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5. Polar Stratospheric Clouds

A PSC at 23 km with a geometrical thickness of 3 km, as it is often observed at Sodankyla in winter, changes also the AMF calculated by the radiative transfer model, as well as the colour index, as shown in previous works (Sarkissian et al., 1991, 1994, 1995b). The relationship between PSC optical thickness and effect on ozone AMF can then be related to a relationship between CI and effect on ozone AMF as shown in Figure 2. We used this relation to correct ozone AMF at Sodankyla in winter because the effect is non-negligeable, for example in January 1996 when PSCs were detected most days.

Figure 2: Correction to SAOZ AMF due to high altitude PSC occurence in winter in polar regions.

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