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Данная статья посвящена дисбактериозу кишечника у детей. Представлены современные данные о формировании, структуре и функциях кишечной микробиоты. На ее состав и состояние оказывают влияние экзогенные и эндогенные факторы, анатомо-физиологические особенности организма ребенка, генетическая предрасположенность и др. Дисбактериоз кишечника может способствовать развитию ряда заболеваний, при которых коррекция кишечной микробиоты может оказаться перспективной терапевтической стратегией. Подробно представлены факторы риска развития, патогенез, особенности клинической картины, изложены диагностические критерии и этапы медикаментозной коррекции рассматриваемой патологии. Показаны преимущества назначения кишечных антисептиков при проведении селективной деконтаминации. The article is devoted to intestinal dysbiosis in children. Modern data on formation, structure and functions of the intestinal microbiota are presented. Its composition and condition are influenced by exogenous and endogenous factors, anatomical and physiological features of the child’s body, genetic predisposition, etc. Intestinal dysbiosis may contribute to a number of diseases in which intestinal microbiota correction could be a promising therapeutic strategy. Risk factors, pathogenesis, and features of the clinical picture are presented in detail, diagnostic criteria and stages of drug correction in this pathology are outlined. The advantages of prescribing intestinal antiseptics during selective decontamination are shown.

Gravity waves are a major source of the middle atmospheric short-term variability. The Hunga Tonga-Hunga Ha‘apai volcanic eruption provided a unique opportunity to study gravity wave propagation around the globe from a well-defined source. The eruption triggered several atmospheric signatures including a lamb wave (troposphere/stratosphere/mesosphere) and a package of gravity waves. Here we present results of gravity wave signatures found in mesospheric winds leveraging multi-static meteor radar networks such as the Nordic Meteor Radar Cluster and CONDOR. We were able to identify the eastward and westward propagating gravity waves. Furthermore, it was possible to estimate the intrinsic wave properties such as a horizontal wavelength of approximately 1600-2000 km and an intrinsic phase speed of 200 m/s.

Solar wind interactions with the Earth’s magnetosphere cause geomagnetic storms and thereby induce ionospheric storms. This study investigates the spatio-temporal evolution of the ionospheric Total Electron Content (TEC) during a moderate but long duration storm driven by solar wind high-speed streams (HSSs) and associated co-rotating interaction region (CIR) during 14-21 March 2016. The storm starts with a strong storm sudden commencement (SSC) with a peak close to 19 UT on 14 March 2016. The GNSS/TEC maps are obtained from the Madrigal database. The associated field-aligned currents (FACs) from AMPERE, ionospheric convection maps from SuperDARN, and the O/N2 ratio from TIMED/GUVI are also studied for understanding the physics behind the different features observed in TEC during the storm.The study predominantly focuses on the changes of TEC at high and middle latitudes. The storm induced changes in the TEC were extracted by removing the quiet time background (mean of five quietest days of the month) from the TEC maps. During the initial phase, TEC enhancements and depletions are found mainly at high latitudes within the auroral oval and close to the cusp, plausibly associated with auroral precipitation and variations in the upward and downward field-aligned currents (FACs). After the onset of the main phase, the TEC is enhanced at mid-latitudes and auroral ovals with a maximum of ~10 TECU. Meanwhile, a significant decrease in TEC is observed in the polar cap region. During the main phase, we observe the evolution of a storm-enhanced-density (SED) plume and a transient enhancement of TEC in the polar cap. Later during the storm, a strong TEC depletion at high and middle latitudes is found on the dayside and in the evening sector. The depletion of O/N2 ratio, triggered by Joule heating and atmospheric upwelling, could be a plausible reason for the TEC depletion. The possible physical mechanisms associated with the observed TEC variations will be discussed.

Atmospheric Gravity Waves (AGWs) forced in the lower atmosphere are known to have a significant impact on the mesosphere and lower thermosphere (MLT) region. In the ionosphere, they can generate Medium-Scale Traveling Ionospheric Disturbances (MSTIDs). These disturbances roughly occur on time scales of 15−80 min and are therefore often parametrized rather than directly resolved in ionosphere models. The energy and momentum transport by AGW-TIDs strongly depends on their wave parameters. Measurements of AGW-TIDs in the MLT region and determination of the wave parameters (vertical and horizontal wavelength, wave period and propagation direction) are therefore an essential step to improve ionosphere modelling. However, measurements that provide a good resolution in the vertical dimension (≲ 10 km) and time (≲ 10 min) as well as a large enough coverage in the horizontal dimension (≳ 300 × 300 km) are difficult at MLT altitudes. We show, that combined measurements of the EISCAT VHF incoherent scatter radar and the Nordic Meteor Radar Cluster allow to determine the wave parameters of AGW-TIDs across the whole MLT region. Fourier filter methods are used to separate wave modes by wavelength, period and propagation direction. The extracted wave modes are fitted with wave functions in time-altitude and horizontal cross sections which gives the wave parameters. The coverage regions of the two applied instruments are separated only by approximately 10 km in altitude, which allows to identify a single wave mode in both measurements. We present the developed techniques on the example of a strongly pronounced AGW-TID measured on July 7, 2020. As a first application, two measurement campaigns have been conducted in early September and mid-October 2022 to study possible changes in AGW-TID parameters due to the MLT fall transition occurring around equinox. Another possible application of our method is to infer thermospheric neutral winds from the observed waves. We demonstrate this process under the assumption of the anelastic dissipative gravity wave dispersion relation.

