scholarly journals Modelling the influence of meteoric smoke particles on artificial heating in the D-region

2021 ◽  
Vol 39 (6) ◽  
pp. 1055-1068
Author(s):  
Margaretha Myrvang ◽  
Carsten Baumann ◽  
Ingrid Mann
Keyword(s):  
Electron Temperature ◽  
Radio Wave ◽  
Electron Density ◽  
Electron Attachment ◽  
Radio Waves ◽  
Night Time ◽  
Smoke Particles ◽  
D Region ◽  
Meteoric Smoke ◽  
Artificial Heating

Abstract. We investigate if the presence of meteoric smoke particles (MSPs) influences the electron temperature during artificial heating in the D-region. By transferring the energy of powerful high-frequency radio waves into thermal energy of electrons, artificial heating increases the electron temperature. Artificial heating depends on the height variation of electron density. The presence of MSPs can influence the electron density through charging of MSPs by electrons, which can reduce the number of free electrons and even result in height regions with strongly reduced electron density, so-called electron bite-outs. We simulate the influence of the artificial heating by calculating the intensity of the upward-propagating radio wave. The electron temperature at each height is derived from the balance of radio wave absorption and cooling through elastic and inelastic collisions with neutral species. The influence of MSPs is investigated by including results from a one-dimensional height-dependent ionospheric model that includes electrons, positively and negatively charged ions, neutral MSPs, singly positively and singly negatively charged MSPs, and photochemistry such as photoionization and photodetachment. We apply typical ionospheric conditions and find that MSPs can influence both the magnitude and the height profile of the heated electron temperature above 80 km; however, this depends on ionospheric conditions. During night, the presence of MSPs leads to more efficient heating and thus a higher electron temperature above altitudes of 80 km. We found differences of up to 1000 K in electron temperature for calculations with and without MSPs. When MSPs are present, the heated electron temperature decreases more slowly. The presence of MSPs does not much affect the heating below 80 km for night conditions. For day conditions, the difference between the heated electron temperature with MSPs and without MSPs is less than 25 K. We also investigate model runs using MSP number density profiles for autumn, summer and winter. The night-time electron temperature is expected to be 280 K hotter in autumn than during winter conditions, while the sunlit D-region is 8 K cooler for autumn MSP conditions than for the summer case, depending on altitude. Finally, an investigation of the electron attachment efficiency to MSPs shows a significant impact on the amount of chargeable dust and consequently on the electron temperature.

scholarly journals Modelling of the influence of meteoric smoke particles on artificial heating in the D-region

2021 ◽  
Author(s):  
Margaretha Myrvang ◽  
Carsten Baumann ◽  
Ingrid Mann
Keyword(s):  
Electron Temperature ◽  
Radio Wave ◽  
Electron Density ◽  
Radio Waves ◽  
Smoke Particles ◽  
Radio Wave Absorption ◽  
D Region ◽  
Meteoric Smoke ◽  
Artificial Heating ◽  
The Difference

Abstract. We investigate if the presence of meteoric smoke particles (MSP) influences the electron temperature during artfical heating in the D-region. The presence of MSP can result in height regions with reduced electron density, so-called electron bite-outs, due to charging of MSP by electrons. Artificial heating depends on the height variation of electron density. By transferring the energy of powerful high frequency radio waves into thermal energy of electrons, artificial heating increases the electron temperature. We simulate the influence of the artificial heating by calculating the intensity of the upward propagating radio wave. The electron temperature at each height is derived from the balance of radio wave absorption and cooling through elastic and inelastic collisions with neutral species. The influence of MSP is investigated by including results from a one-dimensional height-dependent ionospheric model that includes electrons, positively and negatively charged ions, neutral MSP, singly positively and singly negatively charged MSP and photo chemistry such as photo ionization and photo detachment. We apply typical ionospheric conditions and find that MSP can influence both the magnitude and the height profile of the heated electron temperature above 80 km, however this depends on ionospheric conditions. During night, the presence of MSP leads to more efficient heating, and thus a higher electron temperature, above altitudes of 80 km. We found differences up to 1000 K in temperature for calculations with and without MSP. When MSP are present, the heated electron temperature decreases more slowly. The presence of MSP does not much affect the heating below 80 km for night conditions. For day conditions, the difference between the heated electron temperature with MSP and without MSP is less than 25 K.

