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.
Yurganov L.N.,University of Maryland Baltimore County |
Rakitin V.,Obukhov Institute of Atmospheric Physics |
Dzhola A.,Obukhov Institute of Atmospheric Physics |
August T.,EUMETSAT |
And 10 more authors.
Atmospheric Chemistry and Physics | Year: 2011
CO total column data are presented from three space sounders and two ground-based spectrometers in Moscow and its suburbs during the forest and peat fires that occurred in Central Russia in July-August 2010. Also presented are ground-based in situ CO measurements. The Moscow area was strongly impacted by the CO plume from these fires. Concurrent satellite- and ground-based observations were used to quantify the errors of CO top-down emission estimates. On certain days, CO total columns retrieved from the data of the space-based sounders were 2-3 times less than those obtained from the ground-based sun-tracking spectrometers. The depth of the polluted layer over Moscow was estimated using total column measurements compared with CO volume mixing ratios in the surface layer and on the TV tower and found to be around 360 m. The missing CO that is the average difference between the CO total column accurately determined by the ground spectrometers and that retrieved by AIRS, MOPITT, and IASI was determined for the Moscow area between 1.6 and 3.3 Ã- 1018 molec cm-2. These values were extrapolated onto the entire plume; subsequently, the CO burden (total mass) over Russia during the fire event was corrected. A top-down estimate of the total emitted CO, obtained by a simple mass balance model increased by 40-100 % for different sensors due to this correction. Final assessments of total CO emitted by Russian wildfires obtained from different sounders are between 34 and 40 Tg CO during July-August 2010. © 2011 Author(s).
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.
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.
Hellen H.,Finnish Meteorological Institute |
Kouznetsov R.,Finnish Meteorological Institute |
Kouznetsov R.,Obukhov Institute of Atmospheric Physics |
Anttila P.,Finnish Meteorological Institute |
Hakola H.,Finnish Meteorological Institute
Boreal Environment Research | Year: 2015
Non-methane hydrocarbons (NMHCs, C2–C6) have been measured at the Pallas-Sodankylä GAW station since 1994. In 2010, evacuated stainless-steel-canister sampling was replaced by an in-situ gas chromatograph, and parallel measurements were conducted over the period of a year. Results were in good agreement for all other compounds except propene. NMHCs at Pallas show a typical seasonal variation, with the highest mixing ratios in winter and lowest in summer. Alkanes did not show any clear diurnal variation, but ethene had a maximum at midday or during the afternoon in summer. This indicated biogenic sources. i/n-Butane and n/i-pentane ratios were higher than those typically found in urban areas or in traffic emissions, indicating other sources than these (e.g. wood combustion or natural gas) having a strong effect on mixing ratios at Pallas. Trend analysis over twenty years of measurements indicated a significant decreasing trend only for ethyne, even though emissions of NMHCs in the European Union (EU) decreased by 50% during this period. No trend was found for ozone, either. This indicated that some other source areas than the EU must play a significant role at Pallas. This was confirmed by source area estimates, which showed that eastern Europe is the main source area for high mixing ratios at Pallas. © 2015, Finnish Environment Institute. All rights reserved.
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.
