Home – Home – Jornals – Atmospheric and Oceanic Optics 2016 number 12

We discuss the results of complex aerosol experiment, performed during 2014 in two Middle Ural regions: Yekaterinburg and Kourovka astronomical observatory (background region). The measurements of aerosol characteristics were conducted using sun photometers, photoelectric particle counters, aethalometers, and devices collecting aerosol samples on filters. We analyze the differences in the optical characteristics of aerosol between the two regions and specific features of its diurnal behavior, as well as interrelation between aerosol parameters in atmospheric column and near-ground layer. Estimates of how aerosol characteristics depend on meteorological conditions, including airmass back trajectories, are presented. We note that higher atmospheric turbidities are observed in Yekaterinburg than in background region, but the statistical significance of AOD differences (from 0.01 to 0.04) depends on the length of periods analyzed.

We carry out a comparative analysis of optical, microphysical, and chemical characteristics of aerosol, measured simultaneously in two Middle Ural regions: Yekaterinburg and Kaurovka astronomical observatory (background region). For most aerosol characteristics, the average values in urban zone are found to significantly exceed those in the background region; in particular, black carbon content is higher by a factor of 3.4, number concentration of large particles ( r > 0.5 mm) is higher by a factor of 1.57, and aerosol mass concentration is higher by a factor of 1.36. An exception is ion composition of aerosol: concentrations of some ions are higher in Yekaterinburg, while concentrations of most other ions are higher in the background region. Among the main results, there is an identified “city-background” difference in the diurnal behavior of aerosol microphysical characteristics. A characteristic urban feature is minimal concentration of large particles and black carbon at midnight (04:00 LT), which can be explained by reduced effect of traffic and other technogenic sources.

We present the results of our experimental and numerical studies of the multifilamentation of high-intensive pulse titanium-sapphire laser radiation (740 nm) in air. The postfilamentation stage of pulse propagation as specific spatially localized light structures is investigated. The angular divergence of postfilamentation channels is studied under different initial laser beam focusing. The threshold distance for the re-filamentation of postfilamentation channels in a glass plate is measured.

The results of experiments on the study of the spatial characteristics of the multiple filamentation domain of Ti:Sapphire laser gigawatt pulses in glass are presented. The dependences of the coordinates of the beginning, the end, the diameter of the multiple filamentation domain (MFD) vs the laser pulse energy is obtained. It was found that when the average intensity in the beam reaches specific values, MFD is formed near the illuminated side of the glass sample. It is shown that when the threshold intensity of the beam is reached, secondary multiple filamentation domain is formed. The spatial characteristics of MFD depend on the time of influence of pulse-periodoc laser radiation. The diameter of the secondary multiple MFD and coordinates of its start depend on the exposure time. No dependence of the spatial characteristics of the primary MFD on the exposure time was revealed during the experiments.

Lidar polarization measurements of stratospheric (10-40 km) aerosol parameters were fulfilled over Obninsk in 2012-2015. Over 300 altitude profiles of the aerosol backscattering coefficient at 532 nm wavelength were obtained. Parameters of aerosol backscattering measured are generally close to known background values. An increased content of spherical aerosol near tropopause was revealed in spring 2013; it was probably caused by sedimentation of Chelyabinsk meteorite aerosol. Layers of increased aerosol backscattering were observed at 10-15 km levels in July 2014 and July 2015, appeared as a result of transcontinental aerosol transfer from Canadian forest fires. Estimates of integral parameters of backscattering and extinction were made for the lower (from tropopause level to 15 km) and middle (from 15 to 30 km) aerosol layers. It is shown that the contributions of the lower layer in the above optical parameters are 1.8 and 1.6 times higher than those of the middle layer.

Correlation between the vertical distribution of tropospheric aerosol and the direction of air mass transfer at different heights is studied on the basis of regular lidar observations in Tomsk (56°N, 85°E). Joint interpretation of the data of 110 sessions of lidar measurements and simulation of 10-day back trajectories of air mass (AM) movement has shown that in 72% of observation the advection direction changes in height no more than once, and it occurs at the boundary of the main scattering layers - the boundary layer and the free troposphere. The direction changes more than once at movement of AM into the free troposphere in spring and summer (11% of observations). It seems impossible to determine the prevalent direction of transfer in the remaining 17% of observations. The change of all lidar characteristics when passing from one layer to another is observed in practically all nighttime sessions of measurements.

This work presents the results of the study of microphysical characteristics of cirrus clouds by multiwavelength polarization lidar located in China (Hefei). Measurements were carried out from December 2010 to February 2013. In this paper, we consider only dependable characteristics of lidar signal, which is the linear depolarization ratio measured at a wavelength of 532 nm. In addition, the dependences of depolarization ratios on both the size parameter and the distribution of the distortion angle of ice crystals were calculated in this work for the first time. These results were used for retrieving, with some uncertainties, the microphysical parameters of cirrus clouds observed in Hefei within that time period.

