Regional Impact of Ozone Precursor Emissions on NO X and O 3 Levels at ZOTTO Tall Tower in Central Siberia

• Published in: Earth and space science (Hoboken, N.J.) Vol. 8; no. 7
• Main Authors: Moiseenko, K. B., Vasileva, A. V., Skorokhod, A. I., Belikov, I. B., Repin, A. Yu, Shtabkin, Yu. A.
• Format: Journal Article
• Language: English
• Published: 01-07-2021
• ISSN: 2333-5084; 2333-5084
• DOI: 10.1029/2021EA001762

Abstract
Seasonal variations of the near‐surface NO
X
(= NO + NO
2
) and ozone (O
3
) mixing ratios at Zotino Tall Tower (ZOTTO), a remote site in central Siberia, are described for years 2007–2014. Conditional probability function analysis and back trajectories are used to determine the origins of clean (continental baseline, CB) and regional emissions‐influenced air. High NO
X
levels at the site are observed for air from industrial regions of western Siberia and Ural Mountains, whereas CB air originates from remote areas of North Eurasia within 55°–70°N. The estimated annual means of daytime O
3
and NO
X
mixing ratios for CB air are 27.0 and 0.44 ppbv, correspondingly, versus the similar quantities of 27.9 and 0.79 ppbv for all data. Monthly ozone for CB air shows a distinct maximum in April, as is the case for Northern Hemisphere midlatitude baseline (NHMLB) air at the European inflow boundary according to the surface ozone data for Mace Head and Norwegian monitoring sites, and a minimum in late summer–early autumn reflecting a weak continental‐scale ozone production from biogenic sources of ozone precursors and wildfire emissions throughout the warm season. During spring and early summer under hot weather conditions, regional anthropogenic and wildfire emissions are an important source for ozone in the continental boundary layer over southern and central Siberia, resulting in surface ozone levels compared to or larger than those observed in NHMLB air. Throughout the remaining part of year, the central North Eurasia represents a sink for tropospheric ozone on a hemispheric scale.
Key Points
Seasonal variations of NO
X
and O
3
at ZOTTO in Siberia show a signature of weakly polluted air due to the regional pollution
Origins of clean and polluted air for the site are identified; seasonal cycle of the baseline ozone for central North Eurasia is estimated
In spring‐summer, anthropogenic and fire emissions in Siberia provide a net source for tropospheric ozone in the NH midlatitudes