Atmospheric Gravity Waves and Traveling Ionospheric Disturbances can be observed in the neutral atmosphere and the ionosphere at a wide range of spatial and temporal scales. Especially at medium scales, these oscillations are often not resolved in general circulation models and are parameterized. We show that ionospheric disturbances forced by upward propagating atmospheric gravity waves can be simultaneously observed with the EISCAT Very High Frequency incoherent scatter radar and the Nordic Meteor Radar Cluster. From combined multi-static measurements, both vertical and horizontal wave parameters can be determined by applying a specially developed Fourier filter analysis method. This method is demonstrated using the example of a strongly pronounced wave mode that occurred during the EISCAT experiment on 7 July 2020. Leveraging the developed technique, we show that the wave characteristics of Traveling Ionospheric Disturbances are notably impacted by the fall transition of the mesosphere/lower thermosphere. We also demonstrate the application of using the determined wave parameters to infer the thermospheric neutral wind velocities. Applying the dissipative anelastic gravity wave dispersion relation, we obtain vertical wind profiles in the lower thermosphere.

Materials and methods. A comparative analysis of the main indicators of physical development (body length and weight, head and chest) obtained in 2008 (group I) and 2018 (group II) by random sampling was carried out. These populations were homogeneous in place of residence, ethnicity, close in time of inspection and representative in number. The number of boys and girls in the group I was 100 people, in the group II – 75 and 70 people, respectively. Results. Monitoring of anthropometric indicators of body weight in newborn children confirmed the stability of this parameter and higher values in boys than in girls. Boys of group II from the age of 6 months have significantly lower body weight indicators compared to group I. Monitoring of body length in children of the first year of life over a 10-year period indicates that monthly gains in children of group II are lower than in group I. In 2018, boys from the age of 5 months had significantly lower head circumference compared to 2008. A significant decrease in the circumference of the chest was noted in boys of group II, starting from the 2nd month of life, in girls – from the 1st month, compared with children of group I. Conclusion. The analysis of anthropometric indicators in children in the first year of life over a ten-year period revealed a high intensity of their monthly gains in the first months of life with a gradual decrease in their intensity in the second half of the year. Significantly lower indicators of body weight and chest were established and a tendency to decrease body length and head circumference in children in 2018.

The Hunga Tonga–Hunga Ha′apai volcano eruption was a unique event that caused many atmospheric phenomena around the globe. In this study, we investigate the atmospheric gravity waves in the mesosphere/lower-thermosphere (MLT) launched by the volcanic explosion in the Pacific, leveraging multistatic meteor radar observations from the Chilean Observation Network De Meteor Radars (CONDOR) and the Nordic Meteor Radar Cluster in Fennoscandia. MLT winds are computed using a recently developed 3DVAR+DIV algorithm. We found eastward- and westward-traveling gravity waves in the CONDOR zonal and meridional wind measurements, which arrived 12 and 48 h after the eruption, and we found one in the Nordic Meteor Radar Cluster that arrived 27.5 h after the volcanic detonation. We obtained observed phase speeds for the eastward great circle path at both locations of about 250 m s−1, and they were 170–150 m s−1 for the opposite propagation direction. The intrinsic phase speed was estimated to be 200–212 m s−1. Furthermore, we identified a potential lamb wave signature in the MLT winds using 5 min resolved 3DVAR+DIV retrievals.

The Hunga Tonga–Hunga Ha′apai volcano eruption was a unique event that caused many atmospheric phenomena around the globe. In this study, we investigate the atmospheric gravity waves in the mesosphere/lower-thermosphere (MLT) launched by the volcanic explosion in the Pacific, leveraging multistatic meteor radar observations from the Chilean Observation Network De Meteor Radars (CONDOR) and the Nordic Meteor Radar Cluster in Fennoscandia. MLT winds are computed using a recently developed 3DVAR+DIV algorithm. We found eastward- and westward-traveling gravity waves in the CONDOR zonal and meridional wind measurements, which arrived 12 and 48 h after the eruption, and we found one in the Nordic Meteor Radar Cluster that arrived 27.5 h after the volcanic detonation. We obtained observed phase speeds for the eastward great circle path at both locations of about 250 m s−1, and they were 170–150 m s−1 for the opposite propagation direction. The intrinsic phase speed was estimated to be 200–212 m s−1. Furthermore, we identified a potential lamb wave signature in the MLT winds using 5 min resolved 3DVAR+DIV retrievals.

The 13th Symposium on Polar Science/Ordinary sessions [OS] Space and upper atmospheric sciences, Wed. 16 Nov.

Meteor radars have become widely used instruments to study atmospheric dynamics, particularly in the 70 to 110 km altitude region. These systems have been proven to provide reliable and continuous measurements of horizontal winds in the mesosphere and lower thermosphere. Recently, there have been many attempts to utilize specular and/or transverse scatter meteor measurements to estimate vertical winds and vertical wind variability. In this study we investigate potential biases in vertical wind estimation that are intrinsic to the meteor radar observation geometry and scattering mechanism, and we introduce a mathematical debiasing process to mitigate them. This process makes use of a spatiotemporal Laplace filter, which is based on a generalized Tikhonov regularization. Vertical winds obtained from this retrieval algorithm are compared to UA-ICON model data. This comparison reveals good agreement in the statistical moments of the vertical velocity distributions. Furthermore, we present the first observational indications of a forward scatter wind bias. It appears to be caused by the scattering center's apparent motion along the meteor trajectory when the meteoric plasma column is drifted by the wind. The hypothesis is tested by a radiant mapping of two meteor showers. Finally, we introduce a new retrieval algorithm providing a physically and mathematically sound solution to derive vertical winds and wind variability from multistatic meteor radar networks such as the Nordic Meteor Radar Cluster (NORDIC) and the Chilean Observation Network De meteOr Radars (CONDOR). The new retrieval is called 3DVAR+DIV and includes additional diagnostics such as the horizontal divergence and relative vorticity to ensure a physically consistent solution for all 3D winds in spatially resolved domains. Based on this new algorithm we obtained vertical velocities in the range of w = ± 1–2 m s−1 for most of the analyzed data during 2 years of collection, which is consistent with the values reported from general circulation models (GCMs) for this timescale and spatial resolution.

