Chlorine nitrate in the atmosphere over St. Petersburg

Ground-based measurements of the total chlorine nitrate (ClONO 2 ) in the atmosphere have been taken for the first time in Russia using the Bruker IFS-125HR infrared (IR) Fourier spectrometer (FS). The average error of the total ClONO 2 measurements, performed in 2009–2012 in Peterhof, is (25 ± 10)%. The results have been compared with measurements performed using similar devices at the NDACC network, Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) satellite measurements, and the total ClONO 2 numerical simulation (performed using the EMAC chemical climatic model). The total ClONO 2 seasonal variations are similar for three considered observation stations (Peterhof, Kiruna, and Eureka) with the maximum in February-March, which is more pronounced at higher latitudes. High correlations ( R = 0.7–0.9) between the MIPAS satellite data, ground-based measurements near St. Petersburg, and the values calculated using the EMAC model have been revealed. The modeling data are on average smaller than the data of the ground-based and satellite measurements. An analysis of the seasonal variations in the total ClONO 2 monthly average values in the St. Petersburg region indicated that this difference is caused by the fact that the model underestimated the maximal total ClONO 2 values in the atmosphere.