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Moiseenko K.B.,Obukhov Institute of Atmospheric Physics | Malik N.A.,Institute of Volcanology and Seismology
Journal of Volcanology and Geothermal Research | Year: 2014

The December 24, 2006, and December 16, 2009, strong explosion events at Bezymianny Volcano (Kamchatka Peninsula) were accompanied by extensive ash-falls in proximal and medium-distal area (<. 100. km) downwind following the direction of prevailing upper tropospheric winds. In the present study, we apply a limited area atmospheric modeling system RAMS6.0 and a lagrangian stochastic model HYPACT1.5 to predict local airflows in a mountain area around the volcano during these events and quantify effects of atmospheric dispersal, gravitational settling, and particle aggregation on the observed ash-fall deposit patterns. It was found that the orography-induced atmospheric disturbances provided first-order influence on ash dispersal regime in the events owing to enhanced turbulence rates in a free troposphere above mountains and low-level airflows generated by mesoscale pressure perturbations. A total mass of ash from these eruptions is inverted based on grain-size sample data and model-calculated Green's function for atmospheric transport with use of a multiple regression approach. We demonstrate that in the absence of precise data on individual and collective settling rates the proposed inversion technique, which explicitly constrains fall velocity spectrum within individual sieve classes and aggregated modes, provides more reliable estimate for total erupted mass compared to procedures employing constant shape factor or prescribed settling rates within the framework of a simple linear regression model. © 2013 Elsevier B.V. Source

Ostrovskii V.E.,Karpov Institute of Physical Chemistry | Kadyshevich E.A.,Obukhov Institute of Atmospheric Physics
Fuel | Year: 2013

A new ideology and procedure for consideration of the contribution of inverse reactions to the analytic descriptions of the kinetics of heterogeneous catalytic processes (gross-reactions, GRs), which proceed with rate-determining steps (RDSs) and residual equilibrium portions (ExEqms), are proposed instead of the ordinary ideology and procedure that use the notion of the rate-determining step stoichiometric number (RDSSN). Instead of the RDSSNs, the notion of the matching coefficients (MCs) of stoichiometric nature is used. As was first shown by Weller [Catal Rev - Sci Eng 1992;34:227-80], the notion of the RDSSNs has no well-defined physical meaning and the repeated attempts of their experimental measurements gave no reproducible results. The MCs co-ordinate RDS, ExEqm, and GR equations with each other; they are determinable for any GR by a simple chemico-algebraic procedure. The procedures for determination of their values and deduction of kinetic equations are considered by the example of the CH 3OH synthesis from H2 and carbon oxides at Zn/Cu-containing catalysts. An improved kinetic equation is deduced and successfully applied to description of available data on the CH3OH synthesis at 0.1 (453 and 473 K) and 4.5 (513 K) MPa. © 2012 Elsevier Ltd. All rights reserved. Source

Elansky N.,Obukhov Institute of Atmospheric Physics
Urban Climate | Year: 2014

Moscow with a population of 12.1million people is the largest city in Europe. An up-to-date monitoring network organized in Moscow in the early 2000's has made it possible to estimate air quality and the concentrations of key pollutants emitted into the atmosphere. In this work, air-quality estimates obtained earlier were corrected using new observational data. As a result, Moscow ranks among clean megacities in the world. The emissions of CO were calculated on the basis of data on the surface concentration, vertical profile, and total column of CO. The surface concentration of CO was measured at 25 stations uniformly spaced on the territory of Moscow. The vertical profiles of CO were measured at the Ostankino TV tower. Data on the CO total column were obtained from long-term measurements using infrared solar absorption spectroscopy at two sites located in the center of Moscow and in Zvenigorod (53km to the west of the center of Moscow). The annual emissions of CO from the Moscow megacity were estimated at 870±200Ggyr-1 for 1992-2008 and 680±160Ggyr-1 for 2002-2008. These values are slightly lower than those given for Moscow in the global inventories EDGAR and IPCC-AR-4. © 2014 Elsevier Ltd. Source

Wood C.R.,Finnish Meteorological Institute | Jarvi L.,University of Helsinki | Kouznetsov R.D.,Finnish Meteorological Institute | Kouznetsov R.D.,Obukhov Institute of Atmospheric Physics | And 18 more authors.
Bulletin of the American Meteorological Society | Year: 2013

A dedicated intensive research-grade observational network, the Helsinki Urban Boundary-Layer Atmosphere Network (UrBAN) in Helsinki enables studies of the physical processes in the urban atmosphere at high latitude. The long-term purposes of Helsinki UrBAN is to understand the processes in Helsinki's ABL (atmospheric boundary layer), as affected by a range of surfaces within a few kilometers and the strong climatic seasonality. The EC measurements of turbulent fluxes are made at three sites in Helsinki, Kumpula, Fire Station, and Torni. Additional measurements made at Kumpula include wind and temperature profiles at heights of 4, 8, 16, and 32 m. Other measurements include the radiation components and photosynthetically active radiation, at 31-m height. Patterns in the thermal infrared (IR) camera data clearly show the main features of a warm surface by day and cool by night. However, there is variability across the urban surface, primarily since surfaces facing different directions receive different solar irradiance. Source

Kouznetsov R.D.,Finnish Meteorological Institute | Kouznetsov R.D.,Obukhov Institute of Atmospheric Physics | Zilitinkevich S.S.,Finnish Meteorological Institute | Zilitinkevich S.S.,Helsinki Institute of Physics | Zilitinkevich S.S.,University of Bergen
Boundary-Layer Meteorology | Year: 2010

Observations of the dependence of the dimensionless wind speed gradient Φm as a function of the Monin-Obukhov stability parameter z/Lo under strong stability diverge from results of large-eddy simulation (LES) modelling. A kinetic energy budget analysis indicates that it is likely caused by violations of the assumptions of stationarity and/or homogeneity of turbulence in the field experiments rather than in imperfections of the LES. This confirms the validity of the widely used linear approximation for Φm not only at weak to moderate stability, but also under strong stability. The new interpretation of the linear approximation of Φm is given in terms of turbulent scales, which gives hope for its applicability to the free atmosphere as well. © The Author(s) 2010. Source

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