The characteristics of acoustic-gravity waves (waveforms, time durations, amplitudes, azimuths and horizontal phase speeds) from the eruption of the Hunga-Tonga-Hunga-Hapai volcano detected at ...different infrasound stations of the Infrasound Monitoring System and at a network of low-frequency microbarographs in the Moscow region are studied. Using the correlation analysis of the signals at different locations, six arrivals of signals from the volcano, which made up to two revolutions around the Earth, were detected. The Lamb mode of acoustic gravity waves from the volcano eruption is identified and the effect of this mode on generation of tsunami waves and variation of aerosol concentration is studied. The energy released from an underwater volcano into the atmosphere is estimated from the parameters of the Lamb wave and compared with the energy released from the most powerful nuclear bomb of 58 Mt TNT.
Seasonal variations of the near‐surface NOX (= NO + NO2) and ozone (O3) mixing ratios at Zotino Tall Tower (ZOTTO), a remote site in central Siberia, are described for years 2007–2014. Conditional ...probability function analysis and back trajectories are used to determine the origins of clean (continental baseline, CB) and regional emissions‐influenced air. High NOX levels at the site are observed for air from industrial regions of western Siberia and Ural Mountains, whereas CB air originates from remote areas of North Eurasia within 55°–70°N. The estimated annual means of daytime O3 and NOX mixing ratios for CB air are 27.0 and 0.44 ppbv, correspondingly, versus the similar quantities of 27.9 and 0.79 ppbv for all data. Monthly ozone for CB air shows a distinct maximum in April, as is the case for Northern Hemisphere midlatitude baseline (NHMLB) air at the European inflow boundary according to the surface ozone data for Mace Head and Norwegian monitoring sites, and a minimum in late summer–early autumn reflecting a weak continental‐scale ozone production from biogenic sources of ozone precursors and wildfire emissions throughout the warm season. During spring and early summer under hot weather conditions, regional anthropogenic and wildfire emissions are an important source for ozone in the continental boundary layer over southern and central Siberia, resulting in surface ozone levels compared to or larger than those observed in NHMLB air. Throughout the remaining part of year, the central North Eurasia represents a sink for tropospheric ozone on a hemispheric scale.
Key Points
Seasonal variations of NOX and O3 at ZOTTO in Siberia show a signature of weakly polluted air due to the regional pollution
Origins of clean and polluted air for the site are identified; seasonal cycle of the baseline ozone for central North Eurasia is estimated
In spring‐summer, anthropogenic and fire emissions in Siberia provide a net source for tropospheric ozone in the NH midlatitudes
The temperatures of appearance and degradation of short-range and long-range ordering in VDM® Alloy C-4 (UNS 2.4610/N06455) are determined with the help of physical methods of research. The ...sensitivity of the methods to these effects is studied. The results obtained are used to make recommendations on determination of the temperatures of disordering-ordering and ordering-disordering transitions in alloys of the Ni – Cr – Mo system.
The relation between the microstructure and the corrosion behavior of Hastelloy® G-35® in a KCl – AlCl
3
salt solution after different deformation and heat treatments (DHT) is studied. It is shown ...that DHT may be used for creating a structure providing a corrosion rate lower than that of the traditional single-phase structure formed in the alloy by quenching.
—
The results of experimental determination of near-surface aerosol density for particles of different composition and size have been published over many years. Based on the generalization of these ...data, as well as the results of our own field observations of microphysical characteristics and composition of Moscow aerosol, an algorithm and parameters for numerical estimation of mass concentration of submicron and micron urban aerosol are suggested. Using this algorithm, on the basis of experimental data on the size distribution function of aerosol particles in the diameter range 0.3–10 μm obtained during regular observations at IAP RAS in Moscow in 2020–2022, the mass concentration of near-surface aerosol of various fractions was calculated. A comparative analysis of the results of such an assessment and the data of synchronous measurements of mass concentration of aerosol particles using a portable aerosol spectrometer GRIMM 1.108 over the past two years has shown a good correspondence between the calculated and measured values. Density values for four ranges of aerosol particle sizes are selected for more correct numerical estimation of the mass concentration of urban aerosol of fractions PM
2.5
and PM
10
.
