Dr Paul Young is a lecturer in the Lancaster Environment Centre at Lancaster University, UK. Paul visited ACOM for 2 weeks in early September 2015, hosted by his long term collaborator Jean-François Lamarque (ACOM, CESM). During this short visit, Paul started work on analyzing the tropospheric ozone budget and nitrogen deposition in the CAMChem and WACCM simulations for the Chemistry Climate Modeling Initiative (CCMI), an international multi-model project to investigate recent past and possible future atmospheric composition change. His ozone analysis will initially lead into a publication on methods of calculating the ozone budget in chemistry climate models, and the nitrogen deposition analysis will feed into work with ecologist colleagues at Lancaster, both projects together with Jean-François and the ACOM CCMI team. Together with Doug Kinnison and Dan Marsh, Paul and Jean-François have also started a long present day control run of WACCM with the aim to investigate and quantify the role of interannual variability on atmospheric chemical composition.