The Role of Thermospheric Neutral Winds in the Mid-Latitude Ionospheric Evening Anomalies
One of the intriguing features of the F-region ionosphere are anomalous evening enhancements of the electron density over certain mid-latitude sites. The most prominent example of this enhancement is the Weddell Sea Anomaly. Although the evening anomalies have been known for several decades, their g...
Main Author: | |
---|---|
Format: | Text |
Language: | unknown |
Published: |
DigitalCommons@USU
2015
|
Subjects: | |
Online Access: | https://digitalcommons.usu.edu/etd/4238 https://doi.org/10.26076/4427-e4fe https://digitalcommons.usu.edu/context/etd/article/5271/viewcontent/2015_Lomidze_Levan.pdf |
id |
ftutahsudc:oai:digitalcommons.usu.edu:etd-5271 |
---|---|
record_format |
openpolar |
spelling |
ftutahsudc:oai:digitalcommons.usu.edu:etd-5271 2023-06-11T04:17:30+02:00 The Role of Thermospheric Neutral Winds in the Mid-Latitude Ionospheric Evening Anomalies Lomidze, Levan 2015-05-01T07:00:00Z application/pdf https://digitalcommons.usu.edu/etd/4238 https://doi.org/10.26076/4427-e4fe https://digitalcommons.usu.edu/context/etd/article/5271/viewcontent/2015_Lomidze_Levan.pdf unknown DigitalCommons@USU https://digitalcommons.usu.edu/etd/4238 doi:10.26076/4427-e4fe https://digitalcommons.usu.edu/context/etd/article/5271/viewcontent/2015_Lomidze_Levan.pdf Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. All Graduate Theses and Dissertations role thermospheric neutral winds mid-latitude ionospheric evening anomalies Physics text 2015 ftutahsudc https://doi.org/10.26076/4427-e4fe 2023-05-04T17:38:05Z One of the intriguing features of the F-region ionosphere are anomalous evening enhancements of the electron density over certain mid-latitude sites. The most prominent example of this enhancement is the Weddell Sea Anomaly. Although the evening anomalies have been known for several decades, their generation mechanisms are still under debate and their accurate modeling remains a challenge. In this dissertation, the role of thermospheric neutral winds in the generation of these anomalies is investigated. Thermospheric winds play an important role in the dynamics of the F-region ionosphere, and, as it will be shown, in the generation of the evening anomalies. However, to date, their reliable estimation remains a challenge. To mitigate this shortcoming, data assimilation models were employed. First, seasonal global maps of F-region peak parameters (NmF2 and hmF2) from COSMIC radio occultation measurements were assimilated into the Global Assimilation of Ionospheric Measurements Full Physics (GAIM-FP) model. The model estimates magnetic meridional winds at low and mid-latitudes. GAIM-FP estimated winds were shown to be in good agreement with independent ground-based wind observations. Next, in order to address the role of neutral wind components in the generation of anomalies, a separate, 3-D physics-based Thermosphere Wind Assimilation Model (TWAM) was developed. TWAM is based on an implicit Kalman filter technique, and combines GAIM-FP magnetic meridional wind data with the equation of motion of the neutral gas to provide the climatology of the thermospheric wind components. The neutral wind components estimated by TWAM were also found to be in close quantitative agreement with independent ground-based wind observations, and were shown to accurately reproduce NmF2 and hmF2 over the anomalies. To understand the physical mechanism behind the anomalies, the plasma production, loss, and transport processes were analyzed. It was found that, due to the action of the equatorward wind, the evening density maximum forms at ... Text Weddell Sea Utah State University: DigitalCommons@USU Weddell Weddell Sea |
institution |
Open Polar |
collection |
Utah State University: DigitalCommons@USU |
op_collection_id |
ftutahsudc |
language |
unknown |
topic |
role thermospheric neutral winds mid-latitude ionospheric evening anomalies Physics |
spellingShingle |
role thermospheric neutral winds mid-latitude ionospheric evening anomalies Physics Lomidze, Levan The Role of Thermospheric Neutral Winds in the Mid-Latitude Ionospheric Evening Anomalies |
