a, d, g: temporal variation of the H₂O, CO₂, and CH₄ vertical abundances at the equator and longitude = 225°, i.e., nightside. b, e, h: gCV of abundances, from initial values to a steady state at ~ 5 × 10⁹ s. A higher value represents a stronger variation of the abundance at any given pressure level. A choice of gCV = 0.05 seems to reasonably separate the chemical equilibrium and disequilibrium regions (dashed gray vertical lines). c, f, i: quenching timescales. An invariant abundance profile at the longer times ensures a new steady state. See Sect. 3.2 for more details. We note that the quenching level cannot be associated with one particular pressure for all species, but usually spans more than one order of magnitude in pressure.