Seasonal dependence of the longitudinal variations of nighttime ionospheric electron density and equivalent winds at southern midlatitudes

Luan, Xiaoli; Dou, Xiankang

doi:10.5194/angeo-31-1699-2013

Cited by 13 publications

(10 citation statements)

References 30 publications

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“…Xu et al [] have reported west‐east differences of TEC over North America (120°W, 70°W), South America (80°W, 50°W), and Southern Ocean (110°E, 180°E). Luan and Dou [] have found that the longitudinal variation in the evening electron density at southern midlatitudes, based on COSMIC satellite observations, are generally consistent with zonal wind effects. All these reported longitudinal differences are similar to the global maps presented from CHAMP electron density data.…”

Section: Introductionmentioning

confidence: 80%

“…The electron density at midlatitudes shows zonal (or longitudinal) variation, which tends to be explained by vertical drift effects caused by the zonal wind [e.g., Zhang et al , , ; Zhao et al , ; Xu et al , ; Luan and Dou , ; H. Wang et al, Interpretation of longitudinal pattern in the electron density at mid latitudes: CHAMP observation and global ionosphere‐thermosphere model (GITM) simulation, submitted to Chinese Science Bulletin , 2015]. With the magnetic declination, the zonal wind can contribute to the plasma velocity in the geomagnetic field direction.…”

Section: Introductionmentioning

confidence: 99%

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Theoretical study of zonal differences of electron density at midlatitudes with GITM simulation

Wang

Ridley

2015

JGR Space Physics

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(2015), Theoretical study of zonal differences of electron density at midlatitudes with GITM simulation, J. Geophys. Res. Space Physics, 120, 2951-2966, doi:10.1002 The copyright line for this article was changed on 27 AUG 2015 after original online publication.This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Abstract This study investigated various physical processes responsible for the longitudinal modulation of electron density (Ne) at midlatitudes by employing the global ionosphere-thermosphere model (GITM). The good agreements between GITM outputs and CHAMP observations indicate that the model is a suitable tool to perform the theoretical study. Nine runs were carried out to determine the effects from geomagnetic field geometry, zonal wind, meridional wind, high-latitude activity, migrating tides from the lower atmosphere, and solar illumination in quantitative ways. Distinct features were discussed as follows. It was crucial that the geomagnetic and geographical axes were offset for the development of the longitudinal difference of Ne. The zonal wind contributes to about 80% of the fraction of the observed longitudinal dependence of Ne. The meridional wind effect is out of phase with the zonal wind over North America and Southern Ocean regions, which trims the fraction of the longitudinal difference to 65%. Over the South Pacific Ocean, the nighttime Ne maintains at a higher level because of in-phase effects from both zonal and meridional winds. The solar illumination was important in the formation of the background longitudinal pattern of the electron density. The migrating tide from the lower atmosphere could enhance the longitudinal difference of Ne by 15% over North America. Enhanced activities at high latitudes could alter the longitudinal pattern of Ne by transporting thermospheric composition disturbances to midlatitudes.

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Section: Introductionmentioning

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Theoretical study of zonal differences of electron density at midlatitudes with GITM simulation

Wang

Ridley

2015

JGR Space Physics

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“…Xu et al [5] compared the West-East differences of TEC over North America (35°± 7°GLat, 120°W vs. 70°W GLon), South America (-40°± 7°GLat, 80°W vs. 50°W GLon), and South Ocean (-30°± 7°GLat, 110°E vs. 180°E GLon). Luan and Dou [6] studied longitudinal differences in electron densities at southern mid-latitudes during the night time (18-24 h magnetic local time, MLT), based on Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC) satellite observations. The results were theoretically consistent with the zonal wind-magnetic declination effects.…”

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confidence: 99%

Vertical structure of longitudinal differences in electron densities at mid-latitudes

2016

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“…At these altitudes, Ne distribution becomes very dependent on dynamic effects caused by neutral winds and/or vertical drifts by electric fields. The combined effect of geomagnetic configuration and neutral winds could be used to explain the wave number 1 longitudinal pattern of Ne at southern middle latitudes and the wave number 2 pattern of Ne at northern middle latitudes measured by CHAMP at 400 km [ Liu et al ., ], the east‐west coast differences of GPS TEC over the continental U.S. [ Zhang et al ., ], the east‐west differences of Ne from the incoherent scatter radar measurements at Millstone Hill [ Zhang et al ., ], and the longitudinal variations of the nighttime Ne in the Southern Hemisphere [ Luan et al ., ; Luan and Dou , ]. The zonal winds are found to contribute to about 80% of the observed longitudinal dependence of Ne, whereas the meridional winds reduce the wind contribution to the longitudinal dependence to 65% over North America and Southern Ocean areas around the SE in a theoretical study [ Wang et al ., ].…”

Section: Discussionmentioning

confidence: 99%

Statistical behavior of the longitudinal variations of daytime electron density in the topside ionosphere at middle latitudes

Wang

Burns

et al. 2016

JGR Space Physics

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Electron density in the topside ionosphere has significant variations with latitude, longitude, altitude, local time, season, and solar cycle. This paper focuses on the global and seasonal features of longitudinal structures of daytime topside electron density (Ne) at middle latitudes and their possible causes. We used in situ Ne measured by DEMETER and F2 layer peak height (hmF2) and peak density (NmF2) from COSMIC. The longitudinal variations of the daytime topside Ne show a wave number 2‐type structure in the Northern Hemisphere, whereas those in the Southern Hemisphere are dominated by a wave number 1 structure and are much larger than those in the Northern Hemisphere. The patterns around December solstice (DS) in the Northern Hemisphere (winter) are different from other seasons, whereas the patterns in the Southern Hemisphere are similar in each season. Around March equinox (ME), June solstice (JS), and September equinox (SE) in the Northern Hemisphere and around ME, SE, and DS in the Southern Hemisphere, the longitudinal variations of topside Ne have similar patterns to hmF2. Around JS in the Southern Hemisphere (winter), the topside Ne has similar patterns to NmF2 and hmF2 does not change much with longitude. Thus, the topside variations may be explained intuitively in terms of hmF2 and NmF2. This approach works reasonably well in most of the situations except in the northern winter in the topside not too far from the F2 peak. In this sense, understanding variations in hmF2 and NmF2 becomes an important and relevant subject for this topside ionospheric study.

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Seasonal dependence of the longitudinal variations of nighttime ionospheric electron density and equivalent winds at southern midlatitudes

Cited by 13 publications

References 30 publications

Theoretical study of zonal differences of electron density at midlatitudes with GITM simulation

Theoretical study of zonal differences of electron density at midlatitudes with GITM simulation

Vertical structure of longitudinal differences in electron densities at mid-latitudes

Statistical behavior of the longitudinal variations of daytime electron density in the topside ionosphere at middle latitudes

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