Abstract / Description of output
An intrusion of vortex edge air into the interior of the Arctic polar vortex was observed on the 31 January 2005 flight of the NASA DC-8 aircraft. This intrusion was identified as anomalously high values of ozone by Airborne Raman Ozone, Temperature, and Aerosol Lidar (AROTAL) and Differential Absorption Lidar (DIAL). Our analysis shows that this intrusion formed when a blocking feature near Iceland collapsed, allowing edge air to sweep into the vortex interior. Analysis of Aura Microwave Limb Sounder (MLS) observations made along the DC-8 flight track also shows the intrusion in both ozone and HNO3. Polar stratospheric clouds (PSCs) were observed by the DIAL lidar on the DC-8. The spatial variability of the PSCs can be explained using MLS HNO3 and H2O observations and meteorological analysis temperatures. We also estimate vortex denitrification using the relationship between N2O and HNO3. Reverse domain fill back trajectory calculations are used to focus on the features in the MLS data. The trajectory results improve the agreement between lidar measured ozone and MLS ozone and also improve the agreement between the HNO3 measurements and PSC locations. The back trajectory calculations allow us to compute the local denitrification rate and reduction of HCl within the filament. We estimate a denitrification rate of about 10% per day after exposure to below–PSC formation temperature.