Atmospheric and Oceanic Optics最新文献

This work studies the effect of the daily dynamics of turbulent processes on the daily dynamics of the electric field in the surface air layer. During simulation, the coefficient of turbulent diffusion within the electrode layer is specified as a stationary function of altitude in view of hydrodynamic concepts. A mathematical model of the dynamics of the electric field intensity in the surface air layer in the case of a turbulent electrode effect is presented. The main equation of the model is the equation of the total current in the surface layer, which has been derived in the approximation of strong turbulent mixing and describes the electrodynamics of the surface layer under the combined action of local and global current generators. The work examines the non-stationary nature of turbulent exchange in order to confirm the previously ascertained effects in the daily dynamics of the electric field strength in the surface air layer under stationary turbulence. To describe the daily dynamics of turbulent processes, gradient measurements in high-altitude conditions of the Elbrus region were used. Processing of the measurement data enables deriving the time dependence of the turbulent diffusion coefficient from the solution of the total current equation. Taking into account this dependence, the expression for the daily dynamics of the field strength was refined. Time shifts of the daily extremes, a change in their amplitude, and the appearance of additional extremes depending on the electric field strength have been established. All these effects are comparable to the global unitary variation and increase with the electric field strength. The results can be useful for solving a number of applied geophysical problems, in particular, monitoring the electric field of the atmosphere and analyzing atmospheric-electrical measurement data.

Atmospheric temperature anomalies associated with sudden stratospheric warming events (SSWs) observed over the territory of Siberia require detailed study. In Siberia, there are few instruments that can provide the necessary information on the vertical distribution of atmospheric temperature. Unique lidar of the Siberian Lidar Station (SLS) of V.E. Zuev Institute of Atmospheric Optics SB RAS, Tomsk, Russia (56.48° N, 85.05° E), developed for regular lidar measurements of atmospheric parameters, is one of few ground-based devices in Siberia which provide necessary data on the vertical stratification of atmospheric temperature during the SSW effect. To determine the characteristics of atmospheric temperature anomalies during the SSW period in winter 2023 over Tomsk, data on atmospheric temperature in individual nights obtained by the SLS lidar, the WACCM model, the standard mid-latitude winter model, and the ERA5 reanalysis were compared. For the first time, the possibility of using vertical atmospheric temperature profiles obtained by the Raman scattering method to study the SSW effect is show. Use of lidar air temperature profiles to analyze changes in the vertical structure of the atmosphere during SSWs is demonstrated.

The paper considers the methodological features of determining the optical extinction and backscattering coefficients by simultaneous lidar measurements at the following wavelengths: 532 nm (elastic scattering, ES), 607 nm (vibrational-rotational Raman scattering, RS), and 530 nm (purely rotational RS). The ES signal identifies the range of allowable values (RAV) of the coefficients based on the a priori introduction of a physically substantiated lidar ratio. The RS signal at λ = 607 nm, corresponding to a single line of the N₂ spectrum, provides a plausible estimate of the ratios in the boundary layer and part of the middle troposphere. The RS signal at vλ = 530 nm—a set of N₂ and O₂ spectrum lines—is characterized by smaller errors and provides a quantitative estimate of the coefficients in all main tropospheric layers. At a wavelength of 530 nm, the differential backscattering cross section depends on height due to temperature changes, which leads to a redistribution of N₂ and O₂ line intensities. Estimation of parameters from the RS signals is considered plausible when the sought-after coefficients are quantitatively comparable and located within their RAVs. Testing of the algorithms is carried out using ground-based sensing data on the shore of Lake Baikal in August 2023.

The periodicity of synoptic-scale variations in aerosol characteristics in the atmosphere of Eurasian sector of the Arctic Ocean is analyzed on the basic of long-term measurements. Statistically significant maxima of amplitude functions in the range from 3.5 to 18 days were manifested in periodograms of the concentrations of submicron aerosol and black carbon (V_f and еВС). Cases of anomalously high еВС and V_f (5% of data), associated with long-range transports of continental pollutants, were considered in more detail. It is shown that the average duration of “anomalies” in еВС and V_f is few days, and the maximal duration attains 112 hours. The time intervals between “anomalies” are, on the average, 6–16 days, and the maximal intervals are from 28 to 69 days. Despite the short duration and rare occurrence of anomalous situations, they increase the average concentrations of aerosol and black carbon by 28–77%. Calculations showed that the major (79%) contributors to air pollution over the Kara and Barents Seas are made by the outflows of anthropogenic pollutants; and in the eastern sector of the Arctic Ocean, the contribution of smokes from wildfires is maximal. The effect of the products of associated gas combustion at gas-oil plants was manifested most strongly (up to 51%) in the atmosphere of Cape Baranov.

In recent years, laser sources created in airborne laser plasma by powerful femtosecond radiation pulses have been rapidly developing. This work studies coherent radiation generation on ({text{N}}_{2}^{ + }) ions in laser plasma using two-color pumping at λ = 950 and 475 nm. It is shown that the addition of second harmonic radiation, wavelength of which is closer to the lasing lines on ({text{N}}_{2}^{ + }) ions compared to the first harmonic, increases the intensity and stability of supercontinuum radiation which acts as seed radiation for the lasing. Such pumping allows lasing on new lines and controlling the intensity and spectral composition of the generated radiation. The results can be useful for establishing the way(s) of creating population inversion in laser plasma on molecular nitrogen ions.

