Ozone transport and stratospheric filaments

Significant ozone-PV correlations that are not season-related have been found at several isentropic levels, mostly during winter and spring at both TMF and MLO locations. At MLO, anti-correlations calculated at 750 K appear to be QBO-related while positive correlations in the lower stratosphere are associated with higher ozone values transported from mid-latitudes. Although negative correlation is again observed at 750 K at TMF, the variations do not appear to be strongly related to the QBO. Intra-seasonal variations is believed to account the most in this case. Intra-seasonal variations are even more obvious in the lower stratosphere when the positive correlation is again observed this time throughout winter except in March. The sudden drop in ozone-PV correlation in March is partly due to the vary large atmospheric variability at this time of the year. Another possible explanation would be the effect of advection towards mid- and subtropical latitudes of polar air masses that have been either or not ozone-depleted while still within the vortex main body.

Figure 1
Figure 1: Monthly mean ozone profile measured at TMF in February and March 2002

Meridional transport in the vicinity of the Northern hemisphere subtropical barrier was investigated using several years of ozone and temperature lidar measurements obtained by the Jet Propulsion Laboratory (JPL) at Mauna Loa Observatory, Hawaii (19.5°N), and Table Mountain Facility, California (34.4°N), and the high resolution PV advection model MIMOSA developed at Service d'Aéronomie, France. Meridional transport is often identified on our lidar ozone profiles as thin layers of enhanced or depleted ozone. A comparison of a climatological ozone profile (figure 1) and ozone profiles disturbed by meridional transport (figure 2) is shown below.

Figure 2
Figure 2: Ozone profiles measured on four different nights of March 1999 when ozone layering was present


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