Coronal Hole Properties In Solar Cycle 24: Plasma Behavior In The Weakest Period Of Solar Activity Over The Last Half Century
Creators: name: Arteaga, Adrián
Publisher: name: Zenodo
Year: 2014
Subjects: Solar coronal holes
Solar wind
Magnetic fields

description: Coronal holes, regions of low temperature and density in the solar corona which coincide with open and mostly unipolar magnetic field lines, are the primary source of the fast component of the solar wind. I have conducted a systematic study of the properties of coronal holes from 2007 to February 2014. As part of my study, I have created a catalog of 691 coronal holes, the largest in existence for the current solar cycle, cycle 24. For 363 of these coronal holes, I have characterized the proton density, speed, and temperature of the associated solar wind streams measured at 1 AU. For 189 wind streams, I have also been able to collect the ratio of alpha particle to proton number density in the wind. A comparison of these properties has shown that there is an anti-correlation between wind density and speed (higher densities correspond to lower wind speeds), and correlations between wind temperature and alpha to proton number density ratios and speed (higher wind speeds correspond to higher temperatures and larger alpha to proton number density ratios). In addition, a study of the relationship between area and magnetic field strength for the coronal holes of these past seven years has revealed that smaller coronal hole areas correspond to larger magnetic field strengths. I have also found that coronal holes with higher magnetic field strengths produce lower wind speeds, while coronal holes with larger areas generate higher wind stream velocities.
description: See also Presentation: "Coronal Hole Properties in Solar Cycle 24:"
description: {"references": ["Altschuler, M.D., Trotter, D.E., Orrall, F.Q., 1972, \u201cCoronal Holes\u201d, Solar Phys., 26, 354\u2013365.", "Cranmer, Steven R., 2009, \u201cCoronal Holes\u201d, Living Rev. Solar Phys., 6, 3., URL(accessed &lt;12/21/2013&gt;): http://www.livingreviews.org/lrsp-2009-3", "Fisher, R., Sime, D.G., 1984, \u201cSolar activity cycle variation of the K corona\u201d, Astrophys. J.,285, 354\u2013358.", "Huber, M.C.E., Foukal, P.V., Noyes, R.W., Reeves, E.M., Schmahl, E.J., Timothy, J.G., Vernazza, J.E., Withbroe, G. L., 1974, \u201cExtreme-ultraviolet observations of coronal holes: Initial results from Skylab\u201d, Astrophys. J. Lett., 194, L115\u2013L118.", "Hundhausen, A.J., 1972, Coronal Expansion and the Solar Wind, vol. 5 of Physics and Chemistry in Space, Springer, Berlin; New York", "Krieger, A.S., Timothy, A.F., Roelof, E.C., 1973, \u201cA Coronal Hole and Its Identification as the Source of a High Velocity Solar Wind Stream\u201d, Solar Phys., 29, 505\u2013525.", "Kasper, Justin C., et al. 2007 ApJ 660 901, \u201cSolar Wind Helium Abundance as a Function of Speed and Heliographic Latitude: Variation Through a Solar Cycle.", "McComas, D. J., Elbert, R. W., Elliot, H. A., et al 2008, Geophys. Res. Lett., 35, L18103 (2008)", "Miralles, M. P., Cranmer, S. R., Kohl, J. L. 2001a, \u201cComparison of Empirical Models for Polar and Equatorial Coronal Holes\u201d, The Astrophysical Journal, Volume 549, Issue 2, pp. L257-L260", "Miralles, M. P., Cranmer, S. R., Kohl, J. L. 2001b, \u201dUltraviolet Coronagraph Spectrometer Observations of a High-Latitude Coronal Hole with High Oxygen Temperatures and the Next Solar Cycle Polarity\u201d, The Astrophysical Journal, Volume 560, Issue 2, pp. L193-L196", "Miralles, M. P., Cranmer, S. R., Kohl, J. L. 2002, \u201cCyclical variations in the plasma properties of coronal holes\u201d, In: Proceedings of the SOHO 11 Symposium on From Solar Min to Max: Half a Solar Cycle with SOHO, 11-15 March 2002, Davos, Switzerland. A symposium dedicated to Roger M. Bonnet. Edited by A. Wilson, ESA SP-508, Noordwijk: ESA Publications Division, ISBN 92-9092-818-2, 2002, p. 351 - 359", "Miralles, M. P., Cranmer, S. R., Kohl, J. L. 2004,\u201dLow-latitude coronal holes during solar maximum\u201d, Advances in Space Research, Volume 33, Issue 5, p. 696-700", "Miralles, M. P., Cranmer, S. R., Kohl, J. L. 2006, \u201cCoronal Hole Properties During the First Decade of UVCS/SOHO\u201d, SOHO-17: 10 Years of SOHO and Beyond, Proceedings of the conference held 7-12 May, 2006 at Giardini Naxos, Sicily, Italy. Edited by H. Lacoste and L. Ouwehand. ESA SP-617. European Space Agency, 2006. Published on CDROM, p.15.1", "Miralles, M. P., Cranmer, S. R., Kohl, J. L. 2007, \u201cTowards the UVCS Coronal Hole Atlas for Solar Cycle 23: The Data\u201d, American Astronomical Society Meeting 210, #30.05; Bulletin of the American Astronomical Society, Vol. 39, p.143", "Miralles, M. P., Cranmer, S. R., Panasyuk, A. V., Uzzo, M. 2010, \u201cThe Tale of Two Minima and a Solar Cycle in Between: An Ongoing Fast Solar Wind Investigation\u201d,SOHO-23: Understanding a Peculiar Solar Minimum ASP Conference Series Vol. 428, proceedings of a workshop held 21-25 September 2009 in Northeast Harbor, Maine, USA. Edited by Steven R. Cranmer, J. Todd Hoeksema, and John L. Kohl. San Francisco: Astronomical Society of the Pacific, 2010, p.237", "Munro, R.H., Withbroe, G.L., 1972, \u201cProperties of a Coronal \u2018hole\u2019 Derived from Extreme-Ultraviolet Observations\u201d, Astrophys. J.,176, 511\u2013520", "Pneuman, G.W., 1973, \u201cThe Solar Wind and the Temperature-Density Structure of the Solar Corona\u201d, Solar Phys., 28, 247\u2013262.", "Noci, G., 1973, \u201cEnergy Budget in Coronal Holes\u201d, Solar Phys., 28, 403\u2013407.", "Saito, K., 1958, \u201cPolar Rays of the Solar Corona\u201d, Publ. Astron. Soc. Japan, 10, 49\u201378.", "Wilcox, J.M., 1968, \u201cThe Interplanetary Magnetic Field. Solar Origin and Terrestrial Effects\u201d, Space Sci. Rev., 8, 258\u2013328."]}