Analysis of fluctuations of satellite radio signals scattered on small-scale inhomogeneities in the F-region of the ionosphere and received by a ground receiver in Moscow shows that both a single maximum and two or three maxima can be observed in the latitudinal profile of the variance of the logarithm of the relative amplitude. The orientation of the transverse anisotropy of the inhomogeneities is determined and compared to the direction of the drift, obtained by the DPS-4 ionosonde using the LocalDrift software.

A technique for refining unit cell parameters of crystals belonging to arbitrary systems on modern single-crystal diffractometers is described. The technique is based on the 2D-detector position calibration. The elementary orthorhombic unit cell parameters of the α-33S single crystal have been refined. The anisotropy of change in the parameters in the range of 90–350 K has been analyzed. The relative increase in the parameter c is shown to be 6.4

Предложен ряд подходов к уточнению параметров элементарных ячеек монокристаллов на серийных лабораторных дифрактометрах, оснащенных 2D-детекторами, и соответствующий математический аппарат для обработки полученных результатов. Их использование продемонстрировано на примере ромбических кристаллов LiCsMo3O10, выращенных низкоградиентным методом Чохральского при двух разных ориентациях затравок, рентгеноструктурный анализ показал их тождественность. Показано, что параметры элементарных ячеек кристаллов совпадают в пределах оцененной погрешности измерений. Проведено исследование температурного хода параметров элементарной ячейки в диапазоне температур 90-450 К, установлен вид элементов тензора теплового расширения. Обсуждены изменения структурных характеристик LiCsMo3O10 в указанном температурном диапазоне.

A technique for arbitrary symmetry crystals unit cell parameters refining on modern single-crystal diffractometers is described. The technique is based on the 2D detector position calibration. The elementary orthorhombic unit cell parameters of the α-33S single crystal have been refined. The anisotropy of parameters changes in the range of 90–350 K has been studied. It is shown that the relative increase in parameter c is 6.4%. The obtained dependences are approximated by second–third degree polynomials. The absolute increase in cell volume is 138.4 A3, and the relative increase is 4.3%. The temperature dependencies of the thermal expansion tensor elements has been refined. The coefficients of α-33S thermal expansion tensor at the room temperature are: α11 = 15.35 × 10–5, α22 = 8.56 × 10–5, α33 = 9.12 × 10–5 К–1.

Исследованы вариации ионосферных и термосферных параметров в северном полушарии на основе анализа данных высоко- и среднеширотной цепей евразийских ионозондов и приемников GPS/ГЛОНАСС в период сильной магнитной бури в октябре 2016 г. На главной фазе магнитной бури над Евразией наблюдался переход от положительного к отрицательному эффекту ионосферной бури как в высоких, так и средних широтах. Эффект отрицательной ионосферной бури на восстановительной фазе был вызван образованием обширных областей атмосферного газа с пониженным отношением концентраций [O]/[N2] над регионом высоких и средних широт Евразии. The variations of ionospheric and thermospheric parameters in the northern hemisphere were investigated based on the analysis of data from high- and mid-latitude Eurasian ionosonde chains and GPS/GLONASS receivers during a strong geomagnetic storm in October 2016. In the main phase of the geomagnetic storm over Eurasia, a transition from a positive to a negative ionospheric storm effect was observed in both high and mid-latitudes. The negative ionospheric storm effect during the recovery phase was caused by the formation of extensive areas of atmospheric gas with reduced concentration ratio [O]/[N2] over high and mid-latitude regions of Eurasia.

We have analyzed spatial and temporal variations in ionospheric parameters over high and middle latitudes of Eurasia, using data from chains of high- and mid-latitude ionosondes during a severe magnetic storm in March 2015. To analyze the ionospheric response to the severe geomagnetic disturbance of solar cycle 24, we have employed ionosonde data on hourly average values of the critical frequency foF2 of the ionospheric F2 layer, the critical frequency of the sporadic layer foEs, and the minimum reflection frequency fmin. There are strong latitudinal and longitudinal differences between the features of temporal variations in the analyzed ionospheric parameters both under quiet conditions before the magnetic storm onset and during the storm. We discuss possible causes of the observed spatial variations in ionospheric parameters. The source of spatio-temporal variations in ionospheric ionization parameters may be inhomogeneities generated in the high-latitude ionosphere under conditions of increased helio-geomagnetic activity. During the magnetic storm main and recovery phases, periods of blackouts of radio signals from ionosondes were observed at both high and middle latitudes. During these periods, there was a significant increase in the absorption of radio waves used in ionosonde sounding, as well as in the frequency of occurrence of screening sporadic Es layers. The long-term effect of the negative ionospheric storm over high and middle latitudes of Europe is explained by the movement of the vast region of the reduced density ratio [O]/[N2] at thermosphere heights from the Far East and Siberia westward to Europe during the late recovery phase of the magnetic storm. Increased ionization of the ionospheric F2 layer with foF2 exceeding the level for quiet days before the onset of the magnetic disturbance over the vast region of Eastern, Western Siberia and Eastern Europe after the end of the magnetic storm in March 2015 is a manifestation of the aftereffect of magnetic storms. The increase in ionization was especially pronounced, as measured by the chain of mid-latitude ionosondes.

