Time filter

Source Type

Shmerlin B.Ya.,Institute of Experimental Meteorology | Kalashnik M.V.,National Research Nuclear University | Shmerlin M.B.,Russian Academy of Sciences
Journal of Experimental and Theoretical Physics | Year: 2012

The classical Rayleigh problem of convective instability is generalized to the case of water vapor condensation in the atmosphere. We present an analytical solution demonstrating a fundamental difference between moist convection and Rayleigh convection: the curve of the critical Rayleigh number versus the number characterizing the intensity of condensation heat release consists of two parts, with spatially localized neutral solutions corresponding to one of them. Spatially periodic neutral solutions correspond to the second part of the curve; these are characterized by a significant localization of the regions of ascending motions. The theory describes the nucleation and development of individual convective clouds and ordered cloud structures. © 2012 Pleiades Publishing, Ltd.

Baranov Y.I.,Institute of Experimental Meteorology | Buryak I.A.,Moscow State University | Lokshtanov S.E.,Russian Academy of Sciences | Lukyanchenko V.A.,RAS A.M. Prokhorov General Physics Institute | Vigasin A.A.,Russian Academy of Sciences
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2012

The present paper aims at ab initio and laboratory evaluation of the N 2 collision-induced absorption band intensity arising from interactions between N 2 and H 2O molecules at wavelengths of around 4 mm. Quantum chemical calculations were performed in the space of five intermolecular coordinates and varying N-N bond length using Møller-Plesset perturbation and CCSD(T) methods with extrapolation of the electronic energy to the complete basis set. This made it possible to construct the intermolecular potential energy surface and to define the surface of the N-N dipole derivative with respect to internal coordinate. The intensity of the nitrogen fundamental was then calculated as a function of temperature using classical integration. Experimental spectra were recorded with a BOMEM DA3-002 FTIR spectrometer and 2m base-length multipass White cell. Measurements were conducted at temperatures of 326, 339, 352 and 363 K. The retrieved water-nitrogen continuum significantly deviates from the MT -CKD model because the relatively strong nitrogen absorption induced by H 2O was not included in this model. Substantial uncertainties in the measurements of the H 2O-N 2 continuum meant that quantification of any temperature dependence was not possible. The comparison of the integrated N 2 fundamental band intensity with our theoretical estimates shows reasonably good agreement. Theory indicates that the intensity as a function of temperature has a minimum at approximately 500 K. © 2012 The Royal Society.

Drofa A.S.,Institute of Experimental Meteorology | Ivanov V.N.,Institute of Experimental Meteorology | Rosenfeld D.,Hebrew University of Jerusalem | Shilin A.G.,Institute of Experimental Meteorology
Atmospheric Chemistry and Physics | Year: 2010

Experimental and theoretical studies of cloud microstructure modification with hygroscopic particles for obtaining additional precipitation amounts from convective clouds are performed. The experiment used salt powder with the particle sizes that gave the greatest effectiveness according to the simulations of Segal et al. (2004). The experiments were carried out in a cloud chamber at the conditions corresponding to the formation of convective clouds. The results have shown that the introduction of the salt powder before a cloud medium is formed in the chamber results in the formation on a "tail" of additional large drops. In this case seeding with the salt powder leads also to enlargement of the whole population of cloud drops and to a decrease of their total concentration as compared to a cloud medium that is formed on background aerosols. These results are the positive factors for stimulating coagulation processes in clouds and for subsequent formation of precipitation in them. An overseeding effect, which is characterized by increased droplet concentration and decreased droplet size, was not observed even at high salt powder concentrations. The results of numerical simulations have shown that the transformation of cloud drop spectra induced by the introduction of the salt powder results in more intense coagulation processes in clouds as compared to the case of cloud modification with hygroscopic particles with relatively narrow particle size distributions, and for the distribution of the South African hygroscopic flares. The calculation results obtained with a one-dimensional model of a warm convective cloud demonstrated that the effect of salt powder on clouds (total amounts of additional precipitation) is significantly higher than the effect caused by the use of hygroscopic particles with narrow particle size distributions at comparable consumptions of seeding agents, or with respect to the hygroscopic flares. Here we show that seeding at rather low consumption rate of the salt powder initiates precipitation from otherwise non precipitating warm convective clouds, mainly by the effect of adding large cloud drops to the tail of the distribution. © 2010 Author(s).