The Draconid meteor shower shows strong bursts of activity at irregular intervals, with nearly no activity in intervening years. Five outbursts of the Draconid meteor shower were observed with specular meteor radars in Canada and Europe between 1999 and 2018. The outbursts generally lasted between 6 and 8 h, and most were not fully visible at a single geographical site, emphasizing the need for observations at multiple longitudes for short-duration shower outbursts. There is at least a factor of two difference in the peak flux as measured on different radars; the initial trail radius effect is undercorrected for Draconid meteors, which are known to be fragile.

Meteor phenomena cause ionized plasmas that can be roughly divided into two distinctly different regimes: a dense and transient plasma region co-moving with the ablating meteoroid and a trail of diffusing plasma left in the atmosphere and moving with the neutral wind. Interferometric radar systems are used to observe the meteor trails and determine their positions and drift velocities. Depending on the spatial configuration of the receiving antennas and their individual gain patterns, the voltage response can be the same for several different plane wave directions of arrival (DOAs), thereby making it impossible to determine the correct direction. A low signal-to-noise ratio (SNR) can create the same effect probabilistically even if the system contains no theoretical ambiguities. Such is the case for the standard meteor trail echo data products of the Sodankylä Geophysical Observatory SKiYMET all-sky interferometric meteor radar. Meteor trails drift slowly enough in the atmosphere and allow for temporal integration, while meteor head echo targets move too fast. Temporal integration is a common method to increase the SNR of radar signals. For meteor head echoes, we instead propose to use direct Monte Carlo (DMC) simulations to validate DOA measurements. We have implemented two separate temporal integration methods and applied them to 2222 events measured by the Sodankylä meteor radar to simultaneously test the usefulness of such DMC simulations on cases where temporal integration is possible, validate the temporal integration methods, and resolve the ambiguous SKiYMET data products. The two methods are the temporal integration of the signal spatial correlations and matched-filter integration of the individual radar channel signals. The results are compared to Bayesian inference using the DMC simulations and the standard SkiYMET data products. In the examined data set, ∼ 13 % of the events were indicated as ambiguous. Out of these, ∼ 13 % contained anomalous signals. In ∼ 95 % of all ambiguous cases with a nominal signal, the three methods found one and the same output DOA, which was also listed as one of the ambiguous possibilities in the SkiYMET analysis. In all unambiguous cases, the results from all methods concurred.

Comprehensive analysis of a moderate 600 nT substorm was performed using simultaneous optical observations inside the auroral oval and in the polar cap, combined with data from satellites, radars, and ground magnetometers. The onset took place near the poleward boundary of the auroral oval that is not typical for classical substorms. The substorm onset was preceded by two negative excursions of the interplanetary magnetic field (IMF) Bz component, with a 1 min interval between them, two enhancements of the antisunward convection in the polar cap with the same time interval, and 15 min oscillations in the geomagnetic H component in the auroral zone. The distribution of the pulsation intensity along meridian has two local maxima, namely at the equatorial and poleward boundaries of the auroral oval, where pulsations occurred in the out-of-phase mode resembling the field line resonance. At the initial stage, the auroral breakup developed as the auroral torch stretched and expanded poleward along the meridian. Later it took the form of the large-scale coiling structure that also distinguishes the considered substorm from the classical one. Magnetic, radar, and the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) satellite data show that, before the collapse, the coiling structure was located between two field-aligned currents, namely downward at the poleward boundary of structure and upward at the equatorial boundary. The set of GEOTAIL satellites and ground data fit to the near-tail current disruption scenario of the substorm onset. We suggest that the 15 min oscillations might play a role in the substorm initiation.

Multistatic meteor radar observations offer the possibility to investigate the short-term variability at the mesosphere and lower thermosphere on regional scales. Here we present preliminary results of spatially resolved 3D winds and their corresponding horizontal wavelength spectra using the Nordic Meteor Radar Cluster and CONDOR in Chile with a recently developed 3DVAR+div retrieval. The new retrieval provides for the first time a physically consistent solution for the vertical winds that conform the continuity equation. Based on these spectra we can separate the spatial scales that are driven by rotational modes from those dominated by divergent gravity waves. Furthermore, we present the first results of momentum flux spectra derived from these observations on a daily basis.

In recent years, aurora observation networks using high-sensitivity cameras have been developed in the polar regions. These networks allow dimmer auroras such as pulsating auroras (PsAs) to be observed with a high signal-to-noise ratio. We reconstructed the horizontal distribution of precipitating electrons using computed tomography with monochromatic PsA images obtained from three observation points. The three-dimensional distribution of the volume emission rate (VER) of the PsA was also reconstructed. The characteristic energy of the reconstructed precipitating electron flux ranged from 6 keV to 23 keV, and the peak altitude of the reconstructed VER ranged from 90 to 104 km. We evaluated the results using a model aurora and compared the model’s electron density with the observed electron density. The electron density was reconstructed correctly to some extent, even after a decrease in PsA intensity. These results suggest that the horizontal distribution of precipitating electrons associated with PsAs can be effectively reconstructed from ground-based optical observations.

