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Mikhailov, Andrey V
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Mikhailov, Andrey V
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Mikhailov, Andrey
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- PublicationOpen AccessA New Method to Retrieve Thermospheric Parameters From Daytime Bottom-Side Ne(h) ObservationsA new method to extract neutral composition (O, O2, N2), exospheric temperature Tex, vertical plasma drift ,W, and the total solar Extreme Ultraviolet (EUV) flux with 1050Å from routine ionosonde bottom-side electron density, Ne(h), observations has been proposed. The method can be used around noontime hours for all months of the year at middle latitudes where the ionospheric F-layer is formed by solar EUV radiation. The uncertainty of the retrieved neutral gas density coincides with the announced absolute uncertainty (10-15%) of Challenging Minisatellite Payload/ Space Three-axis Accelerometer for Research mission (CHAMP/STAR ) neutral gas density observations. The method provides statistically significant better results with Mean Relative Deviation (MRD) < 15% ; Root Mean Square (RMS) < 0.5 in a comparison with modern empirical models Mass-Spectrometer-Incoherent-Scatter ( MSISE00), Jacchia-Bowman 2008 (JB2008), and Drag Temperature Model 2013 ( DTM2013) (MRD>15% and RMS> 0.5). The thermospheric parameters retrieved for the St. Patrick Day magnetic storm and two so called Q-disturbance periods are given as an example of the method application. The retrieved neutral gas densities for the St. Patrick Day storm are compared to Swarm-B accelerometer observations. The proposed method may be considered as an useful tool for analyses of the state of the upper atmosphere under various geophysical conditions.
75 30 - PublicationOpen AccessMid-Latitude Daytime F2-Layer Disturbance Mechanism under Extremely Low Solar and Geomagnetic Activity in 2008–2009European near-noontime ionosonde observations were considered during the period of deep solar minimum in 2008–2009 to analyze foF2 perturbations not related to solar and geomagnetic activity. Sudden stratospheric warming (SSWs) events in January 2008 and 2009 were analyzed. An original method was used to retrieve aeronomic parameters from observed electron concentration in the ionospheric F-region. Atomic oxygen was shown to be the main aeronomic parameter responsible both for the observed day-to-day and long-term (during SSWs) foF2 variations. Atomic oxygen rather than neutral temperature mainly controls the decrease of thermospheric neutral gas density in the course of the SSW events. Day-to-day variations of thermospheric circulation and an intensification of eddy diffusion during SSWs are suggested to be the processes changing the atomic oxygen abundance in the upper atmosphere for the periods in question. Recent Global-Scale Observations of the Limb and Disk (GOLD) observations of O/N2 column density confirm the depletion of the atomic oxygen abundance not related to geomagnetic activity during SSWs.
82 6 - PublicationOpen AccessLong-term variations of exospheric temperature inferred from f o F 1 observations: A comparison to ISR Ti trend estimatesJune noontime monthly median f(o)F(1) ionosonde observations at Sodankyla (auroral zone), Juliusruh, and Rome (middle latitudes) were used to retrieve exospheric temperature, Tex long-term variations over the (1958-2015) period. After removing solar activity effects the residual linear trends were found to be small (0.05-0.6)% per decade and statistically insignificant at middle latitudes. Therefore, the revealed Tex long-term variations are mainly due to long-term variations of solar activity, i.e., they have a natural (not anthropogenic) origin. Large trends in ion temperature, Ti inferred from incoherent scatter radar (ISR) observations which the researchers identify with trends in neutral temperature, Tn may be related to the incoherent scatter method routinely based on a fixed model of ion composition (O+/Ne ratio and mean ion mass, correspondingly) under varying geophysical conditions. Mean ion mass number manifests a negative trend at 175 km which should correspond to a negative trend in Ti contrary the results obtained below 200 km with ISRs. Therefore, routine ISR observations based on a fixed model of ion composition may be not appropriate for long-term trend analyses.
