Simulated versus observed trace gases: EMAC model & ESMVal HALO campaign

Abstract

During the ESMVal campaign the High Altitude Long Range Aircraft HALO measured selected atmospheric trace gases, from the surface to 15 km altitude. A region ranging from Norway to the southern polar vortex was sampled within 10 days in September 2012. Dedicated hind-cast simulations for the campaign were conducted with the global ECHAM/MESSy Atmospheric Chemistry model, based on the CCMI REF-C1SD setup. In addition, sensitivity simulations are performed to isolate the effects of different parameterizations and settings in the model. We present preliminary comparisons between simulations and observations. Specified dynamics and online sampling along the flight track with a temporal resolution of the model time step improve the comparability, but climatological diagnostics are also needed to identify problems in the model that may need attention. The ESMVal flight path is available from the website of the CCMI working group on improved evaluation of chemistry-climate models using in-situ research aircraft data. In a follow-up study this work can therefore be extended to other CCMI models or similar methods could be applied to compare to other available aircraft data.