(a) Sunspot number. (b) Solar wind speed and (c) Solar wind density at 1 AU (black) and 90 AU (pink) at a time resolution of Carrington rotation. In (b) and (c), the data at 1 AU are available from OMNI data center, while those at 90 AU were obtained by considering differing transit times of solar wind parcels of different CRs using the simplified model of Lee et al. (2009). Accordingly, the solar wind profile at 90 AU (pink) begins about one year later than the profile at 1 AU (black). (For more details, see the first two paragraphs of Sect. 2.2).