Survey of Geomagnetic Observations Made in the Northern Sector of Russia and New Methods for Analysing Them

An overview of the geomagnetic observations made in the northern part of Russia is presented from a historical perspective. Several stations were deployed on the territory of the former Soviet Union during the International Geophysical Year, 1957–1958, with the active participation and guidance of the Interagency Geophysical Committee which is inherited by the Geophysical Center of the Russian Academy of Sciences (GC RAS). In the 1990s, the majority of these stations, especially those in the remoter regions, were closed. Nowadays, the geomagnetic network, including the observatories of the INTERMAGNET program, has been restored. Examples of high-latitude geomagnetic variations in the Russian longitudinal sector are shown, and maps and trends of the secular variation over the territory of Russia presented. Particular attention is paid to the automated processing of data and to the analysis methods used. To process the growing amount of high-resolution geomagnetic data, sophisticated mathematical methods based on the fuzzy logic approach and new discrete mathematical analysis algorithms have been developed. The formal methods and algorithms for recognizing both artificial and natural disturbances in the magnetograms are described.     

Y/Ho Ratios in the Late Cenozoic Basalts from the Eastern Tuva, Russia: An ICP-MS Study with Enhanced Data Quality

A set of forty seven Late Cenozoic basaltic rocks from the Eastern Tuva (southern Siberia, Russia) have been studied by ICP-MS using In as an internal standard. Yttrium and Ho concentrations, determined along with other trace elements, varied systematically from one analytical run to another and covered the entire charge-and-radius-controlled field within the range 24 < Y/Ho < 34, so obscuring any geochemical interpretation. A correction procedure was therefore developed in which the Y/Ho ratios were recalculated using concentrations of these elements determined in international and in-house reference materials (BHVO-1, AGV-1, BIR-1 and U-94-5). Statistical analysis of the recalculated data set revealed two groups of samples not related by their genesis but rather by their respective analytical runs. Fourteen samples originally analysed in five different runs were then re-measured by the same instrument in peak-hopping mode using only specific mass peaks (m/z = 89, 115 and 165). All of these samples yielded Y/Ho ratios in a narrow range between 29 and 31, thus illustrating how analytical problems in the determination of Y and Ho by routine ICP-MS procedures can be overcome. Finally, a mean value of Y/Ho = 30.3 ± 1.1 (1s) was derived for the basaltic rocks of the Eastern Tuva. This is close to the value of 28.8 accepted for chondrites and for ocean island basalts. Despite the uniform Y/Ho ratio, the element concentrations in basaltic rocks from the Eastern Tuva show systematic enrichment in heavy rare earth elements and yttrium from the Miocene to the Quaternary.     

Vector magnetic fields, subsurface stresses and evolution of magnetic helicity

Observations of the strength and spatial distribution of vector magnetic fields in active regions have revealed several fundamental properties of the twist of their magnetic fields. First, the handedness of this twist obeys a hemispheric rule: left-handed in the northern hemisphere, right-handed in the southern. Second, the rule is weak; active regions often disobey it. It is statistically valid only in a large ensemble. Third, the rule itself, and the amplitude of the scatter about the rule, are quantitatively consistent with twisting of fields by turbulence as flux tubes buoy up through the convection zone. Fourth, there is considerable spatial variation of twist within active regions. However, relaxation to a linear force-free state, which has been documented amply in laboratory plasmas, is not observed.     

Modeling the Global Coronal Field with Simulated Synoptic Magnetograms from Earth and the Lagrange Points $L_{3}$, L4$L_{4}$, and L5$L_{5}$

The solar photospheric magnetic flux distribution is key to structuring the global solar corona and heliosphere. Regular full-disk photospheric magnetogram data are therefore essential to our ability to model and forecast heliospheric phenomena such as space weather. However, our spatio-temporal coverage of the photospheric field is currently limited by our single vantage point at/near Earth. In particular, the polar fields play a leading role in structuring the large-scale corona and heliosphere, but each pole is unobservable for \({>}\,6\) months per year. Here we model the possible effect of full-disk magnetogram data from the Lagrange points \(L_{4}\) and \(L_{5}\), each extending longitude coverage by \(60^{\circ}\). Adding data also from the more distant point \(L_{3}\) extends the longitudinal coverage much further. The additional vantage points also improve the visibility of the globally influential polar fields. Using a flux-transport model for the solar photospheric field, we model full-disk observations from Earth/\(L_{1}\), \(L_{3}\), \(L_{4}\), and \(L_{5}\) over a solar cycle, construct synoptic maps using a novel weighting scheme adapted for merging magnetogram data from multiple viewpoints, and compute potential-field models for the global coronal field. Each additional viewpoint brings the maps and models into closer agreement with the reference field from the flux-transport simulation, with particular improvement at polar latitudes, the main source of the fast solar wind.     

