Opposite hemispheric asymmetries during the ionospheric storm of 29–31 August 2004

Astafyeva, Elvira; Zakharenkova, Irina; Doornbos, Eelco

doi:10.1002/2014ja020710

Cited by 26 publications

(41 citation statements)

References 80 publications

(173 reference statements)

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“…At the same time, the in situ plasma density decreased as compared to the previous dayside profile from SWA. One can also notice an increase in the VTEC and Ne at high latitudes in the southern hemisphere, which can be attributed to traveling ionospheric disturbances (TIDs) or to storm enhanced density (SED) occurring due to energy deposition at high latitudes and the consequent heating of the high-latitude atmosphere (e.g., Prölss 1995;Foster et al 2005;Astafyeva et al 2015a). …”

Section: Resultsmentioning

confidence: 99%

“…However, in the topside region the positive disturbances can be led by an ionospheric uplift to higher altitudes where the recombination is slower. Previously, Astafyeva et al (2015a) observed the positive ionospheric disturbance in the topside ionosphere in the summer hemisphere that was explained by a combination of the storm-time PPEF and the enhanced storm-time thermospheric circulation.…”

Section: Discussionmentioning

confidence: 99%

“…It has been recently reported that during several storms the response of the F-layer and the topside ionosphere can differ and even show opposite effects than in the bottomside (e.g., Yizengaw et al 2006;Pedatella et al 2009;Astafyeva et al 2015a), which indicates that these regions might be influenced by different drivers. However, not many instruments are yet available to perform this type of research.…”

Section: Introductionmentioning

confidence: 99%

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Prompt penetration electric fields and the extreme topside ionospheric response to the June 22–23, 2015 geomagnetic storm as seen by the Swarm constellation

2016

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Using data from the three Swarm satellites, we study the ionospheric response to the intense geomagnetic storm of June 22-23, 2015. With the minimum SYM-H excursion of −207 nT, this storm is so far the second strongest geomagnetic storm in the current 24th solar cycle. A specific configuration of the Swarm satellites allowed investigation of the evolution of the storm-time ionospheric alterations on the day-and the nightside quasi-simultaneously. With the development of the main phase of the storm, a significant dayside increase of the vertical total electron content (VTEC) and electron density Ne was first observed at low latitudes on the dayside. From ~22 UT of 22 June to ~1 UT of 23 June, the dayside experienced a strong negative ionospheric storm, while on the nightside an extreme enhancement of the topside VTEC occurred at mid-latitudes of the northern hemisphere. Our analysis of the equatorial electrojet variations obtained from the magnetic Swarm data indicates that the storm-time penetration electric fields were, most likely, the main driver of the observed ionospheric effects at the initial phase of the storm and at the beginning of the main phase. The dayside ionosphere first responded to the occurrence of the strong eastward equatorial electric fields. Further, penetration of westward electric fields led to gradual but strong decrease of the plasma density on the dayside in the topside ionosphere. At this stage, the disturbance dynamo could have contributed as well. On the nightside, the observed extreme enhancement of the Ne and VTEC in the northern hemisphere (i.e., the summer hemisphere) in the topside ionosphere was most likely due to the combination of the prompt penetration electric fields, disturbance dynamo and the storm-time thermospheric circulation. From ~2.8 UT, the ionospheric measurements from the three Swarm satellites detected the beginning of the second positive storm on the dayside, which was not clearly associated with electrojet variations. We find that this second storm might be provoked by other drivers, such as an increase in the thermospheric composition.

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Prompt penetration electric fields and the extreme topside ionospheric response to the June 22–23, 2015 geomagnetic storm as seen by the Swarm constellation

2016

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“…In each observatory, the recovery phase is found to be noticeably long (more than 10 days). Dissimilarities between Figures 5a and 5b are likely due to the fact that F layer and topside ionosphere may not respond in the same way to a solar event [see, e.g., Yizengaw et al, 2006;Astafyeva et al, 2015a]. These plots are produced considering both vTEC and electron density data in the longitudinal range between 90°E and 135°E.…”

