Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Research › peer-review
The Asymmetry of Magnetospheric Configuration and Substorms Occurrence Rate Within a Solar Activity Cycle. / Kubyshkina, Marina; Semenov, Vladimir; Erkaev, Nikolai; Gordeev, Evgeniy; Kubyshkin, Igor.
Problems of Geocosmos–2020. Springer Nature, 2022. p. 451-464 (Springer Proceedings in Earth and Environmental Sciences).Research output: Chapter in Book/Report/Conference proceeding › Conference contribution › Research › peer-review
}
TY - GEN
T1 - The Asymmetry of Magnetospheric Configuration and Substorms Occurrence Rate Within a Solar Activity Cycle
AU - Kubyshkina, Marina
AU - Semenov, Vladimir
AU - Erkaev, Nikolai
AU - Gordeev, Evgeniy
AU - Kubyshkin, Igor
N1 - Publisher Copyright: © 2022, The Author(s), under exclusive license to Springer Nature Switzerland AG.
PY - 2022
Y1 - 2022
N2 - The aim of this work is to test the hypothesis by Kivelson and Hughes (Kivelson and Hughes in Planet. Space Sci. 38:211–220, 1990), according to which, for asymmetric configurations with a curved current sheet and large curvature of magnetic field lines in the tail of the magnetosphere, the substorm breakdown threshold decreases. The work used two databases on the substorms onset: (1) (Frey et al. in J. Geophys. Res. 109:A10304, 2004)—4700 events for 2000–2005, and (2) SUPERMAG—18,800 events for 2000–2010 (Gjerloev in J. Geophys. Res. 117:A09213, 2012). OMNI data was used for the solar wind parameters. We try to answer the question what solar wind parameters are responsible for the bending of the current sheet in the tail of the magnetosphere, how these parameters affect the number of emerging substorms, and what structures of the solar wind are capable of carrying them. Among these possible factors of symmetry break, we explore the alfvénic-type excitations, the dipole tilt, and the direction of solar wind flow, which were traced within the solar activity cycle. As a result, we found a notable correlation (R = 0.65) of yearly substorm occurrence rate and the yearly amount of earthward propagating alfvénic disturbances, while no correlation (R = 0.01) was observed for substorms and sunward propagating alfvénic fluctuations. We also found that the yearly averaged absolute value of dipole tilt at a substorm explosion is always larger (by 0.5°–2.0°) than the mean value of absolute dipole tilt and the difference is larger during the solar cycle maximum when substorm occurrence rate also maximizes. The above difference becomes about 0.5° larger if we take into account the effective tilt angle and consider the input of solar wind flow direction to the actual dipole tilt. We also show that the averaged AL-index for a portion of substorms, which occurred under the dipole tilt less than 8° was −244 nT, and the AL-index for substorms with larger tilt (20°–30°) was −192 nT, which gives more than 20% difference.
AB - The aim of this work is to test the hypothesis by Kivelson and Hughes (Kivelson and Hughes in Planet. Space Sci. 38:211–220, 1990), according to which, for asymmetric configurations with a curved current sheet and large curvature of magnetic field lines in the tail of the magnetosphere, the substorm breakdown threshold decreases. The work used two databases on the substorms onset: (1) (Frey et al. in J. Geophys. Res. 109:A10304, 2004)—4700 events for 2000–2005, and (2) SUPERMAG—18,800 events for 2000–2010 (Gjerloev in J. Geophys. Res. 117:A09213, 2012). OMNI data was used for the solar wind parameters. We try to answer the question what solar wind parameters are responsible for the bending of the current sheet in the tail of the magnetosphere, how these parameters affect the number of emerging substorms, and what structures of the solar wind are capable of carrying them. Among these possible factors of symmetry break, we explore the alfvénic-type excitations, the dipole tilt, and the direction of solar wind flow, which were traced within the solar activity cycle. As a result, we found a notable correlation (R = 0.65) of yearly substorm occurrence rate and the yearly amount of earthward propagating alfvénic disturbances, while no correlation (R = 0.01) was observed for substorms and sunward propagating alfvénic fluctuations. We also found that the yearly averaged absolute value of dipole tilt at a substorm explosion is always larger (by 0.5°–2.0°) than the mean value of absolute dipole tilt and the difference is larger during the solar cycle maximum when substorm occurrence rate also maximizes. The above difference becomes about 0.5° larger if we take into account the effective tilt angle and consider the input of solar wind flow direction to the actual dipole tilt. We also show that the averaged AL-index for a portion of substorms, which occurred under the dipole tilt less than 8° was −244 nT, and the AL-index for substorms with larger tilt (20°–30°) was −192 nT, which gives more than 20% difference.
KW - Asymmetric configurations
KW - Magnetospheric plasma sheet
KW - Substorms
UR - http://www.scopus.com/inward/record.url?scp=85125225172&partnerID=8YFLogxK
UR - https://www.mendeley.com/catalogue/da96a40e-9c3a-38a0-9c3c-21e908417002/
U2 - 10.1007/978-3-030-91467-7_33
DO - 10.1007/978-3-030-91467-7_33
M3 - Conference contribution
AN - SCOPUS:85125225172
T3 - Springer Proceedings in Earth and Environmental Sciences
SP - 451
EP - 464
BT - Problems of Geocosmos–2020
PB - Springer Nature
Y2 - 5 October 2020 through 9 October 2020
ER -
ID: 93248862