98 35 - PublicationOpen AccessPre-storm NmF2 enhancements at middle latitudes: delusion or reality?(2009-03-18)
; ; ;Mikhailov, A. V.; Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Troitsk, Moscow Region 142190, Russia ;Perrone, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia; A critical analysis of recent publications devoted to the NmF2 pre-storm enhancements is performed. There are no convincing arguments that the observed cases of NmF2 enhancements at middle and sub-auroral latitudes bear a relation to the following magnetic storms. In all cases considered the NmF2 pre-storm enhancements were due to previous geomagnetic storms, moderate auroral activity or they presented the class of positive quiet time events (Q-disturbances). Therefore, it is possible to conclude that there is no such an effect as the pre-storm NmF2 enhancement as a phenomenon inalienably related to the following magnetic storm. The observed nighttime NmF2 enhancements at subauroral latitudes may result from plasma transfer from the plasma ring area by meridional thermospheric wind. Enhanced plasmaspheric fluxes into the nighttime F2-region resulted from westward substorm-associated electric fields is another possible source of nighttime NmF2 enhancements. Daytime positive Q-disturbances occurring under very low geomagnetic activity level may be related to the dayside cusp activity.434 247 - PublicationOpen AccessA comparison of Ne (h) model profiles with ground-based and topside sounder observations(2000-02)
; ; ; ; ;Mikhailov, A. V.; Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, Troitsk, Moscow Region, Russia ;Leschinskaya, T. Y.; Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, Troitsk, Moscow Region, Russia ;Miro, G.; National Institute of Aerospace Technology, Mazagón (Huelva), Spain ;Depuev, V. K.; Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, Troitsk, Moscow Region, Russia; ; ; Monthly median empirical models IRI-95 and NeUoG were compared with incoherent scatter EISCAT and Millstone Hill observations as well as with El Arenosillo Digisonde N e (h) bottomside profiles. A comparison was made for various seasons, levels of solar activity, daytime and night-time hours. The results on the topside comparison: 1) the IRI-95 model systematically and strongly overestimates the Ne (h) effective scale height both for daytime and night-time periods especially during maximum and middle solar activity both at EISCAT and Millstone Hill; 2) the NeUoG model on the contrary systematically underestimates the scale height at all levels of solar activity. But the NeUoG model provides much better overall agreement with SD being less by a factor of 1.5-1.7 in comparison with the IRI-95 model results. The results on the bottom-side comparison: 1) the IRI-95 accuracy is different for daytime and night-time hours, being much worse for the night-time; 2) the NeUoG model similar to IRI-95 demonstrates much worse accuracy for the night-time hours; 3) the NeUoG model demonstrates no advantages over the IRI-95 model in the bottomside N e (h) description. A new simple TopN e model for the N e (h) topside distribution based on the EISCAT and Millstone Hill observations is proposed. The model is supposed to be normalized by the observed hmF 2 and NmF 2 values and is valid below a 600 km height. The TopN e model provides good approximation accuracy over EISCAT and Millstone Hill observations. A comparison with the independent Intercosmos-19 topside sounder observations is given.138 440 - PublicationRestrictedFORMOSAT-3/COSMIC E region observations and daytime foE at middle latitudes(2011-06-08)
; ; ; ;Perrone, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Mikhailov, A. V.; Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Troitsk, Russia ;Korsunova, L. P.; Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Troitsk, Russia; ; Ionosonde observations at Rome and Gibilmanna (Sicily) for some months of 2006–2007 were analyzed in the connection with recent COSMIC NmE results. Italy was completely located in the NmE enhanced zone according to COSMIC observations for the periods in question. COSMIC‐observed NmE values in the NmE enhanced zone do not coincide with NmE scaled from ionograms in accordance with the URSI Recommendations, but the IRI model correctly describes monthly median NmE contrary to the Chu et al. (2009) conclusion. Three month averaged COSMIC NmE values turn out to be close to monthly median NmE corresponding to the blanketing frequency fbEs. A conclusion is made that sporadic E practically permanently existing during daytime hours in summer strongly contributes to NmE observed by COSMIC. Possible reasons for the occurrence of the NmE enhanced