Tracer abundance in the advected column of gas from the 1D model as a function of time. From bottom to top we used and a particle radius on the nightside of 1μm. We plot one profile every hour, corresponding to the profiles at equally spaced longitudes. The blue ones are on the nightside, the red ones on the dayside. The curve at the far left (right) of the envelope is the profile at the east (west) terminator. The black curve is the mean over one period. The green line is the analytical model (see Eq. (15)using α = 1/2) and the dotted line is the solution for particles that would be constantly falling (both in the dayside and in the nightside).