Determination of anthropogenic emissions in the Augsburg area by the source–tracer-ratio method

Air-quality models require as input emission inventories of individual compounds high temporal and spatial resolution. These emission inventories are calculated by complex emission models. To evaluate these models, emission rates of CO and NOx of the city of Augsburg were determined in March and October using two independent methods and were compared with emission rates calculated by an emission model. This paper outlines the source–tracer-ratio (STR) method, describes its implementation in Augsburg, and presents the results obtained in four successful experiments. The CO emission rate was derived directly from the STR method, whereas the NOx emission rate is calculated from the CO emission rate using the average CO/NOx correlation in the city plume from the long-term dataset obtained within the Augsburg experiment. The CO and NOx emission rates obtained on 10, 22, and 23 October 1998, were in reasonable agreement with emission rates determined by a mass balance method. The CO emission rate on 23 March 1998, was about twice as large as the autumn emission rates. This observation is consistent with the observed mean emission ratios in March and October obtained from long-term measurements. The CO emission rates were also used to calculate absolute emission rates for a number of hydrocarbons.