Atmospheric and Oceanic Optics最新文献

The prediction of the level of air pollution by gaseous and aerosol constituents in cities becomes increasingly significant in view of their serious negative impact on public health and growing ecological risks. The article presents an approach to estimating and adjusting the emission power of anthropogenic sources based on direct and inverse modeling. The WRF-Chem model was used as a direct simulation tool, and the IMDAF system developed by the authors was used for inverse simulation. The results of direct simulation provided data on meteorological fields and the distribution of admixtures necessary for solving adjoint problems. The use of the adjoint problem method made it possible to calculate a correction factor that determines how much the power of sources that fall into the sensitivity zone should be changed to achieve the best agreement with measurements. Our approach can be used to improve the prediction of air quality, refine the inventories of anthropogenic emissions, and develop the strategies for reducing the ecological risks on global and regional scales.

The paper studies a possibility of remote detection of surface traces of organophosphates using the double-pulse laser fragmentation/laser-induced fluorescence (LP/LIF) method. For liquid-drop traces of triethyl phosphate on a paper surface, the inertial character of origination of characteristic PO fragments (phosphorus oxide molecules) of organophosphates is shown. The concentration of formed fragments is maximal in approximately 2 μs after the action of a fragmenting laser pulse (266 nm). It is found that a delay of 2 μs between a laser pulse (247.78 nm) and a fragmenting pulse multiply increases the fluorescence intensity, by approximately 7 times compared to the single-pulse excitation method and approximately 2.3 times compared to simultaneous double-pulse action. Our experimental data confirm, first, a possibility of remote detection of surface traces of liquid-drop organophosphates by the two-pulse LF/LIF method and, second, a need in organizing optimal laser exposure conditions to increase the efficiency of the LF/LIF process. The results contribute to the knowledge about the efficiency of detecting organophosphate traces on other carrier surface types.

Sulfur dioxide (SO₂) plays a key role in the winter–spring stratosphere of the Arctic because the sulfur compounds SO₂ and H₂SO₄ (together with nitric acid HNO₃) are the primary construction materials in the formation of polar stratospheric clouds (PSCs). This paper studies the maximal SO₂ concentrations and total SO₂ columns at four Arctic sites: Eureka (Canada), Ny-Ålesund (Norway), Thule (Greenland), and Resolute (Canada) based on the data on the minimal air temperature, maximal negative deviations of ozone concentration from the multiyear average, maximal sulfur dioxide concentration in the Arctic stratosphere, and the total ozone and sulfur dioxide columns calculated from the corresponding altitude profiles. The temperature and ozone mixing ratio profiles are obtained from the Aura MLS observations for 2005–2022; the sulfur dioxide mixing ratio profiles are calculated from Aura MLS observations for 2010/11, 2019/20, 2020/21, and 2021/22. The results can be useful for studying of how SO₂ affects the PSC formation and O₃ destruction in the winter–spring stratosphere of the Arctic.

Experience of creating a regional monitoring system for atmosphere–underlying surface turbulent energy exchange is analyzed. An original technique for creating an observation network based on ultrasonic automatic weather stations of domestic production has been developed. Based on this technique, the TomskFluxNet system has been deployed in Tomsk. It is the first urban network for monitoring characteristics of land–air turbulent energy exchange in Northern Eurasia, under condition of pronounced continental climate. The first experimental results show significantly different turbulent heat and momentum fluxes over urban and natural underlying surfaces. The results can be used to verify and improve the parameterizations of the urban surface, which are actively developing in land–air models and weather forecast.

The two-pulse synchronous excitation technique used for remote laser diagnostics of matter is of great interest, since it significantly expands the capabilities of traditional methods of single-pulse laser action. However, the practical implementation of the technique requires strict synchronization of the times of sending laser pulses and automated control of their time positions. The two-pulse excitation scheme needs in more complex equipment. Standard laser triggering and control tools are expensive, cumbersome, and not always applicable. The paper describes a specialized laser triggering system capable of recording the shape and position of excitation pulses and their displaying on a single time scale. The structural diagram and technical characteristics of the system are presented; an example of its operation as a component of a research setup for remote laser detection of organophosphorus compounds by the two-pulse LF/LIF laser fragmentation technique is given. The developed synchronization system can be used in optical diagnostics, where synchronous action of two or more independent laser sources is required, to set and control the time delay between laser pulses.

