Effect of variations in the solar-wind parameters on thunderstorm activity

Possible correlation between variations of the intensity of lightnings, which are estimated from the flux of thunderstorm-generated VLF-signals, and variations of the solar wind parameters has been investigated. The signals representing the intensity of local thunderstorms in summer and winter are received in Yakutsk (the Eastern Siberia) and in the African World Thunderstorm Center, respectively. The highest correlation coefficient has been obtained between the thunderstorm activity and variations of the solar-wind particle density. This correlation has a season-dependent sign-alternating character. The maximum positive and negative correlation coefficients are observed in August–September and February, respectively; i.e., the manifestation of solar wind density variations in the thunderstorm activity is maximal in the near-equinoctial periods. This may be associated with the peculiarities of the transfer of the magnetospheric electric field “from morning to evening,” which is induced by the solar-wind particle flux, to ionospheric heights.     

A new index of solar activity: An index of cosmic ray scintillation

An index of cosmic ray scintillation introduced previously is verified. This procedure has been performed within the scope of the long-term full-scale monitoring of galactic cosmic rays (GCRs) in the real time regime. The 5-min data of the global network of high-latitude neutron monitors at Tixie Bay (Apatity) and Oulu (Finland) stations during the last four solar cycles (cycles 20–23), i.e., during the entire period of data registration with a high (5 min) resolution, have been used. The relationship between the amplitude-frequency-time structure of a precursor in the GCR scintillation index and the soliton-like structure of the heliospheric current sheet during the disturbed period has been established. This indicates that the precursor is of a coherent origin. Only the presence of a coherent process—quasi-week variation—makes it fundamentally possible to predict heliospheric storms. Finally, the justifiability of the effective prediction of heliospheric storms (～80%) has been obtained based on the long-term cosmic ray monitoring during cycle 23.     

The Experience in Applying a Water Reservoir Operation Model Using Dynamic Volume Nomograms in Exercising Special-Purpose Spring Water Releases

Simulation models of river reservoir functioning in which dynamic volume nomograms are used to consider the non-horizontal nature of the reservoir water surface have not been so far applied due to the lack of accurate and fast-working computer realizations of such models. In 2015–2016, the authors of this paper developed such a program. In the periods of carrying out special-purpose spring water releases to the lower reaches of the Volga River in 2016 and in 2017, the developed model was used in a trial mode for a designing the reservoirs’ water regime. The results of water releases carried out under complicated hydrological and economic conditions proved the high performance of the model and confirmed the prospects of its application to solve the inverse problem.     

The distribution of tephra deposits and reconstructing the parameters of 1973 eruption on Tyatya Volcano,Kunashir I., Kuril Islands

We studied the distribution of tephra deposits discharged by the basaltic (52–54% SiO₂) explosive eruption of 1973 on Tyatya Volcano (Kunashir I., Kuril Islands). We made maps showing lines of equal tephra thickness (isopachs) and lines of maximum size of pyroclastic particles (isopleths). These data were used to find the parameters of explosive activity using the standard techniques for each of the two phases of this eruption separately. The first, phreatomagmatic, phase discharged 0.008 km³ of tephra during the generation of maars on the volcano’s northern slope. The tephra mostly consisted of fragmented host rocks with admixtures of fragments of low vesiculated juvenile basalt. The phase lasted 20 hours, the rate of pyroclastic discharge was 2 × 10⁵ kg/s; the eruptive plume reached heights of 4–6 km with wind speeds within 10 m/s. The second, magmatic, phase discharged 0.07 km³ of tephra during the generation of the Otvazhnyi scoria cone on the volcano’s southeastern slope. The tephra mostly consisted of juvenile basaltic scoria. The highly explosive Plinian part of this phase lasted 36 hours, the rate of pyroclastic discharge was 8 × 10⁵ kg/s; the eruptive plume reached heights of 6–8 km with wind speeds of 10–20 m/s. The total tephra volume discharged by the eruption was approximately 0.08 km³; the total amount of ejected pyroclastic material (including the resulting monogenic edifices) was 0.11 km³; the volume of erupted magma was 0.05 km³ (the conversion was based on 2800 kg/m³ density); the volcanic explosivity index, or VEI, was 3. The production rate of the Tyatya plumbing system is estimated as 3 × 10⁵ m³ magma per annum.     

