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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

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. Source

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

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. Source

Visheratin K.N.,Institute of Experimental Meteorology
Izvestiya - Atmospheric and Ocean Physics

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. Source

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

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. Source

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

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. Source

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