Atmospheric and Oceanic Optics最新文献

A system has been developed for numerical prediction of concentrations of pollutants in the atmosphere and their transformation with the use of CHIMERE chemical transport model, which takes into account emissions from stationary and mobile sources and accidental emissions. Meteorological fields are forecasted using the regional high-resolution non-hydrostatic atmospheric model WRF-ARW. The system is fully automated and can be used as a tool for receiving operational information in the work of situation and decision-making centers in the cases of industrial, natural, and man-made accidents. The system was tested for a Russian region. The test results show its efficiency, a possibility of using it in operational and research work and in the development of scenarios of emergency situations anywhere in the Russian Federation, which can help to eliminate the consequences of accidents. The first results of atmospheric pollution calculation with the system are described and can be considered as test. To obtain statistically reliable results, it is necessary to have longer series of measurements of atmospheric pollution concentrations with higher resolution.

The paper investigates the generation of terahertz (THz) radiation during filamentation. A possibility of increasing the generation efficiency THz radiation in a single-color filamentation mode excited in air by laser beams with necklace amplitude profile is considered. A stationary model of THz radiation generation is suggested. It enables studying the dependence of conversion efficiency on the amplitude profiling of pump beams. It is shown that the partitioning of radiation over subapertures allows controlling the energy of THz radiation. The optimal class of gorget beams is found by a genetic algorithm. The results of this work are important for the development of technologies for remote generation of THz radiation in gaseous media.

The ongoing global warming leads to the need in continuous monitoring of greenhouse gas concentrations and the magnitude of their fluxes. Gas exchange between terrestrial ecosystems and the atmosphere is mainly measured using eddy covariance, gradient, and chamber methods. This work compares greenhouse gas fluxes measured using the eddy covariance technique onboard an aircraft laboratory and with the gas analysis system and meteorological sensors at ZOTTO observatory. Instrument suites of the aircraft laboratory and the observatory are described. The comparison results showed that CO₂ and CH₄ fluxes measured by two different methods at the same altitudes coincide in sign, are close to each other in the value for carbon dioxide, and differ by up to 2 times for methane. The results are of interest to specialists who study greenhouse gas fluxes using the eddy covariance method.

Cirrus clouds play an important part in the formation of our planet’s climate due to their influence on its radiation balance. Their study requires solving the problem of interpreting atmospheric laser sounding data, which is implemented differently for clouds consisting of randomly oriented ice crystals and clouds containing layers of horizontally oriented crystals. In this paper, within the framework of the physical optics method, properties of light backscattering by horizontally oriented cirrus cloud ice particles of the “plate,” “column,” and “hollow column” types are numerically simulated. The simulations are carried out for particles ranging in size from 10 to 316 µm for wavelengths of 0.532 and 1.064 μm; the complex refractive index of ice is 1.3116 + i1.48 × 10⁻⁹ and 1.3004 + i1.9 × 10⁻⁶, respectively. The solution is obtained for typical lidar tilt angles of 0°, 0.3°, 3°, and 5°. The results are of interest for developing an optical model of cirrus clouds in problems of interpreting atmospheric laser sounding data in the presence of clouds containing ice crystals of the abovementioned shapes.

Atmospheric aerosols have a significant impact on air quality, climate, and human health. The comparison of gaseous impurity and ionic composition monitoring data in the surface atmosphere over Antwerp and Beijing showed that the hygroscopicity level of dense haze particles over Beijing in winter is determined by the depth of heterogeneous reactions of sulfate and nitrate formation. The paper discusses the dynamics and mechanisms of these nonphotochemical processes, as well as the features of their coupling in a haze-polluted atmosphere. Their rapid occurrence in particles in combination with the uptake of water vapor from the air causes abnormally high mass concentrations of aerosol and their variability during the haze period over Beijing. The results are necessary for forecasting the occurrence of dense hazes, as well as for constructing models of transport of gas and aerosol microimpurities in the atmosphere.

The paper analyzes lidar measurements of vertical ozone distribution in the lower stratosphere–upper troposphere at the Siberian Lidar Station of V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, over Tomsk in 2023. The annual variation in the vertical ozone distribution is shown, as well as high ozone content in the lower stratosphere–upper troposphere recorded on March 9, 2023, which is assumed to be caused by a quire rare process of stratospheric–tropospheric air mass transport through the tropopause.

The effect of vertical and horizontal turbulent heat fluxes on the air temperature variance under conditions of temperature inversions of different intensity is considered. It is shown that the neglect of horizontal turbulent heat fluxes under these conditions in the existing models can lead to significant underestimation of the mixing layer height.

Liquid-drop clouds play a significant role in the evolution of cloud systems and the formation of the Earth’s radiation balance. Determination of their optical and microphysical characteristics is one of the most important problems of optics and atmospheric physics. The paper is devoted to assessing the applicability of an artificial neural network to processing synthetic data of passive satellite measurements of reflected solar radiation of low and medium spatial resolution in the visible and short-wave infrared spectral regions in order to simultaneously retrieve the optical thickness and effective radius of droplets of horizontally inhomogeneous cloudiness. The network is trained using the Monte Carlo calculated values of radiance in marine stratocumulus clouds generated by a fractal model. Through a nonlinear approximation of the dependence of optical and microphysical parameters of clouds on radiation characteristics, the tested algorithm allows taking into account the effects of horizontal radiative transfer, unlike classical IPA/NIPA (Independent Pixel Approximation/Nonlocal Independent Pixel Approximation) schemes. It is shown that the errors in solving the inverse problem can be reduced by assimilating data in adjacent pixels, reducing spatial resolution, and using radiance data received at small solar zenith angles. The high correlation between the test and retrieved optical thickness and effective radius indicate the possibility of using a neural network approach to interpreting satellite measurement data.

The operation of thermal power plants (TPP) is accompanied by the emission of various pollutants into the atmosphere, including nitrogen oxides. This paper presents the results of spectrometric measurements of the atmospheric NO₂ content carried out on circular routes around large urban TPPs of St. Petersburg. The spatial variability of tropospheric NO₂ content in the vicinity of a TPP is determined based on experimental data received by the DOAS (Differential Optical Absorption Spectroscopy) method and shows high values in the downwind side of stacks. The spatial distributions derived from the mobile DOAS measurements are confirmed by the results of numerical calculations of the NO₂ content field with the HYSPLIT (HYbrid Single-Particle Lagrangian Integrated Trajectories) model taking into account a priori information on the volume of NO_x emissions from main urban TPPs. Approximate estimates of NO_x emissions from two the largest TPPs in St. Petersburg from calculations of the total flux of NO₂ molecules through a loop-route DOAS measurements amount to ∼2–3 kt per year. These experimental data are important for determining the contribution of thermal power plants to anthropogenic atmospheric pollution.