Том 55, № 5 (2019)

The method of Dynamic–Stochastic parametrization of the nonconvective cloud amount in the general circulation model of the atmosphere is formulated. The proposed algorithm is evaluated on the basis of the general circulation model of the atmosphere with the specified temperature of the ocean surfaces. The results of calculations are compared to the satellite observation data and to the results of calculations of the cloud amounts performed using a coupled high-resolution atmosphere–ocean general circulation model. This approach looks highly promising in the results.

Using the example of an analysis of an extreme lowering of temperature in Moscow in January 2017, the horizontal and vertical extent of the urban heat island against the background of a strong stable stratification of the atmospheric boundary layer is studied. The possibilities of measuring and monitoring the vertical structure of the atmosphere using ground-based remote sensing are investigated. The capabilities of the mesoscale model WRF, adapted for a detailed description of mixing processes in the atmospheric boundary layer, in reproducing the spatial dynamics of the temperature anomaly are demonstrated. The numerical estimates of the amplitude and vertical extent of the urban heat island are compared with the measurement accuracy and the total errors of the numerical predictions. A comparison of measurement data and numerical simulation results on the WRF model, using the example of a winter urban heat island in January 2017, showed that mesoscale synoptic models so far only capture the main features of the urban heat island. However, deviations between model and observed temperature fields can reach 5°C.

A simple model for the development of submesoscale perturbations in the atmospheric boundary layer (ABL) is proposed. The growth of perturbations is associated with the shear algebraic instability of the wind velocity profile in the ABL. Seeking optimum values of such perturbations (streaks) allows one to solve the problem of estimating their scales, which turn out to be about 100–200 m vertically and 300–600 m horizontally. Similar scales are also revealed for experimental data on the structure of the wind field in the lower part of the ABL; the data were obtained in 2017 and 2018 in summer at the Tsimlyansk Scientific Station of the Obukhov Institute of Atmospheric Physics during acoustic sounding of the atmosphere with a high-resolution three-component Doppler minisodar.

Mathematical models are developed and simulations are performed of the transport of short optical impulses through the cloud layer into space. The optical and physical vertical depths of the cloud layer are chosen as its main variable parameters. The physical processes of the radiative field formation and its amplitude–time characteristics are studied. It is shown that the presence of a cloud layer results in formation of a secondary source at the upper boundary of a cloud and in considerable distortions of the temporal pattern of the initial impulse.

An ocean general circulation model (OGCM) of the Marchuk Institute of Numerical Mathematics of the Russian Academy of Sciences with embedded k–ω vertical turbulent exchange model is developed based on the equations for turbulence kinetic energy k and energy dissipation frequency ω. The solution of the k–ω model equations depends on the frequencies of buoyancy and velocity shift simulated by the OGCM, and the coefficients of vertical turbulence depend on k and ω. The numerical algorithms of both models are based on the method of splitting by the physical processes. The k-ω model equations are split into two stages describing the three-dimensional transport-diffusion of the turbulence kinetic energy k and frequency ω and their local generation-dissipation. The system of ordinary differential equations, arising at the second stage, is solved analytically, which ensures algorithm efficiency. The analytical solution of the equation is also obtained for the vertical turbulence coefficient. The model is used to study the sensitivity of the model circulation of the North Atlantic–Arctic Ocean to variations in the parameters of vertical turbulence. The experiments show that varying the coefficients of the analytical solution of the k–ω model can improve the adequacy of the simulation. The preliminary comparison of the features of the k–ω and k–ε turbulence models is presented using the method of splitting when they are employed in the OGCM.

The aim of this work is to obtain estimates and parameterization of the dissipation rate of the turbulence kinetic energy (TKE dissipation), ε, induced in the upper water layer by the presence of wind waves at the surface. For this purpose, data from the laboratory measurements of the wind waves and three components of currents at six horizons in the upper water layer and four different winds are used. The measurements are performed in the wind-wave channel of the Institute of Applied Physics, Russian Academy of Sciences (IAP RAS) [1, 2]. It is established that, for most horizons, Kolmogorov-type ranges with the property \({{S}_{{Uz}}}(f) \propto {{f}^{{ - 5/3}}}\) are clearly seen in the frequency spectra \({{S}_{{Uz}}}(f)\) for the vertical velocity component U_z of the flow induced by wind and waves. Using the algorithms described in [3, 4], this fact allows us to obtain estimates of the TKE dissipation at the corresponding horizons and then establish the dependence of ε on the friction velocity \({{u}_{*}}\), the height of waves at the surface a₀, the peak frequency of the spectrum ω_p, and the depth of the horizon z. An analysis of the results (according to the available data) makes it possible to propose a parameterization of the form ε ≈ 0.00025\(u_{*}^{3}{{a}_{0}}/{{z}^{2}}\) for which a physical interpretation is proposed.