Solar Extreme Ultraviolet Irradiance Research Articles

Nowcasting Solar EUV Irradiance With Photospheric Magnetic Fields and the Mg II Index

AbstractA new method to nowcast spectral irradiance in extreme ultraviolet (EUV) and far ultraviolet (FUV) bands is presented here, utilizing only solar photospheric magnetograms and the Mg II index (i.e., the core‐to‐wing ratio). The EUV and FUV modeling outlined here is a direct extension of the SIFT (Solar Indices Forecasting Tool) model, based on Henney et al. (2015, https://doi.org/10.1002/2014sw001118). SIFT estimates solar activity indices using the earth‐side solar photospheric magnetic field sums from global magnetic maps generated by the ADAPT (Air Force Data Assimilative Photospheric Flux Transport) model. Utilizing strong and weak magnetic field sums from ADAPT maps, Henney et al. (2015, https://doi.org/10.1002/2014sw001118) showed that EUV & FUV observations can also be well modeled using this technique. However, the original forecasting method required a recent observation of each SIFT model output to determine and apply a 0‐day offset. The new method described here expands the SIFT and ADAPT modeling to nowcast the observed Mg II index with a Pearson correlation coefficient of 0.982. By correlating the Mg II model‐observation difference with the model‐observation difference in the EUV & FUV channels, Mg II can be used to apply the 0‐day offset correction yielding improvements in modeling each of the 37 studied EUV & FUV bands. With daily global photospheric magnetic maps and Mg II index observations, this study provides an improved method of nowcasting EUV & FUV bands used to drive thermospheric and ionospheric modeling.

Energy Deposition into the Ionosphere during a Solar Flare with Extreme-ultraviolet Late Phase

Solar extreme-ultraviolet (EUV) irradiance is the dominant energy source for ionizing and heating the Earth’s upper atmosphere. It is common to assume that the spectra of different EUV lines have the same trend to fill the solar EUV irradiance gap for modeling purposes due to inadequate EUV irradiance measurements. However, the spectra across the EUV bands may not vary in the same trend. The flare radiation energy release in the EUV (10–120 nm) is about twice as much as X-rays (0.1–10 nm) during flare interval ∼03–06 UT on 2012 October 23. By assimilating the observed nonuniform varying, time-dependent, and high-resolution solar spectrum from the Solar Dynamics Observatory mission into the modeling framework, we provide the first direct evidence of nonuniform varying solar EUV fluxes during the solar flare EUV late phase (ELP) having appreciable effects on the dayside ionosphere. The total EUV radiation energy release (5.838 × 1028 erg) during the flare ELP is larger than that (5.698 × 1028 erg) during the flare main phase. The ELP of an X1.8-class solar flare on 2012 October 23 can increase the dayside ionospheric density at the subsolar point by ∼5 TECU and the ionospheric density enhancements extend from the bottom to the peak of the F2 region at low latitudes with relative changes ranging from ∼20% to ∼100%. Our results highlight the importance of incorporating a realistic, high spectral and temporal resolution solar irradiance spectrum into numerical models to capture the observed time-varying ionospheric response to solar flares.

Statistical Properties of Plateau‐Like Turbulence Spectra in the Martian Magnetosheath: MAVEN Observations

AbstractThe Martian magnetosheath provides us with a natural laboratory to study plasma turbulence in the presence of pickup ions and locally generated instabilities. Unlike the typical magnetic‐field spectra with a single spectral scaling at magnetohydrodynamics (MHD) scales in Earth's magnetosheath, the magnetic‐field spectra in the Martian magnetosheath during 4 years of Mars Atmosphere and Volatile EvolutioN observations frequently present an additional spectral break‐point with a shallow slope at MHD scales which we define as a plateau‐like spectral feature. The average occurrence rate of plateau‐like magnetic‐field spectra is 56.6% of our measurement intervals. At moderate pick‐up angles, the occurrence rate increases to a maximum of ∼70.0%. Furthermore, we present a positive correlation with the local ion density and anti‐correlations with the local βi and the solar Extreme Ultra Violet irradiance. A similar occurrence rate in the quasi‐perpendicular and the quasi‐parallel magnetosheath (60.1% vs. 52.9%) indicates that the plateau‐like spectra are more likely formed locally than in the upstream solar wind. Our results suggest that energy injection from pickup ion driven micro‐instabilities, for example, in the form of proton cyclotron waves, has insufficient time to evolve into a fully developed cascade in such a confined space like the Martian magnetosheath.