The influence of meteoric smoke particles on the artificial heating effect in the D-region

2021 ◽  
Author(s):  
Margaretha Myrvang ◽  
Carsten Baumann ◽  
Ingrid Mann
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Ionospheric Model ◽  
Heating Effect ◽  
One Dimensional ◽  
Smoke Particles ◽  
D Region ◽  
Meteoric Smoke ◽  
Artificial Heating ◽  
Night Condition

<p>Artificial heating increases the electron temperature by transferring the energy of powerful high frequency radio waves into thermal energy of electrons. Current models most likely overestimate the effect of artificial heating in the D-region compared to observations [1, 2]. We investigate if the presence of meteoric smoke particles can explain the discrepancy between observations and model. The ionospheric D-region varies in altitude range from about 50 km to 100 km. In the D-region, the electron density is low, the neutral density is relatively high and it is here that meteors ablate. The ablated meteoric material is believed to recondense to form meteoric smoke particles (MSP). The presence of MSP in the D-region can influence plasma densities through charging of dust by electrons and ions, depending on different ionospheric conditions. Charging of dust influence the electron density mainly through electron attachment to the dust, which results in height regions with less electron density. The heating effect varies with electron density height profile [3], since the reduction in radio wave energy is due to absorption by electrons. We study artificial heating of the D-region and consider MSP by using a one-dimensional ionospheric model [4], which also includes photochemistry. In the ionospheric model, we assume that artificial heating only influences the chemical reactions that depend on electron temperature. We model the electron temperature increase during artificial heating with an electron density calculated from the ionospheric model, where we will do the modelling with and without the MSP and compare day and night condition. Our results show a difference in electron temperature increase with the MSP compared to without the MSP and between day and night condition.</p><p>References:</p><ul><li>[1] Senior, A., M. T. Rietveld, M. J. Kosch and W. Singer (2010): «Diagnosing radio plasma heating in the polar summer mesosphere using cross modulation: Theory and observations». Journal of geophysical research, Vol. 115, A09318.</li> <li>[2] Kero, A., C.-F Enell, Th. Ulich, E. Turunen, M. T. Rietveld and F. H. Honary (2007): «Statistical signature of active D-region HF heating in IRIS riometer data from 1994-2004». Ann. Geophys., 25, 407-415.</li> <li>[3] Kassa, M., O. Havnes and E. Belova (2005): «The effect of electron bite-outs on artificial electron heating and the PMSE overshoot». Annales Geophysicae, 23, 3633-3643.</li> <li>[4] Baumann, C., M. Rapp, A. Kero and C.-F. Enell (2013): «Meteor smoke influence on the D-region charge balance –review of recent in situ measurements and one-dimensional model results». Ann. Geophys., 31, 2049-2062.</li> </ul>

scholarly journals Survey of electron density changes in the daytime ionosphere over the Arecibo observatory due to lightning and solar flares

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Caitano L. da Silva ◽  
Sophia D. Salazar ◽  
Christiano G. M. Brum ◽  
Pedrina Terra
Keyword(s):  
Electron Density ◽  
Solar Flares ◽  
Low Frequency ◽  
Lower Ionosphere ◽  
Weather Conditions ◽  
Optical Observations ◽  
Radio Waves ◽  
D Region ◽  
E Region ◽  
Arecibo Observatory

AbstractOptical observations of transient luminous events and remote-sensing of the lower ionosphere with low-frequency radio waves have demonstrated that thunderstorms and lightning can have substantial impacts in the nighttime ionospheric D region. However, it remains a challenge to quantify such effects in the daytime lower ionosphere. The wealth of electron density data acquired over the years by the Arecibo Observatory incoherent scatter radar (ISR) with high vertical spatial resolution (300-m in the present study), combined with its tropical location in a region of high lightning activity, indicate a potentially transformative pathway to address this issue. Through a systematic survey, we show that daytime sudden electron density changes registered by Arecibo’s ISR during thunderstorm times are on average different than the ones happening during fair weather conditions (driven by other external factors). These changes typically correspond to electron density depletions in the D and E region. The survey also shows that these disturbances are different than the ones associated with solar flares, which tend to have longer duration and most often correspond to an increase in the local electron density content.

