A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements
Accurately measuring the location and motion of the polar cap boundary (PCB) in the high-latitude ionosphere can be crucial for studies concerned with the dynamics of the polar cap, e.g. the measurement of reconnection rates. The Doppler spectral width characteristics of backscatter received by the...
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ftdoajarticles:oai:doaj.org/article:641631418c5d45fdb6a50c00f7b5ba28 2023-05-15T13:37:19+02:00 A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements G. Chisham M. P. Freeman 2003-04-01T00:00:00Z https://doi.org/10.5194/angeo-21-983-2003 https://doaj.org/article/641631418c5d45fdb6a50c00f7b5ba28 EN eng Copernicus Publications https://www.ann-geophys.net/21/983/2003/angeo-21-983-2003.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-21-983-2003 0992-7689 1432-0576 https://doaj.org/article/641631418c5d45fdb6a50c00f7b5ba28 Annales Geophysicae, Vol 21, Pp 983-996 (2003) Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 article 2003 ftdoajarticles https://doi.org/10.5194/angeo-21-983-2003 2022-12-31T11:59:13Z Accurately measuring the location and motion of the polar cap boundary (PCB) in the high-latitude ionosphere can be crucial for studies concerned with the dynamics of the polar cap, e.g. the measurement of reconnection rates. The Doppler spectral width characteristics of backscatter received by the SuperDARN HF radars have been previously used for locating and tracking the PCB in the cusp region. The boundary is generally observed in meridional beams of the SuperDARN radars and appears as a distinct change between low spectral width values observed equatorward of the cusp region, and high, but variable spectral width values observed within the cusp region. To identify the spectral width boundary (SWB) between these two regions, a simple algorithm employing a spectral width threshold has often been applied to the data. However, there is not, as yet, a standard algorithm, or spectral width threshold, which is universally applied. Nor has there been any rigorous assessment of the accuracy of this method of boundary determination. This study applies a series of threshold algorithms to a simulated cusp-region spectral width data set, to assess the accuracy of different algorithms. This shows that simple threshold algorithms correctly identify the boundary location in, at the most, 50% of the cases and that the average boundary error is at least ~ 1–2 range gates (~ 1° latitude). It transpires that spatial and temporal smoothing of the spectral width data (e.g. by median filtering), before application of a threshold algorithm can increase the boundary determination accuracy to over 95% and the average boundary error to much less than a range gate. However, this is sometimes at the cost of temporal resolution in the motion of the boundary location. The algorithms are also applied to a year’s worth of spectral width data from the cusp ionosphere, measured by the Halley SuperDARN radar in Antarctica. This analysis highlights the increased accuracy of the enhanced boundary determination algorithm in the cusp region. Away ... Article in Journal/Newspaper Antarc* Antarctica Directory of Open Access Journals: DOAJ Articles Annales Geophysicae 21 4 983 996 |
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Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
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Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 G. Chisham M. P. Freeman A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
topic_facet |
Science Q Physics QC1-999 Geophysics. Cosmic physics QC801-809 |
description |
Accurately measuring the location and motion of the polar cap boundary (PCB) in the high-latitude ionosphere can be crucial for studies concerned with the dynamics of the polar cap, e.g. the measurement of reconnection rates. The Doppler spectral width characteristics of backscatter received by the SuperDARN HF radars have been previously used for locating and tracking the PCB in the cusp region. The boundary is generally observed in meridional beams of the SuperDARN radars and appears as a distinct change between low spectral width values observed equatorward of the cusp region, and high, but variable spectral width values observed within the cusp region. To identify the spectral width boundary (SWB) between these two regions, a simple algorithm employing a spectral width threshold has often been applied to the data. However, there is not, as yet, a standard algorithm, or spectral width threshold, which is universally applied. Nor has there been any rigorous assessment of the accuracy of this method of boundary determination. This study applies a series of threshold algorithms to a simulated cusp-region spectral width data set, to assess the accuracy of different algorithms. This shows that simple threshold algorithms correctly identify the boundary location in, at the most, 50% of the cases and that the average boundary error is at least ~ 1–2 range gates (~ 1° latitude). It transpires that spatial and temporal smoothing of the spectral width data (e.g. by median filtering), before application of a threshold algorithm can increase the boundary determination accuracy to over 95% and the average boundary error to much less than a range gate. However, this is sometimes at the cost of temporal resolution in the motion of the boundary location. The algorithms are also applied to a year’s worth of spectral width data from the cusp ionosphere, measured by the Halley SuperDARN radar in Antarctica. This analysis highlights the increased accuracy of the enhanced boundary determination algorithm in the cusp region. Away ... |
format |
Article in Journal/Newspaper |
author |
G. Chisham M. P. Freeman |
author_facet |
G. Chisham M. P. Freeman |
author_sort |
G. Chisham |
title |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_short |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_full |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_fullStr |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_full_unstemmed |
A technique for accurately determining the cusp-region polar cap boundary using SuperDARN HF radar measurements |
title_sort |
technique for accurately determining the cusp-region polar cap boundary using superdarn hf radar measurements |
publisher |
Copernicus Publications |
publishDate |
2003 |
url |
https://doi.org/10.5194/angeo-21-983-2003 https://doaj.org/article/641631418c5d45fdb6a50c00f7b5ba28 |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_source |
Annales Geophysicae, Vol 21, Pp 983-996 (2003) |
op_relation |
https://www.ann-geophys.net/21/983/2003/angeo-21-983-2003.pdf https://doaj.org/toc/0992-7689 https://doaj.org/toc/1432-0576 doi:10.5194/angeo-21-983-2003 0992-7689 1432-0576 https://doaj.org/article/641631418c5d45fdb6a50c00f7b5ba28 |
op_doi |
https://doi.org/10.5194/angeo-21-983-2003 |
container_title |
Annales Geophysicae |
container_volume |
21 |
container_issue |
4 |
container_start_page |
983 |
op_container_end_page |
996 |
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1766090382003666944 |