The dependence of Martian ion escape on solar EUV irradiance as observed by MAVEN

We analyze the planetary ion, solar wind, interplanetary magnetic field (IMF), and solar extreme ultraviolet (EUV) irradiance data from the NASA Mars Atmosphere and Volatile EvolutioN (MAVEN) mission to quantify the variation in ion escape with solar EUV irradiance. With relatively strict constraints on the upstream solar wind and IMF conditions, we divide the planetary ion data into 4 subsets with different solar EUV conditions to estimate ion escape rates. The results show that the total ion escape rate may increase nonlinearly with solar EUV irradiance and eventually approach an asymptotic limit as EUV increases. Further analysis on different ion species, escape channels, and energy ranges show that the dependence on solar EUV varies between these different ion populations. We also find that the spatial distributions of ion density and velocity vary between high and low solar EUV conditions, which is likely caused by the variations of electromagnetic field distributions. These results suggest that as solar EUV controls the ion production and affects the ion distributions near Mars, it will in turn influence the electromagnetic field distributions and thus affect the acceleration of escaping ions. This feedback mechanism may limit the total ion escape rate as solar EUV increases under constrained solar wind and IMF conditions.

Ionospheric photoelectrons: A lateral thinking approach

This paper presents a personal account of developments in the solution of two related problems that limited the accuracy of ionosphere calculations in the 1980s. The first problem concerns the model-data discrepancies in the ionosphere photoelectron flux spectrum. Early comparisons between measured and modeled data revealed discrepancies in magnitude and shape. A lateral thinking approach revealed that there were problems with two key photoelectron model inputs: namely, the electron impact cross-sections and the solar extreme ultraviolet irradiance. This work led to the development of a widely used EUVAC solar irradiance model for ionosphere electron density calculations. The second problem relates to the neutral winds that are crucial for modeling variations in the ionosphere ion and electron densities. There is a lack of thermosphere neutral wind data because they are difficult to measure. The winds determine the altitude at which the electron density peaks. An accurate solution to this problem was the development of an algorithm that assimilates the altitude of the peak electron density into ionosphere models. This technique works because the altitude of the peak density is very sensitive to variations in the neutral wind.

Quantifying Contributions of External Drivers to the Global Ionospheric State

AbstractTo advance our understanding of the global response of the ionospheric total electron content (TEC) to various external drivers, we apply entropy‐based information theory to quantify contributions of solar, interplanetary, and lower atmospheric drivers to the global ionospheric state described by the Global Ionospheric Map (GIM). By computing normalized transfer entropy on 18 years of GIM TEC, F10.7, solar wind, and lower atmospheric data, we obtain the predictive information transfer from the present drivers to the global ionospheric state at various future times. We find that the solar extreme ultraviolet (EUV) irradiance dominates the information transfer within 3 days into the future, while the lower atmospheric migrating tidal sources dominate beyond 3 days into the future. The maximum information transfer from individual drivers reveals the maximum contributions from the drivers to the global ionospheric state. Among all drivers considered, the lower atmospheric migrating tidal sources contribute most. The solar EUV irradiance and tropospheric deep convection are secondary drivers with comparable contributions at about half of the contribution from migrating tidal sources. The interplanetary driving contributes the least to the global ionospheric state during both geomagnetic storm and quiet time, even though the contribution from the interplanetary magnetic field can enhance four to six times during geomagnetic storm time than quiet time.

PROBA2 LYRA Occultations: Thermospheric Temperature and Composition, Sensitivity to EUV Forcing, and Comparisons With Mars

AbstractA method for retrieving temperature and composition from 150 to 350 km in Earth's thermosphere using total number density measurements made via extreme ultraviolet (EUV) solar occultations by the Project for OnBoard Autonomy 2/Large Yield Radiometer (PROBA2/LYRA) instrument is presented. Systematic and random uncertainties are calculated and found to be less than 5% for the temperature measurements and 5%–20% for the composition measurements. Regression coefficients relating both temperature and the [O]/[N2] abundance ratio with EUV irradiance at 150, 275, and 350 km are reported. Additionally, it is shown that the altitude where [O] equals [N2] decreases with increasing solar EUV irradiance, an effect attributed to thermal expansion. Temperatures from 2010 to 2017 are compared with estimates from the MSIS empirical model and show good agreement at the dawn terminator but LYRA is markedly cooler at the dusk terminator, with the MSIS‐LYRA temperature difference increasing with solar activity. Anthropogenic cooling can explain this discrepancy at periods of lower solar activity, but the divergence of temperature with increasing solar activity remains unexplained. LYRA measurements of the exospheric temperature sensitivity to EUV irradiance are compared with contemporaneous measurements made at Mars, showing that the exospheric temperature at Mars is approximately half as sensitive to EUV variability as that of Earth.

