Dusty space plasma diagnosis using temporal behavior of polar mesospheric summer echoes during active modification

Mahmoudian, A.; Scales, W. A.; Kosch, M. J.; Senior, Andrew; Rietveld, M. T.

doi:10.5194/angeo-29-2169-2011

Cited by 26 publications

(45 citation statements)

References 35 publications

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“…However, it is more surprising that, when the sampling time t 1 is increased to 19.2 s, covering 40 % of the time the heater is on, about 20 % of the samples show a ratio of R1 / R0 > 1 for both MORRO and VHF. This is apparently contrary to model predictions (Mahmoudian et al, 2011;Biebricher and Havnes, 2012), which indicate that even if a radar at the MORRO frequency observes R1 > R0 for much of the time when the heater is on, the observations with the VHF radar should consistently show a much smaller value of R1 / R0, which even tends to be smaller than 1 (Biebricher and Havnes, 2012). The indications that the recovery of the VHF backscatter for a significant number of cases can be large, lends support to the finding by Senior et al (2014) that there appears to be some additional charging effect which increases the space charge of the dust density structures during the heater-on time, compared to what the models predict.…”

Section: Introductioncontrasting

confidence: 55%

“…MORRO and lower-frequency radars may show an immediate increase in backscatter after the heater is switched on, while for the same conditions VHF has a tendency to observe a reduction of the backscatter (Mahmoudian et al, 2011;Biebricher and Havnes, 2012) or at least a much slower increase than for the MORRO frequency. We see from Fig.…”

Section: Individual Occ Profiles For Morro and Vhfmentioning

confidence: 99%

“…We will examine to what degree the observed OCCs for the two radars, their similarities or differences, agree with predictions of existing models (e.g. Mahmoudian et al, 2011;Biebricher and Havnes, 2012). In Sect.…”

Section: Introductionmentioning

confidence: 99%

“…In such cases the plasma adjustment times can often be considerably longer than the dust charging time. Modelling shows that this can have a profound influence on the radar backscatter during a heateron and heater-off time cycle and the overshoot characteristic curve (OCC), the backscatter variation during one heater cycle , can be very different from what it normally is for the EISCAT VHF and UHF frequencies (Scales, 2004;Naesheim et al, 2008, Scales and Chen, 2008, Mahmoudian et al, 2011Biebricher and Havnes, 2012). In Fig.…”

Section: Introductionmentioning

confidence: 99%

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A comparison of overshoot modelling with observations of polar mesospheric summer echoes at radar frequencies of 56 and 224 MHz

Havnes¹,

Pinedo²,

Hoz³

et al. 2015

Ann. Geophys.

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Abstract.We have compared radar observations of polar mesospheric summer echoes (PMSEs) modulated by artificial electron heating, at frequencies of 224 MHz (EISCAT VHF) and 56 MHz (MORRO). We have concentrated on 1 day of observation, lasting ∼ 3.8 h. The MORRO radar, with its much wider beam, observes one or more PMSE layers all the time while the VHF radar observes PMSEs in 69 % of the time. Statistically there is a clear difference between how the MORRO and the VHF radar backscatter reacts to the heater cycling (48 s heater on and 168 s heater off). While MORRO often reacts by having its backscatter level increased when the heater is switched on, as predicted by Scales and Chen (2008), the VHF radar nearly always sees the "normal" VHF overshoot behaviour with an initial rapid reduction of backscatter. However, in some heater cycles we do see a substantial recovery of the VHF backscatter after its initial reduction to levels several times above that just before the heater was switched on. For the MORRO radar a recovery during the heater-on phase is much more common. The reaction when the heater was switched off was a clear overshoot for nearly all VHF cases but less so for MORRO.A comparison of individual curves for the backscatter values as a function of time shows, at least for this particular day, that in high layers above ∼ 85 km height, both radars see a reduction of the backscatter as the heater is switched on, with little recovery during the heater-on time. These variations are well described by present models. On the other hand, the backscatter in low layers at 81-82 km can be quite different, with modest or no reduction in backscatter as the heater is switched on, followed by a strong recovery for both radars to levels several times above that of the undisturbed PMSEs. This simultaneous, nearly identical behaviour at the two very different radar frequencies is not well described by present modelling.

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Section: Introductioncontrasting

confidence: 55%

Section: Individual Occ Profiles For Morro and Vhfmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A comparison of overshoot modelling with observations of polar mesospheric summer echoes at radar frequencies of 56 and 224 MHz

Havnes¹,

Pinedo²,

Hoz³

et al. 2015

Ann. Geophys.

