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

Mapping Intimacies ◽

10.5194/egusphere-egu21-6433 ◽

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): &#171;Diagnosing radio plasma heating in the polar summer mesosphere using cross modulation: Theory and observations&#187;. 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): &#171;Statistical signature of active D-region HF heating in IRIS riometer data from 1994-2004&#187;. Ann. Geophys., 25, 407-415.</li> <li>[3] Kassa, M., O. Havnes and E. Belova (2005): &#171;The effect of electron bite-outs on artificial electron heating and the PMSE overshoot&#187;. Annales Geophysicae, 23, 3633-3643.</li> <li>[4] Baumann, C., M. Rapp, A. Kero and C.-F. Enell (2013): &#171;Meteor smoke influence on the D-region charge balance &#8211;review of recent in situ measurements and one-dimensional model results&#187;. Ann. Geophys., 31, 2049-2062.</li> </ul>

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

Annales Geophysicae ◽

10.5194/angeo-39-1055-2021 ◽

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.

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

10.5194/angeo-2021-39 ◽

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.

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The effect of electron bite-outs on artificial electron heating and the PMSE overshoot

Annales Geophysicae ◽

10.5194/angeo-23-3633-2005 ◽

2005 ◽

Vol 23 (12) ◽

pp. 3633-3643 ◽

Cited By ~ 25

Author(s):

M. Kassa ◽

O. Havnes ◽

E. Belova

Keyword(s):

Electron Temperature ◽

Electron Density ◽

Electron Density Profile ◽

Dust Particles ◽

High Electron ◽

Heating Effect ◽

Ion Temperature ◽

Degree Of Ionization ◽

Electron Heating ◽

Transmitter Power

Abstract. We have considered the effect that a local reduction in the electron density (an electron bite-out), caused by electron absorption on to dust particles, can have on the artificial electron heating in the height region between 80 to 90km, where noctilucent clouds (NLC) and the radar phenomenon PMSE (Polar Mesospheric Summer Echoes) are observed. With an electron density profile without bite-outs, the heated electron temperature Te,hot will generally decrease smoothly with height in the PMSE region or there may be no significant heating effect present. Within a bite-out Te,hot will decrease less rapidly and can even increase slightly with height if the bite-out is strong. We have looked at recent observations of PMSE which are affected by artificial electron heating, with a heater cycling producing the new overshoot effect. According to the theory for the PMSE overshoot the fractional increase in electron temperature Te,hot/Ti, where Ti is the unaffected ion temperature=neutral temperature, can be found from the reduction in PMSE intensity as the heater is switched on. We have looked at results from four days of observations with the EISCAT VHF radar (224 MHz), together with the EISCAT heating facility. We find support for the PMSE overshoot and heating model from a sequence of observations during one of the days where the heater transmitter power is varied from cycle to cycle and where the calculated Te,hot/Ti is found to vary in proportion to the transmitter power. We also looked for signatures of electron bite-outs by examining the variation of Te,hot/Ti with height for the three other days. We find that the height variation of Te,hot/Ti is very different on the three days. On one of the days we see typically that this ratio can increase with height, showing the presence of a bite-out, while on the next day the heating factor mainly decreases with height, indicating that the fractional amount of dust is low, so that the electron density is hardly affected by it. On the third day there is little heating effect on the PMSE layer. This is probably due to a sufficiently high electron density in the atmosphere below the PMSE layer, so that the transmitted heater power is absorbed in these lower layers. On this day the D-region, as given by the UHF (933MHz) observations, extends deeper down in the atmosphere than on the other two days, indicating that the degree of ionization in and below the PMSE layers is higher as well.

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The role of vibrationally excited oxygen and nitrogen in the D and E regions of the ionosphere

Annales Geophysicae ◽

10.1007/s00585-994-1085-1 ◽

1994 ◽

Vol 12 (10/11) ◽

pp. 1085-1090 ◽

Cited By ~ 5

Author(s):

A. V. Pavlov

Keyword(s):

Electron Temperature ◽

Electron Density ◽

Anharmonic Oscillator ◽

Energy Levels ◽

Vibrationally Excited ◽

Continuity Equations ◽

D Region ◽

E Region ◽

Excited Oxygen

Abstract. In this paper we present the results of a study of the effect of vibrationally excited oxygen, O*2, and nitrogen, N*2, on the electron density, Ne, and the electron temperature, Te, in the D and E regions. The sources of O*2 are O-atom recombination, the photodissociation of O3, and the reaction of O3 with O at D region altitudes. The first calculations of O*2( j) number densities, Nj, are obtained by solving continuity equations for the models of harmonic and anharmonic oscillator energy levels, j=1-22. It is found that day time values of Nj are less than nighttime values. We also show that the photoionization of O*2 ( j ≥ 11) by Lα-radiation has no influence on the D region Ne. In the nighttime D region the photoionization O*2 ( j ≥ 11) by scattered Lα-radiation can be a new source of O+2. We show that the N*2 and O*2 de-excitation effect on the electron temperature is small in the E region of the ionosphere and cannot explain experimentally observed higher electron temperatures.

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Meteor smoke influences on the D-region charge balance – review of recent in situ measurements and one-dimensional model results

Annales Geophysicae ◽

10.5194/angeo-31-2049-2013 ◽

2013 ◽

Vol 31 (11) ◽

pp. 2049-2062 ◽

Cited By ~ 13

Author(s):

C. Baumann ◽

M. Rapp ◽

A. Kero ◽

C.-F. Enell

Keyword(s):

Negative Ions ◽

Dissociative Recombination ◽

In Situ Measurements ◽

Ionospheric Model ◽

Charge Balance ◽

Faraday Cup ◽

One Dimensional ◽

Positive Ions ◽

D Region

Abstract. This work investigates the influence of meteoric smoke particles (MSP) on the charge balance in the D-region ionosphere. Both experimental in situ measurements and a one-dimensional ionospheric model reveal a clear impact of MSP on the ionospheric composition of the D-region. The study reviews rocket-borne in situ measurements of electron and positive ion density, which show a distinct deficit of electrons in comparison to positive ions between 80 and 95 km. This deficit can be explained by the ambient negatively charged MSP measured simultaneously with a Faraday cup. The influence of MSP on the D-region charge balance is addressed with a simplified ionospheric model with only six components, i.e. electrons, positive and negative ions and neutral and charged MSP (both signs). The scheme includes reactions of plasma captured by MSP and MSP photo reactions as well as the standard ionospheric processes, e.g. ion-ion recombination. The model shows that the capture of plasma constituents by MSP is an important process leading to scavenging of electrons. Since Faraday cup measurements are biased towards heavy MSP because of aerodynamical filtering, we have applied an estimate of this filter on the modelled MSP densities. By doing that, we find good qualitative agreement between the experimental data and our model results. In addition, the model study reveals an increase of positive ions in the presence of MSP. That is primarily caused by the reduced dissociative recombination with electrons which have been removed from the gas phase by the MSP.

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