Fine structure of the S-component spectrum of the solar radio emission in the frequency range 5.0–7.0 GHz

Fine structure observations of the frequency spectrum of the S-component in the solar radio emission are described. Measurements were carried out in August 1976 and August 1977 using a 22 m parabolic antenna and a radiospectrograph operating over the frequency range 5.0 to 7.0 GHz, with the resolution 60 MHz. Measurement techniques are described. Fine structures (150–800 MHz) as great as 20% of the local source radiation level were observed in radio emission spectra of a number of these sources. The spectrum structures observed were changed in the process of active region development.     

Concentration of Stratospheric Ozone Derived from Lidar,Satellite, and Surface Observations

Data of stratospheric ozone measurements with the AK-3 lidar over Obninsk in 2012–2015 are compared with Aura/MLS and Aura/OMI satellite data and parallel surface observations of total ozone (TO) with the Brewer spectrophotometer. The maximum difference in mean ozone concentration between the lidar and Aura/MLS data in the altitude range of 13 to 32 km does not exceed 0.2 x 10¹² mol./cm³ (or the maximum of 9% at the altitude of 13 km). At the same time, Aura/OMI data have a positive bias of about 20% relative to lidar data in the range of 13 to 20 km that is associated with OMI measurement errors according to literature data. Total ozone values calculated from lidar measurements jointly with the known climatology data are compared with those measured with the Brewer spectrophotometer. It is demonstrated that the correlation between the results of measurements obtained by two methods is close to linear, and the mean relative difference in the overall measurement range does not exceed 5%.     

Determination of stratospheric aerosol parameters from two-wavelength lidar sensing data

We calculate the microphysical characteristics of stratospheric aerosol from lidar-sensing data at wavelengths of 355 and 532 nm using a priori information about the aerosol spectra obtained from balloon and aircraft measurement data. We analyze the mode structure of the spectra and its coupling with the integral microphysical characteristics of aerosol. For most implementations, it was shown that two aerosol modes (of background and volcanic natures) make commensurate contributions to integral aerosol characteristics, which makes it difficult to use the traditional method of model estimates. It is more efficient to use an optical model of a statistical character that is based on approximation dependences between the required integral aerosol characteristics and lidar-measured optical characteristics. We found that the area, volume, and effective size of particles and the lidar ratio at a wavelength of 355 nm correlated with the absolute values of backscattering coefficients at wavelengths of 355 or 532 nm and the lidar ratio at the wavelength of 532 nm correlated with the ratio of backscattering coefficients at these wavelengths. We estimate the error in the determination of integral characteristics of aerosol using the model developed. The model efficiency is demonstrated on real data of stratospheric aerosol lidar sensing.     

The Catoca kimberlite pipe, Republic of Angola: A paleovolcanological model

The Catoca kimberlite pipe is among the world’s largest primary diamond deposits. The Catoca volcanic edifice is only slightly eroded. Kimberlitic rocks of various facies compose a crater of about 1 km in diameter and a diatreme. The structure of the pipe and mining conditions of the deposit are complicated by intense intrapipe tectonic processes related to large-amplitude subsidence. Based on geological data, we propose a structural model of the deposit and a paleovolcanological model of the Catoca pipe formed during a full cycle beginning with a stage of active volcanism and completed by stages of gradually waning volcanic activity and sedimentation. It is suggested that the banded tuffisitic kimberlite of the crater zone was deposited at the stage of active volcanic eruption from specific pyroclastic suspension as a low-viscosity mixture of crystals and aqueous sol rich in serpentine.     

Mineral Composition and Morphological Features of Kaolinite in Ceramic Clays of the Shulepovo Deposit (Ryazan Region,Central European Russia)

Lithology and Mineral Resources - This paper addresses for the first time the internal structure of lens 2 of the Shulepovo refractory clay deposit. The SEM study of representative samples from the...     

Manifestation of pulsation instability in solar radio emission preceding proton flares

The investigation of solar radio emission fluctuations at the wavelength - 3 cm led to the discovery of a visible increase in pulsations with periods of about 30–120 min prior to proton flares. These pulsations were observed before all (seven) proton flares included in our cycle of observations from 1969 to 1974. The phenomenon was not found to occur before non-proton flares. The assumption is made that the observed pulsations are a manifestation of pre-flare instability in coronal structures. Estimations have been made for fluctuations of the gyro-resonance radiation from the regions above spots associated with the magnetic field variations when a groove instability of a coronal condensation is developed. They are in good agreement with the observational data. The discovered manifestation of the pre-flare instability in fluctuations of the solar radio emission open new ways to study the flare development and to predict geo-effective phenomena on the Sun.     

Temporal Variations in the Vertical Distribution of Stratospheric Ozone over Obninsk from Lidar Data

The results of lidar measurements of ozone profiles over Obninsk in the altitude range of 12–35 km in 2012–2016 are presented. Temporal variations in total ozone in the above altitude range and seasonal variations in the vertical distribution of ozone are considered. Basic attention is paid to the analysis of ozone profile variations on the daily and weekly scales. The backtrajectory analysis demonstrated that in most cases the formation of layers with low or high ozone values is explained by the direction of meridional advection. Cross-correlation coefficients for the variations in ozone and temperature relative to the current monthly mean variations are calculated. Rather high values of correlation coefficients (~0.4–0.6) are obtained for summer in the low stratosphere (100 and 160 hPa) and for winter in the upper troposphere (50 and 20 hPa). In general, variations in ozone profiles are consistent with available climatologic data.     

Observation of polar stratospheric clouds over Obninsk in December 2012

In late December 2012 a blocking anticyclone followed by the event of minor stratospheric warming, set in the troposphere over West Siberia and, after that, over the European part of Russia. As a result of the deformation of a polar stratospheric vortex, the temperature in the lower stratosphere over Obninsk dropped below the threshold of the formation of polar stratospheric clouds. The lidar measurements of temperature, ozone values, and aerosol characteristics in the middle atmosphere were carried out at the lidar station during this atmospheric event. In three cases, polar stratospheric clouds (PSCs) referred to NAT I_a type according to the sounding results, were registered at the height of about 20 km. No considerable decrease in the ozone concentration in the area of PSC formation was revealed in these measurements.