Geomagnetic Storm Effect on F<sub>2</sub>-Region Ionosphere during 2012 at Low- and Mid-Latitude-Latitude Stations in the Southern Hemisphere
The ionospheric effects of six intense geomagnetic storms with <i>Dst</i> index ≤ −100 nT that occurred in 2012 were studied at a low-latitude station, Darwin (Geomagnetic coordinates, 21.96° S, 202.84° E), a low-mid-latitude station, Townsville (28.95° S, 220.72° E), and a mid-latitude...
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MDPI AG
2022-03-01
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| Series: | Atmosphere |
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| Online Access: | https://www.mdpi.com/2073-4433/13/3/480 |
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| author | Edwin A. Kumar Sushil Kumar |
| author_facet | Edwin A. Kumar Sushil Kumar |
| author_sort | Edwin A. Kumar |
| collection | DOAJ |
| description | The ionospheric effects of six intense geomagnetic storms with <i>Dst</i> index ≤ −100 nT that occurred in 2012 were studied at a low-latitude station, Darwin (Geomagnetic coordinates, 21.96° S, 202.84° E), a low-mid-latitude station, Townsville (28.95° S, 220.72° E), and a mid-latitude station, Canberra (45.65° S, 226.30° E), in the Australian Region, by analyzing the storm–time variations in the critical frequency of the F<sub>2</sub>-region (<i>fo</i>F2). Out of six storms, a storm of 23–24 April did not produce any ionospheric effect. The storms of 30 September–3 October (minimum <i>Dst</i> = −122 nT) and 7–10 October (minimum <i>Dst</i> = −109 nT) are presented as case studies and the same analysis was done for the other four storms. The storm of 30 September–3 October, during its main phase, produced a positive ionospheric storm at all three stations with a maximum percentage increase in <i>fo</i>F2 (∆<i>fo</i>F2%) of 45.3% at Canberra whereas during the recovery phase it produced a negative ionospheric storm at all three stations with a maximum ∆<i>fo</i>F2% of −63.5% at Canberra associated with a decrease in virtual height of the F-layer (<i>h’F</i>). The storm of 7–10 October produced a strong long-duration negative ionospheric storm associated with an increase in <i>h’F</i> during its recovery phase at all three stations with a maximum ∆<i>fo</i>F2% of −65.1% at Townsville. The negative ionospheric storms with comparatively longer duration were more pronounced in comparison to positive storms and occurred only during the recovery phase of storms. The storm main phase showed positive ionospheric storms for two storms (14–15 July and 30 September–3 October) and other three storms did not produce any ionospheric storm at the low-latitude station indicating prompt penetrating electric fields (PPEFs) associated with these storms did not propagate to the low latitude. The positive ionospheric storms during the main phase are accounted to PPEFs affecting ionospheric equatorial <b>E</b> × <b>B</b> drifts and traveling ionospheric disturbances due to joule heating at the high latitudes. The ionospheric effects during the recovery phase are accounted to the disturbance dynamo electric fields and overshielding electric field affecting <b>E</b> × <b>B</b> drifts and the storm-induced circulation from high latitudes toward low latitudes leading to changes in the natural gas composition [O/N<sub>2</sub>] ratio. |
| first_indexed | 2024-03-09T20:08:06Z |
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| language | English |
| last_indexed | 2024-03-09T20:08:06Z |
| publishDate | 2022-03-01 |
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| spelling | doaj.art-b7dad168eafa40c7b44fefa2f67f87552023-11-24T00:27:37ZengMDPI AGAtmosphere2073-44332022-03-0113348010.3390/atmos13030480Geomagnetic Storm Effect on F<sub>2</sub>-Region Ionosphere during 2012 at Low- and Mid-Latitude-Latitude Stations in the Southern HemisphereEdwin A. Kumar0Sushil Kumar1School of Information Technology, Engineering, Mathematics and Physics, The University of the South Pacific, Suva, FijiSchool of Information Technology, Engineering, Mathematics and Physics, The University of the South Pacific, Suva, FijiThe ionospheric effects of six intense geomagnetic storms with <i>Dst</i> index ≤ −100 nT that occurred in 2012 were studied at a low-latitude