Features of the daily dynamics of aerosol fractions in surface air during the generation of a winter aerosol field above the Fonovaya Observatory of V.E. Zuev Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences, (Tomsk, Russia) are studied. The distributions of hourly average particulate count are analyzed along with the spatial distributions of the probability of transport of moisture-bearing air masses taking into account the time intervals of snow accumulation at the observatory in the first half of winter 2022/23 (from November 17, 2022, to January 30, 2023). It is found that the daily variations in hourly average particulate count in the particle size range d = 0.3–2.0 μm are sometimes determined by radiometric forces, that is, “snow” photophoresis caused by and associated with the manifestation of the microphysical properties of aerosol in the field of infrared radiation outgoing from the snow cover. It is reasonable to assume that “snow” photophoresis certainly affects the radiation balance in the winter atmosphere and should be taken into account when modeling vertical transport of aerosols in the lower troposphere.

Community-acquired pneumonia is among the most common acute infectious diseases. According to official statistics, pneumonia accounted for up to 50% of respiratory-disease mortality in the Russian Federation in 2005–2017. Ground-level ozone, being a key component of urban smog, is one of little-studied risks of community-acquired pneumonia. This work studies the effect of ground-level ozone on the rate of community-acquired pneumonia among Moscow residents in the warm season over a five-year period (2006–2009 and 2011). The study results have enabled us to conclude that ground-level ozone contributes to an increase in the community-acquired pneumonia rate among Moscow residents in summer. Daily average concentrations of ground-level ozone of 60–80 μg/m³ can increase the community-acquired pneumonia rate by 30% compared to low-ozone periods, especially in combination with unfavorable weather conditions, such as high air temperature and low humidity. The results will help human ecologists and health care professionals to make the urban air safer.

One of the indicators of ongoing climate change is the evolution of cloud regimes, both in individual regions and globally. Within this framework, the long-term variability of the structure of multilayered clouds with an optical thickness of less than 15 over Western and Eastern Siberia during the summer and winter seasons from 2006 to 2023 in daytime conditions is estimated based on CALIOP lidar data (CALIPSO satellite). Multilayering refers to the presence of clouds at several levels at the same time located under each other with gaps between them. The applied methodology is based on the use of cloud classification results from daily CALIOP lidar measurements, calculation of seasonal recurrence values for each combination of cloud types in the multilayer structure, deriving time series, determining trends, and evaluating their parameters. It has been found that the fraction of clouds with different numbers of layers over both regions did not significantly change during the period under study. In Western Siberia, the fraction of two-layer clouds is 68% in summer and 71% in winter; in Eastern Siberia, 71 and 75%, respectively. The fraction of three-layer clouds in Western Siberia attains 27% in summer and 25% in winter; in Eastern Siberia, 26 and 23%. The fractions of four- and five-layer clouds do not exceed 5% in both regions together and are almost the same in the two seasons. The most frequent combinations of cloud types in multilayer clouds over Western and Eastern Siberia have been determined. Estimates of linear trends in the fraction of the most frequent combinations in multilayer clouds over the period under study are presented. The results can contribute to improving the accuracy of climate models and radiative transfer estimates.

On-off keying (OOK) signal is affected by the scintillation effect caused by atmospheric turbulence when it is transmitted through atmospheric channel, which results in intensity fluctuation of received signal. This paper proposes nonlinear multiplier (NM) and deep learning (DL) based fixed threshold OOK detection for free-space optical (FSO) communications to compensate the scintillation effect. The strength of the received signal is improved due to the multiplier characteristic of providing different amplification gains according to different signal strengths. Three kinds of nonlinear multipliers are studied in this paper. However, the NM based fixed threshold OOK detection technique is less effective at higher atmospheric turbulence intensities due to the distortion of the OOK signal extinction ratio (ER) caused by the use of highly non-linear compensation. Therefore, an improved Gated Recurrent Unit (GRU) model is used to assist NM. Simulation experiments were conducted at different turbulence intensities. The results showed that the proposed method outperforms traditional fixed threshold decision (FTD), NM based fixed threshold OOK detection, improved GRU based fixed threshold OOK detection, and adaptive threshold decision (ATD). The atmospheric turbulence scintillation effect is effectively compensated.

Biomass burning aerosol has a significant effect on radiation properties of the stratosphere. Some known data about this aerosol type pertain to the cases of dense and altitudinally localized aerosol layers. Optical properties of its background component remain unknown. The processing of two-wavelength (355 and 532 nm) lidar measurements in Obninsk over 2012–2023 was performed to determine them. Lidar data interpretation is based on a two-component model of stratospheric aerosol proposed in this work. Along with the main component (sulfuric acid aerosol), biomass burning aerosol (brown carbon) is considered. As a result, the optical thickness of brown carbon aerosol in the 10–30 km layer is estimated at ∼0.012 and 0.0013 for attenuation at 355 and 532 nm and ∼7.1 × 10⁻³ and 3.5 × 10⁻⁴ for absorption at the same wavelengths. The results can be used in the development of advanced radiation models of the stratosphere.