The middle atmospheric circulation is driven by atmospheric waves, which carry energy and momentum from their source to the area of their dissipation and thus providing an energetic coupling between different atmospheric layers. A comprehensive understanding of the wave-wave or wave-mean flow interactions often requires a spatial characterization of these waves. Multistatic meteor radar observations provide an opportunity to investigate the spatial and temporal variability of mesospheric/lower thermospheric winds on regional scales. We apply the 3DVAR+div retrievals to observations from the Nordic Meteor Radar Cluster and the Chilean Observation Network De Meteor Radars (CONDOR). Here we present preliminary results of a new 3DVAR+div retrieval to infer the vertical wind variability using spatially resolved observations. The new retrieval includes the continuity equation in the forward model to ensure physical consistency in the vertical winds. Our preliminary results indicate that the vertical wind variability is about +/-2m/s. The 3DVAR+div algorithm provides spatially resolved winds resolves body forces of breaking gravity waves, which are typically indicated by two counterrotating vortices. Furthermore, we infer horizontal wavelength spectra for all 3 wind components to obtain spectral slopes indicating a transition of the vertical to the divergent mode at scales of about 80-120 km at the mesosphere.

Using data of the all-sky interferometric meteor radar (SKiYMET, 36.9 MHz) operating in the Sodankylä Geophysical Observatory (67°22′N, 26°38′E, Finland) we found a specific type of polar mesosphere summer echo (PMSE), the power of which exhibits irregular variations at a frequency of the order of a few Hz. We classified such radar echoes as pulsating PMSE. These echoes were observed in late June-July in the morning sector (4–12 MLT) during geomagnetic storms. They were received from a narrow range of altitudes near 82 km, which corresponds to the altitude of noctilucent clouds where ice particles of about 50-nm radii exist. During pulsating PMSE, the SGO ionosonde showed an electron density of the order of 3 × 10¹¹ m⁻³ around 82 km, and enhanced D-region ionization was manifested in the cosmic noise absorption. We suggest that the power of PMSE is modulated by bursts of electron precipitation corresponding to the few-Hz internal modulation of pulsating aurora. During a short precipitation burst of 50–100 keV electrons, additional electrons can attach to the ice particles due to the presence of hyperthermal electrons according to the hypothesis proposed by Rosenberg et al. (2012, https://doi.org/10.1016/j.jastp.2011.10.011). This leads to an increase of the power of PMSE. After the burst is ended, the ice particles are deionized with a characteristic time of about 0.2 s due to attractive interaction with ions.

Multi-instrument observations by a meteor radar (MR), auroral cameras, ionosondes, and ground magnetometers were made in Northern Europe at auroral latitudes (between 64° and 72° corrected ...

The study is based on the data of the rapid-run ionosonde at the Sodankyla Geophysical Observatory at auroral latitude (L = 5.25) which routinely performs one-minute sounding since 2007. This dataset allows a unique opportunity for investigating possible effects of ultra-low frequency (ULF, 1–7 mHz) waves in the auroral ionosphere. Suitable observations were made during moderately disturbed geomagnetic conditions typically at recovery of the geomagnetic storms caused by solar wind high-speed streams, in the daytime between 9 and 16 MLT. The ionospheric oscillations corresponding to Pc5 geomagnetic pulsations were found in variations of the virtual height of the F layer and the power of ionosonde reflections from E and F layers. The later are most probably caused by modulation of electron precipitation, which is also manifested in weak (about 0.01–0.06 dB) variations of cosmic noise absorption. The most important and novel result is that the pulsations of power of reflection from E and F layers typically has a spectral maximum at nearly half the periodicity of the Pc5 geomagnetic pulsations, whereas such spectral peak is negligible in the geomagnetic pulsations.

Ground-based remote sensing of atmospheric parameters is often limited to single station observations of vertical profiles at a certain geographic location. This can be a limiting factor to investigating gravity wave dynamics. In this study we present a new retrieval algorithm for multi-static meteor radar networks to obtain tomographic 3D wind fields within a pre-defined domain area. The algorithm is part of the Agile Software for Gravity wAve Regional Dynamics (ASGARD) called 3DVAR, and based on the optimal estimation technique and Bayesian statistics. The performance of the 3DVAR retrieval is demonstrated using two meteor radar networks, the Nordic Meteor Radar Cluster and the Chilean Observation Network De MeteOr Radars (CONDOR). The optimal estimation implementation provides a statistically sound solution and additional diagnostics from the averaging kernels and measurement response. We present initial scientific results such as body forces of breaking gravity waves leading to two counter-rotating vortices and horizontal wavelength spectra indicating a transition between the vortical κ−3 and divergent κ−5/3 mode at scales of 80–120 km. In addition, we have performed a keogram analysis over extended periods to reflect the latitudinal and temporal impact of a minor sudden stratospheric warming in December 2019. Finally, we demonstrate the applicability of the 3DVAR algorithm to perform large-scale retrievals to derive meteorological wind maps covering a latitude region from Svalbard, north of the European Arctic mainland, to mid-Norway.