zones at middle latitudes are discussed.317 29 - PublicationOpen AccessSolar activity impact on the Earth’s upper atmosphere(2013-12)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Kutiev, I.; National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Tsagouri, I.; Institute for Space Applications and Remote Sensing, National Observatory of Athens, 15236 Mount Penteli, Greece ;Perrone, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pancheva, D.; National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Mukhtarov, P.; National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Mikhailov, A.; Institute of Terrestrial Magnetism, Ionosphere, and Radio Propagation, Russian Academy of Sciences, 142190 Troitsk, Moskovskaya obl., Russia 5 Institute of Atmospheric Physics ASCR, 14131 Prague, Czech Republic 6 Institute of Communications and Navigation, German Aerospace Center, 51147 Cologne, Germany 7 Ebro Observatory, University Ramon Llull, CSIC, E-43520 Roquetes, Spain 8 Dipartimento di Fisica, Universita` degli Studi di Roma, 00185 Rome, Italy 9 Atmospheric Sounding Station ;Lastovicka, J.; Institute of Atmospheric Physics ASCR, 14131 Prague, Czech Republic ;Jakowski, N.; Institute of Communications and Navigation, German Aerospace Center, 51147 Cologne, Germany ;Buresova, D.; Institute of Atmospheric Physics ASCR, 14131 Prague, Czech Republic ;Blanch, E.; Ebro Observatory, University Ramon Llull, CSIC, E-43520 Roquetes, Spain ;Andonov, B.; National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Altadill, D.; Ebro Observatory, University Ramon Llull, CSIC, E-43520 Roquetes, Spain ;Magdaleno, S.; Atmospheric Sounding Station ‘‘El Arenosillo’’, INTA, Huelva, Spain ;Parisi, M.; Dipartimento di Fisica, Universita` degli Studi di Roma, 00185 Rome, Italy ;Torta, J. M.; Ebro Observatory, University Ramon Llull, CSIC, E-43520 Roquetes, Spain; ; ; ; ; ; ; ; ; ; ; ; ; ; The paper describes results of the studies devoted to the solar activity impact on the Earth’s upper atmosphere and ionosphere, conducted within the frame of COST ES0803 Action. Aim: The aim of the paper is to represent results coming from different research groups in a unified form, aligning their specific topics into the general context of the subject. Methods: The methods used in the paper are based on data-driven analysis. Specific databases are used for spectrum analysis, empirical modeling, electron density profile reconstruction, and forecasting techniques. Results: Results are grouped in three sections: Medium- and long-term ionospheric response to the changes in solar and geomag- netic activity, storm-time ionospheric response to the solar and geomagnetic forcing, and modeling and forecasting techniques. Section 1 contains five subsections with results on 27-day response of low-latitude ionosphere to solar extreme-ultraviolet (EUV) radiation, response to the recurrent geomagnetic storms, long-term trends in the upper atmosphere, latitudinal dependence of total electron content on EUV changes, and statistical analysis of ionospheric behavior during prolonged period of solar activity. Section 2 contains a study of ionospheric variations induced by recurrent CIR-driven storm, a case-study of polar cap absorption due to an intense CME, and a statistical study of geographic distribution of so-called E-layer dominated ionosphere. Section 3 comprises empirical models for describing and forecasting TEC, the F-layer critical frequency foF2, and the height of maximum plasma density. A study evaluates the usefulness of effective sunspot number in specifying the ionosphere state. An original method is presented, which retrieves the basic thermospheric parameters from ionospheric sounding data.343 657 - PublicationOpen AccessLong-term trends in the ionosphere and upper atmosphere parameters(2004)
; ; ; ; ; ; ;Bremer, J.; Leibniz-Institute of Atmospheric Physics, Kühlungsborn, Germany ;Alfonsi, Lu.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Bencze, P.; Geodetic and Geophysical Research Institute, Hungarian Academy of Sciences, Sopron, Hungary ;Lastovicka, J.; Institute of Atmospheric Physics, Academy of Sciences of Czech Republic, Prague, Czech Republic ;Mikhailov, A. V.; Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN), Russian Academy of Sciences, Troitsk (Moscow Region), Russia ;Rogers, N.; Centre for RF Propagation and Atmospheric Research, QinetiQ, Malvern, U.K.; ; ; ; ; The first part of the paper is directed to the investigation of the practical importance of possible longterm trends in the F2-layer for ionospheric prediction models. Using observations of about 50 different ionosonde stations with more than 30 years data series of foF2 and hmF2, trends