Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona

Zhao, L.

doi:10.1088/0004-637X/781/2/110

Title: Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona

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Abstract

Fast solar wind can be accelerated from at least two different sources: polar coronal holes and equatorial coronal holes. Little is known about the relationship between the wind coming from these two different latitudes and whether these two subcategories of fast wind evolve in the same way during the solar cycle. Nineteen years of Ulysses observations, from 1990 to 2009, combined with ACE observations from 1998 to the present provide us with in situ measurements of solar wind properties that span two entire solar cycles. These missions provide an ideal data set to study the properties and evolution of the fast solar wind originating from equatorial and polar holes. In this work, we focus on these two types of fast solar wind during the minima between solar cycles 22 and 23 and 23 and 24. We use data from SWICS, SWOOPS, and VHM/FGM on board Ulysses and SWICS, SWEPAM, and MAG on board ACE to analyze the proton kinetic, thermal, and dynamic characteristics, heavy ion composition, and magnetic field properties of these two fast winds. The comparison shows that: (1) their kinetic, thermal, compositional, and magnetic properties are significantly different at any time during the two minima and (2) theymore »« less

Authors:: Zhao, L.

Publication Date:: Sat Feb 01 00:00:00 EST 2014

OSTI Identifier:: 22348094

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal

Additional Journal Information:: Journal Volume: 781; Journal Issue: 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; HEAVY IONS; HELIOSPHERE; MAGNETIC FIELDS; MAGNETIC PROPERTIES; REMOTE SENSING; SOLAR CYCLE; SOLAR WIND; SUN

Citation Formats


                    Zhao, L., and Landi, E., E-mail: lzh@umich.edu. Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona.  United States: N. p., 2014. 
        Web.  doi:10.1088/0004-637X/781/2/110.

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                    Zhao, L., & Landi, E., E-mail: lzh@umich.edu. Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona.  United States.  https://doi.org/10.1088/0004-637X/781/2/110

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                    Zhao, L., and Landi, E., E-mail: lzh@umich.edu. 2014.  
        "Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona".  United States.  https://doi.org/10.1088/0004-637X/781/2/110.

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@article{osti_22348094,

  title        = {Polar and equatorial coronal hole winds at solar minima: From the heliosphere to the inner corona},

  author       = {Zhao, L. and Landi, E., E-mail: lzh@umich.edu},

  abstractNote = {Fast solar wind can be accelerated from at least two different sources: polar coronal holes and equatorial coronal holes. Little is known about the relationship between the wind coming from these two different latitudes and whether these two subcategories of fast wind evolve in the same way during the solar cycle. Nineteen years of Ulysses observations, from 1990 to 2009, combined with ACE observations from 1998 to the present provide us with in situ measurements of solar wind properties that span two entire solar cycles. These missions provide an ideal data set to study the properties and evolution of the fast solar wind originating from equatorial and polar holes. In this work, we focus on these two types of fast solar wind during the minima between solar cycles 22 and 23 and 23 and 24. We use data from SWICS, SWOOPS, and VHM/FGM on board Ulysses and SWICS, SWEPAM, and MAG on board ACE to analyze the proton kinetic, thermal, and dynamic characteristics, heavy ion composition, and magnetic field properties of these two fast winds. The comparison shows that: (1) their kinetic, thermal, compositional, and magnetic properties are significantly different at any time during the two minima and (2) they respond differently to the changes in solar activity from cycle 23 to 24. These results indicate that equatorial and polar fast solar wind are two separate subcategories of fast wind. We discuss the implications of these results and relate them to remote-sensing measurements of the properties of polar and equatorial coronal holes carried out in the inner corona during these two solar minima.},

  doi          = {10.1088/0004-637X/781/2/110},

  url          = {https://www.osti.gov/biblio/22348094},
  journal      = {Astrophysical Journal},

  issn         = {0004-637X},

  number       = 2,

  volume       = 781,

  place        = {United States},

  year         = {Sat Feb 01 00:00:00 EST 2014},

  month        = {Sat Feb 01 00:00:00 EST 2014}

}

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