NOx-limiting regime of ozone generation in a weakly polluted boundary layer over Central Siberia as derived from O3 and Nox observations at Zotto tall tower observatory in 2007-2015

Abstract

Quantitative estimates on the ozone production efficiency (OPE) per a molecular of NOx (=NO+NO2), ΔP, and ozone production rate, PQ, are derived for the region of Central Siberia based on near surface observations of O3, NO, and NO2) at Zotino Tall Tower Observatory in 2007-2015. Experimental data follow are a power law dependencies on NOx abundance: PQ χ [NOx]-n+1, ΔP χ [NOx]-n, n = 0,82±0,06 (coefficient of determination R2 = 0,66), with the power law exponent corresponding to a NOx-limiting regime of ozone production in a weakly polluted air mass. During summer, the value of ΔP ranges from 30,0-43,7 [mol.O3/mol.NOx] which agrees well with the corresponding estimate of 39,8 [mol.O3/mol.NOx] derived from GEOS‑chem CTM model simulations. The derived estimates provide an observation based conclusion on the important role of regional anthropogenic emissions of NOx in summertime ozone photochemistry in the remote areas of Siberia.