K. B. Moiseenko

Estimates of carbon monoxide emissions from wildfires in northern Eurasia for airquality assessment and climate modeling

The emissions from fires in the boreal zone of northern Eurasia significantly contribute to the global emissions of greenhouse gases, their precursors, and aerosols. These emissions are an important component of the global carbon balance, and they significantly affect both seasonal and long-term variations in the chemical composition and radiation properties of the atmosphere on both regional and global scales. The atmospheric emissions of carbon monoxide (CO) from biomass burning have systematically been estimated for the entire territory of northern Eurasia over the period of 2000–2008 on the basis of satellite (MODIS MCD45A1) data on burned vegetation and the Seiler-Crutzen emission model with consideration for both regional and seasonal features. On the whole, for Russia, the annual emissions of CO from biomass burning ranged from 10.6 to 88.2 Mt/y over the indicated period. Depending on fire activity, the atmospheric emissions of CO from natural fires and agricultural work may yield from 25 to 200% of the total technogenic emissions according to the EDGAR-2000 model. In this case, the dominant contribution is made by boreal forest fires (8–57 Mt/y), whose portion amounts to 63–76% of the total emissions from biomass burning. This relatively short observational series does not allow one to reliably estimate long-term variations; however, on the whole, a stable increase in burned areas has been observed in forest, steppe, and agricultural regions over the last decade. Our analysis suggests significant spatial and seasonal variations in the large-scale fields of fire emissions, which are determined by the physical, geographic, and climatic features of individual regions. The calculated fields of emissions can be used in transport-chemical models, studies of the regional transport and quality of air, and climate models.

Identifying anthropogenic sources of nitrogen oxide emissions from calculations of Lagrangian trajectories and the observational data from a tall tower in Siberia during the spring-summer period of 2007.

The task of identifying climatically significant regional anthropogenic emissions and estimating their contribution to the variability of nitrogen oxides observed at a monitoring station is considered on the basis of NO and NO2 surface concentrations measured at the Zotino background observation station (60°26′ N, 89°24′ E, Krasnoyarsk Territory). The approach used is based on an estimation of the conditional probability of polluted air arriving from individual regions by using the results of calculating backward Lagrangian trajectories in the lower troposphere. It is established that the contribution of air masses supplied from industrial regions in the south of the Krasnoyarsk Territory to episodes of high concentrations of nitrogen oxides (>0.7 ppb) is larger than the contribution from cities and towns located in the south of Western Siberia. The results indicate that anthropogenic sources of pollution substantially affect the balance of minor gases in the lower troposphere on a regional scale and that this factor must be taken into account when observational data from the Zotino background station are analyzed and interpreted.

Hydrodynamic aspects of the Novorossiysk bora episodes in 2012–2013

The spatial and time variability of the surface wind field during the bora episodes, including the events of January 27 and February 7, 2012, which were accompanied by windstorms on the coast and Markotkhsky ridge downwind slopes, has been analyzed based on the meteorological parameters observed during the winter expeditions in 2012–2013 to the Novorossiysk—Gelendzhik region. The dependence of the wind velocity on the background atmospheric parameters and incident-flow blocking conditions has been studied for the cases of strong and weak bora. It is assumed that bora is of a wave nature in the considered episodes and the wave drag effect predominated in the observed wind-flow acceleration on a downwind slope. Partial blocking of an incident wind flow by mountains also affects the wind regime in the downwind zone, especially near Gelendzhik, where mountains are higher than in the Novorossiysk region.

Flow over mountains with the stream velocity shear

The dependence of orographic disturbances of the atmosphere on properties of the incident flow is studied within the semianalytic approach. Reducing the initial system of equations of hydrothermodynamics to a single equation for an associative stream function makes it possible to consider a class of solutions of a sufficiently general type when the background velocity of the wind and the Lyra’s scale vary with height. It is shown that the dependence of the solution on the indicated factors can be not only strong, but also sufficiently unexpected. In particular, with the monotonic growth in the wind velocity in the troposphere, which corresponds to conditions of a jet stream near the tropopause, disturbances at low and medium heights can acquire an almost resonant and waveguide nature.

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 GEOS-Chem chemical 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.

