Solar Cycle Occurrence of Alfvénic Fluctuations and Related Geo-Efficiency
dc.contributor.author | Tanskanen, E. I. | |
dc.contributor.author | Snekvik, K. | |
dc.contributor.author | Slavin, J. A. | |
dc.contributor.author | Pérez-Suárez, D. | |
dc.contributor.author | Viljanen, A. | |
dc.contributor.author | Goldstein, Melvyn | |
dc.contributor.author | Käpylä, M. J. | |
dc.contributor.author | Hynönen, R. | |
dc.contributor.author | Häkkinen, L. V. T. | |
dc.contributor.author | Mursula, K. | |
dc.date.accessioned | 2024-01-18T02:23:00Z | |
dc.date.available | 2024-01-18T02:23:00Z | |
dc.date.issued | 2017-10-03 | |
dc.description.abstract | We examine solar wind intervals with Alfvénic fluctuations (ALFs) in 1995–2011. The annual number, the total annual duration, and the average length of ALFs vary over the solar cycle, having a maximum in 2003 and a minimum in 2009. ALFs are most frequent in the declining phase of solar cycle, when the number of high-speed streams at the Earth's vicinity is increased. There is a rapid transition after the maximum of solar cycle 23 from ALFs being mainly embedded in slow solar wind (<400 km/s) until 2002 to ALFs being dominantly in fast solar wind (>600 km/s) since 2003. Cross helicity increased by 30% from 2002 to 2003 and maximized typically 4–6 h before solar wind speed maximum. Cross helicity remained elevated for several days for highly Alfvénic non-ICME streams, but only for a few hours for ICMEs. The number of substorms increased by about 40% from 2002 to 2003, and the annual number of substorms closely follows the annual cross helicity. This further emphasizes the role of Alfvénic fluctuations in modulating substorm activity. The predictability of substorm frequency and size would be greatly improved by monitoring solar wind Alfvénic fluctuations in addition to the mean values of the important solar wind parameters. | |
dc.description.sponsorship | We wish to thank the institutes maintaining the IMAGE magnetometer network. The IMAGE magnetic field measurements are available via http://space.fmi.fi/image/beta/ and auroral substorm and storm lists via http://www.substormzoo.org. The sunspot data were archived through SIDC-team, World Data Center for the Sunspot Index, Royal Observatory of Belgium, and interplanetary measurements via CDAWeb archive. The ICMEs are taken from the http://www.srl.caltech.edu/ACE/ASC/DATA/level3/icmetable2.htm, which is a catalogue by Richardson and Cane, and from the ACE ICME catalogue at http://www.srl.caltech.edu/ACE/ASC/. We acknowledge the financial support by the Academy of Finland to the ReSoLVE Centre of Excellence (project 272157) and by the European Community's Seventh Framework Program under grants 313038/STORM and 283676/ESPAS. M.K. acknowledges funding from the “Active Suns” research project of Helsinki University. We thank D.A Roberts and A.J. Tanskanen for inspiring and constructive comments. | |
dc.description.uri | https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017JA024385 | |
dc.format.extent | 10 pages | |
dc.genre | journal articles | |
dc.identifier.citation | Tanskanen, E. I., Snekvik, K., Slavin, J. A., Pérez-Suárez, D., Viljanen, A., Goldstein, M. L., … Mursula, K. (2017). Solar cycle occurrence of Alfvénic fluctuations and related geo-efficiency. Journal of Geophysical Research: Space Physics, 122, 9848–9857. https://doi.org/10.1002/2017JA024385 | |
dc.identifier.uri | https://doi.org/10.1002/2017JA024385 | |
dc.identifier.uri | http://hdl.handle.net/11603/31340 | |
dc.language.iso | en_US | |
dc.publisher | AGU | |
dc.relation.isAvailableAt | The University of Maryland, Baltimore County (UMBC) | |
dc.relation.ispartof | UMBC Goddard Planetary Heliophysics Institute (GPHI) | |
dc.relation.ispartof | UMBC Faculty Collection | |
dc.rights | This item is likely protected under Title 17 of the U.S. Copyright Law. Unless on a Creative Commons license, for uses protected by Copyright Law, contact the copyright holder or the author. | |
dc.rights | Attribution-NonCommercial-NoDerivs 4.0 International (CC BY-NC-ND 4.0 DEED) | en |
dc.rights.uri | https://creativecommons.org/licenses/by-nc-nd/4.0/ | |
dc.title | Solar Cycle Occurrence of Alfvénic Fluctuations and Related Geo-Efficiency | |
dc.type | Text | |
dcterms.creator | https://orcid.org/0000-0002-5317-988X |
Files
Original bundle
1 - 1 of 1
Loading...
- Name:
- JGR Space Physics - 2017 - Tanskanen - Solar Cycle Occurrence of Alfv nic Fluctuations and Related Geo‐Efficiency.pdf
- Size:
- 1.16 MB
- Format:
- Adobe Portable Document Format
License bundle
1 - 1 of 1
Loading...
- Name:
- license.txt
- Size:
- 2.56 KB
- Format:
- Item-specific license agreed upon to submission
- Description: