Gibson, S. E. and de Toma, G. and Emery, B. and Riley, P. and Zhao, L. and Elsworth, Y. and Leamon, R. J. and Leiner, J. and McIntosh, S. and Mewaldt, R. A. and Thompson, B. J. and Webb, D. (2011) The Whole Heliosphere Interval in the Context of a Long and Structured Solar Minimum: An Overview from Sun to Earth. Solar Physics, 274 (1-2). pp. 5-27. ISSN 0038-0938 http://resolver.caltech.edu/CaltechAUTHORS:20120214-085705096
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Throughout months of extremely low solar activity during the recent extended solar-cycle minimum, structural evolution continued to be observed from the Sun through the solar wind and to the Earth. In 2008, the presence of long-lived and large low-latitude coronal holes meant that geospace was periodically impacted by high-speed streams, even though solar irradiance, activity, and interplanetary magnetic fields had reached levels as low as, or lower than, observed in past minima. This time period, which includes the first Whole Heliosphere Interval (WHI 1: Carrington Rotation (CR) 2068), illustrates the effects of fast solar-wind streams on the Earth in an otherwise quiet heliosphere. By the end of 2008, sunspots and solar irradiance had reached their lowest levels for this minimum (e.g., WHI 2: CR 2078), and continued solar magnetic-flux evolution had led to a flattening of the heliospheric current sheet and the decay of the low-latitude coronal holes and associated Earth-intersecting high-speed solar-wind streams. As the new solar cycle slowly began, solar-wind and geospace observables stayed low or continued to decline, reaching very low levels by June – July 2009. At this point (e.g., WHI 3: CR 2085) the Sun–Earth system, taken as a whole, was at its quietest. In this article we present an overview of observations that span the period 2008 – 2009, with highlighted discussion of CRs 2068, 2078, and 2085. We show side-by-side observables from the Sun’s interior through its surface and atmosphere, through the solar wind and heliosphere and to the Earth’s space environment and upper atmosphere, and reference detailed studies of these various regimes within this topical issue and elsewhere.
|Additional Information:||© 2011 The Author(s). This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited. Received: 22 June 2011; Accepted: 16 September 2011; Published online: 21 December 2011. We thank Todd Hoeksema, Marc DeRosa, Alysha Reinard, and Larisza Krista for useful discussions. The hourly solar-wind plasma and IMF data were taken from the OMNI-2 collection from the Space Physics Data Facility at the Goddard Space Flight Center managed by Natalia Papitashvili. This study used indices from the CEDAR Database at the National Center for Atmospheric Research (NCAR), which is supported by the National Science Foundation. J. Lei thanks Eric Sutton for providing CHAMP data and support from the 100 Talents Program of the Chinese Academy of Science. SOHO is a project of international collaboration between ESA and NASA. We gratefully acknowledge the use of the SolarSoft package for generating PFSS fields developed by Marc DeRosa. Radiation-belt electron-number fluxes from the GOES satellites come from NGDC via SPIDR at http://spidr.ngdc.noaa.gov starting with GOES-05 in January 1986 and extending through GOES-12. We thank Terry Onsager for his comments and assistance with these data. We also thank Anne-Marie Broomhall for assistance with the BiSON data, and Thomas Kuchar for assistance with the CACTus CME data. The research of L. Zhao is supported by the NASA Living with a Star Heliophysics Postdoctoral Fellowship Program, administered by the University Corporation for Atmospheric Research.|
|Group:||Space Radiation Laboratory|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Tony Diaz|
|Deposited On:||14 Mar 2012 19:47|
|Last Modified:||04 Mar 2013 22:44|
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