5:15 PM - 6:30 PM
[AAS11-P11] Variations of stratospheric and tropospheric circulations related with ozone hole
Previous study analyzed this mechanism using monthly or seasonal data; therefore, variations with timescale shorter than a month cannot be analyzed. For this reason, we used 10 days mean data in order to research the detail of the mechanism in the austral summer. As a result, we found out the variations of eastward wind are different among December, January and February. In December, most of eastward wind variations occur in the stratosphere and upper troposphere. In January, stratospheric variations disappear and only tropospheric variation can be found. In February, we could not find any significant variations both stratosphere and troposphere. We tried to find out the reason why these different variations appear using EP-Flux. As a result, we realized that, in December, wavenumber 1 propagating into the stratosphere has the most important role and that baroclinic instabilities with wavenumber 4 and 6 are important in January.
Furthermore we studied the influences of both global warming and ozone hole on Southern Hemisphere climate. We investigated in the Chemical Climate Model based on MIROC 3.2 using three scenarios, one is reference simulation, another is sensitivity simulation which is similar to reference simulation, but halogens fixed at 1960 levels throughout the simulation, and the last is sensitivity simulation which is also similar to reference simulation, but GHGs fixed at 1960 levels. Hence we can discuss two influences both global warming and ozone hole on Southern Hemisphere climate variations separately. As a result, we realized ozone hole has a role to maintain the signal at the lower troposphere in austral summer. On the other hand, global warming makes Brewer-Dobson circulation strong and the transportation of ozone to polar region is also enhanced. Because of ozone heating, global warming has a role to warm the polar atmosphere. Previous studies notice only the GHGs`s radiative cooling in the stratosphere but we suggested that the change of physical field is also important in the variation of Southern Hemisphere climate.