The comparison between the isoprene, methyl vinyl ketone and methacrolein concentrations measured in the TROICA-12 expedition at Far East region

The spatial and temporal distribution of isoprene and its oxidation products products, such as methyl vinyl ketone (MVK) and methacrolein (MACR) was investigated. The measurements were carried out using by the mobile observatory, placed on the railcar chassis. As the object was selected the vast area of deciduous and mixed forests in Far East, which is crossed by Trans-Siberian Railway. It was shown that the isoprene and MVK and MACR have pronounced daily variations. The isoprene growth at night was not observed. The isoprene and MVK + MACR concentrations are satisfy to a linear regress; the slopes (B) are close to the ∼ 1 (0.93 and 1.04 for TROICA-12 East and West, accordingly). The correlation coefficients (R) are significant and equal to 0.68 and 0.79 for TROICA-12 East and West. The noise of initial 10 sec measured values of MVK + MACR-to-isoprene ratio (below ratio) is significant. The high ratios (> 5) are observed not only at night but also during the day. At night, the high values of ratio somewhat larger than in the daytime. The MVK+MACR and isoprene pair has a high correlation (R∼0.60-0.86) and weak dependence of NO_x, except the one case when the twilight emission of isoprene was dominated.