station, Darwin (Geomagnetic coordinates, 21.96° S, 202.84° E), a low-mid-latitude station, Townsville (28.95° S, 220.72° E), and a mid-latitude station, Canberra (45.65° S, 226.30° E), in the Australian Region, by analyzing the storm–time variations in the critical frequency of the F<sub>2</sub>-region (<i>fo</i>F2). Out of six storms, a storm of 23–24 April did not produce any ionospheric effect. The storms of 30 September–3 October (minimum <i>Dst</i> = −122 nT) and 7–10 October (minimum <i>Dst</i> = −109 nT) are presented as case studies and the same analysis was done for the other four storms. The storm of 30 September–3 October, during its main phase, produced a positive ionospheric storm at all three stations with a maximum percentage increase in <i>fo</i>F2 (∆<i>fo</i>F2%) of 45.3% at Canberra whereas during the recovery phase it produced a negative ionospheric storm at all three stations with a maximum ∆<i>fo</i>F2% of −63.5% at Canberra associated with a decrease in virtual height of the F-layer (<i>h’F</i>). The storm of 7–10 October produced a strong long-duration negative ionospheric storm associated with an increase in <i>h’F</i> during its recovery phase at all three stations with a maximum ∆<i>fo</i>F2% of −65.1% at Townsville. The negative ionospheric storms with comparatively longer duration were more pronounced in comparison to positive storms and occurred only during the recovery phase of storms. The storm main phase showed positive ionospheric storms for two storms (14–15 July and 30 September–3 October) and other three storms did not produce any ionospheric storm at the low-latitude station indicating prompt penetrating electric fields (PPEFs) associated with these storms did not propagate to the low latitude. The positive ionospheric storms during the main phase are accounted to PPEFs affecting ionospheric equatorial <b>E</b> × <b>B</b> drifts and traveling ionospheric disturbances due to joule heating at the high latitudes. The ionospheric effects during the recovery phase are accounted to the disturbance dynamo electric fields and overshielding electric field affecting <b>E</b> × <b>B</b> drifts and the storm-induced circulation from high latitudes toward low latitudes leading to changes in the natural gas composition [O/N<sub>2</sub>] ratio.https://www.mdpi.com/2073-4433/13/3/480geomagnetic stormsprompt penetrating electric fieldsdisturbance dynamo electric fields<b>E</b> × <b>B</b> driftsstorm-induced circulation |
| spellingShingle | Edwin A. Kumar Sushil Kumar Geomagnetic Storm Effect on F<sub>2</sub>-Region Ionosphere during 2012 at Low- and Mid-Latitude-Latitude Stations in the Southern Hemisphere Atmosphere geomagnetic storms prompt penetrating electric fields disturbance dynamo electric fields <b>E</b> × <b>B</b> drifts storm-induced circulation |
| title | Geomagnetic Storm Effect on F<sub>2</sub>-Region Ionosphere during 2012 at Low- and Mid-Latitude-Latitude Stations in the Southern Hemisphere |
| title_full | Geomagnetic Storm Effect on F<sub>2</sub>-Region Ionosphere during 2012 at Low- and Mid-Latitude-Latitude Stations in the Southern Hemisphere |
| title_fullStr | Geomagnetic Storm Effect on F<sub>2</sub>-Region Ionosphere during 2012 at Low- and Mid-Latitude-Latitude Stations in the Southern Hemisphere |
| title_full_unstemmed | Geomagnetic Storm Effect on F<sub>2</sub>-Region Ionosphere during 2012 at Low- and Mid-Latitude-Latitude Stations in the Southern Hemisphere |
| title_short | Geomagnetic Storm Effect on F<sub>2</sub>-Region Ionosphere during 2012 at Low- and Mid-Latitude-Latitude Stations in the Southern Hemisphere |
| title_sort | geomagnetic storm effect on f sub 2 sub region ionosphere during 2012 at low and mid latitude latitude stations in the southern hemisphere |
| topic | geomagnetic storms prompt penetrating electric fields disturbance dynamo electric fields <b>E</b> × <b>B</b> drifts storm-induced circulation |
| url | https://www.mdpi.com/2073-4433/13/3/480 |
| work_keys_str_mv | AT edwinakumar geomagneticstormeffectonfsub2subregionionosphereduring2012atlowandmidlatitudelatitudestationsinthesouthernhemisphere AT sushilkumar geomagneticstormeffectonfsub2subregionionosphereduring2012atlowandmidlatitudelatitudestationsinthesouthernhemisphere |