Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar
We present the results from investigation of spectra of polar mesospheric summer echoes (PMSE) observed with EISCAT VHF 224 MHz radar during energetic particle precipitation events in the summer of 2019. We used the sudden enhancements in electron densities derived from the VHF observations above 90...
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Online Access: | https://hdl.handle.net/10037/26602 https://doi.org/10.1016/j.asr.2022.02.015 |
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ftunivtroemsoe:oai:munin.uit.no:10037/26602 2023-05-15T16:04:37+02:00 Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar Viswanathan, Lakshmi Narayanan Häggström, Ingemar Mann, Ingrid 2022-02-23 https://hdl.handle.net/10037/26602 https://doi.org/10.1016/j.asr.2022.02.015 eng eng Elsevier Advances in Space Research Viswanathan, Häggström, Mann. Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar. Advances in Space Research. 2022 FRIDAID 2017221 doi:10.1016/j.asr.2022.02.015 0273-1177 1879-1948 https://hdl.handle.net/10037/26602 openAccess Copyright 2022 COSPAR Journal article Tidsskriftartikkel Peer reviewed publishedVersion 2022 ftunivtroemsoe https://doi.org/10.1016/j.asr.2022.02.015 2022-09-07T23:00:13Z We present the results from investigation of spectra of polar mesospheric summer echoes (PMSE) observed with EISCAT VHF 224 MHz radar during energetic particle precipitation events in the summer of 2019. We used the sudden enhancements in electron densities derived from the VHF observations above 90 km as indicators of particle precipitation. We find that the altitude extent of the PMSE increased along with an enhancement of the strength of the pre-existing PMSE. On some occasions, PMSE suddenly appeared during particle precipitation events. After the particle precipitation subsided, the PMSE intensities continued to be stronger for a few minutes and then decreased. At the altitudes where the maximum enhancement in PMSE backscatter occurred, there is no corresponding broadening in the spectral widths. Interestingly, the most intense PMSE echoes almost always coincided with the lower values of spectral widths both during particle precipitations and other times. In some cases, the spectral widths show well separated regimes between the upper and lower parts of the PMSE layers and this also happened irrespective of particle precipitation. The frequency Doppler shifts showed alternating upward and downward motions without much difference before and after the particle precipitation. Based on these observations, we conclude that the sudden enhancement in the electron densities during particle precipitation intensifies PMSE structures that match the Bragg scale of the incident radio wave thereby enabling an enhancement in the backscatter strength. Similarly, PMSE backscattering may get initiated in the altitudes in which the structures were already present but where electron density was not sufficient before the onset of precipitation. Spectral widths and Doppler velocities does not show sudden variations with particle precipitation because they depend on the neutral dynamics. Article in Journal/Newspaper EISCAT University of Tromsø: Munin Open Research Archive Advances in Space Research 69 9 3350 3361 |
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Open Polar |
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University of Tromsø: Munin Open Research Archive |
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ftunivtroemsoe |
language |
English |
description |
We present the results from investigation of spectra of polar mesospheric summer echoes (PMSE) observed with EISCAT VHF 224 MHz radar during energetic particle precipitation events in the summer of 2019. We used the sudden enhancements in electron densities derived from the VHF observations above 90 km as indicators of particle precipitation. We find that the altitude extent of the PMSE increased along with an enhancement of the strength of the pre-existing PMSE. On some occasions, PMSE suddenly appeared during particle precipitation events. After the particle precipitation subsided, the PMSE intensities continued to be stronger for a few minutes and then decreased. At the altitudes where the maximum enhancement in PMSE backscatter occurred, there is no corresponding broadening in the spectral widths. Interestingly, the most intense PMSE echoes almost always coincided with the lower values of spectral widths both during particle precipitations and other times. In some cases, the spectral widths show well separated regimes between the upper and lower parts of the PMSE layers and this also happened irrespective of particle precipitation. The frequency Doppler shifts showed alternating upward and downward motions without much difference before and after the particle precipitation. Based on these observations, we conclude that the sudden enhancement in the electron densities during particle precipitation intensifies PMSE structures that match the Bragg scale of the incident radio wave thereby enabling an enhancement in the backscatter strength. Similarly, PMSE backscattering may get initiated in the altitudes in which the structures were already present but where electron density was not sufficient before the onset of precipitation. Spectral widths and Doppler velocities does not show sudden variations with particle precipitation because they depend on the neutral dynamics. |
format |
Article in Journal/Newspaper |
author |
Viswanathan, Lakshmi Narayanan Häggström, Ingemar Mann, Ingrid |
spellingShingle |
Viswanathan, Lakshmi Narayanan Häggström, Ingemar Mann, Ingrid Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar |
author_facet |
Viswanathan, Lakshmi Narayanan Häggström, Ingemar Mann, Ingrid |
author_sort |
Viswanathan, Lakshmi Narayanan |
title |
Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar |
title_short |
Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar |
title_full |
Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar |
title_fullStr |
Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar |
title_full_unstemmed |
Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar |
title_sort |
effects of particle precipitation on the polar mesospheric summer echoes observed by eiscat vhf 224 mhz radar |
publisher |
Elsevier |
publishDate |
2022 |
url |
https://hdl.handle.net/10037/26602 https://doi.org/10.1016/j.asr.2022.02.015 |
genre |
EISCAT |
genre_facet |
EISCAT |
op_relation |
Advances in Space Research Viswanathan, Häggström, Mann. Effects of particle precipitation on the polar mesospheric summer echoes observed by EISCAT VHF 224 MHz radar. Advances in Space Research. 2022 FRIDAID 2017221 doi:10.1016/j.asr.2022.02.015 0273-1177 1879-1948 https://hdl.handle.net/10037/26602 |
op_rights |
openAccess Copyright 2022 COSPAR |
op_doi |
https://doi.org/10.1016/j.asr.2022.02.015 |
container_title |
Advances in Space Research |
container_volume |
69 |
container_issue |
9 |
container_start_page |
3350 |
op_container_end_page |
3361 |
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1766400226059354112 |