Time dependent thermospheric neutral response tothe 2–11 November 1993 storm period

Emery, B. A.; Lathuillére, C.; Richards, P. G.; Roble, R. G.; Buonsanto, M. J.; Knipp, D. J.; Wilkinson, Phil; Sipler, D. P.; Niciejewski, R. J.

doi:10.1016/s1364-6826(98)00137-0

Cited by 65 publications

(83 citation statements)

References 36 publications

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“…However, only AGW with relatively large wavelengths could propagate at long distances and reach the mid-latitudes (Vadas 2007). On the other hand, geomagnetic storms lead specifically to a global heating of the thermosphere (Emery et al 1999), and consequently, change the neutral wind conditions . AGW propagation and dissipation conditions would change accordingly (Vadas and Fritts 2006;Vadas 2007).…”

Section: Resultsmentioning

confidence: 99%

Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

et al. 2016

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We present a statistical study of medium-scale traveling ionospheric disturbances (MSTIDs) using the Hokkaido East (43.53°N, 143.61°E) and Ekaterinburg (56.42°N, 58.53°E) high-frequency (HF) radar data. Radar datasets are available from 2007 to 2014 for the Hokkaido and from 2013 to 2014 for the Ekaterinburg radar. In the case of the Hokkaido East radar, we have utilized the elevation angle information to study the MSTIDs propagating at the heights of the E and F ionospheric regions separately. We have analyzed the diurnal and seasonal behavior of the following medium-scale traveling ionospheric disturbance (MSTID) parameters: propagation direction, apparent horizontal velocity and wavelength, period, and relative amplitude. The F region MSTID azimuthal patterns were observed to be quite similar by the two radars. The E region northwestward MSTIDs (from 280°to 320°) were typical of summer daytime. Comparison with the horizontal wind model (HWM07) has showed that the dominant MSTID propagation directions match the anti-wind direction well, at least during sunlight hours. We have also found that the wavelength and period tend to decrease with an increase in solar activity. On the contrary, the relative amplitude increases with an increase in solar activity. Moreover, the relative amplitude tends to increase with increasing auroral electrojet (AE) index, as do the wavelength and velocity.

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Section: Resultsmentioning

confidence: 99%

Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

et al. 2016

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“…This is especially true when they begin to explore results from hemispheric differences driven by auroral input and convection patterns that are different -not only because the seasons are differentbut perhaps as intrinsic hemispheric effects as well. Such an approach has been used in specific case studies of storm effects with the TIE-GCM driven by AMIE patterns (Emery et al, 1999), and thus more comprehensive sets of storms, or statistical results built from many model storm scenarios, is an approach worth considering.…”

Section: Discussionmentioning

confidence: 99%

Ionospheric storms at geophysically-equivalent sites – Part 1: Storm-time patterns for sub-auroral ionospheres

Mendillo

Narvaez

2009

Ann. Geophys.

