Equatorial ionospheric variations during geomagnetic storms

Matsushita, S.

doi:10.1029/jz068i009p02595

Cited by 15 publications

(5 citation statements)

References 17 publications

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“…The height of the F, peak rises in general (Matsushita, 1963). Hirao, et al, (1965) have recently reported that the peak Ne of the nighttime E region increased with increasing K in the middle latitudes.…”

Section: Nightsidementioning

confidence: 87%

The ionosphere at 640 kilometers on quiet and disturbed days

Reddy¹,

Brace²,

Findlay³

1967

J. Geophys. Res.

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Electrostatic probe measurements of electron concentration Ne from the TIROS 7 satellite are the basis for a study of the global response of the topside ionosphere (640 km) to magnetic disturbances at solar minimum. The quiet‐time behavior of Ne shows many of the features previously evident in Explorer 22 measurements at 1000 km. These are the daytime equatorial maximum, the nighttime midlatitude maximums, and the main trough at the boundary of the polar region. The storm‐time response of the ionosphere at 640 km takes the form of strong Ne enhancements at middle and high latitudes on the dayside and smaller enhancements on the nightside. This enhancement is in contrast to present thinking, which is based on bottomside sounding and total content measurements. At the equator, the storms produce depressions of Ne on the dayside and enhancements on the nightside. Measurements of Ne and electron temperature Te from Explorer 22 show similar but smaller Ne enhancements during storms, accompanied by slight decreases in Te, except in the polar regions where both Ne and Te are increased. It is concluded that the storm‐time enhancements of Ne may be explained in terms of the observed thermal expansion of the neutral atmosphere that lifts the entire ionosphere, thereby increasing Ne at the fixed altitude of the observations. The different behavior of the equatorial Ne is consistent with electrodynamic drift theory. The storm‐time increase of Te in the polar region may result from additional heating, while the decrease of Te at all other latitudes is caused by both increased collisional cooling to the expanded neutral atmosphere and by a decrease in the escape flux of photoelectrons which heat the upper F region.

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Section: Nightsidementioning

confidence: 87%

The ionosphere at 640 kilometers on quiet and disturbed days

Reddy¹,

Brace²,

Findlay³

1967

J. Geophys. Res.

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“…Figures a–c illustrate the seasonal variation of ionospheric storm effects over MBAR, SHEB, and NAZR. P ionospheric storm effects are prevalent in all seasons (e.g., Adewale et al, ; Matsushita, , , Prölss, ) during both CME‐ and CIR‐driven storms. Most P ionospheric storm effects were observed in June solstice and September equinox over the Southern (MBAR) and Northern (SHEB) Hemisphere stations during CME‐driven storms.…”

Section: Seasonal Variationmentioning

confidence: 99%

Ionospheric Responses to CME‐ and CIR‐Driven Geomagnetic Storms Along 30°E–40°E Over the African Sector From 2001 to 2015

Matamba

Habarulema

2018

Space Weather

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In this paper, we present the responses of the ionospheric total electron content (TEC) to coronal mass ejection (CME)‐ and corotating interaction region (CIR)‐driven storms using stations that lie within 30°E–40°E geographic longitude in middle, low, and equatorial latitudes over the African sector. CIR‐driven storms are generally weak (−50 nT < Dst < −25 nT) to moderate (−100 nT < Dst < −50 nT) in intensity, while CME‐driven storms are often associated with the intense (Dst < −100 nT) geomagnetic storms. CIR‐driven storms have long recovery phase as compared to CME‐driven storms. CME‐ and CIR‐driven storms were classified based on the features of proton temperature, magnetic field, solar wind speed, and proton density. The storm periods analyzed occurred during the period 2001–2015, which covers part of solar cycles 23 and 24. Disturbance storm time (Dst) ≤ −30 nT and Kp ≥ 3 indices were used simultaneously to identify the storm periods considered. The total number of CME‐ and CIR‐driven storms identified was 148 and 167, respectively. However, due to lack of TEC data, the number of CME‐ and CIR‐driven storms considered for the middle‐latitude, low‐latitude, and equatorial latitude stations are different for different regions. TEC data used in this study was derived from the Global Navigation Satellite System observations. The statistical analysis of ionospheric storm effects were compared over middle, low, and equatorial latitudes in the African sector for the first time. Negative ionospheric storm effects occurred only during CME‐driven storms over midlatitude stations and were more prevalent in summer. For the low and equatorial latitudes, negative ionospheric storm effects were observed during both CME‐ and CIR‐driven storms. Our analysis has shown that positive ionospheric storm effects were more prevalent over middle, low, and equatorial latitudes during both CME‐ and CIR‐driven storms. A significant number of cases where the electron density changes remained within the background variability during storm conditions were observed over the low‐latitude stations compared to other latitude regions.

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“…The ionospheric communities in India, Japan, and Taiwan did extraordinary amounts of work, with publications appearing in both less widely circulated national journals [e.g., Somayajulu et al , 1971; Chandra et al , 1973; Jain et al , 1978] as well as in those of western Europe and the United States [ Rastogi , 1962; Rastogi and Rajaram , 1965; Rajaram et al , 1971; Raghavarao and Sivaraman , 1973; Huang et al , 1974, 1987; Deshpande et al , 1977; Rastogi et al , 1979]. Prior to the widespread availability of TEC data, earlier works dealing with the low‐latitude response to geomagnetic activity were conducted using individual ionosonde stations and chains of stations during storms [e.g., Matsushita , 1963; Rajaram and Rastogi , 1969, 1970]. In the Matuura [1972] review of F region morphologies, two figures with TEC data were used to document how both positive and negative perturbations can be related to changes in the “fountain effect” associated with the ambient equatorial ionization anomaly.…”

Section: Multisite Tec Studies During Geomagnetic Stormsmentioning

confidence: 99%

Storms in the ionosphere: Patterns and processes for total electron content

Mendillo

2006

Reviews of Geophysics

469

440

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[1] The ionosphere's total electron content (TEC) is a parameter widely used in studies of the near-Earth plasma environment. The scientific use of TEC appeared early in the artificial satellite era, and among its many contributions were fundamental insights into how the ionosphere responds to geomagnetic storms. While many excellent reviews of solar-terrestrial disturbances exist in the literature, none have concentrated on the TEC parameter per se. With new TEC data sets increasingly available from the Global Positioning System (GPS), a comprehensive summary of pre-GPS storm studies is needed to set the base for progress in the GPS era. This review summarizes past case studies, describes statistical occurrence pattern, and identifies responsible mechanisms validated via modeling. It presents a new set of results of TEC disturbance patterns during 180 geomagnetic storms to describe seasonal and solar cycle effects. It concludes with a set of open questions that require additional study.Citation: Mendillo, M. (2006), Storms in the ionosphere: Patterns and processes for total electron content, Rev. Geophys., 44, RG4001,

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Equatorial ionospheric variations during geomagnetic storms

Cited by 15 publications

References 17 publications

The ionosphere at 640 kilometers on quiet and disturbed days

The ionosphere at 640 kilometers on quiet and disturbed days

Ionospheric Responses to CME‐ and CIR‐Driven Geomagnetic Storms Along 30°E–40°E Over the African Sector From 2001 to 2015

Storms in the ionosphere: Patterns and processes for total electron content

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