Quantification of the transport of chemically activated air from the northern hemisphere polar vortex

摘要: Output from a three-dimensional off-line chemical transport model and the technique of contour advection are used to give high-resolution view PSC-activated air in northern hemisphere lower stratosphere. Three winters examined, 1991–1992, 1992–1993, 1993–1994. The structure polar vortex area temperatures below 195 K on 475 isentrope compared with 500 hPa geopotential height fields. These show how meridional excursions tropospheric jets can have strong influence vortex. In contrast, approximately westerly flow troposphere result relatively undisturbed large K. Two patterns identified which frequently produce into midlatitudes. ridges over Europe troughs North Pacific. By using vortex-following coordinate system, amount transported midlatitudes is quantified for periods this study at isentropic levels 400 K, 550 This calculation indicates that there considerable interannual variation amount. On ranges nearly 50% total mass 1991–1992 around 10% 1993–1994 or, when expressed as percentage midlatitudes, 25% 5%, respectively. even though was long period PSC threshold, largely contained within vortex, only 20% less than However unlike other two years, much stronger (this increased right down 350 isentrope), figure being mass. results discussed context observed ozone decrease during winter. particular, indicate situ destruction by cannot account winter 1992–1993.