Quantification of NO_x emission from St Petersburg (Russia) using mobile DOAS measurements around the entire city

Abstract

We present mobile differential optical absorption spectroscopy (DOAS) zenith-sky observations of tropospheric NO₂ from field experiments carried out at St Petersburg (Russia) on a number of days during May–October of 2009–2012. We conducted a detailed analysis of our measurements on a closed route around the entire city that took place on 14 August 2012. We used the data from these circular observations to derive our top–down estimate of total NO_x emission from St Petersburg on that day, i.e. (12.6 ± 2.4) ×10²⁴ molecules s⁻¹. This value, if assumed to be constant throughout the year, would correspond to a total emission rate of (31 ± 6) kt/year (calculated on condition that all NO_x was NO₂). Our estimate is half of that reported in a published official inventory of St Petersburg (63 kt/year). Possible reasons for that discrepancy and an outlook for further improvements are considered and discussed further.

Acknowledgements

The instrument used for DOAS mobile measurements belongs to the Centre for Geo-Environmental Research and Modelling (GEOMODEL), St Petersburg State University. The WinDOAS spectral analysis software was developed by Caroline Fayt and Michel van Roozendael in the IASB/BIRA Uccle, Belgium. The authors thank the NASA Aura Validation Data Center (AVDC) for supplying the OMI stratospheric NO₂ vertical column density data.

Additional information

Funding

The data analysis of this study was partly supported by the Russian Foundation for Basic Research under Grant number 14-05-00897. Numerical model simulation was supported by the Russian Science Foundation under Grant number 14-17-00096.