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

Quantitative estimates on the ozone production efficiency (OPE) per a molecular of NO x (=NO+NO2), Δ P , and ozone production rate, P Q , 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 NO x abundance: P Q χ [NO x ] - n + 1 , Δ P χ [NO x ] - n , n = 0,82±0,06 (coefficient of determination R 2 = 0,66), with the power law exponent corresponding to a NO x -limiting regime of ozone production in a weakly polluted air mass. During summer, the value of Δ P ranges from 30,0-43,7 [mol.O3/mol.NO x ] which agrees well with the corresponding estimate of 39,8 [mol.O3/mol.NO x ] derived from GEOS‑chem CTM model simulations. The derived estimates provide an observation based conclusion on the important role of regional anthropogenic emissions of NO x in summertime ozone photochemistry in the remote areas of Siberia.