The non-extensive statistical mechanics method of Tsallis (or q-statistics) is first applied to study pulsating auroras, which are regularly observed in the auroral ionosphere during geomagnetic disturbances. For systems with long-range interactions, such as ionized gas or plasma, whose dynamics are primarily determined by long-range electromagnetic forces, one can expect that non-additive and non-extensive thermostatistical principles may characterize their macroscopic behavior. This paper shows that pulsating polar auroras exhibit non-extensive properties and can be described, in part, by q-statistics. It is also demonstrated that the non-extensive parameter q correlates well with the flatness coefficient and scaling index, indicating the applicability of this approach to auroral emissions. Thus, q-statistics can be used to analyze phenomena in the high-latitude region of the Earth.

Tsallis nonextensive statistical mechanics (or q -statistics) has been used for the first time to study pulsating auroras, which are regularly observed in the auroral ionosphere during geomagnetic disturbances. For systems in which long-range interactions, such as ionized gas or plasma, take place and whose dynamics are determined primarily by long-range electromagnetic forces, it can be expected that nonadditive and nonextensive thermostatistic principles can characterize their macroscopic behavior. In this paper, we argued that pulsating auroras exhibit nonextensive properties and can be described, among other things, by q -statistics. We have also demonstrated that the non-extensive parameter q correlates well with the flatness index and with the scaling index, which indicates the applicability of this approach for auroral glow. Thus, q -statistics can be used to analyze phenomena in the high-latitude region of the Earth.

A system of imaging photometers with high temporal resolution (PAIPS, the Pulsating Aurora Imaging Photometers System) is being created at the observatories of the Polar Geophysical Institute on the Kola Peninsula in order to study the structure of pulsating auroras (PsA) in the near ultraviolet range (300–400 nm). Two PsA measurements using the PAIPS system in combination with all-sky cameras are described. A frequency analysis of the signal is performed for the first one. It is shown that pulsations occur within 1.5 h at a quasi-constant frequency of around 1 Hz. The ratio of intensities in lines 337 and 391 nm is measured for the second one. An analysis of simultaneous observations by the optical cameras in the spectrometer’s field of view shows that pulsations of radiation in the on phase are “greener” (i.e., they correspond to less energetic precipitating electrons). Stereometric observations using the camera at the Lovozero observatory yield the maxima of the coefficient of correlation for the time series of the cameras at altitudes of 145–150 and 92 km.

High-latitude observations from the Polar Geophysical Institute are used to study the development of a typical auroral substorm that occurred on September 13, 2013. According to satellite data, the event was linked to parameters of the solar wind and physical domains and boundaries of the magnetosphere. Characteristics of the spatial structure of polar auroras (scaling indices, anisotropy) are determined for typical auroral structures (quiet and rayed arcs, breakup, pulsating bands, and omega structures).

It is well-known that the auroral region of the magnetosphere-ionosphere interaction is an open, nonlinear dissipative system far from the equilibrium state. It is in this region that auroras are regularly observed, demonstrating not only a wide variety of dynamic forms but also wide range of temporal and spatial scales. Due to the memory effects and fractal properties auroral plasma, as well as strong correlations between its individual parts, the dynamics of high -latitude system are primarily determined by long -range electromagnetic forces. Therefore, it is expected that non -additive and non -extensive thermodynamic principles may characterize their macroscopic behavior. In the presented study, it is shown that pulsating auroras exhibit non -extensive properties and can be described by q-statistics. The correlation of the parameter q with traditional indicators of nonlinear dynamics, such as the flatness coefficient, standard deviation, and scaling index, has been investigated. Small-scale changes are superimposed large-scale processes characterized by a low correlation dimension, and this leads to an increase in the correlation dimension during geomagnetic activity, which approximately coincides with increased values of q. It is concluded that the q-statistics (Tsallis distribution) can be used analyze optical phenomena in the auroral region.

Using high-latitude observations by the Polar Geophysical Institute, the development of a typical auroral substorm on September 13, 2013, is traced. The event, according to satellite data, is linked to solar wind parameters, physical magnetospheric domains, and boundaries. The characteristics of the spatial structure of polar auroras (scaling indices, anisotropy) have been determined for typical auroral structures (quiet and rayed arcs, breakup, pulsating bands, omega structures).

