Valery I. Perevalov

Bio: Valery I. Perevalov is an academic researcher from Russian Academy of Sciences. The author has contributed to research in topics: Hamiltonian (quantum mechanics) & Rotational–vibrational spectroscopy. The author has an hindex of 15, co-authored 25 publications receiving 727 citations.

Total internal partition sums for 166 isotopologues of 51 molecules important in planetary atmospheres: Application to HITRAN2016 and beyond

Abstract: Total internal partition sums (TIPS) are reported for 166 isotopologues of 51 molecules important in planetary atmospheres. Molecules 1 to 50 are taken from the HITRAN2016 list, and, in some cases, additional isotopologues are considered for some of the molecules. Molecules 51–53 are C3H4, CH3, and CS2, respectively. TIPS are not reported for the O atom and CF4; thus, while there are 53 species in the list, data are reported for 51 molecules. The TIPS are determined by various methods from 1 K to a Tmax that ensures the TIPS reported have converged. These data are provided with HITRAN2016 and a new version of the TIPS code is available in both FORTRAN and python languages.

Global fitting of 12c16o2 vibrational-rotational line positions using the effective hamiltonian approach

Abstract: About 13 000 experimental lines of the principal isotopic species of CO2 selected from the literature have been used to derive about 100 parameters of a reduced effective Hamiltonian built up to sixth order in the Amat–Nielsen ordering scheme. This Hamiltonian has been obtained from an effective Hamiltonian describing all vibrational–rotational energy levels in the ground electronic state and containing in explicit form all resonance interaction terms due to the approximate relations between harmonic frequencies ω1≈2ω2andω3≈ω1+ω2. An RMS deviation of 0.001 cm-1 has been achieved in the fitting. In order to test its predictive capabilities, the model has been used to calculate the line positions of six bands: 05511←05501, 1005(1, 2)←1004(1, 2), 1006(1, 2)←1005(1, 2), and 20033←00001, which are compared with experimental lines not included in the data set. The results are discussed and compared with the predictions of the Direct Numerical Diagonalization technique.

A room temperature CO2 line list with ab initio computed intensities

Abstract: Atmospheric carbon dioxide concentrations are being closely monitored by remote sensing experiments which rely on knowing line intensities with an uncertainty of 0.5% or better. We report a theoretical study providing rotation–vibration line intensities substantially within the required accuracy based on the use of a highly accurate ab initio dipole moment surface (DMS). The theoretical model developed is used to compute CO2 intensities with uncertainty estimates informed by cross comparing line lists calculated using pairs of potential energy surfaces (PES) and DMS׳s of similar high quality. This yields lines sensitivities which are utilized in reliability analysis of our results. The final outcome is compared to recent accurate measurements as well as the HITRAN2012 database. Transition frequencies are obtained from effective Hamiltonian calculations to produce a comprehensive line list covering all 12C16O2 transitions below 8000 cm − 1 and stronger than 10 − 30 cm /molecule at T = 296 K .

T.D.S. spectroscopic databank for spherical tops: DOS version

Abstract: T.D.S. is a computer package concerned with high resolution spectroscopy of spherical top molecules like CH 4 , CF 4 , SiH 4 , SiF 4 , SnH 4 , GeH 4 , SF 6 , etc. T.D.S. contains information, fundamental spectroscopic data (energies, transition moments, spectroscopic constants) recovered from comprehensive modeling and simultaneous fitting of experimental spectra, and associated software written in C. The T.D.S. goal is to provide an access to all available information on vibration-rotation molecular states and transitions including various spectroscopic processes (Stark, Raman, etc.) under extended conditions based on extrapolations of laboratory measurements using validated theoretical models. Applications for T.D.S. may include: education/training in molecular physics, quantum chemistry, laser physics; spectroscopic applications (analysis, laser spectroscopy, atmospheric optics, optical standards, spectroscopic atlases); applications to environment studies and atmospheric physics (remote sensing); data supply for specific databases; and to photochemistry (laser excitation, multiphoton processes). The reported DOS-version is designed for IBM and compatible personal computers.

The HITRAN 2008 molecular spectroscopic database

Abstract: This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.

