Thermospheric dynamics during the March 22, 1979, magnetic storm: 1. Model simulations

Roble, R. G.; Forbes, Jeffrey M.; Marcos, F. A.

doi:10.1029/ja092ia06p06045

Cited by 99 publications

(36 citation statements)

References 65 publications

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“…Buonsanto et al, 1989) and models (e.g. Roble et al, 1987;FullerRowell et al, 1996), and are consistent with the observed uplifting of the F-layer height at the mid-latitude radars, e.g. Irkutsk and Kharkov in Fig.…”

Section: Plasma Drifts and Their Effectssupporting

confidence: 71%

Observations of the April 2002 geomagnetic storm by the global network of incoherent scatter radars

et al. 2005

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Abstract. This paper describes the ionospheric response to a geomagnetic storm beginning on 17 April 2002. We present the measurements of ionospheric parameters in the F-region obtained by the network of eight incoherent scatter radars. The main effects of this storm include a deep decrease in the electron density observed at high and middle latitudes in the pre-noon sector, and a minor enhancement in the density observed in the daytime sector at middle latitudes. Extreme plasma heating (>1000−3000 K) is observed at high latitudes, subsiding to 200-300 K at subauroral latitudes. The western hemisphere radar chain observed the prompt penetration of the electric field from auroral to equatorial latitudes, as well as the daytime enhancement of plasma drift parallel to the magnetic field line, which is related to the enhancement in the equatorward winds. We suggest that in the first several hours after the storm onset, a negative phase above Millstone Hill (pre-noon sector) results from counteracting processes -penetration electric field, meridional wind, and electrodynamic heating, with electrodynamic heating being the dominant mechanism. At the lower latitude in the prenoon sector (Arecibo and Jicamarca), the penetration electric field becomes more important, leading to a negative storm phase over Arecibo. In contrast, in the afternoon sector at mid-latitudes (Kharkov, Irkutsk), effects of penetration electric field and meridional wind do not counteract, but add up, leading to a small (∼15%), positive storm phase over these locations. As the storm develops, Millstone Hill and Irkutsk mid-latitude radars observe further depletion of electron density due to the changes in the neutral composition.

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Section: Plasma Drifts and Their Effectssupporting

confidence: 71%

Observations of the April 2002 geomagnetic storm by the global network of incoherent scatter radars

et al. 2005

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Section: Ion-neutral Diffuriorr Coemientsupporting

confidence: 54%

“…Roble et al [ 19781 reported observations of a day-time equatoward propagating disturbance of about three hours duration following a sudden storm commencement on Sept. 18,1974. A similar surge was found by Roble et al [1987a] in their simulations of the storm of March 2%1979. Thus it appears that the occurrence of day-time equatorward surges in the meridional neutral wind during storms may be a consistent feature of thermospheric dynamics.…”

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confidence: 60%

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Observations of neutral circulation at mid‐latitudes during the Equinox Transition Study

Buonsanto¹,

Salah²,

Miller³

et al. 1989

J. Geophys. Res.

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Measurements of ion drift velocity made by the Millstone Hill incoherent scatter radar have been used to calculate the meridional neutral wind velocity during the Sept. 17-24,1984 period. Strong daytime southward neutral surges were observed during the magnetically disturbed days of September 19 and 23, in contrast to the small daytime winds obtained as expected during the magnetically quiet days. The surge on September 19 was also seen at Arecl'bo. In addition, two approaches have been used to calculate the meridional wind component from the radarderived height of the F-layer electron density peak. Results confirm the wind surge, particularly when the strong electric fields measured during the disturbed days are included in the calculations. The two approaches for the F-layer peak wind calculations are applied to the radarderived electron density peak height as a function of latitude to study the variation of the southward daytime surges with latitude. INTRODUCI'IONGood progress has been made in the last decade in advancing our knowledge [Oliver and Salah, 19881. Satellite data has recently been used by Hedin et al. [1988] to create a global empirical wind model. A semi-empirical approach, which combines observations of the F2 peak height with MSIS neutral densities and temperatures and ionospheric models has also proven fruitful [Buonsanto, 1986;Miller et a]., 1986; Forbes et al., Studies of mid-latitude winds during quiet times reveal a generaI pattern of solar EW-driven day-to-night circulation with zonally averaged winds directed from the summer to the winter hemisphere, and a seasonal transition which the NCAR TGCM predicted to occur abruptly near the equinoxes [Roble et al, 1977). On the theoretical side, Thermospheric General Circulation ModelsIt was to investigate this transition period that the Equinox Transition Study (ETS), a global, coordinated, multi-instrument campaign, was organized and carried out during the period Sept. [17][18][19][20][21][22][23][24]1984. This turned out to be an ideal period for detailed study on account of the variety of geomagnetic conditions which occurred.After a period of geomagnetic quiet, a small storm (Ap=36) occurred on September 19. Following a period of recovery, a major storm (Ap==112) occurred on September 23.While the diurnally or zonally averaged global patterns of thermospheric neutral winds are becoming better understood, the diurnal and seasonal variations, particularly under varying geomagnetic conditions, are still poorly known. At high latitudes during storms, ion drag momentum forcing by the magnetospheric convection ionization drifts [eg., Killeen et al., 1984) is important in driving the neutral winds. The associated Joule heating and heating from particle precipitation results in post-midnight equatorward surges in the neutral wind, which have been modeled by the NCAR TGCM [Killeen and Roble, 1986, Roble et al., 1987al Theoretical models do not generally predict large scale changes in the day-time meridional winds during storms at mid-l...