Estimation of biogenic CH4 and CO2 emissions and dry deposition of O3 using 222Rn measurements in TROICA expeditions

On the basis of simultaneous measurements of surface concentrations of CH4, CO2, O3, and 222Rn during 6 TROICA (TRanscontinental Observations Into the Chemistry of the Atmosphere) expeditions along the Trans-Siberian Railway from Moscow to Vladivostok in 1999–2008, we have estimated the biogenic emissions of CH4 and CO2 from terrestrial ecosystems and the nighttime sink of O3 on the underlying surface from data on the accumulation rate of 222Rn under conditions of near-surface temperature inversion. The regional emissions of CH4 were the highest in summer in the Far East (0.87 ± 0.52 μg m−2 s−1) and in West Siberia (0.77 ± 0.41 μg m−2 s−1), which is associated with significant methane flows from wetlands and moist soils that are typical for these regions. The biogenic emissions of CO2 vary on average from 0.18 ± 0.04 μg m−2 s−1 in West Siberia to 0.89 ± 0.07 μg m−2 s−1 in East Siberia. The nighttime sink of O3 has a seasonal maximum in summer and varies from 0.05 ± 0.01 μg m−2 s−1 in West Siberia to 0.07 ± 0.01 μg m−2 s−1 in Central Siberia; the dry deposition rate of O3 varies from 0.10 ± 0.08 cm s−1 in West Siberia to 0.33 ± 0.21 cm s−1 in East Siberia and the Far East.

Consideration for the tropopause’s displacements in the problem of flow over mountains

Within the framework of a two-dimensional, inviscid, stationary model, the problem of an unbounded (in height) two-layer quasi-static airflow over mesoscale mountains is considered. The airflow is characterized by a constant velocity and a discontinuity of temperature stratification at the inner interface (tropopause). The conjugation conditions for the flow fields at the boundary between the layers are formulated exactly, without the standard assumption of small perturbations. According to calculations, partial reflection of wave energy from the tropopause is substantially controlled by nonlinear effects associated with a finite height and shape of terrain. The tropopause’s displacement from the initial (equilibrium) level has a stabilizing effect on the flow, thus interfering with the development of anomalously strong disturbances. As a result, the flow field remains statically stable within a considerably wider range of flow parameters and for a larger mountain heights than predicted in the context of the conventional linear theory. The results obtained in this study are indicative of the importance of a correct consideration of the dynamic interaction between the troposphere and the overlying layers during both simulation of the process of flow and analysis of real atmospheric situations over mountains.

Hydraulic Regimes of Flow over Mountains during Severe Downslope Windstorms: Novorossiysk Bora, Novaya Zemlya Bora, and Pevek Yuzhak

Common features of the flow behavior over mountains within the hydraulic jump model are identified based on an analysis of 36 episodes of severe winds in the regions of Novorossiysk, Pevek, and Novaya Zemlya. In all these episodes, the incoming flow is characterized by a strong inversion layer at altitudes of 0.5–1.5 km and, in the case of bora, by a critical level in the wind profile in the middle troposphere, which creates conditions for a weakened dynamic interaction between the low-level air flowing over mountains and the upper layers of the atmosphere. The wind-speed increase on the lee slope is caused by the transition of the incoming flow from the subcritical to supercritical state. In this case, the velocity amplitude increases with increasing inversion intensity. Model estimates of wind-speed increase are in good agreement with observations at lee-side weather stations for episodes with a strong elevated inversion.

Mountain wave-induced variations of ozone and total nitrogen dioxide contents over the Subpolar Urals

Wavy spatial variations in the contents of trace gases are identified using plane measurements of O3 concentrations in the medium troposphere and the total content (TC) of NO2 in the atmospheric column from flights above the Subpolar Urals in April 1984. The results of model calculations allow us to relate these variations to mesoscale atmospheric disturbances above the mountains, which are caused by the influence of dynamic relief on the leaked-in flow.

Aromatic volatile organic compounds and their role in ground-level ozone formation in Russia

This paper reports proton mass spectrometry data on aromatic volatile organic compounds (VOCs) (benzene, toluene, phenol, styrene, xylene, and propylbenzene) obtained in different Russian regions along the Trans-Siberian Railway from Moscow to Vladivostok, based on expedition data retrieved using the TRO-ICA-12 mobile laboratory in the summer of 2008. The contribution of aromatic VOCs to ozone formation in the cities and regions along the measurement route has been estimated quantitatively. The greatest contribution of aromatic VOCs to ozone formation is characteristic of large cities along the Trans-Siberian Railway (up to 7.5 ppbv O3) specified by the highest concentrations of aromatic VOCs (1–1.7 ppbv) and nitrogen oxides (>20 ppbv). The results obtained are indicative of a considerable contribution (30–50%) of anthropogenic emissions of VOCs to photochemical ozone generation in the large cities along the Trans-Siberian Railway in hot and dry weather against the background of a powerful natural factor such as isoprene emissions controlling the regional balance of ground-level ozone in warm seasons.