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Frequency of the occurrence of type 1a PSCs (left), type 1b PSCs (middle) and type 2 PSCs (right) at model level 5 (approx. 475 K potential temperature) in the ‘no aircraft’ emission scenario (hatched curves) and the ‘supersonic’ scenario (thick curves) using the University of Oslo aircraft induced perturbations in H2O and HNO3 concentrations (Larsen et al., 2002).
