Articles | Volume 27, issue 10
13 Oct 2009
 | 13 Oct 2009

Solar wind ion trends and signatures: STEREO PLASTIC observations approaching solar minimum

A. B. Galvin, M. A. Popecki, K. D. C. Simunac, L. M. Kistler, L. Ellis, J. Barry, L. Berger, L. M. Blush, P. Bochsler, C. J. Farrugia, L. K. Jian, E. K. J. Kilpua, B. Klecker, M. Lee, Y. C.-M. Liu, J. L. Luhmann, E. Moebius, A. Opitz, C. T. Russell, B. Thompson, R. F. Wimmer-Schweingruber, and P. Wurz

Abstract. STEREO has now completed the first two years of its mission, moving from close proximity to Earth in 2006/2007 to more than 50 degrees longitudinal separation from Earth in 2009. During this time, several large-scale structures have been observed in situ. Given the prevailing solar minimum conditions, these structures have been predominantly coronal hole-associated solar wind, slow solar wind, their interfaces, and the occasional transient event. In this paper, we extend earlier solar wind composition studies into the current solar minimum using high-resolution (1-h) sampling times for the charge state analysis. We examine 2-year trends for iron charge states and solar wind proton speeds, and present a case study of Carrington Rotation 2064 (December 2007) which includes minor ion (He, Fe, O) kinetic and Fe composition parameters in comparison with proton and magnetic field signatures at large-scale structures observed during this interval.