COSMIC/FORMOSAT‐3 tomography of SEP ionization in the polar cap

Дмитриев, А. В.; Tsai, Lung Chih; Yeh, Hund‐Der; Chang, Chih-Chien

doi:10.1029/2008gl036146

Cited by 10 publications

(13 citation statements)

References 15 publications

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“…The following major storms have attracted attention to date because they resulted in a specific thermosphere‐ionosphere‐magnetosphere system response: the July event [ Burke et al ., ; Kunitsyn et al ., ; Lazutin , ; Li et al ., ; Ngwira et al ., ; Pedatella et al ., ; Stephan et al ., ]; the November event [ Fejer et al ., ; Paznukhov et al ., ; Balan et al ., , ; Huang , ; Mannucci et al ., ; Deng et al ., ; Sahai et al ., ; Kelley et al ., ; Solovyev et al ., ; Abdu , ] (special issue of Journal of Atmospheric and Solar-Terrestrial Physics , 2010) and the December event [ Lei et al ., , ; Dmitriev et al ., , ; Pedatella et al ., ; de Jesus et al ., ; Klimenko and Klimenko , ; Wei et al ., ; Suvorova et al ., ].…”

Section: Discussionmentioning

confidence: 99%

“…Taking into account the specific ionization of electrons (the energy loss per unit distance) and the standard vertical profile of the upper atmosphere [e.g., Dmitriev et al ., ], we were able calculate the number of bounces between the top point at 800 km and the mirror points at a height of H min until the ~30 keV electron lost its energy in ionization. In this manner, we found that for a H min below 600 km, ~30 keV electrons lose their energy within ~2 h. During this time period, electrons pass eastward no more than ~30° in longitude because of a very slow azimuthal drift.…”

Section: Quasi‐trapped Electron Impacts and Uncertainties In Tec Estimentioning

confidence: 99%

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TEC evidence for near‐equatorial energy deposition by 30 keV electrons in the topside ionosphere

et al. 2013

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[1] Observations of energetic electrons (10 -300 keV) by NOAA/POES and DMSP satellites at heights <1000 km during the period from 1999 to 2010 allowed finding abnormal intense fluxes of~10 6 -10 7 cm À2 s À1 sr À1 for quasi-trapped electrons appearing within the forbidden zone of low latitudes over the African, Indo-China, and Pacific regions. Extreme fluxes appeared often in the early morning and persisted for several hours during the maximum and recovery phase of geomagnetic storms. We analyzed nine storm time events when extreme electron fluxes first appeared in the Eastern Hemisphere, then drifted further eastward toward the South-Atlantic Anomaly. Using the electron spectra, we estimated the possible ionization effect produced by quasi-trapped electrons in the topside ionosphere. The estimated ionization was found to be large enough to satisfy observed storm time increases in the ionospheric total electron content (TEC) determined for the same spatial and temporal ranges from global ionospheric maps. Additionally, extreme fluxes of quasi-trapped electrons were accompanied by the significant elevation of the low-latitude F-layer obtained from COSMIC/FORMOSAT-3 radio occultation measurements. We suggest that the storm time ExB drift of energetic electrons from the inner radiation belt is an important driver of positive ionospheric storms within low-latitude and equatorial regions.

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Section: Discussionmentioning

confidence: 99%

Section: Quasi‐trapped Electron Impacts and Uncertainties In Tec Estimentioning

confidence: 99%

TEC evidence for near‐equatorial energy deposition by 30 keV electrons in the topside ionosphere

et al. 2013

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“…Note that there were no FEE enhancements at that time. At high latitudes, the ionizing effect of the solar energetic electrons was a main source of the enhanced VTEC [ Dmitriev et al , , ]. At middle latitudes (40°–50°) in the noon sector, the localized increase of VTEC was likely caused by electrons precipitating from the radiation belt due to strong compression of the dayside magnetosphere (Figure , left).…”

Section: Discussionmentioning

confidence: 99%

“…On 14 December 2006, the ionosphere was strongly disturbed by solar energetic particles and transient geomagnetic storm. During the day, the solar energetic particles caused intense ionization of the bottomside ionosphere in the polar cap [ Dmitriev et al , , ], while a storm‐associated increase of ionization was observed in the topside ionosphere at lower latitudes [e.g., Suvorova et al , ]. The storm began after a sudden commencement at ~1400 UT followed by a long initial phase lasting until ~2230 UT.…”

