H₂O vertical profiles of the PACS fit model of Fig. 16, in which the latitudinal distribution is a Gaussian centered around the equator with σ = 25°, and y_eq = 9 × 10⁻⁸. The effect of the temperature increases in the B1 and B2 beacons is accounted for when computing the condensation level, and a positive gradient is added for pressures higher than p_gradient = 0.1 mbar and down to the condensation level, with a slope n = log (y)∕log(p) = 2. The value of y_eq applies to p < p_gradient. Condensation between 0.1 and 1 mbar occurs in the equatorial region as a result of a local temperature minimum caused by the quasi-periodic oscillation (see Fig. 4). The corresponding line area and residual maps are shown in Fig. 16.