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

Authors

A. Opitz, University of Bern
R. Karrer, University of Bern
P. Wurz, University of Bern
Antoinette B. Galvin, University of New HampshireFollow
P. Bochsler, University of Bern
L. M. Blush, University of Bern
H. Daoudi, University of Bern
Lorna Ellis, University of New HampshireFollow
Charlie J. Farrugia, University of New HampshireFollow
C. Giammanco, University of Bern
Lynn M. Kistler, University of New HampshireFollow
B. Klecker, MPI for Extraterrestrial Physics
Harald Kucharek, University of New HampshireFollow
Martin A. Lee, University of New Hampshire
Eberhard Mobius, University of New Hampshire
Mark A. Popecki, University of New Hampshire
M. Sigrist, University of Bern
Kristin D. C. Simunac, University of New Hampshire
K. Singer, University of New Hampshire
B. Thompson, NASA/GSFC
R. F. Wimmer-Schweingruber, University of Kiel

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.

Publication Date

1-28-2009

Journal Title

Solar Physics

Publisher

Springer

Digital Object Identifier (DOI)

https://dx.doi.org/10.1007/s11207-008-9304-7

Document Type

Article

Recommended Citation

Opitz, A.; Karrer, R.; Wurz, P.; Galvin, A. B.; Bochsler, P.; Blush, L. M.; Daoudi, H.; Ellis, L.; Farrugia, C. J.; Giammanco, C.; Kistler, L. M.; Klecker, B.; Kucharek, H.; Lee, M. A.; Moebius, E.; Popecki, M.; Sigrist, M.; Simunac, K.; Singer, K.; Thompson, B.; Wimmer-Schweingruber, R. F. (2009). Temporal Evolution of the Solar Wind Bulk Velocity at Solar Minimum by Correlating the STEREO A and B PLASTIC Measurements, SOLAR PHYSICS. Vol. 256, No. 1-2, 365-377. DOI: 10.1007/s11207-008-9304-7

Comments

This is an article published by Springer in Solar Physics in 2009, available online: https://dx.doi.org/10.1007/s11207-008-9304-7