UV variability in Moscow according to long-term UV measurements and reconstruction model

International audienceLong-term measurements of erythemally weighted UV irradiance (Qer) have been analyzed for the 1999?2006 period as well as UV variability according to reconstruction model since 1968. The estimates of different atmospheric parameters effects, including NO2 content, on Qer) have been obtained on seasonal and interannual scales. It has been shown that NO2 content in conditions of large megalopolis provides average Qer decrease of about 1.5?2%. The seasonal variations of the observed UV indices are discussed from the point of view of the impact on health. Using the reconstruction model we showed a distinct growth in Qer since 1980 due to decrease in total ozone (+2.5% per decade), effective cloud amount transmission (+2.1% per decade) and aerosol loading (+1.1% per decade). However, there is no changes in Qer over larger 1968?2006 period due to significant decrease in effective cloud amount transmission (?11% per decade) in 1968?1980

Appropriate prevention of vitamin D deficiency in the population of the Irkutsk region

Purpose of the study. To determine the influence of climatic and geographical factors of the Irkutsk region on the risk of hypovitaminosis D in children and adults. Patients and methods. The contents of 25(OH)D-3 in the blood of children and adults (3261 samples) were evaluated. The materials were obtained in the Diagnostic Center of the region and the InVitro laboratory. Results of monitoring of ultraviolet radiation and precipitation in the Irkutsk region for 2014-2015 were analyzed according to ground and satellite measurements. Results. The Irkutsk region is in the zone of ultraviolet insufficiency during the period from September-October to March-May. The status of the metabolite of vitamin D - 25(oH)D3 in the population of the region is low, especially in adolescents and people older than 70 years. 68 % of children have vitamin D deficiency. Activity of 25(oH)D3 depends on meteorological factors, especially the level of precipitation and the intake of vitamin D. For each geographical area of the region, time intervals were calculated for the formation of vitamin D in the skin under the influence of ultraviolet radiation and time intervals for the intake of vitamin D preparations. The exposure time in the sun was calculated for the formation of vitamin D for individuals with different skin phototypes, depending on the degree of its openness

Kinetic and DFT Studies on the Mechanism of C−S Bond Formation by Alkyne Addition to the [Mo3S4(H2O)9]4+ Cluster

Reaction of [Mo3(μ3-S)(μ-S)3] clusters with alkynes usually leads to formation of two C−S bonds between the alkyne and two of the bridging sulfides. The resulting compounds contain a bridging alkenedithiolate ligand, and the metal centers appear to play a passive role despite reactions at those sites being well illustrated for this kind of cluster. A detailed study including kinetic measurements and DFT calculations has been carried out to understand the mechanism of reaction of the [Mo3(μ3-S)(μ-S)3(H2O)9]4+ (1) cluster with two different alkynes, 2-butyne-1,4-diol and acetylenedicarboxylic acid. Stoppedflow experiments indicate that the reaction involves the appearance in a single kinetic step of a band at 855 or 875 nm, depending on the alkyne used, a position typical of clusters with two C−S bonds. The effects of the concentrations of the reagents, the acidity, and the reaction medium on the rate of reaction have been analyzed. DFT and TD-DFT calculations provide information on the nature of the product formed, its electronic spectrum and the energy profile for the reaction. The structure of the transition state indicates that the alkyne approaches the cluster in a lateral way and both C−S bonds are formed simultaneously

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

Overview: Recent advances in the understanding of the northern Eurasian environments and of the urban air quality in China – a Pan-Eurasian Experiment (PEEX) programme perspective

The Pan-Eurasian Experiment (PEEX) Science Plan, released in 2015, addressed a need for a holistic system understanding and outlined the most urgent research needs for the rapidly changing Arctic-boreal region. Air quality in China, together with the long-range transport of atmospheric pollutants, was also indicated as one of the most crucial topics of the research agenda. These two geographical regions, the northern Eurasian Arctic-boreal region and China, especially the megacities in China, were identified as a “PEEX region”. It is also important to recognize that the PEEX geographical region is an area where science-based policy actions would have significant impacts on the global climate. This paper summarizes results obtained during the last 5 years in the northern Eurasian region, together with recent observations of the air quality in the urban environments in China, in the context of the PEEX programme. The main regions of interest are the Russian Arctic, northern Eurasian boreal forests (Siberia) and peatlands, and the megacities in China. We frame our analysis against research themes introduced in the PEEX Science Plan in 2015. We summarize recent progress towards an enhanced holistic understanding of the land–atmosphere–ocean systems feedbacks. We conclude that although the scientific knowledge in these regions has increased, the new results are in many cases insufficient, and there are still gaps in our understanding of large-scale climate–Earth surface interactions and feedbacks. This arises from limitations in research infrastructures, especially the lack of coordinated, continuous and comprehensive in situ observations of the study region as well as integrative data analyses, hindering a comprehensive system analysis. The fast-changing environment and ecosystem changes driven by climate change, socio-economic activities like the China Silk Road Initiative, and the global trends like urbanization further complicate such analyses. We recognize new topics with an increasing importance in the near future, especially “the enhancing biological sequestration capacity of greenhouse gases into forests and soils to mitigate climate change” and the “socio-economic development to tackle air quality issues”

