Том 31, № 3 (2018)

The study of the ecological state of coastal areas often requires rapid acquisition of detailed data. In this work, sea radiance coefficient spectra are analyzed, which were measured with a new three-channel passive optical complex for ecological monitoring of marine aquatoria (EMMA), developed by us, which operates semiautomatically on board a moving ship. The measurements were carried out near the Brazilian coast at the Rio Grande river mouth. The spectra are processed using an original technique which is based on intrinsic properties of the pure sea water absorption spectrum (WASM – water absorption step method) and has been modified for eutrophic Case II waters. This enables us to estimate the absorption indices of the suspended matter and colored organic matter. The comparison of these remote estimates with the estimates made from water samples taken at special stations shows their high correlation. The distributions of the suspended matter and colored organic matter are retrieved from remote measurement data and compared to the satellite imagery for the water area under study.

Adsorption and desorption of atmospheric gases (N₂, O₂, Ar, CO₂, and H₂O) in silica aerogel is studied. Static parameters of adsorption and kinetic parameters of adsorption and desorption are determined based on the pressure vs time dependence P(t) in the buffer vacuum chamber of an experimental setup during adsorption and desorption of gases in a SiO₂ aerogel sample V = 42.8 cm³ in volume and ρ = 0.34 g/cm³ in density. The ratios of adsorbate molecular density to aerogel molecular density at room temperature T = 293 K and equilibrium pressure P_e ≈ 1 bar are found: γ(N₂) = (9 ± 3)% (nine N₂ molecules adsorbed by pore surface to 100 N₂ molecules in the gas at equilibrium), γ(O₂) = (7 ± 3)%, and γ(CO₂) = (222 ± 8)%; for water vapor, γ(H²O) = (5.9 ± 0.3) × 10⁴% at P_e = 5.7 mbar. It is ascertained that Ar atoms are not adsorbed by the aerogel. It is suggested to use argon as a “zero” gas in spectroscopy of molecules adsorbed by SiO₂ aerogel to determine the amount of adsorbate in a sample. A sum of two exponential functions of kinetic parameters τ₁ and τ₂ is used to fit the P(t) dependence, where τ₁ and τ₂ values are estimated during the adsorption and desorption of each gas under study.

Results of the simulation of multichannel radiation propagation under conditions of thermal blooming are presented. The correction of nonlinear thermal distortion by means of the beam phase and amplitudephase control is considered. The results show the dependence of the correction effectiveness on the number of channels and on the precision of the reference beam phase retrieval. An additional increase in the effectiveness is possible by means of adjustment of amplification in the channels of the optical system, i.e., with the use of amplitude-phase control over the beam wavefront.

Results of measurements of the soot and fine aerosol mass concentration in the center of Moscow and at two points of the Zvenigorod Scientific Site (ZSS) in the spring–autumn periods of 2014–2016 are presented. The results are compared with data of complex measurements made during 1989–2013. Events where the increase in atmospheric air pollution by smokes from burning peat bogs in Bryansk oblast and smoke from burning trees infested by bark beetles in forests in Moscow region, as well as by forest fire smoke coming from Siberia, have been identified. The considerable increase in vehicle density during past 25 years near the ZSS measurement point located 150 m from a highway led to an increase in the level of air contamination by aerosol components by two or three times. At the second point, 1 km from the highway, the soot contamination level is comparable with data obtained in the 1990s and is approximately a third as high as in Moscow.

The results of an experimental study of ultrafine aerosol characteristics in the Baikal region and the Gobi Desert are described. The comparative analysis of the dispersion composition of atmospheric aerosol in different climate conditions is carried out. It is ascertained that the total content of ultrafine aerosol in the atmosphere of the Gobi Desert is significantly lower than in the Baikal atmosphere and soil aerosols prevail. In the Lake Baikal region, nanometer-size aerosols are also present, mainly of anthropogenic and organic origin; two peaks are observable in the diurnal variations in the total number concentration of aerosols in the afternoon and evening. In the morning and afternoon, the number of nucleation-mode particles increases due to intensification of breeze circulation, which promotes transport of anthropogenic impurities from the lake and activation of photochemical reactions.

The results of lidar observations of the atmosphere during the Sichuan (China) earthquake of 2008 are presented. It is shown that atmospheric parameters substantially changed during and after the earthquake. The profile of scattering characteristics formed in the lower troposphere differs from the original, which can serve as a predictor for earthquakes.

Results of field experiments on horizontal paths using the BSA-2 and BSA-3 turbulent lidars, principles and design of which have been described in the first part, are presented. The BSA-2 lidar operated on 2-km path together with an independent image jitter sensor (IJS); and the BSA-3 lidar, on a horizontal 26-km path. The BSA-2 lidar was used in the experiments aimed at the study of the shape of the backscatter amplification peak, which was found to be 6.5 μrad in our experiments; the sounding was performed with apertures of different sizes. The experimental dependence of the q factor of the effect of turbulence on the size of receiving aperture is derived, which agrees satisfactorily with the Vorob’ev formula. The lidar sounding data and results of the data conversion into the structure parameter of the “optical” turbulence С_n² with the use of the Vorob’ev approximation for homogeneous turbulence are presented. The sounding range was ~10 km. The coefficient of correlation between lidar and IJS data is 0.7–0.8. The sounding in urban environment showed that a horizontal path is not statistically homogeneous; therefore, more complex procedures are to be used for the retrieval of the structure parameter С_n² when solving the inverse problems of lidar sounding of turbulence.

We considered Moscow-specific features of time variations in PM_2.5 mass concentration in the surface air layer as a function of a number of atmospheric parameters such as the concentrations of certain atmospheric trace gases, aerosol optical depth, surface air temperature, humidity, and wind speed. The time series of concentrations of PM_2.5 and gaseous pollutants SO₂, NH₃, NO_x, CO, and O₃, obtained during continuous observations in 2011–2013, were analyzed. We studied the diurnal and seasonal variations in concentrations of PM_2.5 and the trace gases, revealed correlations between them, analyzed variations in PM_2.5 concentration as a function of concentration of certain gases participating in the formation of atmospheric aerosols, and as a function of meteorological parameters. Data on PM_2.5 surface concentrations are compared with measurements of aerosol optical depth.

The analysis of Aura MLS data showed that the temperature in the Arctic stratosphere was much lower than normal throughout the period from January to March 2011 in the altitude range 20–35 km. That led to a considerable spread of polar stratospheric clouds (PSCs), which were formed most intensely in periods and at altitudes of minimal temperatures (maximal temperature drop below PSC formation threshold). The main ozone losses were observed in March. They were due to a photochemical release of chlorine that avoided deactivation in view of the nitrogen deficit caused by denitrification in the course of frequent dehydration events indicated by oscillations of the altitude of maximal humidity distortion. Elevated humidity in the stratosphere had raised the threshold temperature of formation of PSCs that persisted until late March; this promoted the chlorine activation and, thereby, delayed the chlorine deactivation, resulting in an even higher level of overall ozone losses during March 2011.

Results of numerical and experimental studies of the control of optical elements of a KrF laser cavity by use of the image processing method are presented. Different methods of beam image binarization for determining the boundary dimensions and flattening the distribution of its radiation intensity are considered. Conditions allowing one to accelerate the process of dispersive cavity adjustment in the automatic regime of laser operation and to restore the initial parameters of the output beam with an accuracy of up to 5% are determined.