Solar Extreme Ultraviolet Irradiance Uncertainties for Planetary Studies

AbstractAccurate estimates of extreme ultraviolet (EUV) irradiance are needed in order to understand the dynamical, chemical, and plasma processes occurring in planetary upper and tenuous atmospheres. Most studies rely on irradiance measurements made at Earth, which are extrapolated to the location of interest. The Mars Atmosphere and Volatile Evolution (MAVEN) orbiter includes the Extreme Ultraviolet Monitor (EUVM) instrument to measure the solar EUV irradiance in situ at Mars, which is used in this study to quantify the error introduced when phase‐shifting EUV measurements from Earth to other locations in the solar system. The MAVEN/EUVM solar soft X‐Ray (SXR) and Lyman‐α measurements are compared with analogous measurements made from Earth to characterize the typical error introduced when phase‐shifting solar EUV irradiance measurements made from Earth to other points in the solar system according to the 27.27 day synodic solar rotation period. The phase‐shifting error, εps, measured at SXR and Lyman‐α wavelengths are extrapolated to the full EUV spectrum by assuming it is proportional to the variability that occurs over the 27‐day timescale of solar rotation. Values for εps as a function of wavelength are reported and used to find the typical error for estimates of photoionization frequencies of some major species found in planetary upper atmospheres. Measuring EUV irradiance in situ reduces the random uncertainty by approximately half of that expected from phase shifting irradiances to the point of interest from Earth. These findings indicate that estimates of EUV induced variability in planetary atmospheres are highly uncertain at timescales of ∼10 days for large phase angles.

Multi‐instrumental Observations of the Quasi‐16‐Day Variations From the Lower Thermosphere to the Topside Ionosphere in the Low‐Latitude Eastern Asian Sector During the 2017 Sudden Stratospheric Warming Event

AbstractVariations of the low‐latitude ionosphere in the eastern Asian sector during the 2017 sudden stratospheric warming (SSW) were studied with multi‐instrumental observations that correspond to different altitudes. Specifically, the variations of the topside ionosphere as high as over 830 km were investigated with data from the Swarm B satellite (~500 km), the Defense Meteorological Satellite Program F15 satellite (~830 km), and the Meteorological Operational satellite‐A (~830 km). The main results are as follows. (1) Simultaneous variations were detected in the ionospheric parameters from the E region to the topside ionosphere around the first peak warming of the 2017 SSW. (2) These variations exhibited similar quasi‐16‐day (Q16D; ~14.5‐day) periods, and these periods were most significant just before the first peak warming. (3) These simultaneous Q16D variations were not due to the solar extreme ultraviolet irradiance or geomagnetic activities but were probably driven from below, by planetary waves or semidiurnal lunar tides that enhanced during the SSW. (4) The Q16D variation of the topside ionospheric electron density at ~830 km was probably driven not only by the upward mapping electric field modulated in the E region dynamo but also by the electric field modulated in the F region dynamo.

The Use of Monthly Mean Average for Investigating the Presence of Hysteresis and Long‐Term Trends in Ionospheric NmF2

AbstractYearly averaging is a basic preprocessing of ionospheric data to smooth out the short‐term, cyclic variations in the observations. However, we find that the use of yearly (running) average method probably leads to a biased evaluated relation between the ionospheric parameters (e.g., 2 peak electron density, ) and the solar extreme ultraviolet (EUV) irradiance. The bias is essentially related to the annual/seasonal variations of the ionosphere, which means that the ionospheric sensitivity to the solar EUV irradiance varies with season and the same solar input can produce different ionization levels in different months/seasons. The yearly method simply averages the observations of different seasons, leading to a biased yearly ‐EUV relation, which will further affect the estimation of the ionospheric hysteresis (different ‐EUV relation in the solar rising and declining phase). Also, the extraction of long‐term trends in the ionosphere will be more uncertain if using a regression approach based on the biased ‐EUV relation. In conclusion, we suggest to do the analysis month by month (using monthly average method) to properly deal with the annual/seasonal variations of the ionosphere, and to obtain accurate estimation of the hysteresis and long‐term trends. Though both the yearly and monthly methods were used in precedent works, the bias introduced by the yearly average method has not been fully recognized prior to this study.

