Field-aligned plasma diffusive fluxes in the topside ionosphere from radio occultation measurements by CHAMP

Chen, Guang ming; Xu, Jiyao; Wang, Wenbin; Lei, Jiuhou; Deng, Yue

doi:10.1016/j.jastp.2009.03.027

Cited by 19 publications

(31 citation statements)

References 33 publications

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“…Chen et al . [, ] calculated O + field‐aligned diffusive velocities and fluxes using satellite radio occultation measurements. They found that in the topside ionosphere daytime diffusive fluxes changed gradually from downward to upward as altitude increases, whereas they are downward at night.…”

Section: Introductionmentioning

confidence: 99%

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The responses of ionospheric topside diffusive fluxes to two geomagnetic storms in October 2002

Chen

Wang

et al. 2014

JGR Space Physics

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O + field-aligned ambipolar diffusive velocities V d and fluxes Ф d in the topside ionosphere have been calculated from the observed profiles of electron density, ion, and electron temperatures during a 30 day incoherent scatter radar experiment conducted at Millstone Hill (288.5°E, 42.6°N) from 4 October to 4 November 2002. Two geomagnetic storms took place during this period. During the negative phases (depleted electron densities) of these two storms, the magnitudes of the daytime upward V d and Ф d were less than their averaged quiet time values. Whereas at nighttime, the downward V d and Ф d were sometimes larger than the averaged quiet time values. The variations in diffusive velocity and flux during the storm main and recovery phases were caused by changes in the ionospheric scale height or the shapes of ionospheric density profiles. The negative storm effect further reduced daytime diffusive flux. During these two storms, positive ionosphere phases (enhanced electron densities) were also observed. The diffusive velocity was much smaller during the period of positive storm effect, which led to a smaller diffusive flux than the quiet time one, although electron density was higher. It appears that storm time variations in diffusive velocity were more the results of storm time changes in the plasma vertical profile, rather than the cause of these plasma density changes.

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Section: Introductionmentioning

confidence: 99%

“…Chen et al . [, ] also studied the seasonal and latitudinal variations of diffusive velocities and fluxes under different solar activity conditions. They found that the largest upward values of diffusive fluxes occurred at between 10° and 30° geomagnetic latitudes and changes according to solar activity conditions.…”

Section: Introductionmentioning

confidence: 99%

The responses of ionospheric topside diffusive fluxes to two geomagnetic storms in October 2002

Chen

Wang

et al. 2014

JGR Space Physics

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“…This allows field‐aligned plasma drifts to occur readily as a result of plasma pressure gradient, gravitational, or collisional forces that align with the magnetic field. The existence and behavior of field‐aligned plasma transport has been inferred from observations of ion composition [ West et al , 1997; West and Heelis , 1996], ion temperature [ Venkatraman and Heelis , 1999; Chao et al , 2004; Su et al , 2004], and electron density [ Tulasi Ram et al , 2009; Chen et al , 2009] in the topside ionosphere. These studies have described the solar cycle, temporal, and spatial variations of field‐aligned plasma transport that are consistent with the measured parameters, but had not been directly observed in the plasma.…”

Section: Introductionmentioning

confidence: 99%

Latitude and local time variations of topside magnetic field-aligned ion drifts at solar minimum

2011

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The movement of ions along terrestrial magnetic field lines frequently causes the redistribution of ionization between northern and southern hemispheres. This behavior is known as interhemispheric transport and is an important source of coupling between the ion and neutral gases in the upper atmosphere. The Communications/Navigation Outage Forecast System (C/NOFS) satellite and the Coupled Ion Neutral Dynamics Investigation (CINDI) provide an opportunity to directly measure ion velocities and ion densities in the topside ionosphere, facilitating the study of the field‐aligned ion motions near the equator. Using data from 2008 and 2009, the field‐aligned ion velocities shows the presence of and variations in the interhemispheric transport during this extreme solar minimum. Solar local time and corrected magnetic latitude variations in field‐aligned plasma transport at equinox and solstice are examined for a fixed longitude region and the consistency or the observed trends are compared to the expected behavior of F region neutral winds.

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“…The plasma in this region is highly magnetized, allowing it to move readily along the magnetic field lines. The field‐aligned drift of plasma across the geomagnetic equator, known as interhemispheric transport, has been the subject of previous investigations using both direct observations [ Venkatraman and Heelis , ; Chao et al ., ; Burrell et al ., , ] and inferences based on measurements of ion composition [ West and Heelis , ; West et al , ], ion temperature [ Su et al , ; Venkatraman and Heelis , ], and electron density [ Tulasi Ram et al , ; Chen et al , ].…”

Section: Introductionmentioning

confidence: 99%

Daytime altitude variations of the equatorial, topside magnetic field‐aligned ion transport at solar minimum

2013

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[1] Above the ion density peak, the interhemispheric transport of plasma plays an important role in shaping the spatial density distribution of the ionosphere. This study uses daytime observations of the ion drift, density, and composition near the geomagnetic equator from the Coupled Ion-Neutral Dynamics Investigation on board the Communication/Navigation Outage Forecasting System satellite, for the period of extremely low solar activity present in 2008 and 2009, to explore the altitude variation in interhemispheric transport at heights reaching up to the O + /H + transition height. These observations revealed that the physical processes leading to interhemispheric transport do not change with altitude. These processes include forcing from the lower thermosphere, E B drift, and chemical processes. Their longitudinal variations combine with the structure of the geomagnetic field to cause the differences in interhemispheric transport seen in different longitude regions. At all longitudes, the quantity of plasma crossing the geomagnetic equator depends strongly on ion density, which causes large changes to the altitude variations of the field-aligned plasma drift speed.

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Field-aligned plasma diffusive fluxes in the topside ionosphere from radio occultation measurements by CHAMP

Cited by 19 publications

References 33 publications

The responses of ionospheric topside diffusive fluxes to two geomagnetic storms in October 2002

The responses of ionospheric topside diffusive fluxes to two geomagnetic storms in October 2002

Latitude and local time variations of topside magnetic field-aligned ion drifts at solar minimum

Daytime altitude variations of the equatorial, topside magnetic field‐aligned ion transport at solar minimum

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