scholarly journals Perspective Ground-based Method for Diagnostics of the Lower Ionosphere and the Neutral Atmosphere

2013 ◽  
Vol 22 (1) ◽  
Author(s):  
N. V. Bakhmetieva ◽  
G. I. Grigoriev ◽  
A. V. Tolmacheva
Keyword(s):  
Radio Wave ◽  
High Power ◽  
Relative Concentration ◽  
Spectral Characteristics ◽  
Lower Ionosphere ◽  
Internal Gravity Waves ◽  
Spatial Period ◽  
Neutral Atmosphere ◽  
Radio Waves ◽  
D Region

AbstractWe present a new perspective ground-based method for diagnostics of the ionosphere and atmosphere parameters. The method uses one of the numerous physical phenomena observed in the ionosphere illuminated by high-power radio waves. It is a generation of the artificial periodic irregularities (APIs) in the ionospheric plasma. The APIs were found while studying the effects of ionospheric high-power HF modification. It was established that the APIs are formed by a standing wave that occurs due to interference between the upwardly radiated radio wave and its reflection off the ionosphere. The API studies are based upon observation of the Bragg backscatter of the pulsed probe radio wave from the artificial periodic structure. Bragg backscatter occurs if the spatial period of the irregularities is equal to half a wavelength of the probe signal. The API techniques makes it possible to obtain the following information: the profiles of electron density from the lower D-region up to the maximum of the F-layer; the irregular structure of the ionosphere including split of the regular E-layer, the sporadic layers; the vertical velocities in the D- and E-regions of the ionosphere; the turbulent velocities, turbulent diffusion coefficients and the turbopause altitude; the neutral temperatures and densities at the E-region altitudes; the parameters of the internal gravity waves and their spectral characteristics; the relative concentration of negative oxygen ions in the D-region. Some new results obtained by the API technique are discussed.

Geographical and solar activity variations in the electron temperature of the upper F -region

1965 ◽  
Vol 286 (1407) ◽  
pp. 537-558 ◽  
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Geomagnetic Latitude ◽  
Minor Effect ◽  
Night Time ◽  
Temperature Variations ◽  
Geographical Variations ◽  
Magnetic Shell ◽  
Time Changes ◽  
A Minor

Electron temperature observations obtained in April-July 1962 on the Ariel I satellite have been further analysed by a statistical method. The general increase of electron temperature with latitude (amounting to about 500 degK) and with altitude between 400 and 1200 km, ( ca . 600 degK) previously reported, are confirmed. In addition, the dawn maximum of electron temperature found by other workers, which at the period of these observations is only a minor effect at 40° geomagnetic latitude, is found to become more pronounced near the magnetic equator. The geographical variations of electron temperature are shown to divide into distinct patterns characteristic of noon, dawn and midnight. The dawn pattern consists essentially of a longitude variation in the amplitude of the dawn maximum. All three patterns are closely associated with the geographical variations of electron density, and by examining the detailed correlation of temperature and density it is shown that the temperature variations result from changes in the collisional cooling rate of the electrons. This provides confirmation of the explanation of the dawn maximum suggested by Dalgarno, McElroy & Moffat (1963). Temperature variations due to changes in the far u.v. emission of the sun are considered. By day it is found that the electron temperature increases with 2800 Mc/s solar emission at a rate of (4.6 ± 2.3) degK per flux unit of 10 -22 Wcm -2 s -1 (c/s) -1 , while at night it decreases at a rate of 2.3 ± 2.7 degK/flux unit. Temperature variations in magnetic storms are compared with density enhancements described by Willmore & Henderson (1965). Electron density increases in the storm are always accompanied by a temperature reduction of about 180 degK, the storm-time changes showing a distinct magnetic shell structure. An instance of a temperature increase near the Brazilian geomagnetic anomaly is also given. Finally it is shown that these results lend support to the suggestion of a departure from thermal equilibrium in the night-time ionosphere.

scholarly journals On the factors controlling occurrence of F-region coherent echoes

