Magnetic storm associated perturbations of the upper atmosphere

Prölss, Gerd W.

doi:10.1029/gm098p0227

Cited by 148 publications

(131 citation statements)

References 69 publications

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“…Overviews of various con¯icting explanations are given in various review articles (e.g. Matuura, 1972;Danilov and Morozova, 1985;ProÈ lss, 1995ProÈ lss, , 1997. Many hypotheses have been tried and most rejected (see, e.g.…”

Section: ] ([O]/[n 2 ])mentioning

confidence: 99%

Analysis of the positive ionospheric response to a moderate geomagnetic storm using a global numerical model

Namgaladze

Förster²,

Yurik³

2000

Ann. Geophys.

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Abstract. Current theories of F-layer storms are discussed using numerical simulations with the Upper Atmosphere Model, a global self-consistent, time dependent numerical model of the thermosphere±iono-sphere±plasmasphere±magnetosphere system including electrodynamical coupling e ects. A case study of a moderate geomagnetic storm at low solar activity during the northern winter solstice exempli®es the complex storm phenomena. The study focuses on positive ionospheric storm e ects in relation to thermospheric disturbances in general and thermospheric composition changes in particular. It investigates the dynamical e ects of both neutral meridional winds and electric ®elds caused by the disturbance dynamo e ect. The penetration of short-time electric ®elds of magnetospheric origin during storm intensi®cation phases is shown for the ®rst time in this model study. Comparisons of the calculated thermospheric composition changes with satellite observations of AE-C and ESRO-4 during storm time show a good agreement. The empirical MSISE90 model, however, is less consistent with the simulations. It does not show the equatorward propagation of the disturbances and predicts that they have a gentler latitudinal gradient. Both theoretical and experimental data reveal that although the ratio of [O]/[N 2 ] at high latitudes decreases significantly during the magnetic storm compared with the quiet time level, at mid to low latitudes it does not increase (at ®xed altitudes) above the quiet reference level. Meanwhile, the ionospheric storm is positive there. We conclude that the positive phase of the ionospheric storm is mainly due to uplifting of ionospheric F 2 -region plasma at mid latitudes and its equatorward movement at low latitudes along geomagnetic ®eld lines caused by large-scale neutral wind circulation and the passage of travelling atmospheric disturbances (TADs). The calculated zonal electric ®eld disturbances also help to create the positive ionospheric disturbances both at middle and low latitudes. Minor contributions arise from the general density enhancement of all constituents during geomagnetic storms, which favours ion production processes above ion losses at ®xed height under daylight conditions.

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Section: ] ([O]/[n 2 ])mentioning

confidence: 99%

Analysis of the positive ionospheric response to a moderate geomagnetic storm using a global numerical model

Namgaladze

Förster²,

Yurik³

2000

Ann. Geophys.

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“…Thermospheric dynamics, including the variability of neutral density, has 2 been studied theoretically and observationally for decades (see Prölss (1997) 3 and references therein). Regions of enhanced neutral densities are of prime 4 concern for the tracking of satellites and space debris.…”

Section: Introductionmentioning

confidence: 99%

Auroral precipitation/ion upwelling as a driver of neutral density enhancement in the cusp

Sadler

Lessard

Lund

et al. 2012

Journal of Atmospheric and Solar-Terrestrial Physics

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Soft electron precipitation in collaboration with ion upwelling is investigated as a possible driver of the cusp neutral density enhancement discovered by the CHAMP satellite. A time-dependent, three-uid numerical model is used to simulate the vertical ionospheric and thermospheric response for this type of event. Particle data from the FAST satellite from a single favorable conjunction alignment event with CHAMP are input to the model. Results are given which suggest that altitude-dependent neutral density enhancements accompany ion upwelling that is driven by soft electron precipitation. The enhancement mechanism is summarized as follows. Su ciently soft electron precipitation transfers energy to the ambient electron gas , which subsequently undergoes a thermal (upward) expansion. This establishes a vertical ambipolar electric eld which pulls the ions upward. The momentum carried by up-owing ions is signi cant and results show it to be capable of dragging neutral gas upward to create density structures above the F-region.

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“…This fact is even more remarkable keeping in mind that the thermosphere is not isolated from the outside, as the thin thermospheric air is constantly under very strong and highly variable (both in space and time) inputs of energy per unit mass from such diverse sources as solar radiative heating, high-latitude particle precipitation, and Joule heating (e.g. Roble, 1995;Prölss, 1997;FullerRowell et al, 2004). It is also interesting to notice in this regard that a comparably fast diffusion in a gravity field results in the diffusive separation of species, and not in their homogeneous distribution.…”

Section: Atmospheric Entropy Balancementioning

confidence: 99%

On the energetics of maximum‐entropy temperature profiles

Akmaev

2008

Quart J Royal Meteoro Soc

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ABSTRACT:The problem of determining a maximum-entropy state in an atmospheric column has different solutions depending on the constraints imposed. As was first shown by J. W. Gibbs, maximization of entropy in a thermally-isolated, i.e. energy-conserving, atmosphere yields an isothermal temperature distribution. It has since been argued that conservation of the mass-weighted integral of potential temperature, or of the column potential enthalpy, is more appropriate for certain dynamical processes. The solution of the maximization problem satisfying this second constraint is quite different: an adiabatic temperature profile.Here, the comparative energetics of entropy maximization is examined in more detail. The main new result is that some exact statements may be formulated as inequalities. It can be rigorously shown, for example, that maximization of entropy under the conservation of potential enthalpy in an initially stable stratification always requires additional energy, and so cannot be accomplished in an isolated layer. Conversely, a temperature profile satisfying the second condition always possesses less entropy than an isothermal state with the same total energy, and so cannot be in thermodynamic equilibrium. Starting with these fundamental results, this paper discusses basic properties, and specific examples, of dynamical processes transporting heat vertically and generating entropy under various constraints, and demonstrates the importance of their physically-consistent parametrization in atmospheric models.

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Magnetic storm associated perturbations of the upper atmosphere

Cited by 148 publications

References 69 publications

Analysis of the positive ionospheric response to a moderate geomagnetic storm using a global numerical model

Analysis of the positive ionospheric response to a moderate geomagnetic storm using a global numerical model

Auroral precipitation/ion upwelling as a driver of neutral density enhancement in the cusp

On the energetics of maximum‐entropy temperature profiles

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