The results of GEOS-Chem chemical-transport model (CTM) simulation of methane (CH₄), carbon monoxide (CO), and nitrogen dioxide (NO₂) total column (TC) trends over Eurasia for different periods and seasons during 2003–2019 are presented. Calculations were conducted for different scenarios of anthropogenic and wildfires emissions. The model trend distributions for all of three gases are compared with estimates obtained from satellite AIRS and OMI data. The TC trends for CO, CH₄, and NO₂ are quite well reproduced by the model, both in terms of the overall domain and the specificity of the regional trends, but the trend values are generally overestimated compared to the AIRS v6 satellite data, especially for CO in polluted regions (China and Southeast Asia). A possible reason for such discrepancies could be the uncertainties in the anthropogenic and wildfire inventories used. The response of CO TC trends to global changes has been estimated. One of the possible reasons for the positive dynamics of the CO trend after 2008 could be a global increase in methane concentrations, which started around 2007, and additional CO production from methane oxidation.

Plasma diffuse jets (PDJs) generating in low-pressure air are experimentally studied. We consider them as a laboratory model of column red sprites. It has been established that red-colored radiation of a positive column of a glow discharge is superimposed on streamer radiation in a PDJ with an increase in the discharge current duration. The positive column in some cases can consist of periodic bright regions. Based on the experimental results, an explanation is suggested for the following phenomena observed in red columnar sprites: (1) the emergence of a region with a brighter luminescence (“glow”) in the upper part of the column sprites; (2) the appearance of bright dots (“beads”) after the passage of the front of the first streamers forming the column sprites.

The remote sensing of inland waters has begun to rapidly develop with the recent setting into operation of high- and medium-resolution satellite constellation Sentinel, as well as the introduction of machine learning to data processing and analysis. However, the collection of large arrays of in situ data remains a weakness due to the significant diversity of inland waters, seasonal features, and the strong influence of meteorological conditions and hydrology. As a possible solution, this paper considers the collection and investigation of bio-optical characteristics of the upper water layer with the use of UFL-9 fluorescent shipborne LiDAR with meter resolution in a 1000 km section of the middle Volga from Nizhny Novgorod to Bolgar (close to Ul’yanovsk) as an example. Continuous measurements were performed on September 9–17, 2023, from a moving boat. Based on the obtained LiDAR data, chlorophyll “a”, suspended matter, and the absorption coefficient at 440 nm as an indicator of colored dissolved organic matter were mapped and described. The ranges of their variability and effects of inflows and meteorological conditions are analyzed. The results expand previous knowledge on the bio-optical characteristics of middle Volga and its variability on different spatial and temporal scales and contribute to the solution of the problem of developing bio-optical models for the Cheboksary and Kuibyshev reservoirs.

The fluxes of lead, cadmium, and elemental carbon from the atmosphere to the coastal zone of the southeastern part of the Baltic Sea were assessed. The highest values of lead (11 341 μg m⁻² month⁻¹) and cadmium (682 μg m⁻² month⁻¹) fluxes were revealed in the summer season, while those of elemental carbon (0.69 mg m⁻² day⁻¹) were noted in spring. According to field measurements over a 15-year observation period (2008–2022), the annual average fluxes into the coastal zone of the southeastern part of the Baltic Sea were 4.1 kg km^–2 year⁻¹ for lead and 0.02 kg km⁻² year⁻¹ for cadmium. The calculated annual average fluxes amounted to 3.8 kg km⁻² year⁻¹ for lead and 0.03 kg km⁻² year⁻¹ for cadmium over the region under study. Cadmium emission was inconsiderable in the region. The annual average lead flux, according to field data, was 9% higher than its emission values calculated with the EMEP database. The lead fluxes obtained from both field data and calculations significantly exceed its background level of 1.86 kg km⁻² year⁻¹. In rainfall over the spring-summer periods of 2019–2022, the average concentration of elemental carbon was more than two time lower than the content of organic carbon. The flux of elemental carbon was characterized by seasonal and interannual variability. The increase in the content of elemental carbon in atmospheric precipitation over the spring season was due to anthropogenic load from local sources, namely, spring grass burning in the region. The ecosystems of the coastal zone of the southeastern part of the Baltic Sea experience the greatest anthropogenic load through the atmosphere over spring and summer with an increase in the flux of elemental carbon, lead, and cadmium.

Results of processing experimental data obtained during expeditions in 2011 and 2023 on the Large Solar Vacuum Telescope (LSVT) are analyzed. An adaptive multi-circuit system for stabilizing the light flux and correcting distortions of images of the solar photosphere under conditions of moderate and strong atmospheric turbulence was tested. To eliminate jitter caused by vibrations of the telescope’s siderostat and the influence of the atmosphere, a wavefront tilt corrector was used in the first circuit of the system. Spectral analysis of the measurements showed that at high wind speeds, the light beam is deflected mainly under the action of the vibration of the telescope’s siderostat with a frequency of about 8 Hz and maximum amplitude of up to 10 arcseconds. In calm weather, the spectra of random jitter have a power-law dependence on frequency, characteristic of the atmosphere. To eliminate blur and improve image quality, specially created software was used for computer processing of digital video frames in real-time observation.