Time profile of SIR 1 identified by PLASTIC and MAG during the period from DOY 191 to DOY 195, 2007. From top to bottom: 1-min averaged bulk speed of solar wind (V_sw), proton density (N_p), thermal speed (V_th), specific entropy (derived with N_p and V_th), IMF magnitude, IMF polar angle, IMF azimuth angle, total pressure (P derived from ), two-hour mean charge state of iron, and count rate of suprathermal protons in the energy range of 10–80 keV. From left to right, we indicate the slow wind, compressed and accelerated slow wind, compressed and decelerated fast wind, and fast wind regions with S, S′, F′, and F respectively, following Richardson et al. (1993), Chotoo et al. (2000). Three vertical black dashed lines indicate the boundaries between these four regions of SIR 1. The horizontal blue and red dashed lines denote 50 pPa and five counts/hour respectively, and are used as thresholds in this work.