Tropospheric trace gases at Bremen measured with FTIR spectrometry.

The total column densities of acetylene (C(2)H(2)), carbon monoxide (CO), hydrogen cyanide (HCN) and ethane (C(2)H(6)) measured in Bremen (Germany, 53.107 degrees N, 8.854 degrees E) were compared with data from Mace Head/Ireland (MHD) and GEOS-Chem model simulations. The data were obtained between August 2002 and October 2006 with the ground based high resolution Fourier Transform Infra-Red (FTIR) Spectrometry, using the sun as the light source. The analysis showed good agreements between all the three data sets for the seasonal cycle of CO. Enhancements in summer 2003 and summer 2004 due to influence of biomass burning were identified in all three data sets. The high correlations between C(2)H(6) and C(2)H(2), C(2)H(2) and CO, and for C(2)H(6) and CO support the similarities in their sources and sinks. The results suggest that the background air in Bremen is mainly influenced by long-ranged transport of biomass burning products. Local pollution plays a minor role for the measurements performed in Bremen.