Vol 32, No 3 (2019)

The frequency dependences of the spectral contributions of the initial, central, and “finite” sections of a power-law structure function (with the exponent less than unity) into the spectral density (SD) of a random process with stationary increments are considered. They are shown to be much more complicated than the strictly positive monotonic power-law frequency dependences of the initial SD. The latter agrees only with the behavior of the spectral contribution of the initial section of the structure function under study. The analytical approximation dependences of the frequency dependences of all these spectral contributions are derived and analyzed. They are recommended for wide practical use.

Regular measurements of the integral formaldehyde content (IFC) in the lower troposphere have been carried out in the impact area of the Moscow urban agglomeration (Zvenigorod Scientific Station, ZSS) and in the southeastern part of Tomsk (Siberian Lidar Station, SLS) since 2009. The paper briefly describes the instrumentation and measurement techniques used and presents the first results of the measurements. The average level of the formaldehyde content at ZSS is shown to exceed that in Tomsk. The most probable cause of increased formaldehyde content during the easterly winds at ZSS is due to the arrival of polluted Moscow air. The observations in Tomsk suggest that the possible influence of polluted urban air on the formaldehyde content begins to show up at temperatures above 25°С. The positive IFC dependence on the air temperature was revealed at both stations.

Line halfwidths and shifts are calculated for water vapor and carbon monoxide confined in nanoporous media. Physically adsorbed H₂O and CO molecules are considered as scattering centers. The influence of changes in the rotational structure of levels in physically adsorbed molecules is numerically analyzed. The comparison with the existing experimental data is performed.

Concentrations of total suspended matter and its coarse and fine fractions in surface waters were determined based on the measurements of the light scattering phase function in the Atlantic tropical area. At the same time, the Secchi disk depth (Z_d) was measured. The correlations between the total concentration of the suspended matter C_TSM, including its coarse and fine fractions, and the Secchi disk depth are studied. It is ascertained that the main factor determining the Secchi disk depth in the Atlantic tropical area is the fine fraction of the suspended matter; its effect is theoretically analyzed.

We present model estimates of diurnally averaged direct radiative effects of smoke aerosol in the solar spectral range obtained using observations at the Tiksi station in the period of anomalously high black carbon (ВС) concentration in the near-surface atmospheric layer (July 2014). These data are compared with the radiative effect of aerosol tipical for summer conditions in this region. It is shown that the monthly average radiative effects, caused, on the one hand, by variations in the optical characteristics of background aerosol and, on the other hand, by short-term BC outflows from forest fires to the region of observations, are comparable in value.

We revise the results of lidar measurements of stratospheric aerosol over Tomsk that were made from June 29 to July 14, 1991, and initially interpreted as aerosol layers after the Pinatubo eruption. Using the NOAA HYSPLIT trajectory model, we show that the aerosol layers detected at altitudes of 12 and 14.2 km on June 29 and July 11, respectively, were the stratospheric smoke plume from massive forest fires occurring in Quebec, Canada, in June 1991. Biomass burning products reached the stratosphere via convective ascent within a pyrocumulonimbus (pyroCb) cloud that was detected at 100 km to the west of Baie-Comeau (Quebec, Canada) on June 19. The aerosol layers observed at altitudes between 11 and 16.5 km on July 8, 9, and 14 represented superpositions of the smoke plume from the Quebec pyroCb and first traces of the Pinatubo eruption.

Conditions for the occurrence and the possibility of a short-term prediction of strong squalls, as well as several tornadoes (mainly, weak), which caused major damage in the European part of Russia May 30, 2018, are considered. The information on the squalls is gathered from the data from the network of weather stations. In addition, data about cases of tornadoes are refined, in particular, based on the analysis of windthrows caused by them in forested regions. Synoptic and aerologic prerequisites for the appearance of squalls are considered. Squalls are modeled using the WRF model (version 3.9.1.1, the grid step is 3 km). Predicted data of the GFS and ECMWF global atmospheric models (from the ERA-5 archive) have been obtained as initial conditions. It has been established that squalls are comparatively successfully reproduced by the model.

Experimental and calculated data on the shape of the peak of backscatter enhancement during beam propagation through a turbulent atmosphere are compared. Two schemes of a two-channel turbulent lidar are considered; the ratio of lidar echoes and the factor of turbulence effect on the average scattered light power on the receiver are calculated versus the geometric characteristics of the transceiver. The advisable diameter of the lidar transceiver apertures is 50–70 mm. To create an efficient eye-safe lidar, it is suggested to use a laser operating at a wavelength of 355 nm. The echo and the turbulence effect are estimated for day and twilight values of the background light. A possibility of an UV turbulent lidar to remotely detect turbulent zones in the troposphere is analyzed.

The lasing characteristics of an atomic europium vapor laser with He and Ne as a buffer gas at the y⁸P_9/2 → \({{8}^{7}}D_{{11/2}}^{0}\) transition at a wavelength of 1.76 µm are compared. It is shown that the output power and pulsed energy of the He + Eu laser, which depend on the pumping power and pulse repetition frequency, are slightly worse than those of the Ne + Eu laser. An empirical model is proposed to explain the behavior of the He + Eu laser output power as a function of the input power. It is ascertained that the He + Eu laser lifetime does not exceed two hours, while the Ne + Eu laser has been operated for about 200 hours by the end of the experiment. It is suggested that the same process, where He participates, is responsible for the relaxation of metastable levels of the Eu ion and atom and the degradation of active media, which consist of a mixture of Eu and He vapors.