Large solar flares and their ionospheric D region enhancements
On 4 November 2003, the largest solar flare ever recorded saturated the GOES satellite X-ray detectors, making an assessment of its size difficult. However, VLF radio phase advances effectively recorded the lowering of the VLF reflection height and hence the lowest edge of the Earth's ionospher...
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ftnerc:oai:nora.nerc.ac.uk:2017 2024-06-09T07:49:52+00:00 Large solar flares and their ionospheric D region enhancements Thomson, Neil R. Rodger, Craig J. Clilverd, Mark A. 2005 http://nora.nerc.ac.uk/id/eprint/2017/ http://www.agu.org/pubs/crossref/2005/2005JA011008.shtml https://doi.org/10.1029/2005JA011008 unknown American Geophysical Union Thomson, Neil R.; Rodger, Craig J.; Clilverd, Mark A. orcid:0000-0002-7388-1529 . 2005 Large solar flares and their ionospheric D region enhancements. Journal of Geophysical Research, 110 (A6), A06306. 10, pp. https://doi.org/10.1029/2005JA011008 <https://doi.org/10.1029/2005JA011008> Atmospheric Sciences Space Sciences Publication - Article PeerReviewed 2005 ftnerc https://doi.org/10.1029/2005JA011008 2024-05-15T08:42:16Z On 4 November 2003, the largest solar flare ever recorded saturated the GOES satellite X-ray detectors, making an assessment of its size difficult. However, VLF radio phase advances effectively recorded the lowering of the VLF reflection height and hence the lowest edge of the Earth's ionosphere. Previously, these phase advances were used to extrapolate the GOES 0.1–0.8 nm (“XL”) fluxes from saturation at X17 to give a peak magnitude of X45 ± 5 for this great flare. Here it is shown that a similar extrapolation, but using the other GOES X-ray band, 0.05–0.4 nm (“XS”), is also consistent with a magnitude of X45. Also reported here are VLF phase measurements from two paths near dawn: “Omega Australia” to Dunedin, New Zealand (only just all sunlit) and NPM, Hawaii, to Ny Alesund, Svalbard (only partly sunlit), which also give remarkably good extrapolations of the flare flux, suggesting that VLF paths monitoring flares do not necessarily need to be in full daylight. D region electron densities are modeled as functions of X-ray flux up to the level of the great X45 flare by using flare-induced VLF amplitudes together with the VLF phase changes. During this great flare, the “Wait” reflection height, H′, was found to have been lowered to ∼53 km or ∼17 km below the normal midday value of ∼70 km. Finally, XL/XS ratios are examined during some large flares, including the great flare. Plots of such ratios against XL can give quite good estimates of the great flare's size (X45) but without use of VLF measurements. Article in Journal/Newspaper Svalbard Natural Environment Research Council: NERC Open Research Archive New Zealand Svalbard Journal of Geophysical Research 110 A6 |
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Natural Environment Research Council: NERC Open Research Archive |
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ftnerc |
language |
unknown |
topic |
Atmospheric Sciences Space Sciences |
spellingShingle |
Atmospheric Sciences Space Sciences Thomson, Neil R. Rodger, Craig J. Clilverd, Mark A. Large solar flares and their ionospheric D region enhancements |
topic_facet |
Atmospheric Sciences Space Sciences |
description |
On 4 November 2003, the largest solar flare ever recorded saturated the GOES satellite X-ray detectors, making an assessment of its size difficult. However, VLF radio phase advances effectively recorded the lowering of the VLF reflection height and hence the lowest edge of the Earth's ionosphere. Previously, these phase advances were used to extrapolate the GOES 0.1–0.8 nm (“XL”) fluxes from saturation at X17 to give a peak magnitude of X45 ± 5 for this great flare. Here it is shown that a similar extrapolation, but using the other GOES X-ray band, 0.05–0.4 nm (“XS”), is also consistent with a magnitude of X45. Also reported here are VLF phase measurements from two paths near dawn: “Omega Australia” to Dunedin, New Zealand (only just all sunlit) and NPM, Hawaii, to Ny Alesund, Svalbard (only partly sunlit), which also give remarkably good extrapolations of the flare flux, suggesting that VLF paths monitoring flares do not necessarily need to be in full daylight. D region electron densities are modeled as functions of X-ray flux up to the level of the great X45 flare by using flare-induced VLF amplitudes together with the VLF phase changes. During this great flare, the “Wait” reflection height, H′, was found to have been lowered to ∼53 km or ∼17 km below the normal midday value of ∼70 km. Finally, XL/XS ratios are examined during some large flares, including the great flare. Plots of such ratios against XL can give quite good estimates of the great flare's size (X45) but without use of VLF measurements. |
format |
Article in Journal/Newspaper |
author |
Thomson, Neil R. Rodger, Craig J. Clilverd, Mark A. |
author_facet |
Thomson, Neil R. Rodger, Craig J. Clilverd, Mark A. |
author_sort |
Thomson, Neil R. |
title |
Large solar flares and their ionospheric D region enhancements |
title_short |
Large solar flares and their ionospheric D region enhancements |
title_full |
Large solar flares and their ionospheric D region enhancements |
title_fullStr |
Large solar flares and their ionospheric D region enhancements |
title_full_unstemmed |
Large solar flares and their ionospheric D region enhancements |
title_sort |
large solar flares and their ionospheric d region enhancements |
publisher |
American Geophysical Union |
publishDate |
2005 |
url |
http://nora.nerc.ac.uk/id/eprint/2017/ http://www.agu.org/pubs/crossref/2005/2005JA011008.shtml https://doi.org/10.1029/2005JA011008 |
geographic |
New Zealand Svalbard |
geographic_facet |
New Zealand Svalbard |
genre |
Svalbard |
genre_facet |
Svalbard |
op_relation |
Thomson, Neil R.; Rodger, Craig J.; Clilverd, Mark A. orcid:0000-0002-7388-1529 . 2005 Large solar flares and their ionospheric D region enhancements. Journal of Geophysical Research, 110 (A6), A06306. 10, pp. https://doi.org/10.1029/2005JA011008 <https://doi.org/10.1029/2005JA011008> |
op_doi |
https://doi.org/10.1029/2005JA011008 |
container_title |
Journal of Geophysical Research |
container_volume |
110 |
container_issue |
A6 |
_version_ |
1801382764011847680 |