Coordinated EISCAT Svalbard radar and Reimei satellite observations of ion upflows and suprathermal ions

Ogawa, Y.; Seki, K.; Hirahara, Masafumi; Asamura, Kazushi; Sakanoi, Takeshi; Buchert, Stephan; Ebihara, Yusuke; Obuchi, Y.; Yamazaki, Atsushi; Sandahl, I.; Nozawa, Satonori; Fujii, Ryoichi

doi:10.1029/2007ja012791

Cited by 24 publications

(29 citation statements)

References 30 publications

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“…IPWM includes an extra ion fluid to represent nonthermal O + . Separating the thermal and nonthermal populations makes it easy to treat a nonthermal population that is a tiny fraction of the total O + density, a case that is commonly observed [e.g., Ogawa et al , ]. The transport equations obeyed by this extra fluid (see supporting information) are as follows:

\frac{\partial}{∂t} n_{j} + \nabla \cdot ([], n_{j} {boldu}_{j}) = 𝚼 n_{i}

\frac{\partial}{∂t} ((), n_{j} u_{∥ j}) + \nabla \cdot ([], n_{j} u_{∥ j} {boldu}_{j}) = n_{j} ((), \frac{e}{m_{j}} E_{∥} + g_{∥} + {boldu}_{j} {boldu}_{j} : \nabla \overset{b}{true}) - \frac{p_{⊥ j}}{m_{j}} \nabla_{∥} \ln B + 𝚼 n_{i} u_{∥ i}

\frac{\partial}{∂t} ϵ_{j} + \nabla \cdot ([], ϵ_{j} {boldu}_{j}) - \frac{p_{⊥ j}}{m_{j}} {boldu}_{⊥} \cdot \nabla_{⊥} \ln B = n_{j} u_{∥ j} ((), \frac{e}{m_{j}} E_{∥} + g_{∥} + {boldu}_{j} {boldu}_{j} : \nabla \overset{b}{true}) + <...>

…”

Section: Model Descriptionmentioning

confidence: 99%

Modeling the interaction between convection and nonthermal ion outflows

2015

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Initial demonstrations of an ionosphere/polar wind model including a phenomenological treatment of transverse heating by wave particle interactions (WPIs) are presented. Tests with fixed WPI parameters in a designated heating region on the dayside with time-varying convection show that the parameters of the resulting nonthermal ion outflow are strongly coupled to the convection. The hemispheric outflow rate is positively correlated with the convection speed with a time delay related to the travel time to the upper boundary. Increases in convection increase the thermal plasma access to the heating region, both by increasing the upflow associated with frictional heating and by increasing the horizontal transport. The average parallel velocities and energies of the escaping nonthermal ions are anticorrelated with the convection speed due to the finite dwell time in the heating region. The computationally efficient model can be readily coupled into global geospace modeling frameworks in the future.

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\frac{\partial}{∂t} n_{j} + \nabla \cdot ([], n_{j} {boldu}_{j}) = 𝚼 n_{i}

\frac{\partial}{∂t} ((), n_{j} u_{∥ j}) + \nabla \cdot ([], n_{j} u_{∥ j} {boldu}_{j}) = n_{j} ((), \frac{e}{m_{j}} E_{∥} + g_{∥} + {boldu}_{j} {boldu}_{j} : \nabla \overset{b}{true}) - \frac{p_{⊥ j}}{m_{j}} \nabla_{∥} \ln B + 𝚼 n_{i} u_{∥ i}

\frac{\partial}{∂t} ϵ_{j} + \nabla \cdot ([], ϵ_{j} {boldu}_{j}) - \frac{p_{⊥ j}}{m_{j}} {boldu}_{⊥} \cdot \nabla_{⊥} \ln B = n_{j} u_{∥ j} ((), \frac{e}{m_{j}} E_{∥} + g_{∥} + {boldu}_{j} {boldu}_{j} : \nabla \overset{b}{true}) + <...>

…”

Section: Model Descriptionmentioning

confidence: 99%

Modeling the interaction between convection and nonthermal ion outflows

2015

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“…[43] Several recent studies suggest that high-altitude ion outflow to the magnetosphere may be causally linked to various ionospheric upflow processes discussed above [Strangeway et al, 2005;Lynch et al, 2007;Ogawa et al, 2008]. It is thought that ionospheric upflows deposit large amounts of plasma into higher-altitude regions where other processes like transverse ion heating and parallel potential drops can accelerate the upflowing ions to escape velocity.…”

Section: Observations Parallel To B: Sondrestrom Isr 26 February 2001mentioning

confidence: 99%

Incoherent scatter radar estimation ofFregion ionospheric composition during frictional heating events

et al. 2011

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[1] A method is developed for estimating F region ion composition from incoherent scatter radar (ISR) measurements during times of frictional ion heating. The technique addresses ion temperature-mass ambiguities in the IS spectra by self-consistently modeling ion temperature profiles, including the effects of ion temperature anisotropies and altitude-independent neutral winds. The modeled temperature profiles are used in a minimization procedure to estimate ion composition consistent with the recorded IS spectra. The proposed method is applicable to short-integration (<5 min) data sets from either single-beam or multiple-beam experiments. Application of the technique to Sondrestrom ISR measurements shows increases in F region molecular ions in response to frictional heating, a result consistent with previous theoretical and observational work. Estimates of ion composition are shown to be relatively insensitive to moderate variations in the neutral atmospheric model, which serves as input to the method. The technique developed in this work is uniquely qualified for studying highly variable ion composition near auroral arcs and associated processes such as molecular ion upflows. It also addresses a systematic source of error in standard ISR analysis methods when they are applied in such situations.

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“…There is a significant body of evidence suggesting that the F-region and topside ionospheric densities modulate the intensity of heavy ion outflows to the magnetosphere (e.g. Ogawa et al, 2008). If this is indeed the case, then depletion processes limit plasma supply to the magnetosphere by reducing the reservoir of F-region plasma available for extraction (Semeter et al, 2003;Lotko, 2007).…”

Section: Plasma Depletions Associated With Composition Variabilitymentioning

confidence: 99%

Dynamic variability in F-region ionospheric composition at auroral arc boundaries

et al. 2010

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Abstract. The work presents a data-model synthesis examining the response of the auroral F-region ion temperature, composition, and density to short time scale (<1 min) electric field disturbances associated with auroral arcs. Ion temperature profiles recorded by the Sondrestrom incoherent scatter radar (ISR) are critically analyzed with the aid of theoretical calculations to infer ion composition variability. The analyses presented include a partial accounting for the effects of neutral winds on frictional heating and show promise as the groundwork for future attempts to address ion temperature-mass ambiguities in short-integration ISR data sets. Results indicate that large NO + enchancements in the F-region can occur in as little as 20 s in response to impulsive changes in ion frictional heating. Enhancements in molecular ion density result in recombination and a depletion in plasma, which is shown to occur on time scales of several minutes. This depletion process, thus, appears to be of comparable importance to electrodynamic evacuation processes in producing auroral arc-related plasma depletions. Furthermore, the potential of ionospheric composition in regulating the amounts and types of ions supplied to the magnetosphere is outlined.

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Coordinated EISCAT Svalbard radar and Reimei satellite observations of ion upflows and suprathermal ions

Cited by 24 publications

References 30 publications

Modeling the interaction between convection and nonthermal ion outflows

Modeling the interaction between convection and nonthermal ion outflows

Incoherent scatter radar estimation ofFregion ionospheric composition during frictional heating events

Dynamic variability in F-region ionospheric composition at auroral arc boundaries

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