Vol 59, No 4 (2023)

The interaction of various forms of convection with stably stratified barrier layers in the atmosphere is theoretically investigated. Three different formulations of the problem are considered. 1) A linear problem with given perturbations of temperature and vertical velocity at the lower boundary of a stably stratified medium. 2) Penetration of an isolated turbulent thermal into such a medium. 3) Impact on the intercepting layer of an intense convective turbulent jet. Analytical solutions of the corresponding model problems are found. The possibility of connecting the considered models with signatures of intense convection, in particular, with dome-shaped protrusions above the anvil of a cumulonimbus cloud (or a cluster of a convective system), which represent the intrusion of a powerful updraft into a stably stratified medium, is discussed.

The experimental seasonal forecasts of the INM-CM5 climate model were used as input data for the temperature-time phenological model of birch dusting. Within the framework of the joint model, a test technology was developed for seasonal forecasting of the timing of the beginning of birch dusting in the European territory of Russia. Verification of this technology on seasonal retrospective forecasts of the INM-CM5 model (1991–2019) showed an adequate reproduction of the birch dusting start dates calculated for the same period according to the ERA5 reanalysis. The mean systematic errors are ±2 days, and the spatial correlation coefficients are above +0.84. The forecasts of the date of dusting start in 2022, calculated from the experimental operational seasonal forecasts of the INM-CM5 model with a monthly lead-time and with a zero lead-time, are also evaluated. It is shown that the errors in forecasting the beginning of dusting are ±5–10 days, and the forecasts with a one-month lead-time have fewer errors. The obtained results allow us to conclude that the seasonal forecast of the surface temperature of the INM-CM5 model can be used as input information for the temperature-time phenological model for the operational forecast of the timing of the start of birch dusting in the European territory of Russia.

The overview of studies of waterspouts over the world is presented. The most well-known schematic models of the waterspouts formation are given. The main factors of waterspouts genesis above the water surface are identified. Open access data about waterspouts formed on the Earth from 2000 to 2022 are collected and analyzed. Three main areas of waterspouts formation are highlighted as the following: Mediterranean Sea, Gulf of Mexico and adjacent Atlantic, Great Lakes. The frequency of occurrence of waterspouts in countries with the largest number of cases of their annual registration (USA, Italy, Greece, Russia, Turkey) has been estimated. Well known data about waterspouts characteristics derived from direct and remote measurements are summarized. A conceptual scheme of their structure is described. Waterspouts in Russia are analyzed. Statistics about cases of their registration off the Russian Black Sea coast are given. Map with places of Black Sea waterspouts landfalls is created.

The article is devoted to the investigation of the nature of the increment in surface concentration of toxic gas sulfur dioxide (SO₂) in Northern Finland. The study is carried out for June 2011 when the increased near-surface SO₂ concentration was registered at Finnish observation station Inari Raja-Jooseppi together with the surface wind blowing from the territory of the Kola Peninsula. The hypothesis of natural increment of near-surface SO₂ concentration as a result of Grímsvötn volcano eruption (Iceland) is verified using satellite SO₂ observations by OMI, numerical weather prediction and atmospheric chemistry model Enviro-HIRLAM and particle dispersion model HYSPLIT. The results show that not only local man-made sources, but also the remote transfer of pollutants from volcanic eruptions can cause an increased near-surface SO₂ concentration. To verify this hypothesis, a large set of statistics is required in Northern Finland during periods of volcanic activity in Iceland.

A new mathematical model of the global transport of multicomponent gas impurities and aerosols has been constructed, including the formation of sulfate aerosols in the atmosphere in both hemispheres. Calculations of the nucleation rates and particle number concentrations were performed for the winter period in the troposphere using a unified model that takes into account chemical and kinetic transformation processes (photochemistry, nucleation, condensation/evaporation, and coagulation). Binary nucleation of sulfuric acid and water vapor was coupled with new-particle formation due to atmospheric ions. The numerical results indicate a significant role of ion nucleation in aerosol formation in the Northern and Southern hemispheres in winter. The factors controlling the dynamics of ionic processes in the atmosphere and their influence on the spatiotemporal distribution of aerosol particles involve not only the level of air ionization but also temperature, relative humidity, and the content of sulfur and water vapor in the air. At a height of 4.2 km, the formation of particle nuclei with the participation of ions occurs only over the Lake Baikal and Kamchatka regions as well as the regions of the northeast and northwest of the American continent. Within the regions of localization of this process in the atmosphere, the rate of new particle generation varies by more than an order of magnitude.

Conditions for the applicability of the dispersionless theory of long waves for reproducing dispersive tsunami waves are analyzed. As a quantitative criterion, the dispersive destruction distance is proposed for use, which is a value that is uniquely determined by the wavelength that dominates in the spectrum of the initial elevation of the water surface in the tsunami source, and the correction factor \(\alpha .\) The physical meaning of the \(\alpha \) value is the fraction of the wavelength by which the dispersive wave packet lags behind the long wave front when propagating over a distance equal to the dispersive destruction distance. Using the model residual displacement of the bottom surface, the geometrical parameters of which vary randomly, under the assumption of instantaneous generation of waves and taking into account the smoothing effect of the water layer, the Monte Carlo method establishes a relationship between the accuracy of wave reproduction by the dispersionless model and the quantity \(\alpha .\) Using the “\(\alpha \) coefficient scale”, the ranking of the criteria that were previously proposed by other authors was performed.

This work is devoted to testing the hypothesis about the presence of a diagnostic connection between the second and third moments of the hydrodynamic quantities \({{c}_{1}}\) and \({{c}_{2}}\) in the atmospheric boundary layer above a geometrically complex surface: \(\overline {w{\kern 1pt} 'c_{1}^{'}c_{2}^{'}} = C{{S}_{{{{c}_{1}}}}}{{\sigma }_{{{{c}_{1}}}}}\overline {w{\kern 1pt} 'c_{2}^{'}} .\) To test this ratio, a seven-month series of high-frequency measurements on an eddy covariance tower installed at the Meteorological Observatory of Lomonosov Moscow State University was used. Based on the statistical distribution of the third moments, the optimal methods for analyzing the reliability of the dependence under study were determined. For the first time on a large series of data, a statistically valid assessment of the validity of the tested hypothesis was obtained in the conditions of the urban underlying surface. The influence of stratification conditions and the nature of the underlying surface in the area of flux formation on the fulfillment of ratio second and third moments is studied. It is established that for the third moments \(\overline {w{\kern 1pt} 'w{\kern 1pt} 'T{\kern 1pt} '} ,\) \(\overline {w{\kern 1pt} 'T{\kern 1pt} 'T{\kern 1pt} '} ,\) \(\overline {w{\kern 1pt} 'u{\kern 1pt} 'u{\kern 1pt} '} ,\) and \(\overline {w{\kern 1pt} 'v{\kern 1pt} 'v{\kern 1pt} '} \) relation second and third moments is valid in 80% of cases.