In this paper we present data on the UV-microburst (300-400 nm flashes with a duration less than 1 s) measurements in the auroral zone. Measurements were performed during the period 09.2021-04.2022 by the highly sensitive imaging photometer installed at the Verkhnetulomsky observatory of the Polar Geophysical Institute. It is shown that microbursts are grouped in a series with a duration from 10 s to 10 min. They were observed in relatively quiet geomagnetic conditions (K-P < 3) at the southern boundary of the auroral oval in the evening magnetic local time (MLT) sector. UV-microbursts are observed in different observational conditions (clouds, transparent clouds and clear sky) and spatially represent various patterns: uniform diffuse illumination, local spots. Joint analyses of the optical measurements and satellite data on charged particle fluxes demonstrates that an auroral oval, characterized by a plasma, is placed to the north of the observatory. At the same time increased flux of electrons with energy more than 100 keV is observed at the same L-shell and MLT sector. The possible origin of the UV-microbursts is a precipitation of energetic electrons from a poleward boundary of the outer radiation belt in a form of relativistic electron microbursts is discussed. (c) 2024 COSPAR. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.

The non-extensive statistical mechanics method of Tsallis (or q-statistics) is first applied to study pulsating auroras, which are regularly observed in the auroral ionosphere during geomagnetic disturbances. For systems with long-range interactions, such as ionized gas or plasma, whose dynamics are primarily determined by long-range electromagnetic forces, one can expect that non-additive and non-extensive thermostatistical principles may characterize their macroscopic behavior. This paper shows that pulsating polar auroras exhibit non-extensive properties and can be described, in part, by q-statistics. It is also demonstrated that the non-extensive parameter q correlates well with the flatness coefficient and scaling index, indicating the applicability of this approach to auroral emissions. Thus, q-statistics can be used to analyze phenomena in the high-latitude region of the Earth.

The interaction of the magnetospheric–ionospheric (MI) system surrounding the Earth with the environment (solar wind) occurs in the form of a series of transient processes at different scales. The largest of them, magnetic storms, are obviously triggered by disturbances in the solar wind (direct driving). The role of the internal dynamics of the MI system, which is caused to a large extent by the nonlinearity and temporal delays of the loading–unloading processes of energy and particle from the solar wind into the magnetosphere, becomes more significant at smaller scales (substorms, pseudobreakups, injections, and activations). A typical dynamic state of the MI system is characterized as self-organized criticality or turbulence, which are characterized by statistical scale invariance (scaling) in the fluctuation distributions of many characteristics. The dynamics of the MI system is projected into the region of the auroral oval, the very existence of which is due to this dynamics. The space–time structure of auroral disturbances largely reflects the structure of processes in the MI plasma. The description of this structure is important both for studying the fundamental study of plasma processes and for many topical applied problems related to the propagation of radio waves in the ionosphere and vital activity at high latitudes. The paper discusses approaches and developments for constructing a model of the space–time structure of the auroral oval, based on fractal and multifractal characteristics.

This paper presents the case study based on data processing of the high temporal resolution Pulsating Aurora Imaging Photometer System observations in the near-ultraviolet and optical measurements of all-sky cameras during one night (March 6–7, 2022). A long interval of aurora pulsations after midnight was observed and analyzed. A detailed frequency analysis, analysis of observational conditions and geomagnetic activity were carried out for this event. The day is characterized by slightly disturbed geomagnetic conditions. Characteristic two frequency pulsations are observed: main pulsation near 0.1 Hz and internal modulation with a period one order of magnitude less.

Spectroscopic measurements of aurora emissions provide valuable insights into the altitude of electron atmospheric penetration and their maximum energy. To achieve this, the photometers used in the PAIPS (Pulsating Aurora Imaging Photometers System) project are equipped with spectrometers. These spectrometers enable the measurement of auroral emissions in narrow spectral lines with a temporal resolution of milliseconds. In this study, we present two cases of PsA (Pulsating Aurora) measurements in the 337 nm and 391 nm spectral lines. We demonstrate that during quiet geomagnetic conditions the ratio of night sky emissions in these bands is close to one and significantly increases during substorms. We propose and implement a special procedure for estimating this ratio. Our findings reveal that the intensity of emissions in both spectral lines correlates with the AL index of geomagnetic activity. However, the ratio between the emissions fluctuates around constant values over time and does not undergo significant changes throughout the entire PsA event, which can last for more than an hour.

Conjunction observations of auroras with electron distributions and broadband electrostatic fluctuations on Van Allen Probe A satellite in the equatorial region are considered. Using triangulation measurements, the energy spectra of the precipitating electrons in the rayed auroral structures were determined for the 17 March 2015 event. A comparison of the spectra of precipitating electrons in the auroral rays with satellite measurements of electrons in the equatorial region related to the aurora showed their agreement. The concomitance between Van Allen Probe A broadband electric waves and auroral variations measured by the ground-based auroral camera was observed on 17 March 2015. This suggests that broadband electrostatic waves may be responsible for electron precipitation, leading to the formation of rayed structures in the aurora.