2002 ◽  
Vol 20 (9) ◽  
pp. 1385-1397 ◽  
Author(s):  
D. W. Danskin ◽  
A. V. Koustov ◽  
T. Ogawa ◽  
N. Nishitani ◽  
S. Nozawa ◽  
...  
Keyword(s):  
Density Distribution ◽  
Radio Wave ◽  
Electron Density ◽  
Electron Density Distribution ◽  
Propagation Path ◽  
Occurrence Rate ◽  
Wave Refraction ◽  
F Region ◽  
D Region ◽  
Field Lines

Abstract. Several factors are known to control the HF echo occurrence rate, including electron density distribution in the ionosphere (affecting the propagation path of the radar wave), D-region radio wave absorption, and ionospheric irregularity intensity. In this study, we consider 4 days of CUTLASS Finland radar observations over an area where the EISCAT incoherent scatter radar has continuously monitored ionospheric parameters. We illustrate that for the event under consideration, the D-region absorption was not the major factor affecting the echo appearance. We show that the electron density distribution and the radar frequency selection were much more significant factors. The electron density magnitude affects the echo occurrence in two different ways. For small F-region densities, a minimum value of 1 × 1011 m-3 is required to have sufficient radio wave refraction so that the orthogonality (with the magnetic field lines) condition is met. For too large densities, radio wave strong "over-refraction" leads to the ionospheric echo disappearance. We estimate that the over-refraction is important for densities greater than 4 × 1011 m-3. We also investigated the backscatter power and the electric field magnitude relationship and found no obvious relationship contrary to the expectation that the gradient-drift plasma instability would lead to stronger irregularity intensity/echo power for larger electric fields.Key words. Ionosphere (ionospheric irregularities; plasma waves and instabilities; auroral ionosphere)

scholarly journals Nichtlineare Welleneinkopplung in ein Plasma erhöhter Elektronentemperatur / Nonlinear Wave Coupling to a Plasma of Enhanced Electron Temperature

1976 ◽  
Vol 31 (12) ◽  
pp. 1566-1571 ◽  
Author(s):  
G. Glomski ◽  
B. Heinrich ◽  
H. Schlüter
Keyword(s):  
Electron Temperature ◽  
Electron Density ◽  
Nonlinear Wave ◽  
Lower Hybrid ◽  
Radio Waves ◽  
Wave Coupling ◽  
Neutral Gas ◽  
At Resonance ◽  
Parametric Effects ◽  
Lower Hybrid Resonance

Abstract Nonlinear Wave Coupling to a Plasma of Enhanced Electron Temperature In continuation of former investigations radio waves of different amplitude in the domain of lower hybrid resonance were coupled to a plasma of enhanced electron temperature. Under linear conditions no dependence of resonance behaviour on the wave amplitude was observed. Exceeding a treshhold maximum of absorption and electron density decreased significantly; both observations may be explained by onset of nonlinear and parametric effects. Increasing the amplitude the discharge only could be maintained by increasing the neutral gas pressure. In the power range of 15 to 20 kW electron density grew rapidly at resonance.

scholarly journals D-region electron density and effective recombination coefficients during twilight – experimental data and modelling during solar proton events

2009 ◽  
Vol 27 (10) ◽  
pp. 3713-3724 ◽  
Author(s):  
A. Osepian ◽  
S. Kirkwood ◽  
P. Dalin ◽  
V. Tereschenko
Keyword(s):  
Electron Density ◽  
Zenith Angle ◽  
Solar Zenith Angle ◽  
Solar Proton ◽  
Radio Waves ◽  
Electron Densities ◽  
Partial Reflection ◽  
D Region ◽  
Density Values ◽  
Solar Proton Events

