Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers
The aspect sensitivity of VHF echoes from field aligned irregularities (FAI) within meteor trails and thin ionization layers is studied using numerical models. Although the maximum power is obtained when a radar is pointed perpendicular to the field line (<IMG WIDTH='15' HEIGHT='14...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2004-01-01
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| Series: | Atmospheric Chemistry and Physics |
| Online Access: | http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-2004.pdf |
| _version_ | 1818693864612954112 |
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| author | Q. H. Zhou Y. T. Morton J. D. Mathews D. Janches D. Janches |
| author_facet | Q. H. Zhou Y. T. Morton J. D. Mathews D. Janches D. Janches |
| author_sort | Q. H. Zhou |
| collection | DOAJ |
| description | The aspect sensitivity of VHF echoes from field aligned irregularities (FAI) within meteor trails and thin ionization layers is studied using numerical models. Although the maximum power is obtained when a radar is pointed perpendicular to the field line (<IMG WIDTH='15' HEIGHT='14' ALIGN='BOTTOM' BORDER='0' src='http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-img1.gif' ALT='$bot$'><B>B</B>), substantial power can be obtained off the <IMG WIDTH='15' HEIGHT='14' ALIGN='BOTTOM' BORDER='0' src='http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-img1.gif' ALT='$bot$'><B>B</B> direction if the ionization trail/layer is thin. When the FAI length along <B>B</B> is 20 m, the power observed 6° off <IMG WIDTH='15' HEIGHT='14' ALIGN='BOTTOM' BORDER='0' src='http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-img1.gif' ALT='$bot$'><B>B</B> is about 10 db below that perpendicular to the <B>B</B> direction. Meteoric FAI echoes can potentially be used to determine the diffusion rate in the mesopause region. Based on the aspect sensitivity analysis, we conclude that the range spread trail echoes far off <IMG WIDTH='15' HEIGHT='14' ALIGN='BOTTOM' BORDER='0' src='http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-img1.gif' ALT='$bot$'><B>B</B> observed by powerful VHF radars are likely due to overdense meteors. Our simulation also shows that ionospheric FAI echoes can have an altitude smearing effect of about 4 km if the vertical extension of a FAI-layer is around 100 m, which has often been observed at Arecibo. The altitude smearing effect can account for the fact that the Es-layers observed by the Arecibo incoherent scatter radar are typically much narrower than FAI-layers and the occurrence of double spectral peaks around the Es-layer altitude in FAI echoes. |
| first_indexed | 2024-12-17T13:20:28Z |
| format | Article |
| id | doaj.art-8fe050b8436c4bb3ada6fad85bf0287f |
| institution | Directory Open Access Journal |
| issn | 1680-7316 1680-7324 |
| language | English |
| last_indexed | 2024-12-17T13:20:28Z |
| publishDate | 2004-01-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Atmospheric Chemistry and Physics |
| spelling | doaj.art-8fe050b8436c4bb3ada6fad85bf0287f2022-12-21T21:46:53ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242004-01-0143685692Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layersQ. H. ZhouY. T. MortonJ. D. MathewsD. JanchesD. JanchesThe aspect sensitivity of VHF echoes from field aligned irregularities (FAI) within meteor trails and thin ionization layers is studied using numerical models. Although the maximum power is obtained when a radar is pointed perpendicular to the field line (<IMG WIDTH='15' HEIGHT='14' ALIGN='BOTTOM' BORDER='0' src='http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-img1.gif' ALT='$bot$'><B>B</B>), substantial power can be obtained off the <IMG WIDTH='15' HEIGHT='14' ALIGN='BOTTOM' BORDER='0' src='http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-img1.gif' ALT='$bot$'><B>B</B> direction if the ionization trail/layer is thin. When the FAI length along <B>B</B> is 20 m, the power observed 6° off <IMG WIDTH='15' HEIGHT='14' ALIGN='BOTTOM' BORDER='0' src='http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-img1.gif' ALT='$bot$'><B>B</B> is about 10 db below that perpendicular to the <B>B</B> direction. Meteoric FAI echoes can potentially be used to determine the diffusion rate in the mesopause region. Based on the aspect sensitivity analysis, we conclude that the range spread trail echoes far off <IMG WIDTH='15' HEIGHT='14' ALIGN='BOTTOM' BORDER='0' src='http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-img1.gif' ALT='$bot$'><B>B</B> observed by powerful VHF radars are likely due to overdense meteors. Our simulation also shows that ionospheric FAI echoes can have an altitude smearing effect of about 4 km if the vertical extension of a FAI-layer is around 100 m, which has often been observed at Arecibo. The altitude smearing effect can account for the fact that the Es-layers observed by the Arecibo incoherent scatter radar are typically much narrower than FAI-layers and the occurrence of double spectral peaks around the Es-layer altitude in FAI echoes.http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-2004.pdf |
| spellingShingle | Q. H. Zhou Y. T. Morton J. D. Mathews D. Janches D. Janches Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers Atmospheric Chemistry and Physics |
| title | Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers |
| title_full | Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers |
| title_fullStr | Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers |
| title_full_unstemmed | Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers |
| title_short | Aspect sensitivity of VHF echoes from field aligned irregularities in meteor trails and thin ionization layers |
| title_sort | aspect sensitivity of vhf echoes from field aligned irregularities in meteor trails and thin ionization layers |
| url | http://www.atmos-chem-phys.net/4/685/2004/acp-4-685-2004.pdf |
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