Helium abundance profiles in the large-scale solar-wind phenomena
Abstract
In this work we analyze the average profiles of helium abundance Nα/Np in different types of solar wind obtained by the double superposed epoch analysis method (Yermolaev etal., 2009) for interval of 1976-2016. We use the plasma and magnetic field measurements in the OMNI2 dataset and our catalog of large-scale solar-wind phenomena: corotating interaction regions (CIRs), interplanetary coronal mass ejections (ICMEs including both magnetic clouds (MCs) and ejecta), and sheaths as well as interplanetary shocks (ISs) (see web-side ftp://ftp.iki.rssi.ru/pub/omni/ and description by Yermolaev et al., 2010; 2015; 2017). Our results confirm main early obtained results: Nα/Np in fast streams from coronal holes is higher than in slow streams from coronal streamer belt and it has the highest values in the MCs. Temporal profile of ICME may be interpreted as a spatial cross-section of the structure. We obtained for first time that the average Nα/Np increases and plasma β-parameter decreases in the center of MC and this effect is small for ejecta. This fact may be used as an indicator of conditions in place of CME formation on the Sun and for identification of MCs in the interplanetary space.
The work was in part supported by the Russian Science Foundation, grant 16-12-10062. References. Yermolaev, Yu. I., N. S. Nikolaeva, I. G. Lodkina, and M. Yu. Yermolaev (2009), Catalog of Large-Scale Solar Wind Phenomena during 1976-2000, Cosmic Research, , Vol. 47, No. 2, pp. 81-94. Yermolaev, Y. I., N. S. Nikolaeva, I. G. Lodkina, and M. Y. Yermolaev (2010), Specific interplanetary conditions for CIR-induced, Sheath-induced, and ICME-induced geomagnetic storms obtained by double superposed epoch analysis, Ann. Geophys., 28, pp. 2177-2186. Yermolaev, Yu. I., I. G. Lodkina, N. S. Nikolaeva, and M. Yu. Yermolaev (2015), Dynamics of large-scale solar wind streams obtained by the double superposed epoch analysis, J. Geophys. Res. Space Physics, 120, doi:10.1002/2015JA021274. Yermolaev, Yu. I., I. G. Lodkina, N. S. Nikolaeva, and M. Yu. Yermolaev (2017), Dynamics of large-scale solar wind streams obtained by the double superposed epoch analysis: 2. Comparisons of CIRs vs. Sheaths and MCs vs. Ejecta, Solar Phys. 292:193. doi:10.1007/s11207-017-1205-1- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMSH51D2870G
- Keywords:
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- 7511 Coronal holes;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7513 Coronal mass ejections;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7514 Energetic particles;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMYDE: 7954 Magnetic storms;
- SPACE WEATHER