Makosko A.A.,Russian Academy of Sciences | Yaroshevich M.I.,Institute of Experimental Meteorology
Izvestiya - Atmospheric and Ocean Physics | Year: 2016

We have obtained regression relationships between vertical components of gravity anomalies in tropical cyclone areas and some cyclonic characteristics. These regressions are more pronounced in territories where negative gravity anomalies are prevalent. Numerical experiments are performed for the cyclonic zone of the northwestern Pacific and western Atlantic. In the zone of the western Atlantic, the main focus is on cyclones entering to the terrestrial part of the United States. We conclude that under some conditions, gravity anomalies can affect the characteristics of tropical cyclones. © 2016, Pleiades Publishing, Ltd.

Baranov Y.I.,U.S. National Institute of Standards and Technology | Baranov Y.I.,Institute of Experimental Meteorology
Journal of Quantitative Spectroscopy and Radiative Transfer | Year: 2016

The IR spectra of water vapor-carbon dioxide mixtures as well as the spectra of pure gas samples have been recorded using a Fourier-transform infrared spectrometer at a resolution of 0.1 cm-1 in order to explore the effect of colliding CO2 and H2O molecules on their continuum absorptions. The sample temperatures were 294, 311, 325 and 339 K. Measurements have been conducted at several different water vapor partial pressures depending on the cell temperature. Carbon dioxide pressures were kept close to the three values of 103, 207 and 311 kPa (1.02, 2.04 and 3.07 atm). The path length used in the study was 100 m. It was established that, in the region around 1100 cm-1, the continuum absorption coefficient CH2O+CO2 is about 20 times stronger than the water-nitrogen continuum absorption coefficient CH2O+N2. On the other hand, in the far wing region (2500 cm-1) of the ν3 CO2 fundamental band, the binary absorption coefficient CCO2+H2O appears to be about one order of magnitude stronger than the absorption coefficient CCO2+CO2 in pure carbon dioxide. The continuum interpretation and the main problem of molecular band shape formation are discussed in light of these experimental facts. © 2016 Elsevier Ltd.

Trifonov A.N.,Institute of Experimental Meteorology | Makarov N.A.,Institute of Experimental Meteorology | Merzlyakov E.G.,Institute of Experimental Meteorology
Geomagnetism and Aeronomy | Year: 2016

Data from meteo radar measurements of the wind in the mesosphere/lower thermosphere region at high latitudes of the Southern Hemisphere (Molodezhnaya station, 68° S, 45° E) and at middle latitudes of the Northern Hemisphere (Obninsk station, 55° N, 37° E) during solar proton events that took place in 1989, 1991, 2000, 2005, and 2012 are analyzed in the paper. In 1989 and 1991, we succeeded in observing the response to solar proton evens at both stations simultaneously. The results show that solar proton events lead to a change in the wind regime of the mesosphere and lower thermosphere. At high latitudes of the Southern Hemisphere, significant changes are observed in the values of the velocities of the meridional and zonal components of the prevailing wind. In the case of powerful solar proton events, the amplitude of the semidiurnal tide grows in the vicinity of the proton flux maximum. The response to these events depends on the season. The reaction of the prevailing wind at middle latitudes shows the same features as the reaction of the wind at high latitudes. However no unambiguous response of the tide amplitude is observed. In the summer season, even powerful events (for example, in July 2000) cause no changes in the wind regime parameters in the midlatitude region of the mesosphere/lower thermosphere. © 2016, Pleiades Publishing, Ltd.

Visheratin K.N.,Institute of Experimental Meteorology
Izvestiya - Atmospheric and Ocean Physics | Year: 2016