The article presents the numerical calculations of the scanning lidar signals for the case of monodisperse cloud of hexagonal ice plates and columns of 100 microns. The calculation was performed within the approximation of single scattering. The calculation results shows that the scanning lidar is an effective tool to restore the effective slope angle (flutter) of the particles in a cloud. It is shown that as compared to traditionally measured lidar characteristics: backscatter coefficient, linear depolarization and lidar ratios, the element m₄₄ of the scattering matrix is more informative and requires scanning to a smaller angle, less than 45°.

The “instantaneous” phase of narrow-band acoustic signals propagating along short near-surface paths under the effect of the wind field has been analyzed. The phase was divided into the deterministic, quasi-deterministic (“local”), and random (“turbulent”) components. Histograms of the turbulent phase component and the results of approximation of these histograms by the normal probability distribution law have been considered. An empirical equation, which relates the dispersion of phase at different frequencies with the dispersion of wind velocity at the sound propagation path, has been derived and compared with theoretical equations.

The paper presents the study of atomic oxygen [OI] 557.7 nm atmospheric emission (airglow heights of 85-115 km) during earthquakes (EQ) with a magnitude of M ³ 5 in the Baikal rift zone during 2014-2016. The analysis of variations in OI 557.7 nm atmospheric emission during the recorded EQs is carried out; it revealed higher values of average nocturnal intensities of this emission within several days before an EQ in comparison with subsequent days. The amplitude of the variations in average nocturnal values of 557.7 nm emission from maximum before an EQ to minimum in subsequent days is 40-60% on the average and can reach ³ 100-200% for some events. The analysis of possible mechanisms of the variations in 557.7 nm emission during EQs can be associated with the sources directly contributing to EQ preparation and with the dynamics of the lower atmosphere independently affecting seismic activity and the upper atmosphere. The latter leads to a correlation between these processes not connected by cause F-effect relations.

The results of the annual series of complex measurements of carbon dioxide, oxygen and nutrients in the water under ice of the littoral of the southern area of Lake Baikal, which were carried out since 2004 till 2016, are analyzed in the paper. An important conclusion is the fact that the photosynthetic activity of the plankton at the end of the period of ice cover leads to a significant decrease in the partial pressure of carbon dioxide in the water(to 240-350 matm), which is noticeably less than the partial pressure of CO₂ in the atmosphere (about 385 matm), and consequently, the carbon dioxide flux during the period of removing ice from the littoral area of southern Baikal can be directed only from the atmosphere to the water surface.

The results of the study of aircraft icing occurrence are presented, depending on the season and altitude, for Tomsk International Airport in the period from 2011 to 2015. It is shown that in the vicinity of the Tomsk International Airport in autumn the maximum icing occurrence is 43% of all cases. In winter and spring, the icing occurrence has an equal probability of 26%, and in summer, an aircraft can be exposed to icing only in 5% of all cases. It was found that, on average over the period, 89.6% of the icing events were recorded at altitudes from the ground level to 2999 m, and above 6000 m icing has not been reported. In winter, the maximum number of icing events was recorded at altitudes from 0 to 999 m. In autumn and spring, the maximum number of icing events was accounted in the layer from 1000 to 1999 m. In summer, the maximum of icing occurrence is in the altitude layer from 1000 to 1999 m, but it is not pronounced. Altitude dependencies of icing occurrence for the Tomsk airport is different from the results previously published for the continental United States and European territory of the USSR.

Тemporal variations of ozone concentrations in the troposphere of St. Petersburg (Russia), little urbanized area in the South of Kirov region (the town of Vyatskiye Polyany) and the Karadag nature reserve in Crimea are presented. A comparative analysis of the dynamics of surface ozone concentrations in these areas was conducted and the basic features of seasonal and diurnal variations was demonstrated. Latitudinal dependence of the concentrations of ground-level ozone are presented.

Monthly and annual average values of direct, diffuse, and total radiation and potential solar resources in the south-east of the Altay Republic were considered. The research for different forms of relief was conducted: Chuiskaya basin (Kosh-Agach) and Severo-Chuiskyi ridge (Aktru valley). Total radiation is considerable, especially in Chuiskaya basin (5398 MJ/m² per year). The sunshine duration and total solar radiation are essentially decreased under the influence of a cloudiness. There is a decreasing trend in monthly and annual values of the total radiation in this region from 1965 to 2013. Cadasters of potential solar resources contained 12 basic indices for Kosh-Agach and Aktru stations. The highest monthly average values were registered when a sun-tracking system was used. The work of the solar systems in clear sky in Chuiskaya basin is effective all the year round, but in Aktru valley only during six months. The territory is perspective for using solar installations of different capacities.