Study of the influence of the source surface radius (R_ss) for the PFSS model. In the top row, we show EUV synoptic maps made from SDO/AIA 193 observations, where we superimpose the boundaries of open magnetic field regions extracted from the PFSS model with yellow contours. In the bottom row, we show the comparison between the LASCO/C2 white-light synoptic maps at 3 R_⊙ with the PFSS model using as input the ADAPT map of February 22, 2021, at 22:00UT (with the AR). From the PFSS, we extract the HCS (blue line) as well as a proxy for pseudo-streamers (red patches). The different panels show this comparison for various R_ss values (from left to right: 1.8 R_⊙, 2.2 R_⊙, 2.6 R_⊙ and 3.0 R_⊙). We indicate the longitude of the AR at the date with a vertical red line.