The Martian Bow Shock Over Solar Cycle 23–24 as Observed by the Mars Express Mission

AbstractThe Martian bow shock position is known to be correlated with solar extreme ultraviolet irradiance. Since this parameter is also correlated with the evolution of the solar cycle, it is expected that the Martian bow shock position should also vary over such a period. However, previous reports on this topic have often proved contradictory. Using 13 years of observations of the Martian bow shock by the Mars Express mission over the period 2004 to 2017, we report that the Martian bow shock position does vary over the solar cycle. Over this period, our analysis shows the bow shock position to increase on average by 7% between the solar minimum and maximum phases of solar cycle 23–24, which could be even larger for more extreme previous solar cycles. We show that both annual and solar cycle variations play major roles in the location of the bow shock at Mars.

Solar Rotation Period Driven Modulations of Plasmaspheric Density and Convective Electric Field in the Inner Magnetosphere

AbstractThis paper presents the first analysis of Van Allen Probes measurements of the cold plasma density and electric field in the inner magnetosphere to show that intervals of strong modulation at the solar rotation period occur in the locations of the outer plasmasphere and plasmapause (~0.7 RE peak‐to‐peak), in the large‐scale electric field (~0.24 mV/m peak‐to‐peak), and in the cold plasma density (~250 to ~70 cm−3 peak‐to‐peak). Solar rotation modulation of the inner magnetosphere is more apparent in the declining phase of the solar cycle than near solar maximum. The periodicities in these parameters are compared to solar extreme ultraviolet irradiance, solar wind dawn‐dusk electric field, and Kp. The variations in the plasmapause location at the solar rotation period anticorrelate with solar wind electric field, magnetospheric electric field, and Kp, but not with extreme ultraviolet irradiance, indicating that convective erosion is the dominant physical process controlling the plasmapause at these timescales.

One‐ to 10‐Day Forecasts of Ionospheric Total Electron Content Using a Statistical Model

AbstractA new, rapid, nonassimilative technique is demonstrated for forecasting the ionosphere's vertical total electron content (TEC) on time scales longer than 1 day. The approach uses a statistical model constructed by regressing solar extreme ultraviolet irradiance and seasonal, diurnal, and geomagnetic predictors at multiple lags against the 2‐hourly International Global Navigation Satellite Systems Service observations, with a formulation that accounts for solar modulation of the seasonal oscillations and solar and seasonal modulation of the diurnal oscillations. Solar irradiance inputs to the statistical model are forecast at successive 2‐hr intervals from 1999 to 2015 using an autoregressive model of irradiance variations during the prior 100 days. As the forecast time increment increases from 1 to 10 days, the average over the globe of the mean absolute error of TEC observations and the forecasts increases from 2.5 to 3.2 TECU (total electron content unit, 1 TECU = 1016 el/m2); the root‐mean‐square error increases from 3.7 to 4.8 TECU. Averaged over the equatorial ionization anomaly region (30°S–30°N) the mean absolute error of the forecasts increases from 3.2 to 4.3 TECU and the root‐mean‐square error increases from 4.6 to 6.4 TECU. The skill of the TEC forecasts at time increments of 3, 5, and 8 days ahead exceeds persistence by 9%, 13%, and 15% and climatology by 9%, 12%, and 10%, respectively. Forecast skill is higher in April than in July. Long‐range, multiyear forecasts from 2018 to 2030 are demonstrated based on current expectations that solar activity in cycle 25 will be comparable to that in cycle 24.

Ionospheric Electron Content During Solar Cycle 23

AbstractThe solar minimum period between solar cycles 23 and 24 has generated extensive study, in part because the changes in the upper atmosphere and ionosphere were so dramatic. Thermospheric density during 2008–2009, at the benchmark 400‐km altitude, was shown to be approximately 30% lower than the previous solar minimum during 1996, in observations and in model simulations. Ionospheric densities were also estimated to be lower, by 10% to 20%. However, earlier analyses using data from the global network of Global Navigation Satellite System receivers did not find any significant reduction in global mean total electron content. Recent work reexamining those data using a limited set of receivers, but with consistent processing, identified a 19% reduction (Emmert et al., 2017, https://doi.org/10.1002/2016JA023680). In this study, we compare model simulations of the thermosphere‐ionosphere system during the 2008–2009 solar minimum to its predecessor and estimate a 16% reduction in global mean total electron content. This is consistent with the neutral thermosphere density change seen in model simulations and in satellite drag observations. In the model simulations, the primary driver is a 10% reduction in solar extreme ultraviolet irradiance, with a smaller contribution from lower geomagnetic activity, and a very small decrement due to increase in atmospheric carbon dioxide.