Section: Magnetic Data 221 Ground-based Magnetometersmentioning

confidence: 99%

Formation of ionospheric irregularities over Southeast Asia during the 2015 St. Patrick's Day storm

et al. 2016

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We investigate the geospace response to the 2015 St. Patrick's Day storm leveraging on instruments spread over Southeast Asia (SEA), covering a wide longitudinal sector of the low‐latitude ionosphere. A regional characterization of the storm is provided, identifying the peculiarities of ionospheric irregularity formation. The novelties of this work are the characterization in a broad longitudinal range and the methodology relying on the integration of data acquired by Global Navigation Satellite System (GNSS) receivers, magnetometers, ionosondes, and Swarm satellites. This work is a legacy of the project EquatoRial Ionosphere Characterization in Asia (ERICA). ERICA aimed to capture the features of both crests of the equatorial ionospheric anomaly (EIA) and trough (EIT) by means of a dedicated measurement campaign. The campaign lasted from March to October 2015 and was able to observe the ionospheric variability causing effects on radio systems, GNSS in particular. The multiinstrumental and multiparametric observations of the region enabled an in‐depth investigation of the response to the largest geomagnetic storm of the current solar cycle in a region scarcely reported in literature. Our work discusses the comparison between northern and southern crests of the EIA in the SEA region. The observations recorded positive and negative ionospheric storms, spread F conditions, scintillation enhancement and inhibition, and total electron content variability. The ancillary information on the local magnetic field highlights the variety of ionospheric perturbations during the different storm phases. The combined use of ionospheric bottomside, topside, and integrated information points out how the storm affects the F layer altitude and the consequent enhancement/suppression of scintillations.

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“…There is overwhelming evidence in literature that perturbation neutral winds develop very slowly that shall change the prevailing dynamo at midlatitude causing disturbance dynamo (Blanc & Richmond, 1980) and when they reach the low latitudes with fresh nitrogen, they change O/N 2 ratio. (Ercha et al, 2012;Astafyeva, Zakharenkova, & Doornbos, 2015;Pancheva et al, 2016;Yiğit et al, 2016;Luo et al, 2016). Also, hemispheric asymmetry at low latitudes has been observed during later phases of the storms, mostly found due to the disturbance dynamo effect and O/N 2 changes.…”

Section: Resultsmentioning

confidence: 94%

Interhemispheric Asymmetry in Response of Low‐Latitude Ionosphere to Perturbation Electric Fields in the Main Phase of Geomagnetic Storms

2019

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Structures of sudden enhancements/depressions and associated interhemispheric asymmetry in low‐latitude total electron content (TEC) during the main phase (MP) of geomagnetic storms have remained unpredictable majorly due to oscillating equatorial vertical E×B drifts and resultant redistribution of plasma in low latitudes in a given seasonal background. Robust analysis of 7 major and 30 moderate ionospheric storms during the years 2000–2018 is performed with comprehensive literature review encompassing various sources of asymmetry in magnetosphere‐ionosphere coupling. Taking advantage of simultaneous long‐term observations of E×B drift from Jicamarca, H component from magnetometers, and global ionospheric map vertical TEC (VTEC) and TEC observations across the dip equator from the South American sector, simultaneous formation of peaks and valleys in VTEC and associated asymmetry are studied. Additionally, a three‐layer neural network‐based E×B drift model is developed using delta‐H observations that provide drift estimates in the absence of Jicamarca drifts. The main results establish simultaneous high‐magnitude short‐lived (1–2 hr) enhancements and depression in VTEC during the MP in daytime in both hemispheres with varying differences of −30 to 100 TECU with respect to quiet time mean and along with prominent existence of interhemispheric asymmetry in TEC during the MP regardless of seasons. Maximum VTEC in the northern and southern low latitudes is found to occur at different times during storms. Large difference of VTEC is found ranging between 10 and 30 TECU between the near conjugate locations of the hemispheres. Coincident global episodic peaks marked by steep VTEC falls show dominance of episodic eastward and westward penetration electric fields in the low‐latitude daytime ionosphere.

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Opposite hemispheric asymmetries during the ionospheric storm of 29–31 August 2004

Cited by 26 publications

References 80 publications

Prompt penetration electric fields and the extreme topside ionospheric response to the June 22–23, 2015 geomagnetic storm as seen by the Swarm constellation

Prompt penetration electric fields and the extreme topside ionospheric response to the June 22–23, 2015 geomagnetic storm as seen by the Swarm constellation

Formation of ionospheric irregularities over Southeast Asia during the 2015 St. Patrick's Day storm

Interhemispheric Asymmetry in Response of Low‐Latitude Ionosphere to Perturbation Electric Fields in the Main Phase of Geomagnetic Storms

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