Seasonal distribution of aerosol properties over Europe and their impact on UV irradiance

Using the aerosol optical thickness at 550 nm (τ<sub>550</sub>) from MODIS (collection 5) for the 2000–2008 period combined with the aerosol products from the ground-based AERONET network since 1996, monthly mean values of key aerosol parameters have been obtained with 1 degree resolution over Europe. Additional tests have revealed a satisfactory quality of the MODIS data, except in a few cases. Quality assured AERONET data are used for evaluating the Angstrom exponent, single scattering albedo and asymmetry factor, and for validating the final aerosol optical thickness in the UV spectral region. A method for extrapolating the aerosol parameters into the UV spectral region is discussed. The aerosol optical thickness distributions are considered together with meteorological fields from NOAA_NCEP_CPC_CAMS_ OPI climatology. The τ<sub>340</sub> is shown to vary significantly from approximately 0.01 to 0.9 depending on the season and location. Permanent elevated aerosol loading over several industrial areas is observed, which agrees with the output of chemical transport models. Using radiative transfer modeling, monthly mean UV loss due to aerosol was estimated. The absolute decrease in UV indices varies from less than 0.1 to 1.5. The relative UV attenuation has large spatial and temporal variations (−1%–−17%) with a minimum towards the northwest and maxima over several southern local areas (Northern Italy, etc.) during the warm period

A new parameterization of the UV irradiance altitude dependence for clear-sky conditions and its application in the on-line UV tool over Northern Eurasia

A new method for calculating the altitude UV dependence is proposed for different types of biologically active UV radiation (erythemally weighted, vitamin-D-weighted and cataract-weighted types). We show that for the specified groups of parameters the altitude UV amplification (<i>A</i>_UV) can be presented as a composite of independent contributions of UV amplification from different factors within a wide range of their changes with mean uncertainty of 1 % and standard deviation of 3 % compared with the exact model simulations with the same input parameters. The parameterization takes into account for the altitude dependence of molecular number density, ozone content, aerosol and spatial surface albedo. We also provide generalized altitude dependencies of the parameters for evaluating the <i>A</i>_UV. The resulting comparison of the altitude UV effects using the proposed method shows a good agreement with the accurate 8-stream DISORT model simulations with correlation coefficient <i>r</i>  &gt;  0.996. A satisfactory agreement was also obtained with the experimental UV data in mountain regions. Using this parameterization we analyzed the role of different geophysical parameters in UV variations with altitude. The decrease in molecular number density, especially at high altitudes, and the increase in surface albedo play the most significant role in the UV growth. Typical aerosol and ozone altitude UV effects do not exceed 10–20 %. Using the proposed parameterization implemented in the on-line UV tool (<a href="http://momsu.ru/uv/" target="_blank">http://momsu.ru/uv/</a>) for Northern Eurasia over the PEEX domain we analyzed the altitude UV increase and its possible effects on human health considering different skin types and various open body fraction for January and April conditions in the Alpine region

Assessments of urban aerosol pollution in Moscow and its radiative effects

Simultaneous measurements by the collocated AERONET CIMEL sun/sky photometers at the Moscow State University Meteorological Observatory (MSU MO) and at the Zvenigorod Scientific Station (ZSS) of the A. M. Obukhov Institute of Atmospheric Physics during September 2006���April 2009 provide the estimates of the effects of urban pollution on various aerosol properties in different seasons. The average difference in aerosol optical thickness between MO MSU and ZSS, which can characterize the effect of aerosol pollution, has been estimated to be about &lt;i&gt;d&lt;/i&gt;AOT = 0.02 in visible spectral region. The most pronounced difference is observed in winter conditions when relative AOT difference can reach 26%. The high correlation of the AOT's, the Angstrom exponent values and the effective radii between the sites confirms that natural processes are the dominating factor in the changes of the aerosol properties even over the Moscow megacity area. The existence of positive correlation between &lt;i&gt;d&lt;/i&gt;AOT and difference in water vapor content explains many cases with large &lt;i&gt;d&lt;/i&gt;AOT between the sites by the time lag in the airmass advection. However, after excluding the difference due to this factor, AOT in Moscow remains higher even in a larger number of cases (more than 75%) with the same mean &lt;i&gt;d&lt;/i&gt;AOT = 0.02. Due to the negative average difference in aerosol radiative forcing at the TOA of about &lt;i&gt;d&lt;/i&gt;ARF&lt;sub&gt;TOA&lt;/sub&gt; = −0.9 W m&lt;sup&gt;−2&lt;/sup&gt;, the aerosol urban pollution provides a distinct cooling effect of the atmosphere. The PAR and UV irradiance reaching the ground is only 2–3% lower in Moscow due to the pollution effects, though in some situations the attenuation can reach 13% in visible and more than 20% in UV spectral region