Estimates of Ionospheric Transport and Ion Loss at Mars

AbstractIon loss from the topside ionosphere of Mars associated with the solar wind interaction makes an important contribution to the loss of volatiles from this planet. Data from NASA's Mars Atmosphere and Volatile Evolution mission combined with theoretical modeling are now helping us to understand the processes involved in the ion loss process. Given the complexity of the solar wind interaction, motivation exists for considering a simple approach to this problem and for understanding how the loss rates might scale with solar wind conditions and solar extreme ultraviolet irradiance. This paper reviews the processes involved in the ionospheric dynamics. Simple analytical and semiempirical expressions for ion flow speeds and ion loss are derived. In agreement with more sophisticated models and with purely empirical studies, it is found that the oxygen loss rate from ion transport is about 5% (i.e., global O ion loss rate of Qion ≈ 4 × 1024 s−1) of the total oxygen loss rate. The ion loss is found to approximately scale as the square root of the solar ionizing photon flux and also as the square root of the solar wind dynamic pressure. Typical ion flow speeds are found to be about 1 km/s in the topside ionosphere near an altitude of 300 km on the dayside. Not surprisingly, the plasma flow speed is found to increase with altitude due to the decreasing ion‐neutral collision frequency.

Linear forecasting of the F10.7 proxy for solar activity

AbstractThe ability to accurately forecast variations in the solar extreme ultraviolet irradiance is important to many aspects of operational space weather. For example, variations in the Sun's radiative output at these wavelengths drive changes in thermospheric density, which perturbs the trajectories of objects in low Earth orbit. Thus, predicting the conjunction of an operational satellite with orbital debris requires accurate forecasts of solar activity. In this paper we present a simple linear forecasting model for the 10.7 cm radio flux (F10.7), a commonly used proxy for solar activity. Comparisons with simple reference models indicate that this linear model has positive skill for all forecast days that we have considered. We also examine the impact of the F10.7 forecast skill on empirical model predictions of thermospheric density and ionospheric total electron content.

The MAVEN EUVM model of solar spectral irradiance variability at Mars: Algorithms and results

AbstractSolar extreme ultraviolet (EUV) radiation is a primary energy input to the Mars atmosphere, causing ionization and driving photochemical processes above approximately 100 km. Because solar EUV radiation varies with wavelength and time, measurements must be spectrally resolved to accurately quantify its impact on the Mars atmosphere. The Mars Atmosphere and Volatile EvolutioN (MAVEN) EUV Monitor (EUVM) measures solar EUV irradiance incident on the Mars atmosphere in three bands. These three bands drive a spectral irradiance variability model called the Flare Irradiance Spectral Model (FISM)‐Mars (FISM‐M) which is an iteration of the FISM model by Chamberlin et al. (2007, 2008) for spectral irradiance at Earth. In this paper, we report the algorithms used to derive FISM‐M and its associated uncertainties, focusing on differences from the original FISM. FISM‐M spectrally resolves the solar EUV irradiance at Mars from 0.5 to 189.5 nm at 1min cadence, and 0.1 nm resolution in the 6–106 nm range or 1 nm resolution otherwise. FISM‐M is suitable for both daily average and flaring spectral irradiance estimates and is based on the linear association of the broadband EUVM measurements with spectral irradiance measurements, including recent high time cadence 0.1 nm resolution measurements from the EUV Variability Experiment (EVE) on the Space Dynamics Observatory (SDO) between 6 and 106 nm. In addition, we present examples of model outputs for EUV irradiance variability due to solar flares, solar rotations, Mars orbit eccentricity, and the solar cycle, between October 2015 and November 2016.

