Atmospheric and Oceanic Optics最新文献

The propagation and accumulation of impurities in the near-surface atmospheric layer largely depend on layer stability, which can be quantitatively characterized by the mixing layer height (MLH). For the first time, using a single methodology, the average values for 2001–2021 were estimated for different territories of Russia in the central months of seasons separately for daytime and nighttime. The analysis is based on MLH (or atmospheric mixing depth) values from the website [www.arl.noaa.gov] obtained during long-term studies of the long-range air mass transport to different Russian regions. The area-averaged MLH values over individual mainland quasi-homogeneous climatic territories or Russian Arctic seas are given, as well as the spatial distribution of MLH over the Russian territory on a geographical grid of 1° × 1°. The results of the study can be used in environmental assessments of, e.g., the atmospheric pollution potential, fluxes of aerosol impurities onto the underlying surface, sources of air pollution, and the degree of their impact on the environment and humans, as well as in comparative analysis of climate of different Russian regions.

The development of the deep underwater neutrino telescope BAIKAL-GVD involves the creation of equipment for regular long-term monitoring of inherent optical properties (IOP) of the aquatic environment within the effective volume of the telescope. Regular monitoring of IOP provides not only an increase in the accuracy of retrieving neutrino energy and direction, but also unique data for limnological studies. The paper describes the design of BAIKAL-5D devices developed to solve this problem and considers the methods and algorithms for in situ monitoring of IOP used in these devices. The sources of instrumental error in measuring the light absorption and scattering in water are examined and the necessary corrections are determined. Some results of measuring IOP of the deep waters of Lake Baikal using BAIKAL-5D devices are presented.

The Monin–Obukhov (MO) scales estimated from experimental data received at two observation sites with different underlying surface structure under different surface air temperature stratification types are analyzed. The MO scale (its sign, first of all) is compared with current temperature profiles in the surface air layer. The MO scale sign is found to differ sometimes from actual temperature stratification, which contradicts the Monin–Obukhov similarity theory. The results can be used for refining surface air layer models which are based on this theory.

The paper studies the composition of output signals of metalvapor laser active optical systems under various operating conditions. The effect of the time characteristics of these systems on the output signal composition is experimentally estimated. A technique for determining the contribution of amplified spontaneous emission (ASE) to the output signals of self-adjoint system and system with independent illumination source is suggested. An optimal time of input signal arrival to the active medium of an amplifier for ensuring the maximal signal/noise ratio is determined. ASE is completely suppressed in the system with independent illumination source at a time delay of −4.3 to +25.8 ns. Complete suppression in the self-adjoint system was not achieved. The minimal ASE value in the self-adjoint system was 80 mW, i.e., ~2% of output signal power. The results can be useful in studying the amplification characteristics of active metalvapor optical systems and in visual-optical diagnostics in laser monitors on their basis.

The Russian Federation regularly participates in the international program of the Acid Deposition Monitoring Network in East Asia (EANET). Two regions in the Asian Russia were selected for monitoring research: South-Eastern Siberia (three sites) and Far East (one site). A database on the chemical composition of atmospheric aerosol has been compiled over the operation period. The spatial and temporal variability of the ion composition of aerosol over five-year periods from 2001 to 2024 was studied using the ratio of the summed concentrations of the main ions. Based on data from other projects, some relevant trace elements in atmospheric aerosol were analyzed: Li, Al, Ti, V, Mn, Fe, Sr, Th, U, Ba, and Co (of terrigenous origin) and Cr, Cu, and Ni (of nonterrigenous origin). Their contribution to the total level of atmospheric air pollution at the EANET monitoring sites was assessed. The monitoring results on atmospheric depositions can be used for practical assessment of the environmental conditions, scientific research, and public information.

Thermophoresis of aerosols has been traditionally studied both theoretically and experimentally for spherical or, more generally, compact isometric particles. This paper compares the theory of thermophoretic motion of fractal-like particles we have developed with experimental data for gas-phase carbon aggregates received under DLCA scenario of their generation. Theoretical results for the thermophoretic velocity are shown to qualitatively and quantitatively agree well with experiment. Possible limitations of the suggested theory and fundamental issues related to the estimation of structural and thermophysical parameters for fractal-like aggregates are discussed. The results can be useful for the physics of atmospheric aerosols in simulating motion of carbonaceous particles with fractal properties.