There is a growing scientific interest to investigate the forcing from the middle atmosphere dynamics on the thermosphere and ionosphere. This forcing is driven by atmospheric waves at various temporal and spatial scales. In this study, we cross-compare the nudged models Ground-to-topside model of Atmosphere and Ionosphere for Aeronomy (GAIA) and Whole Atmosphere Community Climate Model ExtendedVersion (Specified dynamics) ( WACCM-X(SD)), a free-running version of Upper Atmosphere ICOsahedral Non-hydrostatic (ICON-UA) with six meteor radars located at conjugate polar and mid-latitudes. Mean winds, diurnal and semidiurnal tidal amplitudes and phases were obtained from the radar observations at the mesosphere and lower thermosphere (MLT) and compared to the GAIA, WACCM-X(SD), and ICON-UA data for similar locations applying a harmonized diagnostic.Our results indicate that GAIA zonal and meridional winds show a good agreement to the meteor radars during the winter season on both hemispheres, whereas WACCM-X(SD) and ICON-UA seem to reproduce better the summer zonal wind reversal. However, the mean winds also exhibit some deviation in the seasonal characteristic concerning the meteor radar measurements, which are attributed to the gravity wave parameterizations implemented in the models. All three models tend to reflect the seasonality of diurnal tidal amplitudes, but show some dissimilarities in tidal phases. We also found systematic interhemispheric differences in the seasonal characteristic of semidiurnal amplitudes and phases. The free-running ICON-UA apparently shows most of these interhemispheric differences, whereas WACCM-X(SD) and GAIA trend to have better agreement of the semidiurnal tidal variability in the northern hemisphere.

Long-term and continuous observations of mesospheric/lower thermospheric winds are rare, but they are important to investigate climatological changes at these altitudes on time scales of several years, covering a solar cycle and longer. Such long time series are a natural heritage of the mesosphere/lower thermosphere climate, and they are valuable to compare climate models or long term runs of general circulation models (GCMs). Here we present a climatological comparison of wind observations from six meteor radars at two conjugate latitudes to validate the corresponding mean winds and atmospheric diurnal and semidiurnal tides from three GCMs, namely Ground-to-Topside Model of Atmosphere and Ionosphere for Aeronomy (GAIA), Whole Atmosphere Community Climate Model Extension (Specified Dynamics) (WACCM-X(SD)) and Upper Atmosphere ICOsahedral Non-hydrostatic (UA-ICON) model. Our results indicate that there are interhemispheric differences in the seasonal characteristics of the diurnal and semidiurnal tide. There also are some differences in the mean wind climatologies of the models and the observations. Our results indicate that GAIA shows a reasonable agreement with the meteor radar observations during the winter season, whereas WACCM-X(SD) shows a better agreement with the radars for the hemispheric zonal summer wind reversal, which is more consistent with the meteor radar observations. The free running UA-ICON tends to show similar winds and tides compared to WACCM-X(SD).

For two decades meteor radars have been routinely used to monitor atmospheric temperatures around the 90 km altitude. A common method, based on a temperature-gradient model, is to use the height dependence of meteor decay time to obtain a height-averaged temperature in the peak meteor region. Traditionally this is done by fitting a linear regression model in the scattered plot of log10(1/tau) and height, where ’tau’ is the half-amplitude decay time of the received signal. However, this method was found to be consistently biasing the slope estimate. The consequence of such bias is that it produces a systematic offset in the estimated temperature, and thus requiring calibration with other colocated measurements. The main reason for such a biasing effect is thought to be due to the failure of the classical regression model to take into account the measurement error in decay time or the observed height. This is further complicated by the presence of various geophysical effects in the data, as well as observational limitation in the measuring instruments. We demonstrate an alternative regression method that incorporates various error terms in the statistical model. An initial estimate of the slope parameter is obtained by assuming symmetric error variances in normalised height and log10(1/tau). This solution is found to be a good prior solution for the core of this bivariate distribution. However, depending on the data selection process the error variances may not be exactly equal. A first-order correction is then carried out to address the biasing effect due to asymmetric error variances. This allows to construct an analytic solution for the bias-corrected slope coefficient for this data. With this solution, meteor radar temperatures can be obtained independently without using any external calibration procedure. When compared with colocated lidar measurements, the temperature estimated using this method is found to be accurate within 7% or better and without any systematic offset.

In the middle atmosphere, spanning the stratosphere and mesosphere, spring transition is the time period where the zonal circulation reverses from winter westerly to summer easterly which has a strong impact on the vertical wave propagation influencing the tropospheric and ionospheric variability. The spring transition can be rapid in form of a final sudden stratospheric warming (SSW, mainly dynamically driven) or slow (mainly radiatively driven) but also intermediate stages can occur. In most studies spring transitions are classified either by their timing of occurrence or by their vertical structure. However, all these studies focus exclusively on the stratosphere and can give only tendencies under which pre-winter conditions an early or late spring transition takes place and how it takes place. Here we classify the spring transitions regarding their vertical-temporal development beginning in January and spanning the whole middle atmosphere in the core region of the polar vortex. This leads to five classes where the timing of the SSW in the preceding winter and a downward propagating Northern Annular Mode (NAM) plays a crucial role. The results show distinctive differences between the five classes in the months before the spring transition especially in the mesosphere allowing a certain prediction for some of the five spring transition classes which would not be possible considering the stratosphere only.

The process of learning is typical for the most assistive and autonomous robots. Considering the learning as a complex process, the issue of the data labeling is in the focus of this paper, because of the labeling noise effect on the learning results. Distributed redundant labeling is discussed in recent works, yet, no known publications contain the process description in the focus of the distributed decentralized processes, although the manner of distributed implementation of the various areas of the robotics is relevant now in the angle of fog- and edge-robotics. The current paper is devoted to the question of the redundant distributed labeling under the conditions of the decentralized data storing, which is quite relevant in the fog- and edge- robots environments. Two main approaches of the distributed monitoring of the labeling experts groups are considered and compared, as well as some experimental research of the redundant labeling results has been conducted with the results presented.

