Regional background ozone and carbon monoxide variations in remote Siberia/East Asia

Abstract

[1] Continuous measurements of O 3 and CO were made during 1997-1999 at Mondy, a remote mountain site in East Siberia, in order to quantify their mixing ratios and their climatology in the ''background'' troposphere of continental Eurasia. The seasonal cycles of O 3 and CO show the spring maximum-summer minimum similar to that previously reported in the remote Northern Hemisphere. The influences of Siberian forest fires on the variations of CO mixing ratios at Mondy were observed both on a local and a regional scale during spring 1997 and fall 1998, respectively. We further evaluate the possible impact of European pollution export to the remote atmosphere of Siberia using trajectory analysis. It was found that the O 3 and CO mixing ratios in the air masses transported from Europe are higher than those from Siberia and high-latitude regions for most of the year. The medians of O 3 and CO mixing ratios associated with the European air masses are 44.2 and 134 ppb, respectively, in comparison with 42.7 and 128 ppb in the Siberian air masses, and 41.0 and 110 ppb in the high-latitude air masses. The residence time analysis of air masses transported from the European continent indicates that CO mixing ratios significantly decrease with longer transport time of air masses from Europe, while rapid air motion retains higher CO mixing ratios in every season due to the admixture of polluted European air into the continental background air during air mass transport over Eurasia and photochemical loss by OH. Because of a shorter lifetime in summer, CO mixing ratios decrease at a rate of 6-7 ppb per day, while they decrease at a rate of 2-4 ppb per day in winter and spring. The similar trend is found for O 3 but only in summer, at a rate of 2-3 ppb per day. From this analysis, we are able to identify that European pollution exerts an influence, though not very strong, on the background O 3 and CO at Mondy in remote Siberia/East Asia.

Boundary Layer Ozone Transport from Eastern China to Southern Japan: Pollution Episodes Observed during Monsoon Onset in 2004

“…However, the main focus is mostly at data from Cape Hedo as the station is most relevant to the ideal outflow condition due to the minimized effects of emissions from Japan mainland and Korea. Previous studies at most of these sites confirmed the regional representative of the sites and more details have been previously explained and could be found elsewhere (Pochanart et al, 2004(Pochanart et al, , 2003(Pochanart et al, , 2002(Pochanart et al, , 1999. In Fig.…”

“…The instrumental systems and monitoring criteria for ozone in this study are similar to those of our previous studies and details regarding ozone measurement, calibration, regular maintenance and data handling have been reported elsewhere (Tanimoto et al, 2007;Pochanart et al, 2003Pochanart et al, , 1999. The isentropic backward trajectories were applied in order to look for the evidence of direct episodic transboundary ozone transport events from a region nearby Chinese sites in central eastern China to Japanese site.…”

“…In Fig. 1, Mondy observatory in Siberia, though not used in this analysis, is also shown as a representative of Eurasian background or clean air masses in the inflow region of East Asia before the perturbation by source region in China (Pochanart et al, 2003). Ozone data in China were obtained from the observatory sites that were established in 2003.…”

Tropospheric ozone climatology over Beijing: analysis of aircraft data from the MOZAIC program

“…In the interior region of the Asian continent, a summer maximum of O 3 was observed over the northeastern Tibet-Qinghai Plateau (Wang et al, 2006b), which has been attributed to a possible source of stratosphere-to-troposphere exchange . For the broad mid-tropospheric summer maximum of O 3 over Beijing, another important source may be the biomass burnings in Central Asia and Russia (Pochanart et al, 2003;Nedelec et al, 2005;Qin et al, 2006), whose plumes can be rapidly transported to middle and even upper troposphere by warm conveyor belts Real et al, 2007).…”

Determination of enhancement ratios of HCOOH relative to CO in biomass burning plumes by the Infrared Atmospheric Sounding Interferometer (IASI)

“…For these years, the variation in CO does not follow the variation in the number of fires. The large region selected over Siberia is known to also be impacted by CO-enriched plumes transported from other regions, such as polluted air masses from China (e.g., Paris et al, 2008) or from Europe (e.g., Pochanart et al, 2003). These external influences interfere with the CO plumes originating from forest fires measured over this region.…”