We propose a number of approaches for refining unit cell parameters of single crystals using serial laboratory diffractometers equipped with 2D detectors and discuss the corresponding mathematical apparatus for processing the obtained results. The approaches are demonstrated on the example of orthorhombic LiCsMo 3 O 10 crystals grown by the low-gradient Czochralski method using two different seed orientations but being identical in terms of the XRD analysis. It is shown that unit cell parameters of the crystals coincide within the estimated measurement error. The temperature dependence of unit cell parameters in the temperature range 90-450 K is studied, the view of the elements of the thermal expansion tensor is determined. The changes in the structural characteristics of LiCsMo 3 O 10 in the studied temperature range are discussed.

Nine years of ionograms from a higher mid-latitude ionospheric station (Moscow) are analyzed, by applying the ‘height–time–intensity’ (HTI) technique along with Spectrum (Lomb periodogram) analysis with the aim to investigate the daily and seasonal variability of sporadic E (Es) and intermediate descending layers (IDLs). Es and IDL traces are observed over Moscow, which are characterized by a 12-h periodicity prevailing throughout the year. Shorter periodicities in IDL and Es occurrence are also observed. A 6-h periodicity in Es and IDL dominates during November and December, while an 8-h periodicity is found mainly from October to February for IDL and in July for Es. These periodicities are primarily induced by the semi-, quarter- and terdiurnal thermospheric tides, respectively. Our results also establish the systematic and widespread manifestation of shorter-scale (4.8- and 4-h) periodicities observed mainly for IDL and less frequently for Es only during December and January, in the nine years considered, which is most probably linked to higher-order solar tides. Graphical Abstract

New techniques for the calibration of single-crystal diffractometers equipped with a 2D detector are proposed to improve the accuracy of measuring the unit cell parameters. According to these methods, reflection profiles are processed using the original SearchXY-2θ program, and the detector position is refined by recording an external reference. Details of the calibration of diffractometers equipped with a three- or four-circle goniometer are discussed. The use of reflections with 2θ ≈ 100° when refining the unit cell parameters of a test InSb single crystal allowed measuring parameter a of the cubic unit cell with a relative error of 7·10 –5 . The possibilities of the techniques are also demonstrated on the measurements of the a ( T ) dependence for InSb in the range of 90-490 K.

A three-year study (2017, 2020, 2021) of diurnal and seasonal characteristics of nighttime spread F over eight Digisonde European stations covering an extended latitude and longitude range of the European mid-latitude ionosphere is presented. The findings of the study underline the significant seasonal differences between higher and lower latitude stations which is in line with the findings of previous studies. Moreover, we attempt to correlate spread F activity and Travelling Ionospheric Disturbances (TID) over Digisondes, identified on GPS detrended TEC maps from the DRAWING-TEC project at 10-min resolution for 2017. The similarity in spread F activity at nearby stations supports the hypothesis that spread F development over nearby stations can be attributed to common TID activity affecting both stations.

Предложены новые методики калибровки монокристальных дифрактометров, оснащенных 2D-детектором для повышения точности измерения параметров элементарной ячейки. В основе методики лежит обработка профилей дифракционных рефлексов по оригинальной программе SearchXY-2q и уточнение положения детектора путем съемки внешнего эталона. Обсуждаются особенности калибровки дифрактометров, оснащенных трех- или четырехкружным гониометрами. Использование рефлексов с 2q » 100°, при уточнении параметров элементарной ячейки тестового монокристалла InSb позволило провести измерения параметра элементарной кубической ячейки а с относительной погрешностью 7´10-5. Возможности методик также проиллюстрированы результатами измерения зависимостей а(Т) InSb в интервале 90-490 К.