Using data of the ionosonde in Sodankyla, (SOD, 67° N, 27° E, Finland), variations of the critical frequency of o-mode radiowave reflected from ionospheric F2 layer (foF2) in 1–5 mHz frequency range and their possible association with long period (Pc5/Pi3) geomagnetic pulsations are studied. For that, a technique of automatic detection of the foF2 critical frequency from an ionogram is developed and applied to daytime Pc5/Pi3 geomagnetic pulsations and foF2 fluctuations during several months of years 2014–2015 near the maximum of 24-th Solar cycle. The variations of foF2 are compared with the Pc5/Pi3 geomagnetic pulsations at SOD station, and the influence of pulsations' spatial scale is analyzed with the data of a station pair located at the same magnetic meridian but separated in latitude. The variations of foF2 are in the majority of cases decoupled from the geomagnetic pulsations on the ground. Meanwhile, the analysis of geomagnetic and foF2 variations show intervals with noticeable coherence for both horizontal components. These coherent pulsations are predominantly registered in the afternoon sector of the magnetic local time (MLT). Statistically, their spectral content, polarization and spatial distribution differ from averaged parameters of post-noon Pc5 pulsations. The pulsations, coherent to foF2 fluctuations, demonstrate features typical for Alfven field-line resonance. The analysis of space weather conditions favorable for the occurrence of coherent geomagnetic/foF2 pulsations show that these pulsations are registered mostly under moderately disturbed conditions. Comparison of space weather parameters for all the intervals analyzed and the intervals of high geomagnetic/foF2 coherence show that the latter correspond mostly to intermediate values of indexes of geomagnetic (Dst) and auroral (AE) activity, solar wind speed and dynamic pressure fluctuations.

For 2 decades, meteor radars have been routinely used to monitor atmospheric temperature around 90 km altitude. A common method, based on a temperature gradient model, is to use the height dependence of meteor decay time to obtain a height-averaged temperature in the peak meteor region. Traditionally this is done by fitting a linear regression model in the scattered plot of log⁡10(1/τ) and height, where τ is the half-amplitude decay time of the received signal. However, this method was found to be consistently biasing the slope estimate. The consequence of such a bias is that it produces a systematic offset in the estimated temperature, thus requiring calibration with other co-located measurements. The main reason for such a biasing effect is thought to be due to the failure of the classical regression model to take into account the measurement error in τ and the observed height. This is further complicated by the presence of various geophysical effects in the data, as well as observational limitation in the measuring instruments. To incorporate various error terms in the statistical model, an appropriate regression analysis for these data is the errors-in-variables model. An initial estimate of the slope parameter is obtained by assuming symmetric error variances in normalised height and log⁡10(1/τ). This solution is found to be a good prior estimate for the core of this bivariate distribution. Further improvement is achieved by defining density contours of this bivariate distribution and restricting the data selection process within higher contour levels. With this solution, meteor radar temperatures can be obtained independently without needing any external calibration procedure. When compared with co-located lidar measurements, the systematic offset in the estimated temperature is shown to have reduced to 5 % or better on average.

Meteor phenomena cause ionized plasmas that can be roughly divided into two distinctly different regimes: a dense and transient plasma region co-moving with the ablating meteoroid and a trail of diffusing plasma left in the atmosphere and moving with the neutral wind. Interferometric radar systems are used to observe the meteor trails and determine their positions and drift velocities. Depending on the spatial configuration of the receiving antennas and their individual gain patterns, the voltage response can be the same for several different plane wave Directions Of Arrival (DOA), thereby making it impossible to determine the correct direction. Noise can create the same effect even if the system contains no theoretical ambiguities. We propose a method for interferometric meteor trail radar data analysis using coherent integration of the signal spatial correlation to resolve DOA ambiguities. We have validated the method by a combination of Monte Carlo simulations and application on 10 minutes of measurement data (174 meteor events) obtained with the Sodankylä Geophysical Observatory SKiYMET all-sky interferometric meteor radar. We also applied a Bayesian method to determine the true location of ambiguous events in the data set. In 26 out of 27 (~ 96 %) ambiguous cases, the coherently integrated spatial correlation gave the correct output DOA as determined by Bayesian inference. In the one case that was mis-classified there were not enough radar pulses to coherently integrate for the method to be effective.

The middle polar atmosphere dynamics is driven by atmospheric waves from the planetary scale to small scale perturbation due to gravity waves. The different atmospheric waves are characterized by their temporal and spatial variability posing challenges to ground-based remote sensing techniques to disentangle and resolve the spatio-temporal ambiguity. Here we present two ground-based remote sensing techniques to resolving spatio-temporal variability at the polar middle atmosphere.Since 2017 the GROMOS-C radiometer measures ozone and winds at NyÅlesund (78.9°N, 11.9°E) on Svalbard. The radiometer employs four beams in the cardinal directions at 22.5° elevation angle to retrieve ozone profiles and winds at altitudes between 30-75 km. the temporal resolution of the ozone retrievals is 30 minutes. Further, we obtain daily mean winds. Due to the high polar latitude the spatial separation between the beams at stratospheric altitudes covers several degrees in longitude to infer spatial gradients in the ozone densities and their perturbation due to planetary waves.Another recently established ground-based remote sensing approach to retrieve the spatial characteristic at the mesosphere and lower thermosphere (MLT) is provided by the Nordic meteor radar cluster consisting of the meteor radars at Tromsø, Alta, Esrange, Sodankylä and on Svalbard. Since October 2019 horizontally resolved winds are obtained using a 3DVAR approach with a temporal resolution of 30 minutes and a vertical resolution of 2 km. Here we present preliminary results to infer horizontal wavelength spectra, the tidal variability as well as gravity activity of the winter season 2019/20.Both datasets are of high value for data assimilation into weather forecast and reanalysis models or for cross-comparisons and validation of meteorological analysis systems (e.g. NAVGEM-HA).