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“…These data have been analyzed by many authors, including Rees et al (1986) and Roble et al (1987Roble et al ( , 1988a using their thermospheric general circulation models. A good general agreement has been found between TGCMpredicted neutral winds and DE-2 observations showing the dominant in¯uence of magnetospheric convection on high-latitude circulation.…”

Section: Comparison With the Observationsmentioning

confidence: 99%

Seasonal effects in the ionosphere-thermosphere response to the precipitation and field-aligned current variations in the cusp region

Namgaladze¹,

Volkov²

1998

Ann. Geophys.

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Abstract. The seasonal e ects in the thermosphere and ionosphere responses to the precipitating electron¯ux and ®eld-aligned current variations, of the order of an hour in duration, in the summer and winter cusp regions have been investigated using the global numerical model of the Earth's upper atmosphere. Two variants of the calculations have been performed both for the IMF B y < 0. In the ®rst variant, the model input data for the summer and winter precipitating¯uxes and ®eld-aligned currents have been taken as geomagnetically symmetric and equal to those used earlier in the calculations for the equinoctial conditions. It has been found that both ionospheric and thermospheric disturbances are more intensive in the winter cusp region due to the lower conductivity of the winter polar cap ionosphere and correspondingly larger electric ®eld variations leading to the larger Joule heating e ects in the ion and neutral gas temperature, ion drag e ects in the thermospheric winds and ion drift e ects in the F2-region electron concentration. In the second variant, the calculations have been performed for the events of 28±29 January, 1992 when precipitations were weaker but the magnetospheric convection was stronger than in the ®rst variant. Geomagnetically asymmetric input data for the summer and winter precipitating¯uxes and ®eld-aligned currents have been taken from the patterns derived by combining data obtained from the satellite, radar and ground magnetometer observations for these events. Calculated patterns of the ionospheric convection and thermospheric circulation have been compared with observations and it has been established that calculated patterns of the ionospheric convection for both winter and summer hemispheres are in a good agreement with the observations. Calculated patterns of the thermospheric circulation are in a good agreement with the average circulation for the Southern (summer) Hemisphere obtained from DE-2 data for IMF B y < 0 but for the Northern (winter) Hemisphere there is a disagreement at high latitudes in the afternoon sector of the cusp region. At the same time, the model results for this sector agree with other DE-2 data and with the ground-based FPI data. All ionospheric and thermospheric disturbances in the second variant of the calculations are more intensive in the winter cusp region in comparison with the summer one and this seasonal di erence is larger than in the ®rst variant of the calculations, especially in the electron density and all temperature variations. The means that the seasonal e ects in the cusp region are stronger in the thermospheric and ionospheric responses to the FAC variations than to the precipitation disturbances.

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Thermospheric dynamics during the March 22, 1979, magnetic storm: 1. Model simulations

Cited by 99 publications

References 65 publications

Observations of the April 2002 geomagnetic storm by the global network of incoherent scatter radars

Observations of the April 2002 geomagnetic storm by the global network of incoherent scatter radars

Observations of neutral circulation at mid‐latitudes during the Equinox Transition Study

Seasonal effects in the ionosphere-thermosphere response to the precipitation and field-aligned current variations in the cusp region

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