Major phenomena of the equatorial ionosphere-thermosphere system under disturbed conditions

Abdu, M. A.

doi:10.1016/s1364-6826(96)00152-6

Cited by 257 publications

(249 citation statements)

References 52 publications

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“…Sahai et al (2000) using the OI 630 nm all-sky imaging observations of equatorial plasma bubble observations have previously noted the frequent occurrence of ESF during the month of January in both high and low solar activity. Abdu (1997) has pointed out that while the prompt penetration enhances the upward drift and the disturbance dynamo tends to reduce the upward drifts inhibiting the formation of ESF.…”

Section: Resultsmentioning

confidence: 99%

“…Schunk and Sojka (1996) further point out that the energy input to the upper atmosphere maximizes during the main or growth phase, while during the recovery phase the geomagnetic activity and energy input decrease. As described by Abdu (1997;see also Buonsanto, 1999) major modifications in the equatorial ionosphere-thermosphere system during magnetospheric disturbances are produced by (a) prompt equatorward penetration of magnetospheric/high latitude electric fields (see also Senior and Blanc, 1984;Spiro et al, 1988), and (b) disturbance dynamo driven by enhanced global thermospheric circulation resulting from energy input at high latitude (see also Blanc and Richmond, 1980). Recently, Kikuchi et al (2008) and Veenadhari et al (2010) have investigated penetration of magnetospheric electric fields to the equator during magnetic disturbances.…”

Section: Introductionmentioning

confidence: 99%

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Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21–22 January 2005

et al. 2011

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Abstract. In the present investigation, we have studied the response of the ionospheric F-region in the Latin American sector during the intense geomagnetic storm of 21-22 January 2005. This geomagnetic storm has been considered "anomalous" (minimum Dst reached −105 nT at 07:00 UT on 22 January) because the main storm phase occurred during the northward excursion of the B z component of interplanetary magnetic fields (IMFs). The monthly mean

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21–22 January 2005

et al. 2011

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“…Traveling atmospheric disturbances produced by the storm-time energy deposition at high latitudes and downwelling of atomic-rich air because of the storm-related changes in neutral-wind circulation can also result in daytime positive responses (Prölss et al, 1991;Prölss, 1993Prölss, , 1995. The negative storm effects occurred often during the main and recovery phases of storms (Abdu, 1997;Cander and Mihajlovic, 2005). Negative storm effects at high and middle latitudes are caused primarily by neutral composition changes due to the upwelling of molecular-rich air to higher altitudes driven by storm-time enhanced Joule heating (Mayr, Harris, and Spencer, 1978;Burns et al, 1995;Fuller-Rowell et al, 1994).…”

Section: Discussionmentioning

confidence: 99%

Ionospheric Day-to-Day Variability Around the Whole Heliosphere Interval in 2008

et al. 2011

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Ionospheric F2 peak electron densities (NmF2) measured at ten ionosonde stations have been analyzed to investigate ionospheric day-to-day variability around the Whole Heliosphere Interval (WHI) in 2008 (Day of Year (DOY) 50 -140). The ionosonde data showed that there was significant global day-to-day variability in NmF2. This variability had 5-, 7-, 9-, 11-, 13.5-, and 16 -21-day periodicities. At middle latitudes, the ionosphere appeared to respond directly to the solar-wind and interplanetary-magnetic-field (IMF) induced geomagnetic-activity forcing, with the day-to-day variability having the same periods as those in the solar-wind/IMF and geomagnetic activity. At the geomagnetic Equator, the ionosphere had a strong 7-day periodicity, corresponding to the same periodicity in the IMF B z component. In the equatorial anomaly region, the ionosphere showed more complicated day-to-day variability, dominated by the 9-day periodicity. In addition, there were also peri- odicities of 11 days and 16 -21 days in the ionosonde data at some stations. The ionosonde data were compared with the Coupled Magnetosphere Ionosphere Thermosphere (CMIT) simulations that were driven by the observed solar-wind and IMF data during the WHI. The CMIT simulations showed similar ionospheric daily variability seen in the data. They captured the positive and negative responses of the ionosphere at middle latitudes during the first corotating interaction region (CIR) event in the WHI. The response of the model to the second CIR event, however, was relatively weak.