On 1-2 November several Earth- directed CMEs (coronal mass ejections) erupted from the Sun. Subsequently a CME from November 2 overtook the CME from November 1, and the combined event was first detected as a shock wave at 19:57 UTC by the DSCOVR solar wind monitor. Subsequently a strong compression of Earth's magnetosphere due to this shock was detected at 21:29 UTC causing a G1 geomagnetic storm which later developed into a G2 geomagnetic storm and eventually to a G3 (strong storm level). In this study we investigate the ionospheric response over a narrow longitude range over the European sector during 3-4 November 2021.

Описана методика измерения параметров элементарной ячейки, включающая калибровку гониометра по внешнему эталону, обработку 2D-профиля дифракционного отражения и введение поправок. Изучено изменение параметров элементарной ячейки монокристалла Ag0.39Li0.61GaSe2 в интервале температур от 100 до 480 К. При общем увеличении объема элементарной тетрагональной ячейки на 1%, параметр а увеличивается на 0.6%, а параметр с уменьшается на 0.3%.

We collate the drift directions of medium-scale irregularities (MSI) and the orientation of the cross-field anisotropy of small-scale irregularities (SSI) in the F region of the mid-latitude ionosphere. Experimental data were obtained in May–December 2009 in quiet geomagnetic conditions by two independent methods, namely, ionospheric transmission radio sounding from spacecraft (ground-based receiver at the Lomonosov Moscow State University) and radar (DPS-4 ionosonde at IZMIRAN). Using the new LocalDrift program, which permits calculating the direction and velocity of drift in any selected area of the sky map, the drift characteristics are determined in exactly those spatially bounded areas where small-scale irregularities have been studied by transmission radio sounding. It is shown that small-scale field-aligned irregularities are transversely anisotropic. In most cases, they are elongated in a plane perpendicular to the geomagnetic field along the drift direction of medium-scale irregularities. These statements are valid if the experimental data are obtained simultaneously and in the same local region of the ionosphere.

The dependence of scattering in the F2 layer on geomagnetic activity and solar wind parameters is investigated using the example of two isolated strong magnetic storms on March 17 and June 22–23, 2015. It is shown that Moscow was in the region of the auroral oval precipitations during the magnetic storms, and the recorded F- scattering was the result of the superpositioning of several processes. The dependence of F -scattering recorded in the main phase of the June magnetic storm on indices AL and Dst is determined along with the dynamic pressure of the solar wind.

We have studied variations in ionospheric and geomagnetic parameters in the Northern Hemisphere during a series of magnetic storms in March 2012 by analyzing data from the Eurasian mid-latitude ionosonde chain, mid- and high-latitude chains of magnetometers of the global network INTERMAGNET. We have confirmed manifestations of the longitude inhomogeneity of ionospheric effects, which is associated with the irregular structure of the longitudinal variability of geomagnetic field components. The complex physics of the long magnetically disturbed period in March 2012 with switching between positive and negative phases of the ionospheric storm in the same period of the magnetic storm for different spatial regions is emphasized. The change in the effects of the ionospheric storm during this period might have been associated with the superposition in the mid-latitude region of the competing processes affecting the ionospheric ionization whose sources were in the auroral and equatorial ionosphere. We have compared the scenarios for the development of ionospheric disturbances under equinox conditions during magnetic storms in March 2012, October 2016, and March 2015.

Different orientations of the cross-field anisotropy of small-scale inhomogeneities in the F-region of the ionosphere over the Moscow region in January–March 2012 are determined via radio probing. The direction of the drift of medium-sized inhomogeneities in space is determined simultaneously via radiolocation. The agreement and differences between the experimental data are analyzed.

The characteristics of irregular ionospheric structures are studied with two different methods in the course of two independent, long-term experiments. The parameters of the anisotropy of small-scale irregularities of electron density in the F region of the midlatitude ionosphere, as well as the spatial position of local areas in which these parameters have been measured, are determined via radio surveys of the ionosphere with signals from artificial Earth satellites (AESs) with the subsequent mathematical processing of variations of the amplitude of the radio signal recorded by a ground-based receiver (located at the Moscow State University) on different days and at times of day (mainly at night). The approach to the processing of sky maps during radio sounding of the irregular ionosphere from the surface of the Earth using the DPS-4 ionosonde (Moscow, Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (IZMIRAN)), which has been improved by the authors, makes it possible to estimate the velocity and direction of the drift of the medium-scale irregularities in the same local areas. Comparison of the results based on AES and ground-based radio sounding (DPS-4) shows that small-scale irregularities in the plane perpendicular to the geomagnetic field extend predominantly along the direction of the drift of medium-scale irregularities if the experimental data were obtained simultaneously and belong to the same limited spatial region of the ionosphere.