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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.
Digital Object Identifier (DOI)
Galvin, A. B.; Popecki, M. A.; Simunac, K. D. C.; Kistler, L. M.; Ellis, L.; Barry, J.; Berger, L.; Blush, L. M.; Bochsler, P.; Farrugia, C. J.; Jian, L. K.; Kilpua, E. K. J.; Klecker, B.; Lee, M.; Liu, Y. C. -M.; Luhmann, J. L.; Moebius, E.; Opitz, A.; Russell, C. T.; Thompson, B.; Wimmer-Schweingruber, R. F.; Wurz, P. (2009). Solar wind ion trends and signatures: STEREO PLASTIC observations approaching solar minimum, ANNALES GEOPHYSICAE. Vol. 27, No. 10, 3909-3922. DOI: 10.5194/angeo-27-3909-2009