Section: Positive Ionospheric Storm At the Initial Phasementioning

confidence: 99%

“…The quasi‐trapped electron bounces between both hemispheres many times and slowly drifts in longitude (the 30 keV electron for ~20 h) in the eastern direction producing ion pairs and secondary electrons (the secondary electron in turn can produce next ion pairs) before being lost in the SAA region. It was shown by calculating the number of bounces that the electrons lose the whole energy in ionization passing tens of degrees of longitudes for a few hours [ Dmitriev et al , ; Suvorova et al , ]. This feature also explains a wide longitudinal extension and relatively long duration of the ionizing FEE effect in the ionosphere for many events reported by Suvorova and Dmitriev [].…”

Section: Introductionmentioning

confidence: 95%

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Effects of ionizing energetic electrons and plasma transport in the ionosphere during the initial phase of the December 2006 magnetic storm

et al. 2016

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The initial phase of a major geomagnetic storm on 14 December 2006 was selected in order to investigate the ionizing effect of energetic electrons in the ionosphere. The global network of GPS receivers was used to analyze the total electron content (TEC). A strong positive ionospheric storm of ~20 TEC units (TECU) with ~6 h duration was observed on the dayside during the interval of northward interplanetary magnetic field. At the same time, the NOAA/POES satellites observed long‐lasting intense fluxes of >30 keV electrons in the topside ionosphere at middle and low latitudes, including a near‐equatorial forbidden zone outside of the South Atlantic Anomaly (SAA). We found that the TEC increases overlapped well with the enhancements of energetic electrons. Modeling of the ionospheric response by using a Global Self‐consistent Model of the Thermosphere, Ionosphere, and Protonosphere, based on the standard mechanisms of plasma transport, could only partially explain the ionospheric response and was unable to predict the long‐duration increase of TEC. For the energetic electrons, we estimated the ionizing effect of ~45 TECU and ~23 TECU in the topside ionosphere, respectively, inside and outside of SAA. The ionizing effect contributed from 50% to 100% of TEC increases and provided the long duration and wide latitudinal extension of the positive ionospheric storm. This finding is a very important argument in supporting significant ionizing effect of energetic electrons in the storm time ionosphere both at middle and low latitudes.

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Low‐latitude ionospheric effects of energetic electrons during a recurrent magnetic storm

et al. 2014

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We study a magnetosphere-ionosphere coupling at low latitudes during a moderate (corotating interaction regions/high-speed solar wind streams-driven) geomagnetic storm on 22 July 2009. Recently, it has been shown that during major (coronal mass ejection-driven) storms, quasi-trapped >30 keV electrons largely enhance below the radiation belt in the forbidden zone and produce an additional ionization in the topside ionosphere. In this work, we examine a case of the recurrent storm when the magnetosphere-ionosphere coupling through the quasi-trapped electrons also may take place. Data from NOAA/Polar-orbiting Operational Environmental Satellite and Japanese Greenhouse gases Observing Satellite were used to identify the forbidden electron enhancement (FEE). We find a positive vertical gradient of the electron fluxes that indicates to the radiation belt as a source of FEE. Using global ionospheric maps, radiotomography reconstructions from beacon data and COSMIC/FORMOSAT-3 radio occultation measurements, we have observed an unusually large area in the nighttime ionosphere with increased total electron content (TEC) and prominent elevation of the F layer at low latitudes that coincides with FEEs spatially and temporarily. Ionizing particles are considered as an addition source of ionization along with generally accepted mechanisms for storm time TEC increase (a positive ionospheric storm). We discuss relative contributions of the FEE and disturbance dynamo electric field in the TEC increases during the storm recovery phase.

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COSMIC/FORMOSAT‐3 tomography of SEP ionization in the polar cap

Cited by 10 publications

References 15 publications

TEC evidence for near‐equatorial energy deposition by 30 keV electrons in the topside ionosphere

TEC evidence for near‐equatorial energy deposition by 30 keV electrons in the topside ionosphere

Effects of ionizing energetic electrons and plasma transport in the ionosphere during the initial phase of the December 2006 magnetic storm

Low‐latitude ionospheric effects of energetic electrons during a recurrent magnetic storm

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