Yurganov L.,University of Maryland Baltimore County |
McMillan W.,University of Maryland Baltimore County |
Grechko E.,Obukhov Institute of Atmospheric Physics |
Dzhola A.,Obukhov Institute of Atmospheric Physics
Atmospheric Chemistry and Physics | Year: 2010
Interannual variations in AIRS and MOPITT retrieved CO burdens are validated, corrected, and compared with CO emissions from wild fires from the Global Fire Emission Dataset (GFED2) inventory. Validation of daily mean CO total column (TC) retrievals from MOPITT version 3 and AIRS version 5 is performed through comparisons with archived TC data from the Network for Detection of Atmospheric Composition Change (NDACC) ground-based Fourier Transform Spectrometers (FTS) between March 2000 and December 2007. MOPITT V3 retrievals exhibit an increasing temporal bias with a rate of 1.4ĝ€"1.8% per year; thus far, AIRS retrievals appear to be more stable. For the lowest CO values in the Southern Hemisphere (SH), AIRS TC retrievals overestimate FTS TC by 20%. MOPITT's bias and standard deviation do not depend on CO TC absolute values. Empirical corrections are derived for AIRS and MOPITT retrievals based on the observed annually averaged bias versus the FTS TC. Recently published MOPITT V4 is found to be in a good agreement with MOPITT V3 corrected by us (with exception of 2000ĝ€"2001 period). With these corrections, CO burdens from AIRS V5 and MOPITT V3 (as well as MOPITT V4) come into good agreement in the mid-latitudes of the Northern Hemisphere (NH) and in the tropical belt. In the SH, agreement between AIRS and MOPITT CO burdens is better for the larger CO TC in austral winter and worse in austral summer when CO TC are smaller. Before July 2008, all variations in retrieved CO burden can be explained by changes in fire emissions. After July 2008, global and tropical CO burdens decreased until October before recovering by the beginning of 2009. The NH CO burden also decreased but reached a minimum in January 2009 before starting to recover. The decrease in tropical CO burdens is explained by lower than usual fire emissions in South America and Indonesia. This decrease in tropical emissions also accounts for most of the change in the global CO burden. However, no such diminution of NH biomass burning is indicated by GFED2. Thus, the CO burden decrease in the NH could result from a combination of lower fossil fuel emissions during the global economic recession and transport of CO-poor air from the tropics. More extensive modeling will be required to fully resolve this issue. © 2010 Author(s).
Sitnov S.A.,Obukhov Institute of Atmospheric Physics
Doklady Earth Sciences | Year: 2010
Analysis of aerological radiosonde data in the period of 2000-2009 shows that, in the warm period of the year, the air temperature over Moscow region is higher in the first half of the week than in the second half. The statistically significant (at the α = 0.05 significance level) air temperature differences between Tuesday and Friday, as well as between Wednesday and Friday, reach 0.8°C and are manifested in the atmospheric boundary layer (according to nighttime observations) and in the middle troposphere (according to daytime observations). In the upper troposphere, the weekly temperature cycle positively correlates with the weekly cycle of air pressure, while in the lower troposphere, it positively correlates with the weekly cycle of water vapor content. In the upper troposphere, the southerly wind is strengthened in the middle of the week, and northerly wind is strengthened on the weekend. In the boundary layer, the temperature changes induce the weekly cycle of the static stability of the atmosphere. © 2010 Pleiades Publishing, Ltd.
Chunchuzov I.,Obukhov Institute of Atmospheric Physics |
Kulichkov S.,Obukhov Institute of Atmospheric Physics |
Popov O.,Obukhov Institute of Atmospheric Physics |
Hedlin M.,University of California at San Diego
Journal of the Acoustical Society of America | Year: 2014
The long-range propagation of infrasound from a surface explosion with an explosive yield of about 17.6 t TNT that occurred on June 16, 2008 at the Utah Test and Training Range (UTTR) in the western United States is simulated using an atmospheric model that includes fine-scale layered structure of the wind velocity and temperature fields. Synthetic signal parameters (waveforms, amplitudes, and travel times) are calculated using parabolic equation and ray-tracing methods for a number of ranges between 100 and 800 km from the source. The simulation shows the evolution of several branches of stratospheric and thermospheric signals with increasing range from the source. Infrasound signals calculated using a G2S (ground-to-space) atmospheric model perturbed by small-scale layered wind velocity and temperature fluctuations are shown to agree well with recordings made by the dense High Lava Plains seismic network located at an azimuth of 300 from UTTR. The waveforms of calculated infrasound arrivals are compared with those of seismic recordings. This study illustrates the utility of dense seismic networks for mapping an infrasound field with high spatial resolution. The parabolic equation calculations capture both the effect of scattering of infrasound into geometric acoustic shadow zones and significant temporal broadening of the arrivals. © 2014 Acoustical Society of America.
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.