Solar cycle variation of coronal mass ejections contribution to solar wind mass flux
Wageesh Mishra, Nandita Srivastava, Zavkiddin Mirtoshev, Yuming Wang
aa r X i v : . [ a s t r o - ph . S R ] M a y Long-Term Datasets for the Understanding of Solar and StellarMagnetic CycleProceedings IAU Symposium No. 340, 2018Dipankar Banerjee, Jie Jiang, Kanya Kusano, & Sami Solanki c (cid:13) Solar cycle variation of coronal massejections contribution to solar wind mass flux
Wageesh Mishra , Nandita Srivastava , Zavkiddin Mirtoshev andYuming Wang CAS Key Laboratory of Geospace Environment, University of Science and Technology ofChina, Hefei, Anhui-230026, China, email: [email protected] Udaipur Solar Observatory, Physical Research Laboratory, Udaipur-313001, India Department of Physics, Samarkand State University, Samarkand- 140104, Uzbekistan
Abstract.
Coronal Mass Ejections (CMEs) contributes to the perturbation of solar wind inthe heliosphere. Thus, depending on the different phases of the solar cycle and the rate ofCME occurrence, contribution of CMEs to solar wind parameters near the Earth changes. Inthe present study, we examine the long term occurrence rate of CMEs, their speeds, angularwidths and masses. We attempt to find correlation between near sun parameters, determinedusing white light images from coronagraphs, with solar wind measurements near the Earth fromin-situ instruments. Importantly, we attempt to find what fraction of the averaged solar windmass near the Earth is provided by the CMEs during different phases of the solar cycles.
Keywords.
Sun: coronal mass ejections (CMEs), Sun: solar wind
1. Introduction
Coronal Mass Ejections (CMEs) are important for our understanding of solar coronaand heliosphere as they carry a huge amount of magnetized plasma from the Sun tothe near Earth environment. They largely drive the space weather activity which variesalmost in phase with solar cycles. Earlier studies have attempted to quantify the contri-bution of CMEs to background solar wind mass flux wherein the contribution of CMEsranged from 3 to 16% (Hildner et al. 1977, Howard et al. 1985, Jackson & Howard 1993,Lamy et al. 2017). For correct utilization of data of CME occurrence rate, the data shouldbe corrected under consideration of instrument-dependent effects, mass and geometricaldistributions of CMEs. Earlier studies were based on the shorter period of data from dif-ferent coronagraphs (e.g., Skylab, Solwind, and SMM) and thus involved different dutycycle corrections and inter-calibration of visibility function. The CMEs observations hasgreatly improved over last 2 decades with the advent of SOHO/LASCO, and we can studytheir long term patterns. In our study, we reexamine the CMEs contribution using theirhomogeneous datasets obtained from a single instrument, the Large Angle and Spec-troscopic Coronagraph (LASCO) onboard SOlar and Heliospheric Observatory (SOHO)spacecraft Brueckner et al.(1995), for relatively longer period of time during solar cycle23 and 24.
2. Methodology and Analysis ◦ width by making appropriate corrections for CMEs latitude and theirangular sizes, following the method of Howard et al. (1985). Assuming that mass ejectedinto the ecliptic plane is distributed uniformly at all the longitudes, we determined theequatorial mass flux at 1 AU. Further, assuming that helium constitutes 10% of thismass, we determined the proton flux at 1 AU due to CMEs. We noted that the solarwind flux at 1 AU and compared with the average near-ecliptic CMEs flux on an annualbasis over the solar cycle. Figure 1.
The variation of the CMEs and solar wind proton fluxes at 1 AU in the near-eclipticregion is shown in the top panel. The ratio of CME to solar wind mass flux is shown in thebottom panel.
3. Results and Discussion
Based on our analysis as aforementioned, we find that in the ecliptic region, the contri-bution of CMEs to the solar wind mass flux is negligibly small during the solar minimumbut increased to ≈
5% at the maximum of solar cycles 23 and 24. It is also noted thatthe fractional contribution of CMEs to the solar wind mass flux closely tracks the solarcycle. In ecliptic near the Earth, averaged solar wind flux is relatively constant comparedto the CME flux during different phases of the solar cycle 23 and 24 (Figure 1).The analysis also shows that although the occurrence rate of CMEs is more for Solar
MEs and solar wind mass flux
Acknowledgements
W.M. is supported by the Chinese Academy of Sciences (CAS) Presidents Interna-tional Fellowship Initiative (PIFI) grant No. 2015PE015 and National Natural ScienceFoundation of China (NSFC) grant No. 41750110481.
References
Brueckner, G. E., Howard, R. A., Koomen, M. J., et al. 1995,
Solphys , 162, 357Hildner, E. 1977,
Study of Travelling Interplanetary Phenomena , 71, 3Howard, R. A., Sheeley, N. R., Jr., Michels, D. J., & Koomen, M. J. 1985,
JGR , 90, 8173Jackson, B. V., & Howard, R. A. 1993,
Solphys , 148, 359Lamy, P., Floyd, O., Qu´emerais, E., Boclet, B., & Ferron, S. 2017,
JGR , 122, 50Webb, D. F., & Howard, R. A. 1994,