A study of heat transport at the ice base and structure of the under-ice water layer in Southern Baikal

Experimental data and a new model of ice buildup are used to assess and to study variations of heat flux at the water–ice interface. The latter plays an important part in ice cover formation but still is poorly known because of the lack of field temperature measurements with sufficient spatial and temporal resolution along the phase transition boundary, which knowledge gap is filled by this study.     

The Influence of Cyclonic Activity on the Geomagnetic Field Disturbance

Geomagnetism and Aeronomy - The results of observations of geomagnetic disturbances related to cyclonic activity in the troposphere are reported. To reveal these disturbances, we use data on...     

The IKFS-2 Infrared Fourier-Transform Spectrometer Operating Onboard the Meteor-M No.2 Satellite

Izvestiya, Atmospheric and Oceanic Physics - The results of the commissioning of the IKFS-2 instrument and its subsequent operation onboard the Meteor-M no. 2 polar orbiting meteorological...     

Three metamorphic events in the precambrian P-T-t history of the Transangarian Yenisey ridge recorded in garnet grains in metapelites

A study of gneisses and schists from the Yenisey regional shear zone (Garevka complex) at the western margin of the Siberian Craton has provided important constraints on the tectonothermal events and geodynamic processes in the Yenisey Ridge during the Riphean. In situ U-Th-Pb geochronology of monazite and xenotime from different garnet growth zones and the calculation of P-T path derived from chemical zoning pattern in garnet were used to distinguish three metamorphic events with different ages, thermodynamic regimes and metamorphic field gradients. The first stage occurred as a result of the Grenville orogeny during late Meso-early Neoproterozoic (1050–850 Ma) and was marked by low-pressure zoned metamorphism at ～4.8–5.0 kbar and 565–580°C and a metamorphic field gradient with dT/dH = 20–30°C/km typical of orogenic belts. At the second stage, the rocks experienced Late Riphean (801–793 Ma) collision-related medium-pressure metamorphism at ～7.7–7.9 kbar and 630°C with dT/dH ≤ 10°C/km. The final stage evolved as a syn-exhumation retrograde metamorphism (785–776 Ma) at ～4.8–5.4 kbar and 500°C with dT/dH ≤ 12°C/km and recorded a relatively fast uplift of the rocks to upper crustal levels in shear zones. The range of exhumation rates at the post-collisional stage (500–700 m/Ma) correlates with the duration of exhumation and the results of thermophysical numerical modeling of metamorphic rocks within orogenic belts. The final stages of collisional orogeny are marked by the development of rift-related bimodal dyke swarms associated with Neoproterozoic extension (797 ± 11 and 7.91 ± 6 Ma; U-Pb SHRIMP II zircon data) along the western margin of the Siberian craton and the beginning of the breakup of Rodinia. Post-Grenville metamorphic episodes of regional evolution are correlated with the synchronous succession and similar style of the later tectono-metamorphic events within the Valhalla orogen along the Arctic margin of Rodinia and support the spatial proximity of Siberia and North Atlantic cratons at about 800 Ma, as indicated by the latest paleomagnetic reconstructions.     

Characteristics of storm cells from observations in Yakutia

Considered are the methods of thunderstorm cells clustering using the data of one-point and multipoint lightning detectors and their characteristic features based on the observations in Yakutia. As the thunderstorm activity intensifies, i.e., the lightning discharge density in the region increases, the number of storm centers and the number of cells in the center grow up. The sizes and the lifetime of thunderstorm cells in Yakutia correspond to the similar data for North America and the European part of Russia. The maximum area and intensity of both center and thunderstorm cell are observed at the stage of development, in the middle of their lifetime. As the cell area increases, the intensity of lightning discharges decreases inversely to the area. It is revealed that as the cell oblongness increases, the intensity of lightning discharges in these cells becomes higher as well.     

Geodynamic Evolution of the Western Part of the Russian Arctic and Its Diamond Potential

Oceanology - The study of the geodynamic evolution of the Baltic Shield showed that the melts of diamondiferous kimberlites and related rocks were formed due to the pulling of “heavy”...