Vol 43, No 4 (2018)

The results are presented of complex investigation of clouds in India which were seeded with a glaciogenic reagent from the aircraft. The seeding effect was assessed by the comparison of radar characteristics of the seeded clouds with the characteristics of clouds within the radar field of view. The maximum reflectivity increase in the seeded clouds in comparison with clouds in the natural cycle, an increase in the precipitation flux and specific mass of precipitated hail are observed. The merging of seeded clouds was observed during the study. It is shown that this process affects cloud characteristics resulting in the significant (by several times) increase in the precipitation flux. The measurements of electric discharges registered by the lightning detection network demonstrated that there were no lightning strikes in the seeded clouds, although the calculations indicated an increase in the electric activity of the clouds.

The spectral structure of turbulence (spectra and cospectra) and water content characteristics for convective clouds in the tropical region was analyzed using aircraft observations in the meteorological testbed over Cuba; the results are presented. The cospectra for vertical turbulent heat fluxes allow classifying convective clouds based on their development stage and revealing the stages of growth, stabilization, and dissipation of clouds. It is shown that the value of cloud air overheating as compared to the ambient space is a parameter defining the cloud development stage. The interrelation is revealed between the integral characteristics of turbulence and water content (the mean values and distribution functions of parameters) for different stages of development of convective clouds. The recommendations are formulated on using the data on the dynamic structure of clouds for weather modification activities. A method is proposed for the instrumental estimation of cloud suitability for seeding that is aimed at precipitation augmentation.

A high-precision digital elevation model of the Caspian Sea with the spatial resolution of 0.001° x 0.001° is constructed and used as a basis for computation grids of various scales. A three-level scheme for calculating wind waves with the sequence of nested grids (Caspian Sea-Northern Caspian, Absheron Peninsula, Turkmenbashy city-the Northern Caspian key areas) is developed. A scenario designer is implemented which considers in calculations the ice edge position and the coastline dynamics. The SWAN spectral wave model is adapted to the Caspian Sea conditions. The series of calculations and the comparison of the obtained results with observational data are provided. It is found that the best result is obtained when corrected reanalysis data are used for calculations.

The results of studying biological aerosols (pollen spectra) in precipitation registered in the south of Western Siberia in the winter of 2014/15 are presented. Pollen grains of birch (Betula sp.), willow (Salix sp.), pine (Pinus sp.), and poplar (Populus sp.) were identified in the three of 28 analyzed precipitation samples. The comprehensive analysis of synoptic conditions during precipitation, back trajectories of air masses calculated with the HYSPLIT model as well as the analysis of the Northern Hemisphere snow cover dynamics and the area of distribution of the identified taxa were carried out. The results allowed determining the Euro-Scandinavian region as the main source of pollen grains inflow with precipitation to the south of Western Siberia in March 2015.

The results of atmospheric electricity measurements are presented which were conducted at observation points of different types: at the urban point (Rostov-on-Don), at the point near the Sea of Azov (Taganrog and Primorka), and at the high-mountain point (Cheget Peak) near Elbrus. The patterns of spatiotemporal variations in electrical conductivity (concentration of light ions) of the atmospheric surface layer are revealed for different conditions. The impact of natural radioactivity and aerosol pollution on the concentration of light ions is assessed for observation points near the Taganrog Bay (the Sea of Azov). The results of the comparative analysis of urban and high-mountain data of atmospheric electricity observations are presented.

The atmosphere-soil measurement system being an automatic weather station with the coupled set of soil sensors is described. It is used for measuring the profiles of soil temperature and surface soil moisture and for the synchronous measurements of air temperature and air humidity at the height of 1 and 2 m, wind speed and wind direction, amount of precipitation, and snow depth as well as of soil-water conductivity. Special software combines all sensors of the system into a single environmental monitoring system. The example of using measurement data for assessing the spatiotemporal dynamics of climate parameters is provided for contrasting landscapes of the Repubiic of Buryatia (eastern Baikalia and southern Vitim Plateau).