Time dependence of the mean tracer abundance averaged between 1mbar and 0.1mbar. The abundances are averaged horizontally over a circular region of radius 45° centered on the substellar point (top) and averaged horizontally around the terminator, including all regions within ± 5° of the terminator (bottom). The top panel is relevant for inferring the presence of a stratosphere (see Sect. 6.1), albedo variations (see Sect. 6.2) or secondary eclipse measurements (see Sect. 6.3). The bottom panel is relevant for transit spectroscopy measurements.