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4. Summary
Meridional mixing of air masses at the time of breakup of polar vortices in both SH and NH in 1996/1997 were investigated using the Improved Limb Atmospheric Spectrometer (ILAS) data onboard the ADEOS satellite. Mixing ratios of several minor species (CH4, N2O, O3, NO2, HNO3, and aerosols) were plotted in the Equivalent Latitude-Potential Temperature (EL-PT) coordinate in each 10-day periods, which enables us to investigate meridional distribution of these species even from a solar-occultation sensor data. It was shown that mixing ratios of these species were kept higher outside the polar vortex than inside, due to the existence of transport barrier which may be formed by the existence of strong wind at 60 degrees equivalent latitude. As polar vortex started to disappear from higher altitudes, meridional mixing of air mass started to occur from the higher altitude. This sometimes leave vortex interior air below the location where upper part is already outside the polar vortex, and form a kind of "double-peak" structure for species like CH4 or N2O. After the collapse of polar vortex, meridional distribution of minor species becomes very homogeneous. It was also shown that there were no strong polar vortex barriers below 500K throughout the winter, enabling easy meridional mixing of minor species.