Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999
We use the SYM-H index to indicate the ring current index. We find that there were two periods during which the SYM-H index decreased quickly during the main phase of the geomagnetic storm on 21–22 October 1999. The first period from 11:44 p.m. UT on 21 October 1999 to 1:35 a.m. UT on 22 October 199...
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| Format: | Article |
| Language: | English |
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MDPI AG
2022-06-01
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| Series: | Universe |
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| Online Access: | https://www.mdpi.com/2218-1997/8/7/346 |
| _version_ | 1797433032708194304 |
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| author | Qi Li Ming-Xian Zhao Gui-Ming Le |
| author_facet | Qi Li Ming-Xian Zhao Gui-Ming Le |
| author_sort | Qi Li |
| collection | DOAJ |
| description | We use the SYM-H index to indicate the ring current index. We find that there were two periods during which the SYM-H index decreased quickly during the main phase of the geomagnetic storm on 21–22 October 1999. The first period from 11:44 p.m. UT on 21 October 1999 to 1:35 a.m. UT on 22 October 1999 is defined as step 1. Another period from 3:36 a.m. UT to 5:49 a.m. UT on 22 October 1999 is defined as step 3. The durations of step 1 and step 3 are defined as <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msub><mi>t</mi><mn>1</mn></msub></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msub><mi>t</mi><mn>3</mn></msub></mrow></semantics></math></inline-formula>, respectively. The variation of the pressure-corrected SYM-H index during step 1 and step 3 are defined as <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>1</mn></mrow><mo>∗</mo></msubsup></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>3</mn></mrow><mo>∗</mo></msubsup></mrow></semantics></math></inline-formula>, respectively. The interplanetary (IP) sources responsible for <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>1</mn></mrow><mo>∗</mo></msubsup></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>3</mn></mrow><mo>∗</mo></msubsup></mrow></semantics></math></inline-formula> are determined as the solar wind during period 1 and period 3, respectively. We find that the largest southward component of the interplanetary magnetic field (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>B</mi><mrow><mi>s</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></semantics></math></inline-formula>) during period 3 was larger than that during period 1, and the largest solar wind dawn-to-dusk electric field (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>E</mi><mrow><mi>y</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></semantics></math></inline-formula>) during period 3 was also larger than that during period 1. We also find that the time integral of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>E</mi><mi>y</mi></msub></semantics></math></inline-formula> during period 3 was much larger than that during period 1. However, we find that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>|</mo><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi></mrow><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>1</mn></mrow><mo>∗</mo></msubsup><mrow><mo>|</mo></mrow></mrow></semantics></math></inline-formula> was larger than <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>|</mo><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi></mrow><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>3</mn></mrow><mo>∗</mo></msubsup><mrow><mo>|</mo></mrow></mrow></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>|</mo><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi></mrow><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>1</mn></mrow><mo>∗</mo></msubsup><mrow><mo>/</mo><mo>Δ</mo><mi>t</mi><mn>1</mn><mo>|</mo></mrow></mrow></semantics></math></inline-formula> was larger than <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>|</mo><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi></mrow><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>3</mn></mrow><mo>∗</mo></msubsup><mrow><mo>/</mo><mo>Δ</mo><mi>t</mi><mn>3</mn><mo>|</mo></mrow></mrow></semantics></math></inline-formula>, indicating that the geomagnetic activity intensity during a period does not depend on <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>B</mi><mrow><mi>s</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></semantics></math></inline-formula> or <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>E</mi><mrow><mi>y</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></semantics></math></inline-formula>, nor does it depend on the time integral of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>E</mi><mi>y</mi></msub></semantics></math></inline-formula>. What is the reason for this? We find that the solar wind dynamic pressure during period 1 was larger than that during period 3, indicating that the geomagnetic storm intensity during a period not only depends on the solar wind speed and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>B</mi><mi>s</mi></msub></semantics></math></inline-formula>, but it also depends on the solar wind dynamic pressure. The magnetosphere took 4 min to respond to the IP shock. When the <i>z</i>-component of the interplanetary magnetic field (IMF) turned from northward to southward, the response time of the SYM-H index to the southward component of the IMF was 21 min. |
| first_indexed | 2024-03-09T10:10:17Z |
| format | Article |
| id | doaj.art-3eac457bc69b48f19f83c8d658fcc30a |
| institution | Directory Open Access Journal |
| issn | 2218-1997 |
| language | English |
| last_indexed | 2024-03-09T10:10:17Z |
| publishDate | 2022-06-01 |
| publisher | MDPI AG |
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| series | Universe |