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“…This technique has also been used extensively to investigate the charged dust layers in the mesosphere [Chilson et al, 2000;Havnes et al, 2003;Mahmoudian et al, 2011;Mahmoudian and Scales, 2012]. High power electromagnetic waves transmitted from the ground interact with the local plasma in the ionosphere and can produce stimulated electromagnetic emissions (SEEs) through the parametric decay instability [Thide et al, 1982].…”

Section: Introductionmentioning

confidence: 99%

Ion gyro‐harmonic structuring in the stimulated radiation spectrum and optical emissions during electron gyro‐harmonic heating

et al. 2013

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[1] Stimulated electromagnetic emissions (SEEs) are secondary radiation produced during active space experiments in which the ionosphere is actively heated with high power high frequency (HF) ground-based radio transmitters. Recently, there has been significant interest in ion gyro-harmonic structuring the SEE spectrum due to the potential for new diagnostic information available such as electron acceleration and creation of artificial ionization layers. These relatively recently discovered gyro-harmonic spectral features have almost exclusively been studied when the transmitting frequency is near the second electron gyro-harmonic frequency. The first extensive systematic experimental investigations of the possibility of these spectral features for third electron gyro-harmonic heating are provided here. Discrete spectral features shifted from the transmit frequency ordered by harmonics of the ion gyro-frequency were observed for third electron gyro-harmonic heating for the first time at a recent campaign at the High Frequency Active Auroral Research Program (HAARP) facility. These features were also closely correlated with a broader band feature at a larger frequency shift from the transmit frequency known as the downshifted peak (DP). The power threshold of these spectral features was measured, as well as their behavior with heater beam angle, and proximity of the transmit frequency to the third electron gyro-harmonic frequency. Comparisons were also made with similar spectral features observed during second electron gyro-harmonic heating during the same campaign. A theoretical model is provided that interprets these spectral features as resulting from parametric decay instabilities in which the pump field ultimately decays into high frequency upper hybrid/electron Bernstein and low frequency neutralized ion Bernstein IB and/or obliquely propagating ion acoustic waves at the upper hybrid interaction altitude. Coordinated optical and SEE observations were carried out in order to provide a better understanding of electron acceleration and precipitation processes. Optical emissions were observed associated with SEE gyro-harmonic features for pump heating near the second electron gyro-harmonic during the campaign. The observations affirm strong correlation between the gyro-structures and the pump-induced optical emissions.

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Investigation of ionospheric stimulated Brillouin scatter generated at pump frequencies near electron gyroharmonics

et al. 2013

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[1] Stimulated Electromagnetic Emissions (SEEs), secondary electromagnetic waves excited by high power electromagnetic waves transmitted into the ionosphere, produced by the Magnetized Stimulated Brillouin Scatter (MSBS) process are investigated. Data from four recent research campaigns at the High Frequency Active Auroral Research Program (HAARP) facility is presented in this work. These experiments have provided additional quantitative interpretation of the SEE spectrum produced by MSBS to yield diagnostic measurements of the electron temperature and ion composition in the heated ionosphere. SEE spectral emission lines corresponding to ion acoustic (IA) and electrostatic ion cyclotron (EIC) mode excitation were observed with a shift in frequency up to a few tens of Hz from the pump frequency for heating near the third harmonic of the electron gyrofrequency 3f ce . The threshold of each emission line has been measured by changing the pump wave power. The excitation threshold of IA and EIC emission lines originating at the reflection and upper hybrid altitudes is measured for various beam angles relative to the magnetic field. Variation of strength of MSBS emission lines with pump frequency relative to 3f ce and 4f ce is also studied. A full wave solution has been used to estimate the amplitude of the electric field at the interaction altitude. The estimated instability threshold using the theoretical model is compared with the threshold of MSBS lines in the experiment and possible diagnostic information for the background ionospheric plasma is discussed. Simultaneous formation of artificial field-aligned irregularities (FAIs) and suppression of the MSBS process is investigated. This technique can be used to estimate the growth time of artificial FAIs which may result in determination of plasma waves and physical process involved in the formation of FAIs.Citation: Mahmoudian, A., W. A. Scales, P. A. Bernhardt, H. Fu, S. J. Briczinski, and M. J. , Investigation of ionospheric stimulated Brillouin scatter generated at pump frequencies near electron gyroharmonics, Radio Sci., 48,[685][686][687][688][689][690][691][692][693][694][695][696][697]

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Dusty space plasma diagnosis using temporal behavior of polar mesospheric summer echoes during active modification

Cited by 26 publications

References 35 publications

A comparison of overshoot modelling with observations of polar mesospheric summer echoes at radar frequencies of 56 and 224 MHz

A comparison of overshoot modelling with observations of polar mesospheric summer echoes at radar frequencies of 56 and 224 MHz

Ion gyro‐harmonic structuring in the stimulated radiation spectrum and optical emissions during electron gyro‐harmonic heating

Investigation of ionospheric stimulated Brillouin scatter generated at pump frequencies near electron gyroharmonics

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