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Abstract. The systematic study of ionospheric storms has been conducted primarily with groundbased data from the Northern Hemisphere. Significant progress has been made in defining typical morphology patterns at all latitudes; mechanisms have been identified and tested via modeling. At higher mid-latitudes (sites that are typically sub-auroral during non-storm conditions), the processes that change significantly during storms can be of comparable magnitudes, but with different time constants. These include ionospheric plasma dynamics from the penetration of magnetospheric electric fields, enhancements to thermospheric winds due to auroral and Joule heating inputs, disturbance dynamo electrodynamics driven by such winds, and thermospheric composition changes due to the changed circulation patterns. The ∼12 • tilt of the geomagnetic field axis causes significant longitude effects in all of these processes in the Northern Hemisphere. A complementary series of longitude effects would be expected to occur in the Southern Hemisphere. In this paper we begin a series of studies to investigate the longitudinal-hemispheric similarities and differences in the response of the ionosphere's peak electron density to geomagnetic storms.The ionosonde stations at Wallops Island (VA) and Hobart (Tasmania) have comparable geographic and geomagnetic latitudes for sub-auroral locations, are situated at longitudes close to that of the dipole tilt, and thus serve as our candidate station-pair choice for studies of ionospheric storms at geophysically-comparable locations. They have an excellent record of observations of the ionospheric penetration frequency (foF2) spanning several solar cycles, and thus are suitable for long-term studies. During solar cycle #20 (1964)(1965)(1966)(1967)(1968)(1969)(1970)(1971)(1972)(1973)(1974)(1975)(1976), 206 geomagnetic storms occurred that had A p ≥30 or K p ≥5 for at least one day of the storm. Our analCorrespondence to: C. Narvaez (cnarvaez@bu.edu) ysis of average storm-time perturbations (percent deviations from the monthly means) showed a remarkable agreement at both sites under a variety of conditions. Yet, small differences do appear, and in systematic ways. We attempt to relate these to stresses imposed over a few days of a storm that mimic longer term morphology patterns occurring over seasonal and solar cycle time spans. Storm effects versus season point to possible mechanisms having hemispheric differences (as opposed to simply seasonal differences) in how solar wind energy is transmitted through the magnetosphere into the thermosphere-ionosphere system. Storm effects versus the strength of a geomagnetic storm may, similarly, be related to patterns seen during years of maximum versus minimum solar activity.

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“…This study suggests that it might be better to use the 6 = 1.2 factor to derive a more realistic assessment of Joule heating. This may explain why the AMIE model underestimated the temperature rise resulting from the storm of early November 1993 (Emery et al, 1999). The technique used here could be extended to add a 'correction' factor when using models such as CTIP and AMIE which tend not to completely capture the electric field variations.…”

Section: Discussionmentioning

confidence: 99%

“…For example, Joule heating causes ion upwelling (Kivanc and Heelis, 1999), gravity waves (Williams et al, 1988;Buonsanto et al, 1999;Balthazor et al, 1997), winds, which in turn change the F-region electron concentrations (Emery et al, 1999) and thermospheric composition (Hecht et al, 1999;Mikhailov and Foster, 1997).…”

Section: Introductionmentioning

confidence: 99%

The variability of Joule heating, and its effects on the ionosphere and thermosphere

et al. 2001

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Abstract.A considerable fraction of the solar wind energy that crosses the magnetopause ends up in the high-latitude thermosphere-ionosphere system as a result of Joule heating, the consequences of which are very significant and global in nature. Often Joule heating calculations use hourly averages of the electric field, rather than the time-varying electric field. This leads to an underestimation of the heating. In this paper, we determine the magnitude of the underestimation of Joule heating by analysing electric field data from the EISCAT Incoherent Scatter Radar, situated at the 67 • E magnetic latitude. We find that the underestimation, using hourly-averaged electric field values, is normally ∼20%, with an upper value of about 65%. We find that these values are insensitive to changes in solar flux, magnetic activity and magnetic local time, implying that the electric field fluctuations are linear related to the amplitude of the electric field. Assuming that these changes are representative of the entire auroral oval, we then use a coupled ionosphere-thermosphere model to calculate the local changes these underestimations in the heating rate cause to the neutral temperature, mean molecular mass and meridional wind. The changes in each parameter are of the order of a few percent but they result in a reduction in the peak F-region concentration of ∼20% in the summer hemisphere at high latitudes, and about half of this level in the winter hemisphere. We suggest that these calculations could be used to add corrections to modelled values of Joule heating.

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Time dependent thermospheric neutral response tothe 2–11 November 1993 storm period

Cited by 65 publications

References 36 publications

Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

Statistical characteristics of medium-scale traveling ionospheric disturbances revealed from the Hokkaido East and Ekaterinburg HF radar data

Ionospheric storms at geophysically-equivalent sites – Part 1: Storm-time patterns for sub-auroral ionospheres

The variability of Joule heating, and its effects on the ionosphere and thermosphere

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