Solar wind High-Speed Streams (HSSs) affect the auroral ionosphere in many ways, and several separate studies have been conducted of the different effects seen e.g. on aurora, geomagnetic disturbances, F-region behavior, and energetic particle precipitation. In this work, we study an HSS event in the solar cycle (24), which was associated with a co-rotating interaction region (CIR) that hit the Earth’s magnetopause at about 17:20 UT on 14 March 2016. The associated magnetic storm lasted for seven days, and the Dst index reached -56 nT. We use a very comprehensive set of measurements to study the whole period of this storm, following day by day for the magnetic indices and solar wind parameters and relating its consequences on ionospheric plasma parameters. We use EISCAT radar data from Tromsø and Svalbard stations to see the response in plasma parameters at different altitudes, riometer data for cosmic noise absorption, and IMAGE magnetometers to see the intensities of auroral electrojets. TomoScand ionospheric tomography provides us with electron densities over a wide region in Scandinavia and AMPERE data the global field-aligned currents. We identified 13 local substorms in the Scandinavian sector from the IL (IMAGE lower) index. Altogether, there were 11 global substorms, for which the AE index reaches 1000 nT. We discuss the development of currents, as well as E and D region precipitation during the course of this long-duration storm and compare local versus global behavior.

Meteoroids entering the Earth’s atmosphere produce ionized trails, which are detectable by radio sounding. Majority of such radar detections are the echoes from cylindrical ionized trails, which occur if the radar beam is perpendicular to the trail, i.e., the reflection is specular. Typically such echoes detected by VHF radars last less than one second. However, sometimes meteor radars (MR) observe unusually long-lived meteor echoes and these echoes are non-specular (LLNS echoes). The LLNS echoes last up to several tens of seconds and show highly variable amplitude of the radar return. The LLNS echoes are received from the non-field-aligned irregularities of ionization generated along trails of bright meteors and it is believed that key role in their generation belongs to the aerosol particles arising due to fragmentation and burning of large meteoroids. The occurrence and height distributions of LLNS are studied using MR observations at Sodankylä Geophysical Observatory (SGO, 67° 22' N, 26° 38' E, Finland) during 2008-2019. Two parameters are analyzed: the percentage and height distribution of LLNS echoes. These LLNS echoes constitute about 2% of all MR detections. However during certain meteor showers (Geminids, Perseids, Quadrantids, Arietids or/and Daytime ζ-Perseids, and Lyrids) the percentage of LLNS echoes is noticeably higher (about 6, 5, 4, 4, and 3%, respectively). Typically, the LLNSs occur ~2 km higher than other echoes (in June-July the height difference is reduced to ~1 km). Due to this elevation, a larger percentage of LLNSs is manifested as an upward shift of the height distribution of meteor trails during meteor showers. Moreover, during Lyrids, η-Aquariids, Perseids, Orionids, and Leonids the LLNS echoes occur noticeably, up to 3-6 km, higher than the echoes from other types of trails. Thus, enhanced heights of meteor detections during major meteor showers (Quadrantids, Lyrids, η-Aquariids, Arietids or/and Daytime ζ-Perseids, Perseids, Orionids, Leonids, and Geminids) are predominantly due to long-lived non-specular echoes from the non-field-aligned irregularities associated with large meteoroids.

Very low frequency (VLF) auroral hiss at Kannuslehto (KAN), Finland, was analyzed with reference to the progress of 98 isolated magnetic substorms measured during the winter months of 2015–2018. Of these, 91 were accompanied by auroral hiss during the substorm growth phase. No auroral hiss was recorded during the expansion and recovery phases. We found that auroral hiss was observed under rising polar cap (PC) index, showing an increased solar wind energy input into the magnetosphere during the substorm growth phase. We also found that in 58 of the 65 events studied, KAN was located in the vicinity of enhanced field‐aligned currents (FACs) during auroral hiss occurrence. For the first time, it was established that auroral VLF hiss generation in the equatorial part of the auroral oval is a typical signature of a substorm growth phase. Plain Language Summary Auroral hiss is a well‐known type of nighttime natural VLF emission with a noise‐like structure generated by the Cherenkov instability of precipitating soft electrons above the ionosphere. Auroral hiss occurrence up to 39 kHz was studied in the equatorward region of the auroral oval at the Finnish station Kannuslehto (KAN, MLAT = 64.2°N) during 11 winter months in 2015–2018. During this time interval, 98 isolated and rather powerful magnetic substorms were recorded over Scandinavia. In 93% of the substorms studied, an auroral VLF hiss was recorded at the same time as enhancement of field‐aligned currents (FACs). FACs are caused by soft electron precipitation which could be a plausible source of the auroral VLF hiss generation. For the first time, it was found that auroral VLF hiss occurrence in the equatorward region of the auroral oval is a typical signature of the substorm growth phase.