A Nongray Theory of Extrasolar Giant Planets and Brown Dwarfs

Abstract: We present the results of a new series of nongray calculations of the atmospheres, spectra, colors, and evolution of extrasolar giant planets (EGPs) and brown dwarfs for effective temperatures below 1300 K This theory encompasses most of the mass/age parameter space occupied by substellar objects and is the first spectral study down to 100 K These calculations are in aid of the multitude of searches being conducted or planned around the world for giant planets and brown dwarfs and reveal the exotic nature of the class Generically, absorption by H2 at longer wavelengths and H2O opacity windows at shorter wavelengths conspire to redistribute flux blueward Below 1200 K, methane is the dominant carbon bearing molecule and is a universal diagnostic feature of EGP and brown dwarf spectra We find that the primary bands in which to search are Z (~105 ?m), J (~12 ?m), H (~16 ?m), K (~22 ?m), M (~5 ?m), and N (~10 ?m), that enhancements of the emergent flux over blackbody values, in particular in the near infrared, can be by many orders of magnitude, and that the infrared colors of EGPs and brown dwarfs are much bluer than previously believed In particular, relative to J and H, the K band flux is reduced by CH4 and H2 absorption Furthermore, we conclude that for Teff's below 1200 K most or all true metals may be sequestered below the photosphere, that an interior radiative zone is a generic feature of substellar objects, and that clouds of H2O and NH3 are formed for Teff's below ~400 and ~200 K, respectively This study is done for solar-metallicity objects in isolation and does not include the effects of stellar insulation Nevertheless, it is a comprehensive attempt to bridge the gap between the planetary and stellar realms and to develop a nongray theory of objects from 03MJ (Saturn) to 70MJ (~007 M?) We find that the detection ranges for brown dwarf/EGP discovery of both ground- and space-based telescopes are larger than previously estimated

Models of very-low-mass stars, brown dwarfs and exoplanets

Abstract: Within the next few years, GAIA and several instruments aiming to image extrasolar planets will be ready. In parallel, low-mass planets are being sought around red dwarfs, which offer more favourable conditions, for both radial velocity detection and transit studies, than solar-type stars. In this paper, the authors of a model atmosphere code that has allowed the detection of water vapour in the atmosphere of hot Jupiters review recent advances in modelling the stellar to substellar transition. The revised solar oxygen abundances and cloud model allow the photometric and spectroscopic properties of this transition to be reproduced for the first time. Also presented are highlight results of a model atmosphere grid for stars, brown dwarfs and extrasolar planets.

Advancements in the Aerosol Robotic Network (AERONET) Version 3 database – automated near-real-time quality control algorithm with improved cloud screening for Sun photometer aerosol optical depth (AOD) measurements

Abstract: The Aerosol Robotic Network (AERONET) has provided highly accurate, ground-truth measurements of the aerosol optical depth (AOD) using Cimel Electronique Sun–sky radiometers for more than 25 years In Version 2 (V2) of the AERONET database, the near-real-time AOD was semiautomatically quality controlled utilizing mainly cloud-screening methodology, while additional AOD data contaminated by clouds or affected by instrument anomalies were removed manually before attaining quality-assured status (Level 20) The large growth in the number of AERONET sites over the past 25 years resulted in significant burden to the manual quality control of millions of measurements in a consistent manner The AERONET Version 3 (V3) algorithm provides fully automatic cloud screening and instrument anomaly quality controls All of these new algorithm updates apply to near-real-time data as well as post-field-deployment processed data, and AERONET reprocessed the database in 2018 A full algorithm redevelopment provided the opportunity to improve data inputs and corrections such as unique filter-specific temperature characterizations for all visible and near-infrared wavelengths, updated gaseous and water vapor absorption coefficients, and ancillary data sets The Level 20 AOD quality-assured data set is now available within a month after post-field calibration, reducing the lag time from up to several months Near-real-time estimated uncertainty is determined using data qualified as V3 Level 20 AOD and considering the difference between the AOD computed with the pre-field calibration and AOD computed with pre-field and post-field calibration This assessment provides a near-real-time uncertainty estimate for which average differences of AOD suggest a +002 bias and one sigma uncertainty of 002, spectrally, but the bias and uncertainty can be significantly larger for specific instrument deployments Long-term monthly averages analyzed for the entire V3 and V2 databases produced average differences (V3–V2) of + 0002 with a ± 002 SD (standard deviation), yet monthly averages calculated using time-matched observations in both databases were analyzed to compute an average difference of −0002 with a ±0004 SD The high statistical agreement in multiyear monthly averaged AOD validates the advanced automatic data quality control algorithms and suggests that migrating research to the V3 database will corroborate most V2 research conclusions and likely lead to more accurate results in some cases

The UMIST database for astrochemistry 2012

Abstract: We present the fifth release of the UMIST Database for Astrochemistry (UDfA). The new reaction network contains 6173 gas-phase reactions, involving 467 species, 47 of which are new to this release. We have updated rate coefficients across all reaction types. We have included 1171 new anion reactions and updated and reviewed all photorates. In addition to the usual reaction network, we also now include, for download, state-specific deuterated rate coefficients, deuterium exchange reactions and a list of surface binding energies for many neutral species. Where possible, we have referenced the original source of all new and existing data. We have tested the main reaction network using a dark cloud model and a carbon-rich circumstellar envelope model. We present and briefly discuss the results of these models.