In situ measurements of the fine‐scale structure and turbulence in the mesosphere and lower thermosphere by means of electrostatic positive ion probes

Blix, T. A.; Thrane, E. V.; Andreassen, Øyvind

doi:10.1029/jd095id05p05533

Cited by 103 publications

(68 citation statements)

References 30 publications

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“…2 we show the observed currents I G1 , I G2 and I BP to grids G1, G2, and to the bottom plate and I CONE to the CONE electron probe (Blix et al, 1990). In Fig.…”

Section: A New Look At the Ect-0measurementsmentioning

confidence: 99%

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On the secondary charging effects and structure of mesospheric dust particles impacting on rocket probes

Havnes

Næsheim

2007

Ann. Geophys.

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Abstract. The dust probe DUSTY, first launched during the summer of 1994 (flights ECT-02 and ECT-07) from Andøya Rocket Range, northern Norway, was the first probe to unambiguously detect heavy charged mesospheric aerosols, from hereon referred to as dust. In ECT-02 the probe detected negatively charged dust particles in the height interval of 83 to 88.5 km. In this flight, the lower grid in the detector (Grid 2) measures both positive and negative currents in various regions, and we find that the relationship between the current measurements of Grid 2 and the bottom plate can only be explained by influence from secondary charge production on Grid 2. In ECT-07, which had a large coning, positive currents reaching the top grid of the probe were interpreted as due to the impact of positively charged dust particles. We have now reanalyzed the data from ECT-07 and arrived at the conclusion that the measured positive currents to this grid must have been mainly due to secondary charging effects from the impacting dust particles. The grid consists of a set of parallel wires crossed with an identical set of wires on top of it, and we find that if the observed currents were created from the direct impact of charged dust particles, then they should be very weakly modulated at four times the rocket spin rate ω R . Observations show, however, that the observed currents are strongly modulated at 2ω R . We cannot reproduce the observed large modulations of the impact currents in the dust layer if the currents are due only to the transfer of the charges on the impacted dust particles. Based on the results of recent ice cluster impact secondary charging experiments by Tomsic (2003), which found that a small fraction of the ice clusters, when impacting with nearly grazing incidence, carried away one negative charge −1e, we have arrived at the conclusion that similar, but significantly more effective, charging effects must be predominantly responsible for the positive currents measured by the top grid in ECT-07 and their large rotational modulation at 2ω R .Correspondence to: O. Havnes (ove.havnes@phys.uit.no) Since the secondary effect is dependent on the size of the impacting dust, this opens up for the possibility of mapping the relative dust sizes throughout a dust layer by comparing the observed direct and secondary currents.

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“…2 we show the observed currents I G1 , I G2 and I BP to grids G1, G2, and to the bottom plate and I CONE to the CONE electron probe (Blix et al, 1990). In Fig.…”

Section: A New Look At the Ect-0measurementsmentioning

confidence: 99%

“…However, secondary production by the dust impact on the bottom plate at low impact angles θ i Ann. Geophys., 25, 623-637, 2007 www the CONE electron probe (Blix et al, 1990). In Fig.…”

Section: A New Look At the Ect-0measurementsmentioning

confidence: 99%

On the secondary charging effects and structure of mesospheric dust particles impacting on rocket probes

Havnes

Næsheim

2007

Ann. Geophys.

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“…Ionospheric plasma densities were measured by a set of different probes, yielding relative densities of electrons (Langmuir probe and CONE), positive ions (by positive ion probe), and charged aerosols (by particle detector, PD), including their variations down to meter scales (e.g., Blix et al, 1990a). Absolute electron densities were precisely measured with the radio-wave propagation technique (Bennett et al, 1972;Jacobsen and Friedrich, 1979).…”

Section: Wadis Payloadmentioning

confidence: 99%

Spatial and temporal variability in MLT turbulence inferred from in situ and ground-based observations during the WADIS-1 sounding rocket campaign

et al. 2017

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Abstract. In summer 2013 the WADIS-1 sounding rocket campaign was conducted at the Andøya Space Center (ACS) in northern Norway (69 • N, 16 • E). Among other things, it addressed the question of the variability in mesosphere/lower thermosphere (MLT) turbulence, both in time and space. A unique feature of the WADIS project was multi-point turbulence sounding applying different measurement techniques including rocket-borne ionization gauges, VHF MAARSY radar, and VHF EISCAT radar near Tromsø. This allowed for horizontal variability to be observed in the turbulence field in the MLT at scales from a few to 100 km. We found that the turbulence dissipation rate, ε varied in space in a wavelike manner both horizontally and in the vertical direction. This wavelike modulation reveals the same vertical wavelengths as those seen in gravity waves. We also found that the vertical mean value of radar observations of ε agrees reasonably with rocket-borne measurements. In this way defined ε radar value reveals clear tidal modulation and results in variation by up to 2 orders of magnitude with periods of 24 h. The ε radar value also shows 12 h and shorter (1 to a few hours) modulations resulting in one decade of variation in ε radar magnitude. The 24 h modulation appeared to be in phase with tidal change of horizontal wind observed by SAURA-MF radar. Such wavelike and, in particular, tidal modulation of the turbulence dissipation field in the MLT region inferred from our analysis is a new finding of this work.

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“…Hinze, 1975) will increase. The time scales modelled here correspond to the Kolmogorov microscale η (Kolmogorov, 1941), at which, one could roughly say that turbulent eddies are allowed to complete, since inertia overcomes viscous drag (although this visualisation is perhaps better suited to the inner scale = 7.4η; Blix et al, 1990) At longer time scales, and, therefore, at scales within the inertial subrange (Obukov, 1941), the ionisation structure within the trail is quickly destroyed; however, after this time delay, the backscattered power has become so weak that it does not feature in the determination of the characteristic fading time. It should also be stressed that the turbulent contribution to the dissipation of the ionisation structure is indeed just that: a contribution, an enhancement.…”

Section: Discussionmentioning

confidence: 99%

“…The length scale η is the scale at which the extrapolations of the slopes of viscous and inertial regimes of the turbulent spectrum meet. An alternative is to consider the length scale at which the inertial subrange begins to depart from a power-law dependence; this scale, the inner scale l 0 , is typically given by 7.4η (Blix et al, 1990), this perhaps better representing the smallest eddies, and is also shown in Fig. 3.…”

Section: Simulation Of Ambipolar Diffusivity Profilesmentioning

confidence: 99%

On the influence of neutral turbulence on ambipolar diffusivities deduced from meteor trail expansion

Hall¹

2002

Ann. Geophys.

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Abstract. By measuring fading times of radar echoes from underdense meteor trails, it is possible to deduce the ambipolar diffusivities of the ions responsible for these radar echoes. It could be anticipated that these diffusivities increase monotonically with height akin to neutral viscosity. In practice, this is not always the case. Here, we investigate the capability of neutral turbulence to affect the meteor trail diffusion rate.

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In situ measurements of the fine‐scale structure and turbulence in the mesosphere and lower thermosphere by means of electrostatic positive ion probes

Cited by 103 publications

References 30 publications

On the secondary charging effects and structure of mesospheric dust particles impacting on rocket probes

On the secondary charging effects and structure of mesospheric dust particles impacting on rocket probes

Spatial and temporal variability in MLT turbulence inferred from in situ and ground-based observations during the WADIS-1 sounding rocket campaign

On the influence of neutral turbulence on ambipolar diffusivities deduced from meteor trail expansion

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