the specific pump power to more than 3 MW/cm³. The use of an external alternating magnetic field superimposed on a pulsed longitudinal discharge makes it possible to increase the total pressure of the gas mixture in the laser to 0.4 atm while maintaining the combustion of the volume discharge.