topic_facet |
role thermospheric neutral winds mid-latitude ionospheric evening anomalies Physics |
description |
One of the intriguing features of the F-region ionosphere are anomalous evening enhancements of the electron density over certain mid-latitude sites. The most prominent example of this enhancement is the Weddell Sea Anomaly. Although the evening anomalies have been known for several decades, their generation mechanisms are still under debate and their accurate modeling remains a challenge. In this dissertation, the role of thermospheric neutral winds in the generation of these anomalies is investigated. Thermospheric winds play an important role in the dynamics of the F-region ionosphere, and, as it will be shown, in the generation of the evening anomalies. However, to date, their reliable estimation remains a challenge. To mitigate this shortcoming, data assimilation models were employed. First, seasonal global maps of F-region peak parameters (NmF2 and hmF2) from COSMIC radio occultation measurements were assimilated into the Global Assimilation of Ionospheric Measurements Full Physics (GAIM-FP) model. The model estimates magnetic meridional winds at low and mid-latitudes. GAIM-FP estimated winds were shown to be in good agreement with independent ground-based wind observations. Next, in order to address the role of neutral wind components in the generation of anomalies, a separate, 3-D physics-based Thermosphere Wind Assimilation Model (TWAM) was developed. TWAM is based on an implicit Kalman filter technique, and combines GAIM-FP magnetic meridional wind data with the equation of motion of the neutral gas to provide the climatology of the thermospheric wind components. The neutral wind components estimated by TWAM were also found to be in close quantitative agreement with independent ground-based wind observations, and were shown to accurately reproduce NmF2 and hmF2 over the anomalies. To understand the physical mechanism behind the anomalies, the plasma production, loss, and transport processes were analyzed. It was found that, due to the action of the equatorward wind, the evening density maximum forms at ... |
format |
Text |
author |
Lomidze, Levan |
author_facet |
Lomidze, Levan |
author_sort |
Lomidze, Levan |
title |
The Role of Thermospheric Neutral Winds in the Mid-Latitude Ionospheric Evening Anomalies |
title_short |
The Role of Thermospheric Neutral Winds in the Mid-Latitude Ionospheric Evening Anomalies |
title_full |
The Role of Thermospheric Neutral Winds in the Mid-Latitude Ionospheric Evening Anomalies |
title_fullStr |
The Role of Thermospheric Neutral Winds in the Mid-Latitude Ionospheric Evening Anomalies |
title_full_unstemmed |
The Role of Thermospheric Neutral Winds in the Mid-Latitude Ionospheric Evening Anomalies |
title_sort |
role of thermospheric neutral winds in the mid-latitude ionospheric evening anomalies |
publisher |
DigitalCommons@USU |
publishDate |
2015 |
url |
https://digitalcommons.usu.edu/etd/4238 https://doi.org/10.26076/4427-e4fe https://digitalcommons.usu.edu/context/etd/article/5271/viewcontent/2015_Lomidze_Levan.pdf |
geographic |
Weddell Weddell Sea |
geographic_facet |
Weddell Weddell Sea |
genre |
Weddell Sea |
genre_facet |
Weddell Sea |
op_source |
All Graduate Theses and Dissertations |
op_relation |
https://digitalcommons.usu.edu/etd/4238 doi:10.26076/4427-e4fe https://digitalcommons.usu.edu/context/etd/article/5271/viewcontent/2015_Lomidze_Levan.pdf |
op_rights |
Copyright for this work is held by the author. Transmission or reproduction of materials protected by copyright beyond that allowed by fair use requires the written permission of the copyright owners. Works not in the public domain cannot be commercially exploited without permission of the copyright owner. Responsibility for any use rests exclusively with the user. For more information contact digitalcommons@usu.edu. |
op_doi |
https://doi.org/10.26076/4427-e4fe |
_version_ |
1768376750658551808 |