2D constructed solar wind configuration at 31 July 00:00 UT obtained by the data-driven background model. The Sun is at (X, Y) = (r cos ϕ, r sin ϕ) = (0, 0) and the stationary observer (STEREO-A) marked by a red filled circle is at (X, Y)≈(1, 0). The solar wind background rotates counterclockwise over time. Panels a and b: V_r(r, ϕ) and N^*(r, ϕ) = N(r, ϕ)(r/R_ob)² within 1 AU and the studied CIR region identified by the magenta line. Panels c and d: V_r(r, ϕ) and N^*(r, ϕ) within 5 AU.