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3. Results of the 990922 case

In the sounding of 990922 there is two ozone minima on 520 K and 405 K thetas and a deep layer of air rich of ozone in between (PLATE 1.).

PV from the trajectory analysis is presented in Table 990922. The initial value of PV (PVs) on 405 K theta is -21 PVU which is slightly greater than the PV value after 7 days backward advection (PVt) (ö22 PVU). Both are anyway smaller than the PV value of the edge (PVe)(ö18 PVU). On 520 K theta the difference is slightly greater and the sign of the change is the same implying of intrusion from inside the vortex into the edge region.

In the high ozone thetas of 469 K and 425 K the difference of PVt to PVs is opposite to the low ozone thetas implying transport from opposite direction.

In Figure 1. the vortex situation during sounding and the vortex situation after seven days backward advection is presented. From there it seems like the air parcel has crossed the PV isolines and moved from more inside vortex towards edge region. The same applies to 520 K (not shown). On 469 K theta the air parcel seem to stay between the same PV isolines (not shown) where as on 425 K theta it seem to have moved from edge towards inside of vortex, see Figure 2.

On 585 K theta PVt is much greater than the PVe and the difference of PVt to PVs is positive implying intrusion from outside in to the vortex edge region. On 585 K theta PVt is much greater than the PVe and the difference of PVt to PVs is positive implying intrusion from outside in to the vortex edge region. When the 585 K trajectory is plotted on the corresponding vortex situation (not shown) no such phenomena is seen.