Complementing the overview contribution about the whitepaper on ultra-high-energy cosmic rays (UHECR) prepared for the Snowmass community survey in the U.S. [Astroparticle Physics 149 (2023) 102819 - arXiv:2205.05845], this contribution focuses on Chapter 6, the ‘Instrumentation Roadmap’ for UHECR physics in the next decades. In addition to an increase in statistics, a higher measurement accuracy of cosmic-ray air showers is needed to answer open questions regarding the astrophysics and particle physics related to UHECR. The needed boost in exposure can be provided by space-borne fluorescence detectors with POEMMA or by huge ground arrays using a single cost-effective technique, such as the giant radio arrays envisioned with GRAND. These observatories maximizing the exposure need to be complemented by ground arrays featuring an event-by-event resolution of the rigidity of the primary particle, which is the essence of GCOS. The required high mass resolution demands the simultaneous measurement of the electromagnetic (energy and $X_\mathrm{max}$) and muonic shower components, possibly by combining layered water-Cherenkov with radio detectors and next-generation fluorescence telescopes, together with novel analysis techniques, such as neural networks. The higher accuracy for air-shower measurements is also important for UHECR particle physics because it will enable stricter tests of hadronic interaction models and will help to identify ultra-high-energy photons or neutrinos. This contribution will give an overview of the instrumentation needed for the future of UHECR physics in the context of the next generation experiments discussed in the whitepaper.

A new photometer with spatial resolution was installed in addition to the all-sky camera at the Verkhnetulomsky observatory of the Polar Geophysical Institute, located inside the auroral zone, to study the fine space–time structure of the auroral luminescence. We describe the scientific equipment and the case of simultaneous observations of pulsating auroras with internal modulation in the hertz range.

The present white paper is submitted as part of the "Snowmass" process to help inform the long-term plans of the United States Department of Energy and the National Science Foundation for high-energy physics. It summarizes the science questions driving the Ultra-High-Energy Cosmic-Ray (UHECR) community and provides recommendations on the strategy to answer them in the next two decades.

As part of the US "Snowmass" community planning exercise, the UHECR community has come together to write a comprehensive white paper discussing the recent progress and open questions of the field, as they relate to the overarching goals of particle and astroparticle physics. The document outlines strategies and recommendations for answering these questions over the next two decades. It also proposes an integrated timeline, which considers the progress expected to be achieved by the upgraded Pierre Auger Observatory and Telescope Array experiment in this decade, and the need for a set of complementary next-generation experiments combining high-accuracy measurements (GCOS, IceCube-Gen2 with its surface array) and very high exposure at the highest energies (GRAND, POEMMA) in the next decade. The resulting document, entitled "Ultra-High Energy Cosmic-Rays: at the Intersection of the Cosmic and Energy Frontiers", appears as a special issue of Astroparticle Physics (Astropart.Phys. 149 (2023) 102819 – arXiv:2205.05845). This contribution provides a summary of the document with a focus on (selected) recommendations and proposed roadmap.

The altitudes of typical auroral forms observed on the polar and equatorial boundaries of the auroral oval are analyzed. Triangulation based on data from two pairs of cameras located in Apatity and Barentsburg is used. The cameras in pairs are separated by ~4 km. The energy of precipitating electrons is estimated in dynamics for different auroral structures.

A new telescope-spectrometer was installed at Verkhnetulomsky observatory (68?36'N, 31?47'E) to supplement the data from all-sky cameras with measurements of the fine space-time structure of the auroral luminescence. The telescope uses 5 cm ultraviolet (UV) transparent lens as an optical system and a matrix of multi-anode photomultiplier tubes as a photo detector. The angular resolution of the telescope is 1.2? and the temporal resolution is 0.3 ms. The telescope observes a central part (20?) of the all-sky camera field of view (FOV). Description of both optical instruments and results of the first joint measurements are presented.

The highly sensitive TUS telescope with high temporal resolution operated on board the Lomonosov satellite in 2016 and 2017. The detector measured UV pulsations in the auroral zone with a time resolution of 6.6 ms. Examples of joint observations by the TUS detector and all-sky cameras on the Kola Peninsula are analyzed. It is shown that the TUS field of view covered a wide region of pulsating auroras, and the fine temporal structure of pulsations is determined.