The rates of ozone production (
P
) and sink (
L
) and total peroxide (OX) content are assessed with the use of the photostationary state approach from measurements of ozone (O
3
) and nitrogen ...oxides (NO and NO
2
) at the Zotino Tall Tower Observatory (ZOTTO), central Siberia, in 2007–2014. Mean daily cycles of the above quantities for May–September cloud-free days peak at 6 ppb/hour (
P
), 1.4 ppb/hour (
L
), and 115 ppb (OX) between 11:00 and 15:00 LT. The linear dependence of
P
on NO
x
is derived in the range of measured NO
x
mixing ratios from 0.2–0.8 ppb, suggesting for NO
x
-limiting conditions of ozone production, with the slope rate
P
(O
3
)/NO
x
estimated at 13 (ppb/h)/ppb. The estimated high OX levels along with the condition
P
⪢
L
manifest for high rates of the in situ oxidation of biogenic volatile organic compounds and photochemical ozone generation. The surface air layer can be treated as an ozone source for the atmospheric boundary layer over remote areas of Siberia at NO
x
concentrations corresponding to conditions of both regionally background air and weakly polluted air. The obtained estimates indicate the significant role of regional NO
x
emissions in the ground-level ozone budget and necessity of taking this factor into account when forecasting ecological risks in Siberian regions that are commonly considered pollution-free.
Within the program “Ecosystems of the Siberian Arctic Seas,” carried out by Shirshov Institute of Oceanology, Russian Academy of Sciences since 2007, studies of the water structure and spatial ...variability of the parameters of the carbonate system have been performed, and the intensity and direction of the carbon dioxide flux over the continental slope of the Laptev Sea and in the Vilkitsky Strait in September 2018 have been calculated. The presence of several main water masses that govern the water structure in the study area is shown. A strong spatial variability of the parameters of the carbonate system of seawater, determined by complexes of physical and chemical–biological processes, has been revealed. The intensity and direction of the carbon dioxide flux at the water–atmosphere boundary were calculated, which range from –12 to 4 mmol m
–2
day
–1
. It was revealed that the investigated area of the outer shelf and continental slope of the Laptev Sea is an emitter of carbon dioxide into the atmosphere as of September 2018. Conversely, the area of the Vilkitsky Strait, is a CO
2
sink zone.
Results of the analysis of interannual, seasonal, and diurnal variations in the ratios of the mixture of CH
4
, CO
2
, CO, benzene, and δ13C–CH
4
in the surface air of Moscow based on the ...measurements at the station of the Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences (IAP RAS), in 2018–2020 are presented. The annual maximum concentration of CH
4
, CO
2
, and CO (>2.2, 430, and 0.20 ppm, respectively) occurs in the winter months due to the seasonal increase in the anthropogenic load from the main sources of urban pollution: motor transport and thermal power plants and a decrease in the role of vertical air mixing. The greatest contribution of local and remote microbial sources to the CH
4
concentration is noted in the summer months against the background of low δ13C–CH
4
values (–50 to –60‰). In all seasons, CH
4
, CO
2
, and CO ground level peaks lasting up to several hours are due to the transport from industrial sites in the E–SE sector. The calculated mean emission ratios in urban air were CH
4
/benzene = 0.52–0.54 ppm/ppb, CH
4
/СО = 0.56–0.75 ppm/ppm, CO
2
/benzene = 77–93 ppm/ppb, CO
2
/СО = 81–131 ppm/ppm, and CO/benzene = 0.65–1.11 ppm/ppb. These ratios characterize the predominant contribution of emissions from motor transport and the heat and power equipment and can be used to refine the absolute values of emissions, including those on the basis of existing inventories of sources of anthropogenic air pollution.
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 O
3
) 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.
A
bstract
We present the study of the decay
J/ψ
→
ρπ
. The results are based on of 5.2 million
J/ψ
events collected by the KEDR detector at the VEPP-4M collider. The branching fractions are measured ...to be
B
(
J/ψ
→
ρπ
) = (2
.
072 ± 0
.
017 ± 0
.
062) ∙ 10
−
2
and
B
(
J/ψ
→
π
+
π
−
π
0
) = (1
.
878 ± 0
.
013 ± 0
.
051) ∙ 10
−
2
, where the first uncertainties are statistical and the second systematic. Our results are more precise than the previous relative measurements.
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