Total carbon monoxide column variability: CTM model results and satellite measurements

Carbon Monoxide is an important atmospheric trace gas. It plays a key role in the global OH budget and thus in the cleansing capacity of the atmosphere and often is also used as a tracer for pollutant transport. The satellite instruments SCIAMACHY and MOPITT have been measuring CO total columns for several years now, while other are just starting their measurements (e.g. TES on EOS-AURA, AIRS nf AUQA). These global CO measurements allow studying its inter and intra-annual variability. Therefore, we analyzed modeled CO total columns for the years 2003 and 2004 to investigate how CO total columns and their variability can be used in studying tropospheric processes. The model simulation was done with the TM4 model, developed at Utrecht University (IMAU) and the Royal Dutch Meteorological Institute (KNMI). Among others, we identify known and less well known pollution transport pathways and also show that the CO total columns should be treated carefully when they are to be used as a proxy for near-surface CO. We also analyze SCIAMACHY total CO column measurements from the SRON-IMLM retrieval algorithm with regard to seasonal variations and compare them with the TM4 model results.