Atmospheric aerosol affects astronomical observations in the visible spectral region (400−700 nm). Therefore, information on the dynamics of optical properties of the atmosphere in the region of an astrophysical experiment is required for correct interpretation of experimental results. In the lack of local measurements, data on the state of the atmosphere can be derived, for example, from numerical simulation. The paper discusses the simulation results for AOD in the region of TAIGA gamma-ray observatory, where EAS Cherenkov radiation is recorded at night, with the use of GEOS-CHEM chemical transport model and CAMS chemical reanalysis. According to GEOS-CHEM and CAMS data, the average AODs (at a wavelength of 550 nm) over September–April in 2019–2022 were ∼0.08 and ∼0.05, respectively. The AOD maximum is observed in April and can attain 0.6. Verification of the simulation results with AERONET data shows their satisfactory agreement: the correlation coefficient is 0.92 for GEOS-CHEM and 0.91 for CAMS. Hence, the results of GEOS-CHEM and CAMS can be used for processing data from TAIGA gamma-ray observatory, as well as from similar astrophysical projects.

Lake Baikal is a unique natural object. Study of the composition and optical characteristics of aerosols in the atmosphere above it is an urgent problem. This work analyzes the results of studies of the microstructural and physicochemical properties of near-water and near-ground aerosol in the atmosphere of Lake Baikal basin in summer 2024 onboard Research Vessel Akademik V.A. Koptyug and at the Boyarsky research station on the southeastern coast of the lake. The aerosol spatial distribution over the lake water area and the content of black carbon in aerosol particles are shown to be determined by the location of anthropogenic sources in the absence of smoke plumes from wildfires. Hygroscopicity and volatility of atmospheric aerosols, which depend on aerosol particle size, are studied for the first time. The aerosol condensation activity over the coastal zone is found to be stronger than over the lake. The results can be useful for the development of regional models of atmospheric aerosol.

This study examines the meteorological variables influencing lightning activity over Pakistan from 2001 to 2014 focusing on three regions: R1 (26°–29° N, 64°–69° E), R2 (29°–32° N, 69°–73° E), and R3 (32°–36° N, 70°–73° E). To understand regional variations, we analyzed several meteorological parameters, including aerosol optical depth (AOD), relative humidity (RH), convective available potential energy (CAPE), precipitation (P), liquid water cloud effective radius (LWCER), ice water content (IWC), and liquid water content (LWC) during lightning days. Our findings indicate that lightning activity is correlated with the vertical extent (or thickness) of the mixed-phase zone defined as the layer between 0°C and −40°C isotherms and associated ice and liquid water content. In the lower atmosphere, increased rainfall is associated with higher LWC, whereas in the mixed-phase zone, lightning activity shows a stronger dependence on both IWC and the vertical structure of the mixed-phase cloud layer. Lightning activity exhibits a strong relationship with relative humidity. An inverse correlation between AOD and lightning suggests that aerosols can modulate lightning activity by influencing cloud microphysics, particularly under thermodynamically favorable conditions. These insights underscore the importance of continuous lightning monitoring in Pakistan. A better understanding of these meteorological influences can enhance lightning prediction and improve safety measures in the region.

Observations of the state of Venus’ mesosphere from spacecraft have not yet revealed transient luminous events similar to those observed in the Earth’s atmosphere. In this work, the possibility of such phenomena is proved in laboratory conditions. For this purpose, an experiment has been carried out on the formation of apokamps in carbon dioxide at different pressure values. The obtained data experimentally confirm the hypothesis that conditions at altitudes corresponding to the cloud tops in the atmosphere of Venus are favorable for generating analogues of transients of the Earth’s mesosphere. Based on this, recommendations have been developed for the design of systems for detecting such phenomena from orbiting satellites or balloons.