Vol 55, No 2 (2019)

This paper discusses approaches to constructing bulk convective boundary layer (CBL) models based on the concept of complete mixing. Large-eddy simulation (LES) results are used to test the basic similarity hypotheses. The empirical constants of the bulk CBL model that are obtained from LES data for the case of free convection agree well with previously published data from laboratory experiments. It is also shown that the flux of kinetic energy from the upper CBL boundary transported by gravity waves is small compared with other components of the balance of turbulence kinetic energy (TKE) in the convective layer. The parametrization of TKE generation for the case of a sheared CBL in terms of the friction velocity and the average wind velocity in the CBL is derived; all dimensionless constants of the theoretical model are obtained from LES data. The results allow us to formulate an integral model of the sheared CBL suitable for practical use.

Data on internal gravity and infrasound waves recorded during the passage of both warm and cold fronts throughout Moscow, which are associated with the atmospheric storm of May 29, 2017, are given. These waves were recorded by four microbarographs located in the city of Moscow and Moscow region (and marked IFA, MGU, MSR, and ZNS in Fig. 1) and the data obtained were compared with data on infrasound waves recorded at the IS43 station in the town of Dubna. Time variations in the characteristics of internal gravity and infrasound waves (coherence, propagation azimuths, phase velocities, characteristic periods, and frequency spectra) during the passage of both warm and cold fronts are studied. The transition from the gravity to acoustic dispersive branch of acoustic-gravity waves due to increasing frequency and the temporal modulation of the phase velocity of infrasound waves due to internal gravity waves (IGWs) are also studied. Data on both aerosol (PM₁₀) and gas (NO₂) concentrations measured at different Moscow stations during the approaching atmospheric storm are given. The possibility of detecting wave precursors of atmospheric storms in simultaneous variations in atmospheric pressure, wind velocity, and pollutant concentrations is studied.

Using a high-resolution version of the QUODDY-4 three-dimensional finite-element hydrostatic model, we have carried out two series of numerical experiments. The first estimates tidal changes characterizing the role of tides in the formation of climatic characteristics of the Kara Sea in the ice-free period (the magnitude and directions of velocity of permanent surface currents, temperature, and salinity at the pycnocline base and level of the free sea surface). The second series checks the adequacy of the indirect description of tidal changes in terms of tide-induced baroclinic tidal-energy dissipation and diapycnal diffusion when compared to the explicit method and obtains a quantitative measure that can be used for their comparison. The modeling results indicate, first, that the tidal changes are a significant, if not key, factor; second, that the indirect description of tidal changes is adequate when compared to the explicit method; third, that it is unjustified to disregard these changes (this is common in predicting and computing the climates of marine systems); and, finally, that the correlation averaged over the sea surface area can be taken as a quantitative measure of the similarity of the fields of climatic characteristics obtained for the total (wind + thermohaline + tidal) forcing, on the one hand, and the combined (wind + thermohaline) forcing coupled with the indirect method for the description of tidal changes, on the other.