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“…These low-latitude characteristic properties of the ionosphere have been studied observationally and theoretically for many years (Moffett, 1979;Anderson, 1981;Walker, 1981;Abdu et al, 1991;Bailey and Balan, 1996;Buonsanto, 1999;Rishbeth, 1975Rishbeth, , 2000Rishbeth and Fukao, 1995;Abdu, 1997Abdu, , 2001.…”

Section: Introductionmentioning

confidence: 99%

<i>F</i>-region ionospheric perturbations in the low-latitude ionosphere during the geomagnetic storm of 25-27 August 1987

2004

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Abstract.We have presented a comparison between the modeled N mF 2 and hmF 2, and N mF 2 and hmF 2 which were observed at the equatorial anomaly crest and close to the geomagnetic equator simultaneously by the Akita, Kokubunji, Yamagawa, Okinawa, Manila, Vanimo, and Darwin ionospheric sounders and by the middle and upper atmosphere (MU) radar (34.85 • N, 136.10 • E) during the 25-27 August 1987 geomagnetically storm-time period at low solar activity near 201 • , geomagnetic longitude. A comparison between the electron and ion temperatures measured by the MU radar and those produced by the model of the ionosphere and plasmasphere is presented. The corrections of the storm-time zonal electric field, E , from 16:30 UT to 21:00 UT on 25 August bring the modeled and measured hmF 2 into reasonable agreement. In both hemispheres, the meridional neutral wind, W, taken from the HWW90 wind model and the NRLMSISE-00 neutral temperature, T n , and densities are corrected so that the model results agree with the ionospheric sounders and MU radar observations. The geomagnetic latitude variations in N mF 2 on 26 August differ significantly from those on 25 and 27 August. The equatorial plasma fountain undergoes significant inhibition on 26 August. This suppression of the equatorial anomaly on 26 August is not due to a reduction in the meridional component of the plasma drift perpendicular to the geomagnetic field direction, but is due to the action of storm-time changes in neutral winds and densities on the plasma fountain process. The asymmetry in W determines most of the northsouth asymmetry in hmF 2 and N mF 2 on 25 and 27 August between about 01:00-01:30 UT and about 14:00 UT when the equatorial anomaly exists in the ionosphere, while asymmetries in W, T n , and neutral densities relative to the geomagnetic equator are responsible for the north-south asymmetry in N mF 2 and hmF 2 on 26 August. A theory of the primary mechanisms causing the morning and evening peaks in the electron temperature, T e , is developed. An appearCorrespondence to: A. V. Pavlov (pavlov@izmiran.rssi.ru) ance, magnitude variations, latitude variations, and a disappearance of the morning T e peaks during 25-27 August are caused by variations in E , thermospheric composition, T n , and W. The magnitude of the evening T e peak and its time location are decreased with the lowering of the geomagnetic latitude due to the weakening of the effect of the plasma drift caused by W on the electron density. The difference between 25 August and 26-27 August in an appearance, magnitude and latitude variations, and a disappearance of the evening T e peak is caused by variations in W, the thermospheric composition, T n , and E .

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Major phenomena of the equatorial ionosphere-thermosphere system under disturbed conditions

Cited by 257 publications

References 52 publications

Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21–22 January 2005

Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21–22 January 2005

Ionospheric Day-to-Day Variability Around the Whole Heliosphere Interval in 2008

<i>F</i>-region ionospheric perturbations in the low-latitude ionosphere during the geomagnetic storm of 25-27 August 1987

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Major phenomena of the equatorial ionosphere-thermosphere system under disturbed conditions

Cited by 257 publications

References 52 publications

Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21–22 January 2005

Studies of ionospheric F-region response in the Latin American sector during the geomagnetic storm of 21–22 January 2005

Ionospheric Day-to-Day Variability Around the Whole Heliosphere Interval in 2008

&lt;i&gt;F&lt;/i&gt;-region ionospheric perturbations in the low-latitude ionosphere during the geomagnetic storm of 25-27 August 1987

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<i>F</i>-region ionospheric perturbations in the low-latitude ionosphere during the geomagnetic storm of 25-27 August 1987