Parameterization of the main ionospheric trough in the European sector

Pryse, S. E.; Kersley, L.; Malan, D.; Bishop, G. J.

doi:10.1029/2005rs003364

Cited by 32 publications

(57 citation statements)

References 11 publications

(10 reference statements)

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“…This maximum TEC is likely to be the effect of the boundary blob (Crowley, 1996) at the poleward extreme of the trough and at the equatorward side of the auroral oval. The set of parameters reflect those used in the earlier study of Pryse et al (2006) but there are differences that arise due to the different observing techniques, with the earlier study using the polar orbiting NIMS satellites.…”

Section: Parameterizationmentioning

confidence: 99%

“…The trough parameters modelled by EDAM are compared with observations of the earlier study (Pryse et al, 2006), which used multi-station measurements of the phasecoherent radio signals from the satellites of NIMS. In this earlier study TEC observations at three ground receivers in the UK, aligned in longitude but separated in latitude, were used to image the trough by tomographic reconstruction.…”

Section: Introductionmentioning

confidence: 99%

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Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

et al. 2018

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Abstract. The main ionospheric trough is a large-scale spatial depletion in the electron density distribution at the interface between the high-and mid-latitude ionosphere. In western Europe it appears in early evening, progresses equatorward during the night, and retreats rapidly poleward at dawn. It exhibits substantial day-to-day variability and under conditions of increased geomagnetic activity it moves progressively to lower latitudes. Steep gradients on the trough-walls on either side of the trough minimum, and their variability, can cause problems for radio applications. Numerous studies have sought to characterize and quantify the trough behaviour.The Electron Density Assimilative Model (EDAM) models the ionosphere on a global scale. It assimilates observations into a background ionosphere, the International Reference Ionosphere 2007 (IRI2007), to provide a full 3-D representation of the ionospheric plasma distribution at specified times and days. This current investigation studied the capability of EDAM to model the ionosphere in the region of the main trough. Total electron content (TEC) measurements from 46 GPS stations in western Europe from September to December 2002 were assimilated into EDAM to provide a model of the ionosphere in the trough region. Vertical electron content profiles through the model revealed the trough and the detail of its structure. Statistical results are presented of the latitude of the trough minimum, TEC at the minimum and of other defined parameters that characterize the trough structure. The results are compared with previous observations made with the Navy Ionospheric Monitoring System (NIMS), and reveal the potential of EDAM to model the large-scale structure of the ionosphere.

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Section: Parameterizationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

et al. 2018

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“…Tomographic reconstructions of the mid-latitude ionosphere confirmed that such an enhancement formed the poleward edge of the mid-latitude trough . A more recent investigation, aimed at characterising the morphology of the trough for the validation of ionospheric models, showed that a boundary blob could be identified at the poleward wall for some 2 3 of the 600 troughs studied (Pryse et al, 2006). However, the production mechanism behind the formation of the blob still remains open to debate and the observations presented here provide experimental evidence for plasma reconfiguration, as opposed to impact ionisation from soft particle precipitation, thus supporting the original modelling work of Robinson et al (1985).…”

Section: Discussionmentioning

confidence: 99%

“…However, after the Harang discontinuity, the return flow at the auroral edge of the dawn cell is no longer opposed to the co-rotation. While information is now available on the statistical character and morphology of the postmidnight trough (Pryse et al, 2006), little investigation has been done on the mechanisms operating in this sector. While troughs of "fossil" ionisation from the evening may be carried round in the co-rotating flow towards dawn, the present results suggest the reconfiguration of trans-polar plasma may have a role to play in the location and details of the poleward wall of troughs to be found after midnight.…”

Section: Discussionmentioning

confidence: 99%

“…However, a second field-aligned enhancement was also observed in the region of return, sunward flow that was consistent with production by soft-particle precipitation. The understanding of the occurrence and formation of the boundary blobs is of relevance to the mitigation of propagation effects on radio systems, where steep density gradients at the poleward edge of the mid-latitude trough can present particular problems (Pryse et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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Reconfiguration of polar-cap plasma in the magnetic midnight sector

et al. 2006

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Abstract. Radio tomography and the EISCAT and Super-DARN radars have been used to identify long-lived, highaltitude, cold plasma in the antisunward convective flow across the polar cap. The projection of the feature to later times suggests that it was reconfigured in the Harang discontinuity to form an enhancement that was elongated in longitude in the sunward return flow of the high-latitude convection pattern. Comparison with a tomographic image at a later time supports the interpretation of a polar patch being reconfigured into a boundary blob. There is also evidence for a second plasma enhancement equatorward of the reconfigured blob, likely to have been produced by in situ precipitation. The observations indicate that the two mechanisms proposed in the literature for the production of boundary blobs are operating simultaneously to form two distinct density features separated slightly in latitude.

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Peculiar features of the low‐latitude and midlatitude ionospheric response to the St. Patrick's Day geomagnetic storm of 17 March 2015

Nayak

Tsai

et al. 2016

JGR Space Physics

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The current study aims at investigating and identifying the ionospheric effects of the geomagnetic storm that occurred during 17–19 March 2015. Incidentally, with SYM‐H hitting a minimum of −232 nT, this was the strongest storm of the current solar cycle 24. The study investigates how the storm has affected the equatorial, low‐latitude, and midlatitude ionosphere in the American and the European sectors using available ground‐based ionosonde and GPS TEC (total electron content) data. The possible effects of prompt electric field penetration is observed in both sectors during the main phase of the storm. In the American sector, the coexistence of both positive and negative ionospheric storm phases are observed at low latitudes and midlatitudes to high latitudes, respectively. The positive storm phase is mainly due to the prompt penetration electric fields. The negative storm phase in the midlatitude region is a combined effect of disturbance dynamo electric fields, the equatorward shift of the midlatitude density trough, and the equatorward compression of the plasmapause in combination with chemical compositional changes. Strong negative ionospheric storm phase is observed in both ionosonde and TEC observations during the recovery phase which also shows a strong hemispherical asymmetry. Additionally, the variation of equatorial ionization anomaly as seen through the SWARM constellation plasma measurements across different longitudes has been discussed. We, also, take a look at the performance of the IRI Real‐Time Assimilative Mapping during this storm as an ionospheric space weather tool.

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Parameterization of the main ionospheric trough in the European sector

Cited by 32 publications

References 11 publications

Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

Modelling the main ionospheric trough using the Electron Density Assimilative Model (EDAM) with assimilated GPS TEC

Reconfiguration of polar-cap plasma in the magnetic midnight sector

Peculiar features of the low‐latitude and midlatitude ionospheric response to the St. Patrick's Day geomagnetic storm of 17 March 2015

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