Comparison of expansion height maps for the classical PFSS implementation using spherical harmonic coefficients with order 9 in the left column, with order 20 in the middle column, and our grid solver in the right column. Again Carrington rotation 2066 is depicted. All models employ a spherical source surface at 2.5R_⊙ heliocentric distance. The height levels in rows 1 to 4 are spheres at heliocentric distances of 1.0R_⊙, 1.5R_⊙, 2.0R_⊙, and 2.5R_⊙.