Home – Home – Jornals – Atmospheric and Oceanic Optics 2017 number 9

The formation and propagation of postfilamentation channels along a controllable path 150 m long are studied experimentally for collimated beams of different diameters. During multiple filamentation, a laser beam is compressed in global focus, after the passage of which its angular divergence is much greater than the divergence of postfilamentation channels generated during the filamentation. It is shown that postfilamentation channels have the intensity sufficient for the formation of multiple filamentation in optical elements after the end of the filamentation region at distances much longer than the filamentation length.

The vertical distribution of the organic component of aerosol in the boundary air layer and free atmosphere was studied on the basis of sampling from a board of Tu-134 “Optic” airborne-laboratory. The altitude range was divided into two layers: 0.5-2.0 and 3.0-7.0 km. It is shown that the aerosol organic component concentration exponentially decreases with altitude. The drop of the concentration makes 7.5 times from the surface air layer to the free troposphere. The maximal concentration in the surface air layer is observed for n-C₁₉H₄₀; in the boundary layer and free atmosphere, for n-C₁₇H₃₄. In the free troposphere, compounds heavier than n-C₂₂H₄₆ are fixed only at the trace concentration level. Redistribution of the organic component of aerosol between the surface and boundary air layers occurs during the year.

The contribution of wildfires into the content of the organic component of aerosol is studied on the basis of data of two flight campaigns carried out along the route Novosibirsk - Yakutsk - Novosibirsk in 2012 and 2013. The campaign of 2012 took place under conditions of extensive wildfires in Siberia, the campaign of 2013, on the contrary, in background conditions. The analysis of the selected aerosol samples shows that concentration of organic compounds during fires increases on the average by 35 times in the surface air layer and from 3 to 23 times in the free atmosphere in comparison with the background conditions. The composition of the organic component in the free atmosphere during fires changes depending on the region. At the Tomsk - Mirnyi segment, alkanes n-C₁₉H₄₀ - n-C₂₁H₄₄ prevailed in the aerosol samples; from Mirnyi to Yakutsk, the main concentration peak fell in the range of high-molecular compounds n-C₁₉H₄₀ - n-C₂₅H₅₂; at the Bratsk - Novosibirsk segment, low-molecular alkanes n-C₁₂H₂₆ -_{n-C18H38 prevailed in the aerosol composition.}

According to the long-term (1963-2000) observational data on depth of the Secchi Disk visibility, the main peculiarities of the annual cycle of transparency distribution in the surface water layer of the north-western Black Sea are considered. The statistical estimates of the seasonal variations in the areas differing in the degree of influence of river and open-sea water flow on their hydrophysical parameters are derived. Intra-annual transparency variations in these areas are in a good agreement with the intra-annual variations in phytoplankton biomass and water salinity. It is shown that long-term (1950-2013) intra-annual seasonal transparency variations (according to the data measured and reconstructed by means of a neural network model) show a satisfactory agreement with the intra-annual variations in the hydrobiological parameters. The dependences of the variations in these parameters on the regional meteorological conditions within El Niño - Southern Oscillation period and within the period of its absence are studied.

We describe a new algorithm for retrieving the atmospheric fine particulate matter total column (particles less than 1.0 and 2.5 μm) from multi-spectral satellite images in visible and IR regions of the electromagnetic spectrum. The algorithm is based on the regression relations between the top of atmosphere (TOA) reflectance, microphysical parameters of aerosol, and geometrical parameters of satellite scene. The regression equations are derived from the TOA reflectance calculations in the spectral channels of the satellite instrument for the ensemble of random generated parameters of the atmospheric radiative transfer model and the geometrical parameters of the satellite scene. Subsequently, this allows real-time mapping the fine particulate matter pollutions directly from the satellite images without solving ill-posed inverse problems of the solar radiation transfer in the atmosphere and aerosol light scattering. The proposed algorithm is implemented and tested for MERIS (Medium Resolution Imaging Spectrometer) satellite instrument. The comparison of the MERIS-retrieved total fine particulate matter content in the atmosphere with AERONET (Aerosol Robotic Network) data shows the standard deviation ~ 0.5 μg/cm². The application of the developed algorithm to real-time monitoring of the regional and transboundary transport of the atmospheric particulate matter pollutants during the wildfires is demonstrated.

A model of the solar radiation transfer in the Earth's atmosphere is developed for explicit calculations of the transfer characteristics of the atmosphere (reflectance, transmission, and spherical albedo) in its visible and near-IR transparency windows depending on the surface air pressure (or terrain elevation), the aerosol optical parameters, and angles indicating the position of the Sun and the satellite system with respect to the Earth's target. The model is based on the spectrally dependent approximations obtained using the atmospheric radiative transfer code DISORT. The sensitivity of underlying surface spectral albedo retrieval from top-of-atmosphere reflectance to vertical distribution of atmosphere optical parameters is investigated. The algorithm is designed for the atmospheric correction of multispectral satellite images with the developed model and applied to MERIS instrument (Medium Resolution Imaging Spectrometer). It is shown that accounting of optical properties of the atmosphere and adjacency effects in the processing of satellite images substantially improves visibility of underlining surface targets and rendering their spectral reflectance parameters

The possibilities and limitations of determining the skewness and kurtosis of sea surface slopes by spaceborne optical scanners are analysed. It is shown that these data do not allow precise retrieval of the values of skewness and kurtosis. The empirical probability density of slopes, determined according to the optical scanner data, is defined in a limited range of slopes. The Cox-Munk model used in the calculations is also defined in a limited area.

The feasibility of Levenberg-Marquardt method, modified for the case of inaccessibility of a priori covariance matrices for methane vertical profiles, for atmospheric methane total column amount retrieval from the spectra measured by IASI/METOP is studied. The method and algorithm were implemented into software package together with iterative evaluation of a posteriori covariance matrices and averaging kernels for each individual case of retrieval. This allows selection of the results on the basis of properties of both matrices. The comparison between our results and IASI standard methane products retrieved from the same spectra shows their satisfactory agreement.

The action of enhanced UV radiation at the 308 nm wavelength on the photosynthetic apparatus of Siberian spruce seedlings (Picea obovata Ledeb.) from June to August has been studied in two-year experiment. The negative effect on the photosynthetic apparatus of spruce needles is ascertained, with a pronounced cumulative effect. The suppression of the photosynthesis rate and transpiration intensity in the radiation-exposed two-year spruce needles and current-year spruce needles, primordia formed in July-September of the previous vegetation period, is shown to be deeper during the second vegetation period as compared to the first one. We revealed that the water balance of spruce needles corresponded to seasonal norms in the both groups during the experiment. The decrease of the transpiration intensity in the spruce seedlings exposed to radiation as compared to the control group is conditioned by a need in maintaining the water homeostasis in the needles. The experimental group of spruce seedlings showed a weaker correlation between the photosynthesis rate and transpiration intensity than the control group, which is clearly pronounced in the two-year needles exposed to the radiation.

We have measured the sedimentation rates of the pollen particles of several species of anemogamous plants (including those introduced by a man) growing in Western Siberia (pine trees: ordinary, Siberian, mountain, Crimean; inoculum hemp, rib grass). It is shown that upon spraying, the anemophilous pollen particles are represented by both single pollen grains and agglomerates of two or more grains. The portion of agglomerates in the total number of particles deposited is estimated. The sedimentation rates of the pollen particles are determined. The sedimentation rates of the pollen agglomerates of one or more grains are measured. The dependence of the sedimentation rate on the number of grains in an agglomerate is established.