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The chemical composition of dry deposition in the industrial center of Eastern Siberia, Irkutsk (Russia) in 2020 is analyzed. In the warm season, the content of PO₄³_¯ in the dry deposition was increased, especially in calm weather. In autumn, the average concentration of NH₄⁺ was three time higher as compared to August; Si²⁺, two time higher, and PO₄³_¯, three time lower.

The paper estimates the gross and net primary production based on long-term series of complex measurements of carbon dioxide concentrations in the near-water atmosphere and surface and bottom water, as well as fluxes in the “water - atmosphere” system for the most characteristic seasonal cycles of the life of the Baikal plankton. The calculations were carried out according to the scheme similar to the diel method. With regard to the conditions of the coastal zone, the analysis of methodological issues was carried out, neglect of which can lead to a significant uncertainty in these characteristics. It is shown that in this scheme, having only CO₂ concentration measurement data, it is not possible to correctly estimate the net primary production. For periods of open water, its calculation was carried out using the daily average CO₂ flux. The results of the assessment of bioproductivity, carried out in detail for individual series of measurements in different periods, quite adequately show the main features and are consistent with the data of long-term observations.

Here we discuss methodological aspects and approaches to solar radiation measurements at the Fonovaya Observatory of IAO SB RAS, as well as capabilities of the new radiation unit mounted there in 2020. It is equipped with a set of instruments which allow continuous monitoring of the total (0.285-2.8 mm), total UV (0.280-0.400 mm), and UV-B radiation (0.280-0.315 mm) and the energy balance between incoming short-wave and long-wave far infrared radiation. The capabilities of measurement data collecting, transmitting, and processing of the specially developed software are described.

The CO₂ content in tree wood and the radial increment of trees can change under the impact of ground fires. The larch discs under study survived the fire of 1908 after the explosion of the space body in the Podkamennaya Tunguska revealed a number of features in the behavior of absorbed CO₂ and (CO₂ + H₂O) in larch wood. The photoacoustic analysis of samples vacuum-desorbed from tree rings has shown a long-term annual accumulation of CO₂ and (CO₂ + H₂O) in tree stems after 1908. A change in CO₂ release cycling in the post-catastrophic period is ascertained. A change in variation cycling is also noted in the tree ring chronologies. According to the analysis of the correlation coefficients, the specific behavior of the larch ring width chronologies in this region is most likely due to variations in the solar activity.

Trace atmospheric gases (TAGs) emitted by the Earth's water surface significantly impact the chemical processes in the atmosphere, weather formation, and the global climate change. The main TAGs emitted from the ocean surface and wetlands are described and analyzed. The laser absorption spectroscopy technique for local/remote gas-analysis suitable for detection of several TAGs is considered, including cavity-ring down spectroscopy and optical-acoustic spectroscopy. Approaches to the development of laser absorption spectroscopy tools for the control of a large number of TAGs using an optical parametric oscillator as a tunable laser source are considered, as well as examples of their implementations.

The results of experimental studies of the spectra of fluctuations of the scattered radiation intensity of a laser beam propagating through the surface atmosphere in rains, drizzle, haze, and fog are presented. The laser beam radiation was focused at the end of a 130 m path. The intensity fluctuations were measured at a distance of 10 mm from the focal spot, in the region of radiation scattered on the particles in the atmosphere. The spectrum of scattered radiation fluctuations U ( ƒ ) = ƒW ( ƒ )/∫ W ( ƒ ) dƒ in rain, drizzle, and haze is characterized by four parameters: the maximum frequency ƒ _max, the inclination of the low-frequency part of the spectrum 1 > γ_v > 0 at ƒ < ƒ _max and two inclinations of the high-frequency region γ_v = -2.5…-5/3 and γ_v1 = -3…-5 at ƒ > ƒ _max; and in a weak fog, mainly by two negative inclinations γ_v = -0.5 and γ_v1 = -4…5. The frequency of the scattered field spectrum maximum is determined by the interaction of the vortex field of wind speed fluctuations, the field of particle size and mass distributions, and the drag coefficient.

Variations in solar radiation in the wavelength ranges λ = 0.285 ÷ 2.8 mm, λ = 0.280 ÷ 0.400 mm, and λ = 0.280 ÷ 0.315 mm are analyzed on the basis of ground-based measurements at the Fonovaya observatory in 2021. The results of calculations of the radiation balance and albedo of the underlying surface are presented. During the period of a stable snow cover, from November to March, the daily average radiation balance is shown to be -1.20 ± 1.18 MJ/m², and in the absence of snow, from May to September, +8.83 ± 4.49 MJ/m². The daily solar radiation absorption by the Earth's surface is estimated. During the period of a stable snow cover, from December to March, the daily solar radiation absorbed by the Earth's surface did not exceed 2 MJ/m², and it varied from to 25 MJ/m² in summer.

The electro-physical process in the discharge circuit of a copper vapor laser (CVL) with an LT-10Cu industrial gas-discharge tube has been studied. It is shown that the pumping of the active medium of the CVL is carried out in two stages. During the first (preparatory) stage, the capacitive components of the laser discharge circuit are charged from the storage capacitor, and during the second stage, the active medium is directly pumped. The transition from the preparatory stage to the pumping stage is carried out as a result of “breakdown”. It is shown that under these conditions it is possible to achieve a practical CVL efficiency of ~ 1% in pump circuits with magnetic compression units and ~ 2.5-3% when the energy input is cut off after the generation pulse. The conditions for implementing the mode of cutting off the energy input after the generation pulse are considered.

The results of high-sensitivity recording of the Wulf group absorption bands of the ozone molecule in the range 9350-10000 cm^-1, which corresponds to transitions from the ground to an excited triplet electronic state, are discussed. The spectrum in this range above the main molecular dissociation threshold was recorded for the first time with the use of a cw-CRDS spectrometer with sensitivity of 1 × 10^-10 cm^-1 in terms of the absorption coefficient. The measurement technique and the procedure of ozone generation and its concentration monitoring are described. A comparison with the previously calculated theoretical spectra of the ³A₂(000) ← X¹A₁(000), ³A₂(010) ← X¹A₁(000) and ³A₂(010) ← X¹A₁(010) singlet-triplet bands is carried out.

Based on known expressions applied to diffraction-limited optical systems, estimates are given and a method is proposed for determining the measurement error of the longitudinal coordinates of particles from images reconstructed from digital holograms. A correction factor for visual focusing is determined for different distances between a detected particle and the plane of a CMOS matrix. The experimental results of testing the method are presented. It is shown that the error of automatic digital focusing can be reduced by simultaneously applying focusing curves for several quality indicators and optimizing the image area for their construction.