Modeling the plasma response to small‐scale aerosol particle perturbations in the mesopause region

Lie-Svendsen, Øystein; Blix, T. A.; Hoppe, Ulf-Peter; Thrane, E. V.

doi:10.1029/2002jd002753

Cited by 76 publications

(127 citation statements)

References 39 publications

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“…A concentration of charged dust will influence the ion and electron density, so that if the dust is charged negatively, there will be a depletion of electrons and an increase of ions inside the dust concentration, compared to the values outside it. As long as the dust concentration or clumping exists and the dust particles are charged, the effect on the ion and electron density will be present (Havnes et al, 1984(Havnes et al, , 1990(Havnes et al, , 2003Lie-Svendsen et al, 2003). If the photoelectric effect is not important for dust charging, the dust particles and the dust clumps will be charged negatively.…”

Section: The Electron Heating As Deduced From the Overshoot Charactermentioning

confidence: 99%

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

2005

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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 90 km, where noctilucent clouds (NLC) and the radar phenomenon PMSE (Polar Mesospheric Summer Echoes) are observed. With an electron density profile without biteouts, the heated electron temperature T e,hot will generally decrease smoothly with height in the PMSE region or there may be no significant heating effect present. Within a biteout T e,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 T e,hot /T i , where T i 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 EIS-CAT 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 T e,hot /T i is found to vary in proportion to the transmitter power. We also looked for signatures of electron bite-outs by examining the variation of T e,hot /T i with height for the three other days. We find that the height variation of T e,hot /T i 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 densityCorrespondence to: O. Havnes (oha003@asp.uit.no) 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 (933 MHz) 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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Section: The Electron Heating As Deduced From the Overshoot Charactermentioning

confidence: 99%

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

2005

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“…As pointed out in the introduction, the new PMSE theory by Rapp and Lübken (2003) predicts an anticorrelation of electrons and negatively charged particles (see also Lie-Svendsen et al, 2003).…”

Section: Small Scale Plasma Variationsmentioning

confidence: 99%

“…Lübken et al, 2002). The first breaktrough in the understanding of PMSE was achieved by Kelley et al (1987) who proposed that the electrons at the polar summer mesopause are low diffusivity tracers due to the presence of large and heavy positive ions such as water cluster ions. If the tracer diffusivity is significantly smaller than the viscosity of air, the fluctuations in the tracer field can extend to much smaller scales than in the neutral gas (Batchelor, 1959).…”

Section: Introductionmentioning

confidence: 99%

Small scale density variations of electrons and charged particles in the vicinity of polar mesosphere summer echoes

Rapp¹,

Lübken²,

Blix

2003

Atmos. Chem. Phys.

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Abstract. We present small scale variations of electron number densities and particle charge number densities measured in situ in the presence of polar mesosphere summer echoes. It turns out that the small scale fluctuations of electrons and negatively charged particles show a strong anticorrelation down to the smallest scales observed. Comparing these small scale structures with the simultaneously measured radar signal to noise profile, we find that the radar profile is well described by the power spectral density of both electrons and charged particles at the radar half wavelength (=the Bragg scale). Finally, we consider the shape of the power spectra of the observed plasma fluctuations and find that both charged particles and electrons show spectra that can be explained in terms of either neutral air turbulence acting on the distribution of a low diffusivity tracer or the fossil remnants of a formerly active turbulent region. All these results are consistent with the theoretical ideas by Rapp and Lübken (2003) suggesting that PMSE can be explained by a combination of active and fossil neutral air turbulence acting on the large and heavy charged aerosol particles which are subsequently mirrored in the electron number density distribution that becomes visible to a VHF radar when small scale fluctuations are present.

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“…The numerical model (see Lie-Svendsen et al, 2003) solves the coupled, time-dependent fluid continuity and momentum equations for an arbitrary number of ions and (neutral and charged) aerosol particles, in addition to electrons, in one spatial dimension. Collisions are assumed to be sufficiently frequent to keep all species at the neutral air temperature T , which is measured with the CONE instrument.…”

Section: The Modelmentioning

confidence: 99%

The ECOMA 2007 campaign: rocket observations and numerical modelling of aerosol particle charging and plasma depletion in a PMSE/NLC layer

et al. 2009

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Abstract. The ECOMA series of rocket payloads use a set of aerosol particle, plasma, and optical instruments to study the properties of aerosol particles and their interaction with the ambient plasma environment in the polar mesopause region. In August 2007 the ECOMA-3 payload was launched into a region with Polar Mesosphere Summer Echoes (PMSE) and noctilucent clouds (NLC). An electron depletion was detected in a broad region between 83 and 88 km, coincident with enhanced density of negatively charged aerosol particles. We also find evidence for positive ion depletion in the same region. Charge neutrality requires that a population of positively charged particles smaller than 2 nm and with a density of at least 2×10 8 m −3 must also have been present in the layer, undetected by the instruments. A numerical model for the charging of aerosol particles and their interaction with the ambient plasma is used to analyse the results, showing that high aerosol particle densities are required in order to explain the observed ion density depletion. The model also shows that a very high photoionisation rate is required for the particles smaller than 2 nm to become positively charged, indicating that these may have a lower work function than pure water ice.

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Modeling the plasma response to small‐scale aerosol particle perturbations in the mesopause region

Cited by 76 publications

References 39 publications

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

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

Small scale density variations of electrons and charged particles in the vicinity of polar mesosphere summer echoes

The ECOMA 2007 campaign: rocket observations and numerical modelling of aerosol particle charging and plasma depletion in a PMSE/NLC layer

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