Additional model fits of the 1670 GHz north, center and south observations. Determination of the torus vertical scale height H. Assuming that the column density falls as N(z) = Neq e−z/H, where z is the distance from the equatorial plane, the red, green, and dark blue curves correspond to H = 0.8, 0.4, and 0.2 RS, and Neq = (2.5, 4, 8) × 1013 cm-2, respectively. The lower absorption in the northern spectrum compared to center and south indicates that RS. Test of a physical model. The light blue curves are based on the distribution of NH2O predicted from the Cassidy & Johnson (2010) model for a 0.85 × 1028 s-1 Enceladus source rate (and shown in the left panel of Fig. 3, main text). This model provides an overall good match of all H2O lines, including the sorth-south asymmetry. Although not shown here, this physical model also gives a good match of the 557 and 1113 GHz absorption, and also underestimates the 987 GHz absorption by a factor ~1.7.