Solar Physics

, Volume 256, Issue 1–2, pp 365–377 | Cite as

Temporal Evolution of the Solar Wind Bulk Velocity at Solar Minimum by Correlating the STEREO A and B PLASTIC Measurements

  • A. Opitz
  • R. Karrer
  • P. Wurz
  • A. B. Galvin
  • P. Bochsler
  • L. M. Blush
  • H. Daoudi
  • L. Ellis
  • C. J. Farrugia
  • C. Giammanco
  • L. M. Kistler
  • B. Klecker
  • H. Kucharek
  • M. A. Lee
  • E. Möbius
  • M. Popecki
  • M. Sigrist
  • K. Simunac
  • K. Singer
  • B. Thompson
  • R. F. Wimmer-Schweingruber
Open Access
STEREO SCIENCE RESULTS AT SOLAR MINIMUM

Abstract

The two STEREO spacecraft with nearly identical instrumentation were launched near solar activity minimum and they separate by about 45° per year, providing a unique tool to study the temporal evolution of the solar wind. We analyze the solar wind bulk velocity measured by the two PLASTIC plasma instruments onboard the two STEREO spacecraft. During the first half year of our measurements (March – August 2007) we find the typical alternating slow and fast solar wind stream pattern expected at solar minimum. To evaluate the temporal evolution of the solar wind bulk velocity we exclude the spatial variations and calculate the correlation between the solar wind bulk velocity measured by the two spacecraft. We account for the different spacecraft positions in radial distance and longitude by calculating the corresponding time lag. After adjusting for this time lag we compare the solar wind bulk velocity measurements at the two spacecraft and calculate the correlation between the two time-shifted datasets. We show how this correlation decreases as the time difference between two corresponding measurements increases. As a result, the characteristic temporal changes in the solar wind bulk velocity can be inferred. The obtained correlation is 0.95 for a time lag of 0.5 days and 0.85 for 2 days.

Keywords

Solar wind STEREO Plasma Multipoint spacecraft observations 

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Copyright information

© Springer Science+Business Media B.V. 2009

Authors and Affiliations

  • A. Opitz
    • 1
    • 2
  • R. Karrer
    • 1
  • P. Wurz
    • 1
  • A. B. Galvin
    • 3
  • P. Bochsler
    • 1
  • L. M. Blush
    • 1
  • H. Daoudi
    • 1
  • L. Ellis
    • 3
  • C. J. Farrugia
    • 3
  • C. Giammanco
    • 1
  • L. M. Kistler
    • 3
  • B. Klecker
    • 4
  • H. Kucharek
    • 3
  • M. A. Lee
    • 3
  • E. Möbius
    • 3
  • M. Popecki
    • 3
  • M. Sigrist
    • 1
  • K. Simunac
    • 3
  • K. Singer
    • 3
  • B. Thompson
    • 5
  • R. F. Wimmer-Schweingruber
    • 6
  1. 1.Department of Space Science and Planetology, Physics InstituteUniversity of BernBernSwitzerland
  2. 2.Centre d’Etude Spatiale des Rayonnements (CNRS-UPS)University of ToulouseToulouseFrance
  3. 3.SSCUniversity of New HampshireDurhamUSA
  4. 4.MPI for Extraterrestrial PhysicsGarchingGermany
  5. 5.NASA/GSFCGreenbeltUSA
  6. 6.Institute for Experimental and Applied PhysicsUniversity of KielKielGermany

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