Home – Home – Jornals – Atmospheric and Oceanic Optics 2020 number 11

In this paper, we suggest an original method for solving the inverse problem of hyperspectral satellite sensing of the atmosphere to retrieve HDO/H₂O ratio vertical profile in the atmosphere with simultaneous inversion of thermal and near-IR spectra. A computational experiment was performed to retrieve the vertical profile of relative abundance of HDO isotopologue in atmospheric water vapor using high-resolution simulated spectra with parameters of TANSO-FTS spectrometer onboard GOSAT-2 satellite. The inverse problem was solved by the optimal estimation method with simultaneous inversion of thermal and near-IR spectra. The output data of the isotopic version of the atmospheric general circulation model ECHAM6-wiso were used as a priori statistical data on water vapor isotopologue vertical profiles.

The retrieval of the vertical structure of carbon dioxide content is important for studying the exchange of greenhouse gases between the troposphere, where the anthropogenic factor determines the growth of their content, and the stratosphere. In this study, we analyzed the potential information content and vertical resolution of the ground-based IR spectroscopic method for determining CO2 profiles using solar radiation measurements with the Bruker 125 HR Fourier spectrometer at the St. Petersburg site. Based on methodological studies of various spectral windows and areas, we have shown that it is possible to determine 3-4 independent parameters of the CO₂ vertical structure. Measurements in the strong and medium absorption lines provide maximum information on the CO₂ content in the lower and middle troposphere with a vertical resolution of 3-5 km. The weak absorption lines provide information on the CO₂ content in the stratosphere with a vertical resolution of 10-25 km.

Analysis of the annual СО₂ distribution in the gas samples vacuum-extracted from the tree-ring wood of several conifer discs has been performed. The results indicate that part of CO₂ released by forest communities into the atmosphere can vary with a period of about 4 years. Two groups of trees were identified, in each the 4-year CO₂ variations are approximately synchronous, and the variations in different groups are opposite in phase. Variations with periods in the vicinity of 2 and 4 years were revealed in the series of CO₂ content in the atmospheric air.

The paper analyzes the published data on such parameter as self-broadening of lines of the main isotopic modification of the ³²S¹⁶O₂ molecule. A method for evaluating this parameter for spectroscopic databases is proposed. The analysis of literature sources was carried out, low-confidence data was revealed, regression analysis was performed, a model for calculating the self-broadening parameter was proposed, and the obtained models were analyzed. Some estimates of its applicability are made for the models obtained.

The method for estimating the turbulent energy dissipation rate from measurements by a conically scanning pulsed coherent Doppler lidar (PCDL), generalized to the case of arbitrary ratios of the average wind velocity to the linear scanning velocity, was tested on the data of atmospheric experiments while the use of a Stream Line PCDL and an sonic anemometer. A comparative analysis of the measurement results with the two devices showed that the improved method, which, unlike the previous approach, takes into account the wind transfer of turbulent inhomogeneities, allows obtaining unbiased estimates of the dissipation rate for any ratio of the average wind speed to the linear scanning speed.

In this paper, the average radius of suspended organic particles in Atlantic Ocean waters is calculated from the measurements of light scattering phase function. The relationship between average sizes of suspended organic particles calculated from light scattering and the average sizes of phytoplankton cells determined visually using a microscope is established. The relationship between the size of suspended organic particles and the water trophic state is studied. It is ascertained that the average sizes of suspended organic particles increase with a decrease in the water productivity (trophic state). Taking into account the relationship of the average sizes of suspended organic particles with the average sizes of phytoplankton cells, a conclusion is drawn that oligotrophic waters (low trophic state) are dominated by phytoplankton species with cell sizes larger than those of phytoplankton in eutrophic waters (high trophic state).

The results of two-frequency lidar sensing of the atmosphere at the lidar station of Kamchatka (52°58¢17¢¢ N, 158°15¢07¢¢ E) are discussed. The results of sounding were registered in the altitude range 25-600 km. The results obtained in the middle atmosphere are considered. The possibility of resonance scattering in imaginary aerosol formations in the middle atmosphere is studied. Examples are given in which the increased scattering at wavelengths of 532.08 and 561.106 nm in the middle atmosphere should be explained by the resonance scattering on excited ions of atomic oxygen and nitrogen. These ions may appear as a result of the ionization of the atmosphere by relativistic electrons.

The results of an experiment in which the intensity distribution of scattered radiation at the transmitting-receiving aperture of a turbulent lidar was studied are presented. Sounding was performed along a horizontal path in moderate turbulence with a narrow laser beam located in the center of the receiving aperture, the size of which could be changed. As the size of the receiving aperture increased, the relative contribution to the echo signal due to turbulence decreased. It was found that the BSE effect localized in the center of the receiving aperture: the peak of the scattered radiation is located at the axis of the sounding beam, and its size is approximately equal to the beam size; at the periphery, the average intensity of scattered radiation slowly decreased to background values as the distance from the beam axis increased. The result can be used in practice for optimal selection of parameters of the transceiver when designing a turbulent lidar.

Part 2 of the paper analyzes the relation of the heights of the zone of intense turbulent heat exchange and the corresponding air temperature gradients to the surface values of the wind speed and the vertical turbulent heat flux. Only the cases of temperature inversions in winter (January-February 2020) are considered. The division of inversions into two types (surface and elevated) and four forms is introduced. The statistics of the height of the layer of intense turbulent heat exchange is obtained for various versions (types and forms) of temperature inversions. It is concluded from the analysis that under conditions of temperature inversions (in the winter period) there is no direct (well pronounced) relation between the height of the layer of intense turbulent heat exchange and the surface values of the wind speed and the turbulent heat flux.

An algorithm for energy calculation of the threshold illumination of the entrance pupil of an optoelectronic system (OES) in the range 0.9-5.3 mm is presented. The dependence of the time of accumulation t_ac on the photodetector array on the rate of counting signal photons n _s, as well as the dependence of n _s on the signal-to-noise ratio are derived. The illumination of the entrance pupil of the OES lens from a spherical space object illuminated by the Sun is calculated. The program is developed and its interface is presented for the energy calculation of the OES in various sections of the considered IR range.

The conditions for the formation of ball and cylindrical streamers in a corona discharge were studied. It is shown that formation of cylindrical streamers from a positive tip or from a plasma at a positive tip can explain the stepwise progression of the main negative leader in lightning and during the breakdown of long gaps.