| spelling | doaj.art-3eac457bc69b48f19f83c8d658fcc30a2023-12-01T22:45:47ZengMDPI AGUniverse2218-19972022-06-018734610.3390/universe8070346Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999Qi Li0Ming-Xian Zhao1Gui-Ming Le2Institute of Geophysics, China Earthquake Administration, Beijing 100081, ChinaKey Laboratory of Space Weather, National Satellite Meteorological Center (National Center for Space Weather), China Meteorological Administration, Beijing 100081, ChinaKey Laboratory of Space Weather, National Satellite Meteorological Center (National Center for Space Weather), China Meteorological Administration, Beijing 100081, ChinaWe use the SYM-H index to indicate the ring current index. We find that there were two periods during which the SYM-H index decreased quickly during the main phase of the geomagnetic storm on 21–22 October 1999. The first period from 11:44 p.m. UT on 21 October 1999 to 1:35 a.m. UT on 22 October 1999 is defined as step 1. Another period from 3:36 a.m. UT to 5:49 a.m. UT on 22 October 1999 is defined as step 3. The durations of step 1 and step 3 are defined as <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msub><mi>t</mi><mn>1</mn></msub></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><msub><mi>t</mi><mn>3</mn></msub></mrow></semantics></math></inline-formula>, respectively. The variation of the pressure-corrected SYM-H index during step 1 and step 3 are defined as <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>1</mn></mrow><mo>∗</mo></msubsup></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>3</mn></mrow><mo>∗</mo></msubsup></mrow></semantics></math></inline-formula>, respectively. The interplanetary (IP) sources responsible for <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>1</mn></mrow><mo>∗</mo></msubsup></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>3</mn></mrow><mo>∗</mo></msubsup></mrow></semantics></math></inline-formula> are determined as the solar wind during period 1 and period 3, respectively. We find that the largest southward component of the interplanetary magnetic field (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>B</mi><mrow><mi>s</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></semantics></math></inline-formula>) during period 3 was larger than that during period 1, and the largest solar wind dawn-to-dusk electric field (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>E</mi><mrow><mi>y</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></semantics></math></inline-formula>) during period 3 was also larger than that during period 1. We also find that the time integral of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>E</mi><mi>y</mi></msub></semantics></math></inline-formula> during period 3 was much larger than that during period 1. However, we find that <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>|</mo><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi></mrow><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>1</mn></mrow><mo>∗</mo></msubsup><mrow><mo>|</mo></mrow></mrow></semantics></math></inline-formula> was larger than <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>|</mo><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi></mrow><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>3</mn></mrow><mo>∗</mo></msubsup><mrow><mo>|</mo></mrow></mrow></semantics></math></inline-formula>, and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>|</mo><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi></mrow><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>1</mn></mrow><mo>∗</mo></msubsup><mrow><mo>/</mo><mo>Δ</mo><mi>t</mi><mn>1</mn><mo>|</mo></mrow></mrow></semantics></math></inline-formula> was larger than <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mrow><mo>|</mo><mo>Δ</mo><mi>S</mi><mi>Y</mi><mi>M</mi></mrow><msubsup><mi>H</mi><mrow><mi>o</mi><mi>b</mi><mn>3</mn></mrow><mo>∗</mo></msubsup><mrow><mo>/</mo><mo>Δ</mo><mi>t</mi><mn>3</mn><mo>|</mo></mrow></mrow></semantics></math></inline-formula>, indicating that the geomagnetic activity intensity during a period does not depend on <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>B</mi><mrow><mi>s</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></semantics></math></inline-formula> or <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>E</mi><mrow><mi>y</mi><mi>m</mi><mi>a</mi><mi>x</mi></mrow></msub></semantics></math></inline-formula>, nor does it depend on the time integral of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>E</mi><mi>y</mi></msub></semantics></math></inline-formula>. What is the reason for this? We find that the solar wind dynamic pressure during period 1 was larger than that during period 3, indicating that the geomagnetic storm intensity during a period not only depends on the solar wind speed and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><msub><mi>B</mi><mi>s</mi></msub></semantics></math></inline-formula>, but it also depends on the solar wind dynamic pressure. The magnetosphere took 4 min to respond to the IP shock. When the <i>z</i>-component of the interplanetary magnetic field (IMF) turned from northward to southward, the response time of the SYM-H index to the southward component of the IMF was 21 min.https://www.mdpi.com/2218-1997/8/7/346geomagnetic stormsolar windinterplanetary drivers |
| spellingShingle | Qi Li Ming-Xian Zhao Gui-Ming Le Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999 Universe geomagnetic storm solar wind interplanetary drivers |
| title | Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999 |
| title_full | Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999 |
| title_fullStr | Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999 |
| title_full_unstemmed | Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999 |
| title_short | Properties of the Geomagnetic Storm Main Phase and the Corresponding Solar Wind Parameters on 21–22 October 1999 |
| title_sort | properties of the geomagnetic storm main phase and the corresponding solar wind parameters on 21 22 october 1999 |
| topic | geomagnetic storm solar wind interplanetary drivers |
| url | https://www.mdpi.com/2218-1997/8/7/346 |
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