Formation and Evolution of Corotating Interaction Regions and their Three Dimensional Structure
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Corotating interaction regions are a consequence of spatial variability in the coronal expansion and solar rotation, which cause solar wind flows of different speeds to become radially aligned. Compressive interaction regions are produced where high-speed wind runs into slower plasma ahead. When the flow pattern emanating from the Sun is roughly time-stationary these compression regions form spirals in the solar equatorial plane that corotate with the Sun, hence the name corotating interaction regions, or CIRs. The leading edge of a CIR is a forward pressure wave that propagates into the slower plasma ahead, while the trailing edge is a reverse pressure wave that propagates back into the trailing high-speed flow. At large heliocentric distances the pressure waves bounding a CIR commonly steepen into forward and reverse shocks. Spatial variation in the solar wind outflow from the Sun is a consequence of the solar magnetic field, which modulates the coronal expansion. Because the magnetic equator of the Sun is commonly both warped and tilted with respect to the heliographic equator, CIRs commonly have substantial north-south tilts that are opposed in the northern and southern hemispheres. Thus, with increasing heliocentric distance the forward waves in both hemispheres propagate toward and eventually across the solar equatorial plane, while the reverse shocks propagate poleward to higher latitudes. This paper provides an overview of observations and numerical models that describe the physical origin and radial evolution of these complex three-dimensional (3-D) heliospheric structures.
KeywordsSolar Wind Heliocentric Distance Heliospheric Current Sheet Solar Wind Stream Astronomical Unit
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- Gosling, J. T.: 1986, ‘Global Aspects of Stream Evolution in the Solar Wind’, in R. I. Epstein and W. C. Feldman(eds.), Magnetospheric Phenomena in Astrophysics, AIP Conf. Proceed.144, New York, pp. 124–144.Google Scholar
- Gosling, J. T., Bame, S. J., Feldman, W.C., McComas, D. J., Phillips, J. L., Goldstein, B. E., Neugebauer, M., Burkepile, J., Hundhausen, A. J., and Acton, L.: 1995b, ‘The Band of Solar Wind Variability at Low Heliographic Latitudes near Solar Activity Minimum: Plasma Results from the Ulysses Rapid Latitude Scan’, Geophys. Res. Lett. 22, 3329–3332.CrossRefADSGoogle Scholar
- Gosling, J. T., Feldman, W.C., McComas, D. J., Phillips, J. L., Pizzo, V. J., and Forsyth, R. J.: 1995c, ‘Ulysses Observations of Opposed Tilts of Solar Wind Corotating Interaction Regions in the Northern and Southern Solar Hemispheres’, J. Geophys. Res. 22, 3,333–3,336.Google Scholar
- Hundhausen, A. J.: 1972, Coronal Expansion and Solar Wind, Springer-Verlag, New York.Google Scholar
- Hundhausen, A. J.: 1977, ‘An Interplanetary View of Coronal Holes’, in J. B. Zirker (ed.), Coronal Holes and High Speed Wind Streams, Colorado Assoc. Univ. Press., Boulder, pp. 225–329.Google Scholar
- Kóta, J.: 1992, ‘A Numerical Model of the Large-Scale Solar Wind in the Outer Heliosphere’, in E. Marsch and R. Schwenn(eds.), Solar Wind Seven, Pergamon, New York, pp. 205–208.Google Scholar
- Ogilvie, K.W.: 1972, ‘Corotating Shock Structures’, in P. J. Coleman, C. P. Sonett, and J.M. Wilcox (eds.), Solar Wind, NASA SP 308, Washington DC, pp. 430–434.Google Scholar
- Phillips, J. L., Balogh, A., Bame, S. J., Goldstein, B. E., Gosling, J. T., Hoeksema, J. T., McComas, D. J., Neugebauer, M., Sheeley, N.R., and Wang, Y.-M.: 1994, ‘Ulysses at 50_ South: Constant Immersion in the High-Speed Solar Wind’, J. Geophys. Res. 21, 1,105–1,108.Google Scholar
- Schwenn, R.: 1990, ‘Large-Scale Structure of the Interplanetary Medium’, in R. Schwenn and E. Marsch(eds.), Physics of the Inner Heliosphere, Springer-Verlag, Berlin Heidelberg, pp. 99–181.Google Scholar
- Sime, D.G.: 1983, ‘Interplanetary Scintillation Observations of the Solar Wind Close to the Sun and out of the Ecliptic’, in M. Neugebauer (ed.), Solar Wind Five, NASA CP 2280, pp. 453–467.Google Scholar
- Smith, E. J., and Wolfe, J.H.: 1976, ‘Observations of Interaction Regions and Corotating Shocks between One and Five AU: Pioneers 10 and 11’, J. Geophys. Res. 3, 137-140.Google Scholar