Equatorwards Expansion of Unperturbed, High-Latitude Fast Solar Wind
- 163 Downloads
Abstract
We use dual-site radio observations of interplanetary scintillation (IPS) with extremely long baselines (ELB) to examine meridional flow characteristics of the ambient fast solar wind at plane-of-sky heliocentric distances of 24 – 85 solar radii (R ⊙). Our results demonstrate an equatorwards deviation of 3 – 4∘ in the bulk fast solar wind flow direction over both northern and southern solar hemispheres during different times in the declining phase of Solar Cycle 23.
Keywords
Solar wind Interplanetary scintillation Fast Solar Wind Parker Spiral Radio observations Heliosphere Interplanetary magnetic field IPSNotes
Acknowledgements
We would like to thank the directors and staff of both the European Incoherent SCATter (EISCAT) radar consortium and the Multi-Element Radio Linked Interferometer Network (MERLIN). EISCAT is supported by the scientific research councils of Finland, France, Germany, Japan, Norway, Sweden, the UK, and China. MERLIN is supported by the UK Science and Technology Facilities Council (STFC). Four of us (Dorrian, Breen, Fallows, and Bisi) were also supported by STFC throughout the majority of this research.
References
- Armstrong, J.W., Coles, W.A.: 1972, Analysis of three station interplanetary scintillation. J. Geophys. Res. 77, 4602 – 4610. ADSCrossRefGoogle Scholar
- Bisi, M.M.: 2006, Interplanetary scintillation studies of the large-scale structure of the solar wind. Ph.D. Thesis, The University of Wales, Aberystwyth. http://cadair.aber.ac.uk/dspace/handle/2160/4064.
- Bisi, M.M., Breen, A.R., Fallows, R.A., Thomasson, P., Jones, R.A., Wannberg, G.: 2005, Combined EISCAT/ESR/MERLIN interplanetary scintillation observations of the solar wind. In: Proc. Solar Wind 11/SOHO 16, ESA SP-592, 593 – 596. Google Scholar
- Bisi, M.M., Fallows, R.A., Breen, A.B., Habbal, S.R., Jones, R.A.: 2007, Large scale structure of the fast solar wind. J. Geophys. Res. 112, A06101. ADSCrossRefGoogle Scholar
- Bisi, M.M., Fallows, R.A., Breen, A.R., O’Neill, I.J.: 2010, Interplanetary scintillation observations of stream interaction regions in the solar wind. Solar Phys. 261, 149 – 172. doi: 10.1007/s11207-009-9471-1 ADSCrossRefGoogle Scholar
- Bourgois, G., Daigne, G., Coles, W.A., Silen, J., Turunen, T., Williams, P.J.S.: 1985, Measurements of the solar wind velocity with EISCAT. Astron. Astrophys. 144, 452 – 462. ADSGoogle Scholar
- Breen, A.R., Coles, W.A., Grall, R., Lovhaug, U.-P., Markkanen, J., Misawa, H., Williams, P.J.S.: 1996, EISCAT measurements of interplanetary scintillation. J. Atmos. Solar-Terr. Phys. 58, 507 – 519. ADSCrossRefGoogle Scholar
- Breen, A.R., Riley, P., Lazarus, R.J., Canals, A., Fallows, R.A., Linker, J., Mikic, Z.: 2002, The solar wind at solar maximum: comparisons of EISCAT IPS and in situ observations. Ann. Geophys. 20, 1291 – 1309. ADSCrossRefGoogle Scholar
- Breen, A.R., Fallows, R.A., Bisi, M.M., Thomasson, P., Jordan, C.A., Wannberg, G., Jones, R.A.: 2006, Extremely long baseline interplanetary scintillation measurements of solar wind velocity. J. Geophys. Res. 111, A08104. ADSCrossRefGoogle Scholar
- Breen, A.R., Fallows, R.A., Bisi, M.M., Jones, R.A., Jackson, B.V., Kojima, M., Dorrian, G.D., Middleton, H.R., Thomasson, P., Wannberg, G.: 2008, The solar eruption of 2005 May 13 and its effects: long-baseline interplanetary scintillation observations of the Earth-directed coronal mass ejection. Astrophys. J. Lett. 683, L79 – L82. ADSCrossRefGoogle Scholar
- Coles, W.A.: 1995, Interplanetary scintillation observations of the high-latitude solar wind. Space Sci. Rev. 72, 211 – 222. ADSCrossRefGoogle Scholar
- Dennison, P.A., Hewish, A.: 1967, The solar wind outside the plane of the ecliptic. Nature 213(5074), 343 – 346. ADSCrossRefGoogle Scholar
- Dorrian, G.D.: 2009, Large scale 3-dimensional structure of the solar wind. Ph.D. Thesis, Aberystwyth University. http://cadair.aber.ac.uk/dspace/handle/2160/3125.
- Fallows, R.A., Breen, A.R., Dorrian, G.D.: 2008, Developments in the use of EISCAT for interplanetary scintillation. Ann. Geophys. 26, 2229 – 2236. ADSCrossRefGoogle Scholar
- Fallows, R.A., Williams, P.J.S., Breen, A.R.: 2002, EISCAT measurements of solar wind velocity and the associated level of interplanetary scintillation. Ann. Geophys. 20, 1279 – 1289. ADSCrossRefGoogle Scholar
- Fallows, R.A., Breen, A.R., Bisi, M.M., Jones, R.A., Wannberg, G.: 2006, Dual-frequency interplanetary scintillation observations of the solar wind. Geophys. Res. Lett. 33, L11106. ADSCrossRefGoogle Scholar
- Grall, R.R., Coles, W.A., Klinglesmith, M.T.: 1996, Observations of the solar wind near the Sun. In: Proc. Eight International Solar Wind Conf.: Solar Wind Eight, Astron. Soc. Pac., San Francisco, 108. Google Scholar
- Hewish, A., Scott, P.F., Wills, D.: 1964, Interplanetary scintillation of small diameter radio sources. Nature 203, 1214 – 1217. ADSCrossRefGoogle Scholar
- Moran, P.J., Breen, A.B., Varley, C.A., Williams, P.J.S., Wilkinson, W.P., Markkanen, J.: 1998, Measurements of the direction of the solar wind using interplanetary scintillation. Ann. Geophys. 16, 1259 – 1264. ADSCrossRefGoogle Scholar
- Morgan, H., Habbal, S.R., Lugaz, N.: 2009, Mapping the structure of the corona using Fourier backprojection tomography. Astrophys. J. 690, 1119 – 1129. ADSCrossRefGoogle Scholar
- Neugebauer, M., von Steiger, R.: 2003, The solar wind. In: Bleeker, J.A.M., Geiss, J., Huber, M.C.E. (eds.) The Century of Space Science, Kluwer Academic Publishers, Dordrecht, 1115 – 1140. Chapter 47. Google Scholar
- Parker, E.N.: 1963, Interplanetary Dynamic Processes, Interscience Publishers, New York. Google Scholar
- Rishbeth, H., Williams, P.J.S.: 1985, The EISCAT ionospheric radar – the system and its early results. Q. J. Roy. Astron. Soc. 26, 478 – 512. ADSGoogle Scholar
- Thomasson, P.: 1986, MERLIN. Q. J. Roy. Astron. Soc. 27, 413 – 431. ADSGoogle Scholar