have been derived with the solar sunspot number R12 as index of the solar activity. The final result of this trend analysis is that the differences between the trends derived from the data of the individual stations are relatively large, the calculated global mean values of the foF2 and hmF2 trends, however, are relatively small. Therefore, these small global trends can be neglected for practical purposes and must not be considered in ionospheric prediction models. This conclusion is in agreement with the results of other investigations analyzing data of globally distributed stations. As shown with the data of the ionosonde station Tromsø, however, at individual stations the ionospheric trends may be markedly stronger and lead to essential effects in ionospheric radio propagation. The second part of the paper deals with the reasons for possible trends in the Earth’s atmo- and ionosphere as investigated by different methods using characteristic parameters of the ionospheric D-, E-, and F-regions. Mainly in the F2-region different analyses have been carried out. The derived trends are mainly discussed in connection with an increasing greenhouse effect or by long-term changes in geomagnetic activity. In the F1-layer the derived mean global trend in foF1 is in good agreement with model predictions of an increasing greenhouse effect. In the E-region the derived trends in foE and h´E are compared with model results of an atmospheric greenhouse effect, or explained by geomagnetic effects or other anthropogenic disturbances. The trend results in the D-region derived from ionospheric reflection height and absorption measurements in the LF, MF and HF ranges can at least partly be explained by an increasing atmospheric greenhouse effect.245 739 - PublicationOpen AccessA comparison of f0F hmE model calculations with El Arenosillo digisonde observations. Seasonal variations(1999-08)
; ; ; ; ;Mikhailov, A. V.; Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation, Russian Academy of Sciences, Troitsk, Moscow Region, Russia ;de la Morena, B. A.; National Institute of Aerospace Technology, Mazagón (Huelva), Spain ;Miro, G.; National Institute of Aerospace Technology, Mazagón (Huelva), Spain ;Marin, D.; National Institute of Aerospace Technology, Mazagón (Huelva), Spain; ; ; Seasonal variations of hmE and f0F2 are analyzed using El Arenosillo digisonde observations during solar minimum (1995-1996). Unlike some widely used empirical models daytime hmE show seasonal variations with winter hmE being higher than summer ones and seasonal differences increase with solar zenith angle. Model calculations enable us to reproduce the observed hmE seasonal variations but the calculated daytime f0E values are too low if conventional EUV fluxes and dissociative recombination rate constants are used. A reduction of a (NO+ ) by taking into account Te > Tn in the E-region as it follows from probe measurements seems to be a plausible solution. The E-region ion composition corresponding to rocket observations may be obtained in model calculations using an appropriate [NO] height distribution. Calculated summer concentrations of [NO] are by a factor of 3-4 larger than winter ones at the hmE-heights.129 257 - PublicationOpen AccessThermospheric parameters’ long-term variations over the period including the 24/25 solar cycle minimum. Whether the CO2 increase effects are seen?The CO2 concentration has been increasing for more than five decades reaching ~29 % at present with respect to the pre-industrial era. The largest CO2 cooling effects in the thermosphere are predicted for solar minimum conditions. A comparison of solar minima in 1954/1964 to the recent one in 2019 was used to check at the quantitative level the theoretical predictions and the validity of the CO2 cooling hypothesis. June monthly median noontime ionospheric observations at Moscow, Rome, and Slough/Chilton were used to infer neutral gas density ρ, exospheric temperature Tex, height of the F2-layer maximum hmF2, and total solar EUV flux for the (1954–2020) period. Solar and geomagnetic activity was shown to explain ~99 % of the whole variability in the retrieved neutral gas density and Tex during the (1958–2020) period resulting in statistically insignificant residual linear trends. A comparison of 1954/1964 to 2019 solar minima does not confirm the theoretically predicted decrease of ~21 % in ρ, ~15 K in Tex, and ~7 km in hmF2 related to a 29 % increase of the CO2 abundance. The main conclusion: despite continuous CO2 increase in the Earth's atmosphere long-term variations of thermospheric parameters are controlled by solar and geomagnetic activity.
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