Normalised HCl profiles produced by our 1D photochemical model, driven by approximately colocated water ice profiles measured by ACS TIRVIM (presented in blue) and NOMAD/ACS NIR measured H₂O profiles. Semi-transparent lines are individual profiles, and the opaque lines represent the mean and standard deviation of the plotted profiles. The profiles are centred on the altitude corresponding to the centre of the ice holes; the maximum HCl abundances calculated by the model closely coincide with the locations of the ice holes.