Analysis of the Evolution of the Chemical Composition of the Atmosphere over the Past Three Decades: Comparisons of Chemistry-Climate Model Simulations with In-situ and Remote Sensing Observations

Global chemistry-climate models have been used to simulate the evolution of the atmospheric composition over the past decades. These simulations have been performed in free-running and specified dynamic modes, using the Community Atmosphere Model version 4 included in the the NCAR Community Earth System Model. We have analyzed the long-term changes as well as the interannual variability of several atmospheric compounds with a focus on ozone, carbon monoxide and nitrogen dioxide. We have investigated the behavior of these species by focusing on two regions, Europe and Asia. In Europe, surface emissions have decreased significantly since the 1980s, which have led to a decrease in the concentrations of several tropospheric compounds. On the contrary, emissions in Asia have dramatically increased, particularly during the past two decades, which has resulted in large increases in the atmospheric content of several species. We have used in-situ observations of O3, CO and NO2 from the Cooperative Air Sampling Network and from network of the European monitoring and evaluation programme (EMEP) to analyze the model results in different stations in the regions under consideration. We have also compared the model results with remote sensing observations from MOPITT, OMI, GOME, GOME-2 and SCIAMACHY instruments. Results show an underestimation of modeled CO concentrations, which has also been reported by previous studies. We will also analyse the simulated O3 and NO2 concentrations through comparisons with monitoring surface stations and satellite observations.