Sources and variations of tropospheric ozone in central Siberia: observations and model simulations

IOP Conference Series: Earth and Environmental Science, Climate change: causes, risks, consequences, problems of adaptation and management" 26-28 November 2019, Moscow, Russian Federatio

Regional Photochemical Surface-Ozone Sources in Europe and Western Siberia

The influence of climatically significant regional sources of NOx (=NO + NO2), CO, and biogenic volatile organic compounds (VOCs) on the photochemical generation of surface ozone (O3) in the lower troposphere over Europe and Siberia is studied. The sensitivity of the O3 field to the total emissions of ozone precursors is calculated using a global 3D chemical transport model (GEOS-Chem) based on the 2007–2012 databases for anthropogenic (EDGAR) and biogenic (MEGAN, GFED) emissions. The amount of photochemical ozone generated during the summer months is in good correlation with the air-mass age determined from the ratio between NOx and (total reactive nitrogen) NOy, when the mean contribution of regional sources is ΔO3 ~ 10–15 ppb, which is 20–30% of its background concentration in the middle latitudes (O3 ~ 35–45 ppb). The quantitative estimates of the ozone production efficiency ΔO3/Δ(NOy−NOx) (NOy is the total reactive nitrogen) for the summer months of the indicated period (~10–30 mol O3/mol NOx) are in good agreement with the theory of photochemical ozone generation under the conditions of slightly polluted air

Sources of and variations in tropospheric CO in Central Siberia: Numerical experiments and observations at the Zotino Tall Tower Observatory

Contributions of climatically significant natural and anthropogenic emission sources in northern Eurasia to seasonal carbon monoxide (CO) variations observed at the Zotino Tall Tower Observatory (ZOTTO) in Central Siberia in 2007–2011 have quantitatively been estimated using the GEOSChem chem ical transport model. It is shown that the formation of a stable continental pollution plume from sources in Western Europe, European Russia and southern Siberia during winter plays an important role in the regional balance of surface CO and allows one to explain 55–80% of the amplitude of the CO annual cycle observed at the ZOTTO station (~70–90 ppbv). During the warm period, the effect of the anthropogenic factor is weakly pronounced, and the background concentration of CO is regulated, first and foremost, by the oxidation of biogenic volatile organic compounds and fire activity in the region

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 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