The inter-annual variability, climatological mean wind and tide fields in the northern polar mesosphere/lower thermosphere region of 82–98 km height are studied using observations by the meteor radar which has operated continuously during solar cycle 24 ( from December 2008 onward) at the Sodankyla Geophysical Observatory (67N, 26E). Summer mean zonal winds are characterized by westward flow, up to 25 m/s, at lower heights and eastward flow, up to 30 m/s, at upper heights. In the winter an eastward flow, up to 10 m/s, dominates at all heights. The meridional winds are characterized by a relatively weak poleward flow (few m/s) in the winter and equatorward flow in the summer, with a jet core (∼15 m/s) located slightly below 90 km. These systematically varying winds are dominated by the semidiurnal tides. The largest amplitudes, up to 30 m/s, are observed at higher altitudes in winter and a secondary maximum is seen in August–September. The diurnal tides are almost a factor of two weaker and peak in summer. The variability of individual years is dominated by the winter perturbations. During the period of observations major sudden stratospheric warmings (SSW) occurred in January 2009 and 2013. During these events the wind fields were strongly modified. The lowest altitude eastward winds maximized up to 25 m/s, that is by more twice that of the non-SSW years. The poleward flow considerably increases (up 10 m/s) and extends from the lower heights throughout the whole altitude range. The annual pattern in temperature at ∼90 km height over Sodankyla consists of warm winters (up to 200 K) and cold summers (∼120 K).

Two Rayleigh lidars were employed at a southern-hemisphere mid-latitude site in New Zealand (45°S) and a northern-hemisphere high-latitude site in Finland (67°N) in order to observe gravity waves between 30 and 85 km altitude under wintertime conditions. Two-dimensional wavelet analysis is used to analyze temperature perturbations caused by gravity waves and to determine their vertical wavelengths and phase progression. In both datasets, upward phase progression waves occur frequently between 30 and 85 km altitude. Six cases of large-amplitude wave packets are selected which exhibit upward phase progression in the stratosphere and/or mesosphere. We argue that these wave packets propagate downward and we discuss possible wave generation mechanisms. Spectral analysis reveals that superpositions of two or three wave packets are common. Furthermore, their characteristics often match those of upward-propagating waves which are observed at the same time or earlier. In the dataset means, the contribution of upward phase progression waves to the potential energy density E p is largest in the lower stratosphere above Finland. There, E p of upward and downward phase progression waves is comparable. At 85 km one third of the potential energy carried by propagating waves is attributed to upward phase progression waves. In some cases E p of upward phase progression waves far exceeds E p of downward phase progression waves. The downward-propagating waves might be generated in situ in the middle atmosphere or arise from reflection of upward-propagating waves.

This study investigates the contribution of energetic (E > 30 keV) particle precipitation during a pulsating aurora event over Kilpisjarvi (L = 6.2) on 26 February 2014. It is based on the comparison of auroral blue-line emission (427.8 nm) data from an all-sky camera and cosmic noise absorption (CNA) data obtained from a multi-beam experiment of the Kilpisjarvi Atmospheric Imaging Receiver Array (KAIRA) riometer. The data sets are compared for three KAIRA beams close to magnetic zenith. Results show a clear correlation between the measured CNA and the auroral blue-line emission during the event, for each beam. In addition, individual pulsations are observed for the first time in the cosmic noise absorption data measured by KAIRA, and are found to be close-to-identical to the optical pulsations. This suggests that the modulation of electron precipitation during pulsating aurora takes place in a consistent way over a broad range of energies.

On 9 December 2009 at about 07 UT a solid propellant 36.8 metric tons ballistic rocket was self-destroyed at an altitude of 170-260 km, at a distance of about 500 km to the east of Sodankyla Geophysical Observatory (SGO, 67° 22' N, 26° 38' E, Finland). After 2-3 hours the SGO meteor radar (operating at a frequency 36.9 MHz) received unusual echoes, which indicate turbulence of ionospheric plasma (irregularities of electron density) with a temporal scale of the order of 0.1 s and a spatial scale of a few to tens meters. The turbulence occurred at a height of about 80 km and was localized in several areas of about 60 km in horizontal scale. Line-of-sight velocity of the irregularities was up to a few tens meters of per second toward the radar. The event occurred in the winter high-latitude mesosphere during extremely low solar and geomagnetic activity. Aerosol particles caused by the missile explosion played a key role in producing the electron density irregularities. As a possible explanation, we suggest that sedimented by gravity and, hence, moving with respect to the air, charged aerosol particles (presumably composed of aluminum oxide) might produce meter scale irregularities (electrostatic waves) via dissipative instability, which is a mechanism analogous to that of the resistive beam-plasma instability.

The effect of solar wind high-speed streams (HSSs) on energetic particle precipitation at auroral and subauroral latitudes (L = 3.8–5.7) is studied by using cosmic noise absorption (CNA) data measured by the Finnish riometer chain during 95 HSS events occurring between 2006 and 2008. The data are divided into “long” and “short” HSS events, depending on whether the maximum solar wind speed is reached within 24 h or later after the arrival of the corotating interaction region (CIR) at the bow shock. We find that CNA is more frequent during long events and extends to subauroral latitudes, unlike during short events. CNA is observed for at least 4 days after the CIR arrival during long events, and only 3 days during short events. In addition, CNA is divided into three categories, depending on whether it is associated with local substorm activity, with ultra-low-frequency (ULF) wave activity, or neither of these. Substorm-type CNA dominates in the 21–06 magnetic local time (MLT) sector, while ULF-type CNA dominates from morning to afternoon and follows the daily SYM-H index variations. This indicates the importance of having energetic (E > 30 keV) electrons available for interacting with the very-low-frequency (VLF) chorus waves, which may be modulated by ULF waves. Finally, we find a correlation between ULF-type CNA on the dayside and substorm activity on the nightside with a 30-min delay, suggesting that substorm injections energize electrons, which then drift to the morning and dayside, where they precipitate into the ionosphere.

The Tenth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper atmospheric sciences, Wed. 4 Dec. /Entrance Hall (1st floor) at National Institute of Polar Research (NIPR)