Attribution of interminimum changes in global and hemispheric total electron content

AbstractWe use a new data product of electron column density (total electron content, or TEC) maps to estimate and attribute the interminimum changes (the differences between annual averages centered on the 2008 and 1996 solar minima) in TEC global and hemispheric averages (dividing the globe in three different ways). We attribute the observed changes to corresponding changes in solar and geomagnetic activity. The new TEC map product was constructed with temporally consistent processing, and it resolves some of the apparent inconsistencies of earlier studies. The estimated global average TEC interminimum change is −19.3% ± 1.0% (2σ uncertainty), of which −9.1% is attributable to the interminimum change in solar extreme ultraviolet (EUV) irradiance (as represented by the F10.7 index), −2.2% is attributable to the change in geomagnetic activity (Kp index), and −9.3% remains unattributed. The hemispheric results are very similar to the global results, but the values tend to be slightly larger in the Southern Hemisphere, at low latitudes, and at night, compared to the opposing respective hemispheres. The interminimum changes and temporal variations of thermospheric mass density anomalies (i.e., the difference between the data and the empirical model) are very similar to those of the global and hemispheric TEC residuals, suggesting that they are driven by a common, globally distributed mechanism. Thermospheric composition changes and additional (unobserved) decreases in solar EUV irradiance are possible mechanisms behind the TEC and mass density unattributed changes; we estimate a plausible range of −6% to −13% for the solar EUV irradiance interminimum change.

Hot oxygen escape from Mars: Simple scaling with solar EUV irradiance

AbstractThe evolution of the atmosphere of Mars and the loss of volatiles over the lifetime of the solar system is a key topic in planetary science. An important loss process for atomic species, such as oxygen, is ionospheric photochemical escape. Dissociative recombination of O2+ ions (the major ion species) produces fast oxygen atoms, some of which can escape from the planet. Many theoretical hot O models have been constructed over the years, although a number of uncertainties are present in these models, particularly concerning the elastic cross sections of O atoms with CO2. Recently, the Mars Atmosphere and Volatile Evolution mission has been rapidly improving our understanding of the upper atmosphere and ionosphere of Mars and its interaction with the external environment (e.g., solar wind), allowing a new assessment of this important loss process. The purpose of the current paper is to take a simple analytical approach to the oxygen escape problem in order to (1) study the role that variations in solar radiation or solar wind fluxes could have on escape in a transparent fashion and (2) isolate the effects of uncertainties in oxygen cross sections on the derived oxygen escape rates. In agreement with several more elaborate numerical models, we find that the escape flux is directly proportional to the incident solar extreme ultraviolet irradiance and is inversely proportional to the backscatter elastic cross section. The amount of O lost due to ion transport in the topside ionosphere is found to be about 5–10% of the total.

ВАРИАЦИИ ПЛАЗМЕННЫХ ТЕМПЕРАТУР В ИОНОСФЕРЕ НАД ХАРЬКОВОМ В ТЕЧЕНИЕ ГЛУБОКОГО МИНИМУМА СОЛНЕЧНОЙ АКТИВНОСТИ

PACS numbers: 93.30.Ge, 94.20.Cf, 94.20.Dm, 94.20.Fg Purpose: to present temperature variations of electrons and ions obtained at the Institute of Ionosphere (Kharkiv) with an incoherent scatter radar during the 23rd solar cycle minimum, and compare the obtained results with the corresponding data of IRI-2012 model. Design/methodology/approach : Data are obtained by incoherent scattering. Method of solving the inverse radiophysics problem was used for analysis. Two-dimensional ambiguity function was used for specification. Findings: It has been found that in most cases the IRI-2012 model overestimates the values of electron and ion temperatures as against experimental data. The maximum differences are observed at night and can be about 500 K in summer, and 700 K in winter. Also, the effects of sunrise and sunset in magnetoconjugate area are considered. Conclusions: It is confirmed that to adequately describe processes in the ionosphere it is necessary to have a systematic approach which takes into account interaction in ionospheric regions located in magneto-conjugate area. Such regularities must be taken into account for correction of ionospheric model for the Central European region. Key words: method of incoherent scattering, electron temperature, ion temperature, magneto-conjugate area Manuscript submitted: 22.02.2016 Radio phys. radio astron. 2016, 21(2): 132-140 REFERENCES 1. CHERNOGOR, L. F., 2006. Earth–atmosphere–ionosphere–magnetosphere as an open dynamic nonlinear physical system (Part 1). Nelinejnyj mir. vol. 4, no. 12, pp. 655–697 (in Russian). 2. CHERNOGOR, L. F., 2007. Earth–atmosphere–ionosphere–magnetosphere as an open dynamic nonlinear physical system (Part 2). Nelinejnyj mir. vol. 5, no. 4, pp. 198–231 (in Russian). 3. EVANS, J. V., 1969. Theory and Practice of Ionospheric Study by Thomson Scatter Radar. Proc. 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