We present the results of the analysis of the phase relationships between the quasi-decadal variations (QDVs) (in the range from 8 to 13 years) in the total ozone content (TOC) at the Arosa station for 1932–2012 and a number of meteorological parameters: monthly mean values of temperature, meridional and zonal components of wind velocity, and geopotential heights for isobaric surfaces in the layer of 10–925 hPa over the Arosa station using the Fourier methods and composite and cross-wavelet analysis. It has been shown that the phase relationships of the QDVs in the TOC and meteorological parameters with an 11-year cycle of solar activity change in time and height; starting with cycle 24 of solar activity (2008–2010), the variations in the TOC and a number of meteorological parameters occur in almost counter phase with the variations in solar activity. The periods of the maximum growth rate of the temperature at isobaric surfaces 50–100 hPa nearly correspond to the TOC’s maximum periods, and the periods of the maximum temperature correspond the periods of the decrease of the peak TOC rate. The highest correlation coefficients between the meridional wind velocity and temperature are observed at 50 hPa at positive and negative delays of ~27 months. The times of the maxima (minima) of the QDVs in the meridional wind velocity nearly correspond to the periods of the maximum amplification (attenuation) rate of the temperature of the QDVs. The QDVs in the geopotential heights of isobaric surfaces fall behind the variations in the TOC by an average of 1.5 years everywhere except in the lower troposphere. In general, the periods of variations in the TOC and meteorological parameters in the range of 8–13 years are smaller than the period of variations in the level of solar activity. © 2016, Pleiades Publishing, Ltd.

Baranov Y.I.,U.S. National Institute of Standards and Technology | Baranov Y.I.,Institute of Experimental Meteorology | Lafferty W.J.,U.S. National Institute of Standards and Technology
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2012

The pure water vapour and water-nitrogen continuum absorption in the 1000 and 2500 cm -1 atmospheric windows has been studied using a 2m base-length Whitetype multi-pass cell coupled with a BOMEM DA3-002 Fourier transform infrared spectrometer. The measurements were carried out at the National Institute of Standards and Technology (NIST, Gaithersburg, MD) over the course of several years (2004, 2006-2007, 2009). New data on the H2O:N2 continuum in the 1000 cm -1 window are presented and summarized along with the other experimental results and the continuum model. The experimental data reported on the water vapour continuum in these atmospheric windows basically agree with the most reliable laboratory data from the other sources. The MT -CKD (Mlawer-Tobin-Clough-Kneizys-Davies) continuum model significantly departs from the experimental data in both windows. The deviation observed includes the continuum magnitude, spectral behaviour and temperature dependence. In the 2500 cm -1 region, the model does not allow for the nitrogen fundamental collisioninduced absorption (CIA) band intensity enhancement caused by H2O:N2 collisions and underestimates the actual absorption by over two orders of magnitude. The water vapour continuum interpretation as a typical CIA spectrum is reviewed and discussed. © 2012 The Royal Society.

Korshunov V.A.,Institute of Experimental Meteorology | Zubachev D.S.,Institute of Experimental Meteorology
Izvestiya - Atmospheric and Ocean Physics | Year: 2013

We calculate the microphysical characteristics of stratospheric aerosol from lidar-sensing data at wavelengths of 355 and 532 nm using a priori information about the aerosol spectra obtained from balloon and aircraft measurement data. We analyze the mode structure of the spectra and its coupling with the integral microphysical characteristics of aerosol. For most implementations, it was shown that two aerosol modes (of background and volcanic natures) make commensurate contributions to integral aerosol characteristics, which makes it difficult to use the traditional method of model estimates. It is more efficient to use an optical model of a statistical character that is based on approximation dependences between the required integral aerosol characteristics and lidar-measured optical characteristics. We found that the area, volume, and effective size of particles and the lidar ratio at a wavelength of 355 nm correlated with the absolute values of backscattering coefficients at wavelengths of 355 or 532 nm and the lidar ratio at the wavelength of 532 nm correlated with the ratio of backscattering coefficients at these wavelengths. We estimate the error in the determination of integral characteristics of aerosol using the model developed. The model efficiency is demonstrated on real data of stratospheric aerosol lidar sensing. © 2013 Pleiades Publishing, Ltd.

Yaroshevich M.I.,Institute of Experimental Meteorology | Ingel L.K.,Institute of Experimental Meteorology
Izvestiya - Atmospheric and Ocean Physics | Year: 2013

We statistically study diurnal variations in the maximum wind velocity in tropical cyclones on the basis of vast experimental material. We have found notable oscillations in the acceleration of rotation velocity (rate of variations in the maximum wind velocity), which are most pronounced in the periods of intensification and decay of the cyclones. The diurnal variations can differ notably in phase in different geographical conditions. © 2013 Pleiades Publishing, Ltd.

Loading Institute of Experimental Meteorology collaborators
Loading Institute of Experimental Meteorology collaborators