Volume 60, Nº 6 (2024)

Large-eddy simulation of the dynamics of a turbulent, droplet-laden air-flow over a waved water surface has been carried out. Sufficiently small droplets (with diameter up to 300 micron) are considered which allows us to neglect their deformation. Collisions between the droplets as well as their evaporation are also not taken into account. The droplet mass fraction is prescribed sufficiently small, such that their impact on the air-flow is negligible; the surface wave is prescribed and not affected by either droplets or air-wind. Numerical model is based on the solution of three-dimensional, filtered over subgrid-scale fluctuations, Eulerian equations of air-phase motion, and thr Lagrangian equations of individual droplets motion. A turbulent-viscosity concept is employed for the closure for the subgrid stresses in the air-velocity equations where the kinetic energy of the pulsations unresolved by the mesh is determined by the solution of a prognostic equation. The model is verified by a comparison with the results of a direct numerical simulation of the full equations of motion of the air and dispersed phases. Phase-averaged profiles of the air velocity and momentum flux and droplet concentration for different Reynolds numbers of the carrier flow and droplet injection scenarios are obtained.

Field measurements of sea waves are carried out off the coast of Sakhalin Island using an antenna of three bottom pressure sensors. The stability of statistical characteristics estimated by different devices in the antenna is analyzed. The probability distribution of wave heights qualitatively corresponds to the Glukhovsky distribution, but demonstrate a lower probability of high wave occurrence. The space-time spectra of waves are reconstructed. It is shown that the angular distribution of the spectral density of waves over two days of measurements is well described by the theoretical cosine squared distribution, and its width varies in the range of 50-90 degrees. The dominant direction of wave propagation is from the northeast. An independent method is proposed for estimating the local water depth using data from the antenna.

The results of determining the ozone total column (OTC) from the spectra of the outgoing thermal infrared radiation measured by the IKFS-2 instrument from the “Meteor-M” No. 2 spacecraft during 8 years of measurements are presented. The previously developed methodology for the interpretation of spectral measurements made in 2015–2020 with a scanning bandwidth (SBW) of 1000 km is applied to the measurements in 2021–2022 with SBW of 1500 km. It is shown that the observed increase in the differences between the IKFS-2 data and the results of independent measurements is caused not by the expansion of the OTC variability statistics, but by the increase in the range of scanning angle variation. After finalization of the methodology for the measurements with a 1500–km SBW, the comparison with independent data showed that the standard deviations of differences with the results of ground and satellite measurements for all 8 years do not exceed 3% and did not increase compared to the first 6 years of measurements. To analyze the results in the polar regions, the OTC values obtained from the IKFS-2 spectra are compared with the ozonesonde data, which are performed continuously throughout the year, including the polar night. A good qualitative agreement of the IKFS-2 data and ozone sounding data, including winter-spring periods of extreme OTC decrease at high latitudes of both hemispheres, is shown. The standard deviations of the differences between the IKFS-2 data and the OTC values from ozone sounding data were from 5.3 to 11 % (17–33 D.U.) for different stations, or on average for all stations 7.9 %, which is consistent with the uncertainty of the estimates of the integrated ozone content in the vertical column from ozonesonde data.

In the last decade, it has been shown that in most cases atmospheric ice consists of a mixture of ices Ih and Ic, it is called ice with stacking disorder or stacking disordered ice Isd. In addition, it became known about the existence of another crystalline modification of ice, called ice 0. Ice 0 is a transitional form from deeply supercooled water to ices Ih and Ic, which form at temperatures below ‒23°C (at low pressures). For this reason, the question arose about the possibility of forming ice 0 in the structure of ice Isd. To clarify the issue, laboratory experiments were carried out to obtain layers of ice 0 on the surface of ice Ih, as well as dielectric measurements of the material of atmospheric ice from fallen hail. The results obtained confirmed the possibility of forming ice 0 in the structure of stacking disordered ice Isd. A special property of such a structure is the appearance of contact layers with high conductivity, which significantly changes the electrophysical characteristics of ice particles. For example, in particles of small sizes, resonances of plasmon oscillations arise, which affect the transfer of electromagnetic radiation in cloud formations. The study of electromagnetic properties of small ice particles containing ice 0, and their features in various areas of the atmosphere will allow solving a number of important tasks. These include refining the radiation balance of the Earth’s surface, thunderstorm phenomena, radiation transfer in cloud formations, and physicochemical processes in aerosols and snow covers.