Quantitative Analysis of 2010/11 Arctic Ozone Loss Using EOS MLS and WACCM4

Arctic ozone loss rates are quantitatively investigated using WACCM4 (Whole Atmosphere Community Climate Model version 4) with specified dynamics and initialized with EOS MLS (Earth Observing System Microwave Limb Sounder) observations. EOS MLS onboard the Aura satellite has provided well-proven data since August 2004 and is thus appropriate for monitoring the evolution of measured atmospheric constituents and for initializing and validating models. WACCM4 is nudged daily by GEOS (Goddard Earth Observing System) horizontal winds, temperature, and surface pressure reanalysis data in order to simulate realistic dynamical behavior. Ozone loss rates due to heterogeneous chemistry in Arctic winters are investigated by applying the pseudo-passive subtraction method. With this method two model simulations are compared. The first includes complete chemistry, while in the second simulation heterogeneous chemistry on polar stratospheric clouds (PSCs) is turned off. Ozone in the first simulation is referred to as "active" ozone, whereas ozone in the second simulation is referred to as a "pseudo-passive" tracer. A comparison of active ozone to the pseudo-passive tracer enables quantification of ozone loss due to heterogeneously activated halogens only, presuming the modeled ozone is well validated and heterogeneous chemistry is comprehensively implemented in the model. Results from the 2010/11 Arctic winter are compared to the cold Arctic season of 2004/05.