Statistical analysis of magnetopause response during substorm phases
<p>We investigate variations in the position of the magnetopause in response to the interplanetary magnetic field (IMF) and different phases of magnetospheric substorms. The average location of the magnetopause is examined using magnetic field observations from multiple satellites (Time Histor...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2025-02-01
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| Series: | Annales Geophysicae |
| Online Access: | https://angeo.copernicus.org/articles/43/137/2025/angeo-43-137-2025.pdf |
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| Summary: | <p>We investigate variations in the position of the magnetopause in response to the interplanetary magnetic field (IMF) and different phases of magnetospheric substorms. The average location of the magnetopause is examined using magnetic field observations from multiple satellites (Time History of Events and Macroscale Interactions during Substorms, THEMIS; Radiation Belt Storm Probes, RBSP; and Magnetospheric Multiscale, MMS), and the Shue model utilizing OMNI solar wind data for a period of 5 years, from 2016–2020. We estimate the average position of the magnetopause using the Shue model through superposed epoch analysis of the standoff distance and tail flaring angle at different substorm timings (onset, peak, and end) and from in situ measurements through 2D equatorial maps of average <span class="inline-formula"><i>B</i><sub><i>Z</i></sub></span> under IMF <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>|</mo><msub><mi>B</mi><mi>Z</mi></msub><mo>|</mo><mo>></mo><mn mathvariant="normal">0</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="8704d3729bb7350cbb58b3da9c804c86"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="angeo-43-137-2025-ie00001.svg" width="39pt" height="13pt" src="angeo-43-137-2025-ie00001.png"/></svg:svg></span></span> conditions. We found that southward IMF is associated with a greater number of substorms compared to northward IMF orientations. Our analysis highlights a very small movement of the magnetopause during substorm phases for both northward and southward IMF orientations (<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>|</mo><msub><mi>B</mi><mi>Z</mi></msub><mo>|</mo><mo>></mo><mn mathvariant="normal">0</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="21001242fdb10b7b76502ff50094f984"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="angeo-43-137-2025-ie00002.svg" width="39pt" height="13pt" src="angeo-43-137-2025-ie00002.png"/></svg:svg></span></span>). Notably, magnetopause experiences inward movement, reaching its closest point to the Earth, particularly during the substorm growth phase followed by a relaxation from the substorm peak to the recovery end. The empirical model provides an accurate estimation of the magnetopause location during periods of both northward and southward IMF <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M4" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>|</mo><msub><mi>B</mi><mi>Z</mi></msub><mo>|</mo><mo>></mo><mn mathvariant="normal">0</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="39pt" height="13pt" class="svg-formula" dspmath="mathimg" md5hash="bb1ac9b65b8a35ef212900de1048b614"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="angeo-43-137-2025-ie00003.svg" width="39pt" height="13pt" src="angeo-43-137-2025-ie00003.png"/></svg:svg></span></span> as the model curve traverses a distinct location representing the magnetopause shown in the 2D average map of observed <span class="inline-formula"><i>B</i><sub><i>Z</i></sub></span>.</p> |
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| ISSN: | 0992-7689 1432-0576 |