Visible light nitrogen dioxide spectrophotometer intercomparison: Mount Kobau, British Columbia, July 28 to August 10, 1991

Under the auspices of the World Meteorological Organization, Environment Canada hosted an international comparison of visible light spectrophotometers at Mt. Kobau, British Columbia in August of 1991. Instruments from four countries were involved. The intercomparison results have indicated that some significant differences exist in the responses of the various instruments, and have provided a basis for the comparison of the historical data sets which currently exist as a result of the independent researches carried out in the past in the former Soviet Union, New Zealand, and Canada

Airborne trichloroacetic acid and its deposition in the catchment area of the Caspian Sea

Abstract The main sources of pollution discharge into the Caspian Sea are metal and oil processing plants in the catchment areas of the Ural and Volga rivers, as well as the coastal and oshore oil industry in the countries bordering the sea. The high evaporation from the surface of this largest inland sea introduces highly volatile C 2 -chlorohydrocarbons into the atmosphere. Subsequent reactions with OH radicals and other oxidants results in the formation of secondary pollutants, such as phytotoxic trichloroacetic acid (TCA), which are then delivered by the air or rain into the neighbouring ecosystems of various vegetation zones. Biomonitoring investigations in the catchment area of the Caspian Sea have revealed that dierences in pollution levels in the southern Russian area between the Black Sea and the Caspian Sea, resulting from TCA originating in the atmosphere, are attributable to climatic conditions and the geographical position of the measuring sites.

Spatial distribution of Δ14CO2 across Eurasia:measurements from the TROICA-8 expedition

Because fossil fuel derived CO2 is the only source of atmospheric CO2 that is devoid of 14C, atmospheric measurements of Δ14CO2 can be used to constrain fossil fuel emission estimates at local and regional scales. However, at the continental scale, uncertainties in atmospheric transport and other sources of variability in Δ14CO2 may influence the fossil fuel detection capability. We present a set of Δ14CO2 observations from the train-based TROICA-8 expedition across Eurasia in March–April 2004. Local perturbations in Δ14CO2 are caused by easily identifiable sources from nuclear reactors and localized pollution events. The remaining data show an increase in Δ14CO2 from Western Russia (40° E) to Eastern Siberia (120° E), consistent with depletion in 14CO2 caused by fossil fuel CO2 emissions in heavily populated Europe, and gradual dispersion of the fossil fuel plume across Northern Asia. Other trace gas species which may be correlated with fossil fuel CO2 emissions, including carbon monoxide, sulphur hexafluoride, and perchloroethylene, were also measured and the results compared with the Δ14CO2 measurements. The sulphur hexafluoride longitudinal gradient is not significant relative to the measurement uncertainty. Carbon monoxide and perchloroethylene show large-scale trends of enriched values in Western Russia and decreasing values in Eastern Siberia, consistent with fossil fuel emissions, but exhibit significant spatial variability, especially near their primary sources in Western Russia. The clean air Δ14CO2 observations are compared with simulated spatial gradients from the TM5 atmospheric transport model. We show that the change in Δ14CO2 across the TROICA transect is due almost entirely to emissions of fossil fuel CO2, but that the magnitude of this Δ14CO2 gradient is relatively insensitive to modest uncertainties in the fossil fuel flux. In contrast, the Δ14CO2 gradient is more sensitive to the modeled representation of vertical mixing, suggesting that Δ14CO2 may be a useful tracer for training mixing in atmospheric transport models

Pan-Eurasian Experiment (PEEX): Towards a holistic understanding of the feedbacks and interactions in the land-Atmosphere-ocean-society continuum in the northern Eurasian region

The northern Eurasian regions and Arctic Ocean will very likely undergo substantial changes during the next decades. The Arctic-boreal natural environments play a crucial role in the global climate via albedo change, carbon sources and sinks as well as atmospheric aerosol production from biogenic volatile organic compounds. Furthermore, it is expected that global trade activities, demographic movement, and use of natural resources will be increasing in the Arctic regions. There is a need for a novel research approach, which not only identifies and tackles the relevant multi-disciplinary research questions, but also is able to make a holistic system analysis of the expected feedbacks. In this paper, we introduce the research agenda of the Pan-Eurasian Experiment (PEEX), a multi-scale, multi-disciplinary and international program started in 2012 (https://www.atm.helsinki.fi/peex/). PEEX sets a research approach by which large-scale research topics are investigated from a system perspective and which aims to fill the key gaps in our understanding of the feedbacks and interactions between the land-Atmosphere-Aquatic-society continuum in the northern Eurasian region. We introduce here the state of the art for the key topics in the PEEX research agenda and present the future prospects of the research, which we see relevant in this context

Observations of the Atmospheric Composition over Russia: TROICA Experiments

Results obtained in the course of unique observations (as part of the TROICA project) of the composition and state of the atmosphere over Russia have been summarized. Scientists and engineers from different countries took part in these observations. The main task of these observations was to measure atmospheric contents of trace gases and aerosols and both meteorological and radiative characteristics of the atmosphere using a mobile laboratory designed and brought into operation specially for transcontinental observations along the network of Russian electrified railroads. A large database obtained in the TROICA experiments using the mobile laboratory, in field experiments, and at scientific stations is still under analysis. In this work, the most important results published earlier and obtained recently are discussed, which makes it possible to form a comprehensive picture of the spatial distribution and temporal variability of the atmospheric composition over northern Eurasia

Low concentrations of near-surface ozone in Siberia

International audienceSiberia with its large area covered with boreal forests, wetlands and tundra is believed to be an important sink for ozone via dry deposition and reactions with biogenic volatile organic compounds (BVOCs) emitted by the forests. To study the importance of deposition of ozone in Siberia, we analyse measurements of ozone mixing ratios taken along the Trans-Siberian railway by train, air-borne measurements andpoint measurements at the Zotino station. For all data, we ran the Lagrangian particle dispersion model FLEXPART in backward mode for 20 d, which yields the so-called potential emission sensitivity (PES) fields. These fields give a quantitative measure of where andhow strongly the sampledair masses have been in contact with the surface and hence possible influenced by surface fluxes. These fields are further statistically analysed to identify source andsink regions that are influencing the observedozone. Results show that the source regions for the surface ozone in Siberia are located at lower latitudes: the regions around the Mediterranean Sea, the Middle East, Kazakhstan andChina. Low ozone mixing ratios are associated to transport from North West Russia, the Arctic region, andthe Pacific Ocean. By calculating PES values for both a passive tracer without consideration of removal processes and for an ozone-like tracer where dry deposition processes are included, we are able to quantify the ozone loss occurring en route to the receptor. Strong correlations between low ozone concentrations andthe spatially integratedfootprints from FLEXPART, especially during the period summer to autumn, indicate the importance of the Siberian forests as a sink for tropospheric ozone