An Empirical Orthogonal Function Study of the Ionospheric TEC Predicted Using the TIEGCM Model over the South Atlantic Anomaly in 2002 and 2008
In this study, the variability of the ionospheric total electron content (TEC) in the South Atlantic Anomaly (SAA) in the solar maximum of 2002 and the solar minimum of 2008 were compared by using an empirical orthogonal function (EOF) analysis. The ionospheric TEC data were simulated using the Nati...
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2023-02-01
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| author | Jing Yu Zheng Li Yan Wang Jingjing Shao Luyao Wang Jingyuan Li Hua Zhang Xiaojun Xu Chunli Gu |
| author_facet | Jing Yu Zheng Li Yan Wang Jingjing Shao Luyao Wang Jingyuan Li Hua Zhang Xiaojun Xu Chunli Gu |
| author_sort | Jing Yu |
| collection | DOAJ |
| description | In this study, the variability of the ionospheric total electron content (TEC) in the South Atlantic Anomaly (SAA) in the solar maximum of 2002 and the solar minimum of 2008 were compared by using an empirical orthogonal function (EOF) analysis. The ionospheric TEC data were simulated using the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM). The first three EOFs accounted for 94.8% and 93.86% of the variability in the data in 2002 and 2008, respectively. The results showed that the TEC variations of the first three EOFs were generally consistent in 2002 and 2008. The first mode showed the equatorial anomaly caused by plasma drift and the east–west asymmetry possibly caused by the change in geomagnetic declination and zonal wind; EOF<sub>2</sub> exhibited the zonal variation influenced by the solar EUV radiation and the semiannual variation possibly controlled by the [O/N<sub>2</sub>], solar zenith angle, and atmospheric circulation. EOF<sub>3</sub> suggested an equatorial anomaly and winter anomaly influenced by the [O/N<sub>2</sub>] variation. However, the values and amplitude variations in the TEC were significantly greater in the solar maximum than that in the solar minimum, and the spring–autumn asymmetry of the TEC was more obvious in the solar minimum. In addition, we used the EOF method to extract the annual variation characteristics of the time coefficients and carried out a correlation analysis. The results showed that the annual variation in the TEC in 2002 was mainly affected by the solar EUV radiation, which was strongly correlated with F10.7 (r = 0.7348). In contrast, the TEC was mainly influenced by the geomagnetic activity in 2008 and had a strong correlation with Dst (r = −0.7898). |
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| spelling | doaj.art-352f5a0aaf044836b74734eeab085bcf2023-11-16T23:40:57ZengMDPI AGUniverse2218-19972023-02-019210210.3390/universe9020102An Empirical Orthogonal Function Study of the Ionospheric TEC Predicted Using the TIEGCM Model over the South Atlantic Anomaly in 2002 and 2008Jing Yu0Zheng Li1Yan Wang2Jingjing Shao3Luyao Wang4Jingyuan Li5Hua Zhang6Xiaojun Xu7Chunli Gu8School of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaInstitute of Space Weather, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaInstitute of Space Weather, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaSchool of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaSchool of Mathematics and Statistics, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaInstitute of Space Weather, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaInstitute of Space Weather, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaState Key Laboratory of Lunar and Planetary Science, Macau University of Science and Technology, Macau 999078, ChinaBeijing Institute of Applied Meteorology, Beijing 100081, ChinaIn this study, the variability of the ionospheric total electron content (TEC) in the South Atlantic Anomaly (SAA) in the solar maximum of 2002 and the solar minimum of 2008 were compared by using an empirical orthogonal function (EOF) analysis. The ionospheric TEC data were simulated using the National Center for Atmospheric Research Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM). The first three EOFs accounted for 94.8% and 93.86% of the variability in the data in 2002 and 2008, respectively. The results showed that the TEC variations of the first three EOFs were generally consistent in 2002 and 2008. The first mode showed the equatorial anomaly caused by plasma drift and the east–west asymmetry possibly caused by the change in geomagnetic declination and zonal wind; EOF<sub>2</sub> exhibited the zonal variation influenced by the solar EUV radiation and the semiannual variation possibly controlled by the [O/N<sub>2</sub>], solar zenith angle, and atmospheric circulation. EOF<sub>3</sub> suggested an equatorial anomaly and winter anomaly influenced by the [O/N<sub>2</sub>] variation. However, the values and amplitude variations in the TEC were significantly greater in the solar maximum than that in the solar minimum, and the spring–autumn asymmetry of the TEC was more obvious in the solar minimum. In addition, we used the EOF method to extract the annual variation characteristics of the time coefficients and carried out a correlation analysis. The results showed that the annual variation in the TEC in 2002 was mainly affected by the solar EUV radiation, which was strongly correlated with F10.7 (r = 0.7348). In contrast, the TEC was mainly influenced by the geomagnetic activity in 2008 and had a strong correlation with Dst (r = −0.7898).https://www.mdpi.com/2218-1997/9/2/102South Atlantic Anomalyionospheric total electron contentempirical orthogonal function |
| spellingShingle | Jing Yu Zheng Li Yan Wang Jingjing Shao Luyao Wang Jingyuan Li Hua Zhang Xiaojun Xu Chunli Gu An Empirical Orthogonal Function Study of the Ionospheric TEC Predicted Using the TIEGCM Model over the South Atlantic Anomaly in 2002 and 2008 Universe South Atlantic Anomaly ionospheric total electron content empirical orthogonal function |
| title | An Empirical Orthogonal Function Study of the Ionospheric TEC Predicted Using the TIEGCM Model over the South Atlantic Anomaly in 2002 and 2008 |
| title_full | An Empirical Orthogonal Function Study of the Ionospheric TEC Predicted Using the TIEGCM Model over the South Atlantic Anomaly in 2002 and 2008 |
| title_fullStr | An Empirical Orthogonal Function Study of the Ionospheric TEC Predicted Using the TIEGCM Model over the South Atlantic Anomaly in 2002 and 2008 |
| title_full_unstemmed | An Empirical Orthogonal Function Study of the Ionospheric TEC Predicted Using the TIEGCM Model over the South Atlantic Anomaly in 2002 and 2008 |
| title_short | An Empirical Orthogonal Function Study of the Ionospheric TEC Predicted Using the TIEGCM Model over the South Atlantic Anomaly in 2002 and 2008 |
| title_sort | empirical orthogonal function study of the ionospheric tec predicted using the tiegcm model over the south atlantic anomaly in 2002 and 2008 |
| topic | South Atlantic Anomaly ionospheric total electron content empirical orthogonal function |
| url | https://www.mdpi.com/2218-1997/9/2/102 |
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