Abstract. Accurate measurements of electron density in the lower D-region (below 70 km altitude) are rarely made. This applies both with regard to measurements by ground-based facilities and by sounding rockets, and during both quiet conditions and conditions of energetic electron precipitation. Deep penetration into the atmosphere of high-energy solar proton fluxes (during solar proton events, SPE) produces extra ionisation in the whole D-region, including the lower altitudes, which gives favourable conditions for accurate measurements using ground-based facilities. In this study we show that electron densities measured with two ground-based facilities at almost the same latitude but slightly different longitudes, provide a valuable tool for validation of model computations. The two techniques used are incoherent scatter of radio waves (by the EISCAT 224 MHz radar in Tromsø, Norway, 69.6° N, 19.3° E), and partial reflection of radio-waves (by the 2.8 MHz radar near Murmansk, Russia, 69.0° N, 35.7° E). Both radars give accurate electron density values during SPE, from heights 57–60 km and upward with the EISCAT radar and between 55–70 km with the partial reflection technique. Near noon, there is little difference in the solar zenith angle between the two locations and both methods give approximately the same values of electron density at the overlapping heights. During twilight, when the difference in solar zenith angles increases, electron density values diverge. When both radars are in night conditions (solar zenith angle >99°) electron densities at the overlapping altitudes again become equal. We use the joint measurements to validate model computations of the ionospheric parameters f+, λ, αeff and their variations during solar proton events. These parameters are important characteristics of the lower ionosphere structure which cannot be determined by other methods.

scholarly journals Dynamic processes in the magnetic field and in the ionosphere during the 30 August–2 September 2019 geospace storm: influence on high frequency radio wave characteristics

2021 ◽  
Vol 39 (4) ◽  
pp. 657-685
Author(s):  
Yiyang Luo ◽  
Leonid Chernogor ◽  
Kostiantyn Garmash ◽  
Qiang Guo ◽  
Victor Rozumenko ◽  
...  
Keyword(s):  
Radio Wave ◽  
Electron Density ◽  
High Frequency ◽  
Geomagnetic Field ◽  
Recovery Phase ◽  
Radio Waves ◽  
Ionospheric Storm ◽  
Period Range ◽  
Multiple Method ◽  
S Period

Abstract. The concept that geospace storms are comprised of synergistically coupled magnetic storms, ionospheric storms, atmospheric storms, and storms in the electric field originating in the magnetosphere, the ionosphere, and the atmosphere (i.e., electrical storms) was validated a few decades ago. Geospace storm studies require the employment of multiple-method approaches to the Sun–interplanetary medium–magnetosphere–ionosphere–atmosphere–Earth system. This study provides general analysis of the 30 August–2 September 2019 geospace storm, the analysis of disturbances in the geomagnetic field and in the ionosphere, as well as the influence of the ionospheric storm on the characteristics of high frequency (HF) radio waves over the People's Republic of China. The main results of the study are as follows. The energy and power of the geospace storm have been estimated to be 1.5×1015 J and 1.5×1010 W, and thus, this storm is weak. The energy and power of the magnetic storm have been estimated to be 1.5×1015 J and 9×109 W, i.e., this storm is moderate, and a characteristic feature of this storm is the duration of the main phase of up to 2 d. The recovery phase also was lengthy and was no less than 2 d. On 31 August and 1 September 2019, the variations in the H and D components attained 60–70 nT, while the Z-component variations did not exceed 20 nT. On 31 August and 1 September 2019, the level of fluctuations in the geomagnetic field in the 100–1000 s period range increased from 0.2–0.3 to 2–4 nT, while the energy of the oscillations showed a maximum in the 300–400 to 700–900 s period range. During the geospace storm, a moderately to strongly negative ionospheric storm manifested itself by the reduction in the ionospheric F-region electron density by a factor of 1.4 to 2.4 times on 31 August and 1 September 2019, compared to the its values on the reference day. Appreciable disturbances were also observed to occur in the ionospheric E region and possibly in the Es layer. In the course of the ionospheric storm, the altitude of reflection of radio waves could sharply increase from ∼150 to ∼300–310 km. The atmospheric gravity waves generated within the geospace storm modulated the ionospheric electron density; for the ∼30 min period oscillation, the amplitude of the electron density disturbances could attain ∼40 %, while it did not exceed 6 % for the ∼15 min period. At the same time, the height of reflection of the radio waves varied quasi-periodically with a 20–30 km amplitude. The results obtained have made a contribution to the understanding of the geospace storm physics, to developing theoretical and empirical models of geospace storms, to the acquisition of detailed understanding of the adverse effects that geospace storms have on radio wave propagation, and to applying that knowledge to effective forecasting of these adverse influences.

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