243
Atmospheric
Radiation
the Line-by-Line (LbL) and “local estimation” Monte Carlo (MC) methods and
can calculate the Stokes parameters of the outgoing radiation in vertically inho‑
mogeneous atmospheres with any spectral resolution. The influence of 3D effect
on snow reflection function and albedo has been studied in the framework of the
stochastic radiative transfer theory [Zhuravleva and Kokhanovsky, 2011]. In par‑
ticular, the corresponding equations for the averaged intensity of reflected light
are solved for the ensemble of realizations of the stochastic field, describing the
distribution of 3D elements on the flat semi-infinite snow layer. It is found that
the albedo of snow layer is reduced (in particular, in the infrared region), if 3D
effects are taken into account. The sea and land surface models used in remote
sensing have been developed [Zapevalov and Lebedev, 2014; Matelenok and
Melentyev, 2014]. The method of integral distributions is developed for deter‑
mining the atmospheric aerosol micro‑structure from spectral measurements of
the aerosol optical depth [Veretennikov and Men’shchikova, 2013].
2. Atmospheric Molecular Spectroscopy
Main directions of investigations in the molecular spectroscopy of atmos‑
pheric gases are experimental studies of spectroscopic parameters, the develop‑
ment of methods for calculating the parameters of spectral lines, transmittance
functions and the updating of spectroscopic databases.
At the IAO RAS, the analysis and theoretical modeling of experimental spec‑
tra of H
2
O, CO
2
, O
3
, O
2
, CH
4
, N
2
O, NO
2
, C
2
H
2
molecules
and their isotopic
modifications in different spectral ranges and under different conditions are in‑
tensively carried on in cooperation with foreign scientists. The investigations are
directed to studying the spectroscopic parameters of gases, speculiarities of the
spectra obtained by different methods and intermolecular interactions. Results
of such studies for atmospheric gases and water vapor are given, for example, in
papers [Lyulin et al., 2011, 2013, 2014; Beguier et al., 2011; Liu et al., 2011;
Mikhailenko et al., 2011; Lu et al., 2012; Jacquemart et al., 2012; Leshchishina
et al., 2011a, 2011b, 2012, 2013; Lukashevskaya et al., 2013; Karlovets et al.,
2013, 2014; Oudot et al., 2012; Régalia et al., 2014; Daumont et al., 2012]. Re‑
sults of these studies contributed greatly to the development of databases and
information systems by new and refined information [Rothman et al., 2013; Tash‑
kun et al., 2011; Rey et al., 2014; Lavrentieva et al., 2014; Babikov et al., 2013].
In the frames of the Project IUPAC «A database of water transitions from exper‑
iment and theory» jointly with scientists of other countries, a critical expertise
of the water vapor rotational-vibrational spectra and transitions has been per‑
formed [Tennyson et al., 2013, 2014a, 2014b].
A number of studies have been carried out in context of remote sensing the
atmospheric methane and carbon dioxide. The main spectroscopic factors
244
Yu. M. Timofeyev, E. M. Shulgina
contributing to the uncertainty in calculations of atmospheric radiative transfer
in methane strong absorption bands in near-IR range, which are used to retrieve
the methane content in the atmosphere, have been studied. The uncertainties in
the parameters of the absorption lines of atmospheric
gases in modern databases,
as well as the effect of the methane line mixing, are estimated. Methods for en‑
hancing the accuracy of modeling the atmospheric transmittance are proposed.
It is shown, that the different spectroscopic databases can give significantly dif‑
ferent results for both forward simulations of the atmospheric transmittance and
the inverse problem of retrieving the CH
4
total content using spectra measured
by ground-based FTIR spectrometer [Chesnokova et al., 2011; Chesnokova,
2013]. On the basis of laboratory measurements of methane absorption spectra,
using acoustic and photometric spectrometers
based on a tunable diode laser,
parameters of overlapping absorption lines of R5 and R9 methane multiplets
broadened by nitrogen and neon were defined at pressures of broadening gases
of 0.005–0.5 atm. [Osipov et al., 2012; Kapitanov et al., 2012, 2013]. Analysis
of laboratory data showed a significant deviation of the line shapes from the Voigt
profile, which is typically used in atmospheric modeling. The use of contour
Routine-Sobelman profile allowed with an error of less than 1% to describe the
experimental spectra.
In paper [Chentsov et al., 2013] the influence of differences in the parameters
of CO
2
spectral lines in spectroscopic databases HITRAN-2008 and CDSD on
the modeling of atmospheric transmittance has been studied, and it is shown that
the difference in the transmissions can reach 10% or more in the strong CO
2
absorption bands.
3. Radiative Climatology
The research work in the frames of this topic has been
carried out in several
directions: the monitoring of components of radiation budget (RB) and atmos‑
pheric constituents effecting the radiation; the study of RB climatic trends near
a surface; the analysis of radiative effects caused by atmospheric gases.
Influence of variations of meteorological parameters and distinctions in mod‑
els of the H
2
O continual absorption on calculations of solar and thermal radiation
fluxes under conditions realized during various seasons in Western Siberia [Ches‑
nokova et al., 2012, 2013; Zhuravleva et al., 2014] and the Lower Volga Region
[Firsov et al., 2013, 2015] have been estimated. Based on calculations of total,
direct and diffusion solar radiation fluxes in the 0.2–5 mm range under cloudless
atmosphere for various models of the water vapor continual absorption and var‑
ious total moisture contents characteristic for summer and winter conditions of
Western Siberia, it is shown that the CAVIAR model of the continual absorption
based on new experimental data provides the higher sensitivity of calculated