Abstract. Carbon-14 monoxide is an unique tracer for certain important aspects of atmospheric chemistry and transport. Particularly, it may provide an independent means of testing model-based OH distributions and seasonality. The cosmogenic source strength of ¹⁴CO is inversely correlated with the solar activity. This time dependence demands a rescaling of ¹⁴CO measurements or model results to comparable conditions regarding the solar cycle, in order to achieve information on global distributions and trends of OH. For this rescaling, a two-parameter filter is derived using the three-dimensional global Model of Atmospheric Transport and Chemistry (MATCH). The filter function defines the atmospheric response time of the ¹⁴CO concentration to changes in the total cosmogenic ¹⁴CO source strength. The latitude dependence of the response time in addition to the atmospheric lifetime of the tracer provides useful information about the model's transport properties, especially about the role of stratosphere-troposphere exchange. It may serve as a direct indicator for possible solutions of the unresolved hemispheric asymmetry of the atmospheric ¹⁴CO concentration. The general concept can be applied as a diagnostic test for coupled changes in atmospheric transport and chemistry in models. Time series of ¹⁴CO measurements can provide this information about the real atmosphere.