Chemical ozone loss and ozone mini-hole event during the Arctic winter 2010/2011 as observed by SCIAMACHY and GOME-2

摘要

Record breaking loss of ozone (O) in the Arctic stratosphere hasbeen reported in winter–spring 2010/2011. We examine in detail thecomposition and transformations occurring in the Arctic polar vortex usingtotal column and vertical profile data products for O, bromine oxide(BrO), nitrogen dioxide (NO), chlorine dioxide (OClO),and polar stratospheric clouds (PSC) retrieved from measurements made bySCIAMACHY (Scanning Imaging Absorption SpectroMeter for Atmospheric CHartography) on-board Envisat (Environmental Satellite), as well as total column ozone amount, retrievedfrom the measurements of GOME-2 (Global Ozone Monitoring Experiment) on MetOp-A (Meteorological Experimental Satellite). Similarly we usethe retrieved data from DOAS (Differential Optical Absorption Spectroscopy) measurements made in Ny-Ålesund(78.55° N, 11.55° E). A chemical transport model (CTM) has beenused to relate and compare Arctic winter–spring conditions in 2011 with thosein the previous year. In late winter–spring 2010/2011 the chemical ozone lossin the polar vortex derived from SCIAMACHY observations confirms findingsreported elsewhere. More than 70% of O was depleted by halogencatalytic cycles between the 425 and 525 K isentropicsurfaces, i.e. in the altitude range ~16–20 km. Incontrast, during the same period in the previous winter 2009/2010, a typicalwarm Arctic winter, only slightly more than 20% depletion occurred below 20 km,while 40% of O was removed above the 575 K isentrope(~23 km). This loss above 575 K is explained by the catalytic destruction by NO descending from themesosphere. In both Arctic winters 2009/2010 and 2010/2011, calculated Olosses from the CTM are in good agreement to our observations and other modelstudies. The mid-winter 2011 conditions, prior to the catalytic cycles beingfully effective, are also investigated. Surprisingly, a significant loss ofO around 60%, previously not discussed in detail, is observed inmid-January 2011 below 500 K (~19 km) andsustained for approximately 1 week. The low O region had anexceptionally large spatial extent. The situation was caused by twoindependently evolving tropopause elevations over the Asian continent.Induced adiabatic cooling of the stratosphere favoured the formation of PSC,increased the amount of active chlorine for a short time, and potentiallycontributed to higher polar ozone loss later in spring.