Tilt of Sunspot Bipoles in Solar Cycles 15 to 24

We use recently digitized sunspot drawings from Mount Wilson Observatory to investigate the latitudinal dependence of tilt angles of active regions and its change with solar cycle. The drawings cover the period from 1917 to present and contain information as regards polarity and strength of magnetic field in sunspots. We identified clusters of sunspots of same polarity, and used these clusters to form “bipole pairs”. The orientation of these bipole pairs was used to measure their tilts. We find that the latitudinal profile of tilts does not monotonically increase with latitude as most previous studies assumed, but instead, it shows a clear maximum at about 25?–?30 degree latitudes. Functional dependence of tilt (\(\gamma\)) on latitude (\(\varphi\)) was found to be \(\gamma= (0.20\pm0.08) \sin(2.80 \varphi) + (-0.00\pm0.06)\). We also find that latitudinal dependence of tilts varies from one solar cycle to another, but larger tilts do not seem to result in stronger solar cycles. Finally, we find the presence of a systematic offset in tilt of active regions (non-zero tilts at the equator), with odd cycles exhibiting negative offset and even cycles showing the positive offset.     

3D spectroscopy of merger Seyfert galaxy Mrk 334: nuclear starburst, superwind and the circumnuclear cavern

We are presenting new results on kinematics and structure of the Mrk 334 Seyfert galaxy. Panoramic (3D) spectroscopy is performed at the 6-m telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences using the integral-field Multi-Pupil Fiber Spectrograph (MPFS) and scanning Fabry–Pérot interferometer. The deep images have revealed that Mrk 334 is observed during the final stage of its merging with a massive companion. A possible mass ratio ranges from 1/5 to 1/3. The merger has triggered mass redistribution in the disc resulting in an intensification of nuclear activity and in a burst of star formation in the inner region of the galaxy. The circumnuclear starburst is so intense that its contribution to the gas ionization exceeds that contribution of the active galactic nuclei (AGN). We interpret the nuclear gas outflow with velocities of  ∼200 km s⁻¹  as a galactic superwind that accompanies the violent star formation. This suggestion is consistent with the asymmetric X-ray brightness distribution in Mrk 334. The trajectory of the fragments of the disrupted satellite in the vicinity of the main galaxy nucleus can be traced. In the galaxy disc, a cavern is found that is filled with a low-density ionized gas. We consider this region to be the place where the remnants of the companion have recently penetrated through the gaseous disc of the main galaxy.     

Distribution, magnitude and characterization of the toxicity of Ukrainian estuarine sediments

During the Soviet era, Ukraine was an important industrial and agricultural region of the Soviet Union. This industrial and agricultural activity resulted in contamination of Ukraine’s estuaries with legacy anthropogenic pollutants. Investigations on the toxicological effects of this estuarine contamination have been limited. For this research, we measured the toxicity of contaminated sediments from four Ukrainian estuaries to several aquatic organisms over 3 years. Sediment chemical analyses and whole sediment toxicity identification evaluations (TIEs) were also performed to determine the classes of contaminants contributing to toxicity. Toxic sediments were observed in several of the Ukrainian estuaries and chemical analyses of the sediments demonstrated anthropogenic contaminants were widely distributed. Contaminants were also detected in macrobenthic organisms collected from the sediments. Several lines of evidence, including TIEs, indicated hydrophobic organic chemicals (HOCs) were contributing substantially to observed toxicity. This information can guide environmental managers to prioritize portions of the estuaries requiring remediation.     

Learning wind fields with multiple kernels

This paper presents multiple kernel learning (MKL) regression as an exploratory spatial data analysis and modelling tool. The MKL approach is introduced as an extension of support vector regression, where MKL uses dedicated kernels to divide a given task into sub-problems and to treat them separately in an effective way. It provides better interpretability to non-linear robust kernel regression at the cost of a more complex numerical optimization. In particular, we investigate the use of MKL as a tool that allows us to avoid using ad-hoc topographic indices as covariables in statistical models in complex terrains. Instead, MKL learns these relationships from the data in a non-parametric fashion. A study on data simulated from real terrain features confirms the ability of MKL to enhance the interpretability of data-driven models and to aid feature selection without degrading predictive performances. Here we examine the stability of the MKL algorithm with respect to the number of training data samples and to the presence of noise. The results of a real case study are also presented, where MKL is able to exploit a large set of terrain features computed at multiple spatial scales, when predicting mean wind speed in an Alpine region.     

Jom-Bolok Holocene volcanic field in the East Sayan Mts., Siberia,Russia: structure,style of eruptions,magma compositions,and radiocarbon dating

Jom-Bolok volcanic field is located in the East Sayan Mts. of Siberia (Russia), a portion of the Asian convergent zone. It is located at the boundary of the Riphean Tuva-Mongolia massif, which was probably reactivated because of the interplay between far-field tectonic stress derived from the India–Asia collision zone and extension in the south-western Baikal rift system. The volcanic field comprises a number of hawaiitic lava flows, of various lengths, which flowed down paleorivers. Flows were fed by fissure eruptions and the largest lava flow field was dated as 7,130?±?140 cal ¹⁴C years BP using a buried organic sample found inside the associated cinder cone. This lava flow field is about 70 km long, ～100 km² in area, and 7.9 km³ in volume. The area and volume of this flow field ranks this eruption highly in the global record of fissure-fed effusive eruptions. This lava flow field makes up 97% of the entire Jom-Bolok volcanic field, a fact which raises a puzzling question: why and/or how did a relatively small-volume volcanic field produce such a large-volume individual eruption? A working hypothesis is that a pond of sublithospheric melt accumulated over a relatively prolonged period. This was then rapidly drained in response of tectonic changes triggered by unloading of ice in the Early Holocene.