Ground-based measurements of the total chlorine nitrate (ClONO2) in the atmosphere have been taken for the first time in Russia using the Bruker IFS125HR infrared (IR) Fourier spectrometer (FS). The average error of the total ClONO2 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 ClONO2 numerical simulation (performed using the EMAC chemical climatic model). The total ClONO2
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