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Volume 61, Nº 5 (2025)
Articles
INSTABILITY OF THE KOLMOGOROV FLOW IN A MODEL TAKING INTO ACCOUNT EKMAN FRICTION AND THE BETA EFFECT
Resumo
The paper studies the stability of spatially periodic flow in a model taking into account bottom friction and the beta effect. Within the framework of the linear approximation, a stability criterion for the flow in a quasi-geostrophic model with bottom friction is obtained. To describe the nonlinear stability, the Galerkin method with three basic Fourier harmonics is used. It is shown that the exponential growth of linear disturbances at the nonlinear stage of development is replaced by the regime of establishing stationary periodic disturbances. A linear model of periodic flow stability with joint consideration of bottom friction and the beta effect is developed. It is shown that taking into account the beta effect leads to the development of oscillatory instability.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):555-564
555-564
ANALYTICAL MODEL OF SHEAR FLOW OVER A THERMALLY HETEROGENEOUS SURFACE
Resumo
As is well known, one of the most important factors in the development of dangerous convective phenomena in the atmosphere is the vertical shear of the background wind speed. Therefore, the problems of theoretical description of the interaction of convection, thermal circulations with a shear flow are very relevant. A linear stationary problem of the interaction between a horizontal flow with a vertical shear and thermal circulations (density currents) existing over a thermally inhomogeneous horizontal surface is considered. It is assumed that in the absence of thermal inhomogeneities, there is a background flow with a constant vertical shear of velocity (Couette flow) in a stably stratified medium. Stationary disturbances caused by thermal inhomogeneities of the underlying surface, extended along the background flow, are studied. Thus, a linear stationary two-dimensional problem is considered in the Boussinesq approximation. Coriolis accelerations are not taken into account, since relatively small horizontal scales of inhomogeneities are assumed. The consideration is limited to one horizontal harmonic of disturbances. An essential dimensionless determining parameter is an analogue of the Rayleigh number R, in which the horizontal scale of the harmonic under consideration acts as a spatial scale. An approximate analytical solution is found. An essential new result is as follows: although thermal circulations penetrate relatively shallowly into a stably stratified medium, they can cause stationary disturbances of the background flow, which penetrate much deeper into the medium.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):565-569
565-569
REPRODUCTION OF THE TEMPERATURE RESPONSE TO THE PINATUBO VOLCANIC IMPACT IN THE EARTH SYSTEM MODEL INMCM6
Resumo
The results of experiments on tuning the aerosol block of the INMCM6 model for correct reproduction of the temperature response to volcanic emissions of sulfate aerosol are presented. Calculations were carried out using the INMCM6 Earth system model for the period from 1979 to 1995, during which two explosive volcanic eruptions occurred: El Chichon in 1982 and Pinatubo in 1991. Time series of the volume concentration and effective radius of sulfate stratospheric aerosol were specified according to the SADS v.3 database. Based on these data, optical properties of sulfate stratospheric aerosols (SSA) were calculated, which were then averaged for the wavelength intervals used in the radiation block of the INMCM6 climate model. In a series of model ensemble experiments, optical properties of SSA were varied in order to most realistically reproduce the temperature response of the climate system to volcanic action — cooling near the surface and heating of air in the stratosphere. If thermal heating of SSA is not considered, as a result of adjusting the short-wave optical parameters of the SSA, it was possible to reproduce with good accuracy (when compared with the ERA5 reanalysis data) the time course of the global optical thickness of the SSA, the amplitude of the warming of the lower stratosphere and the cooling of the lower troposphere. It was revealed that in the INMCM model the absorption of short-wave radiation by the SSA at wavelengths of 1–2 μm has the greatest influence on the magnitude of stratospheric warming.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):570–578
570–578
INFLUENCE OF THERMAL ROUGHNESS PARAMETERIZATIONS ON THE TURBULENT FLUXES SIMULATIONS BY ATMOSPHERIC SURFACE LAYER MODEL
Resumo
Models of the atmospheric surface layer describe the processes of momentum, heat and moisture exchange between the atmosphere and the underlying surface. In the framework of the Monin-Obukhov similarity theory, the height of thermal roughness determines the efficiency of heat transfer in the surface layer. This paper considers different ways of determining this characteristic on the basis of existing parameterizations implemented in the actively developing the surface layer model of the INM RAS Earth System Model. The results obtained using the previously proposed parameterizations were analyzed and compared with observational data for different surface types. The sensitivity of the model reproduction of the heat flux to the choice of the thermal roughness parameterization was evaluated. The obtained significant differences both in the roughness parameter and in the estimates of heat and momentum fluxes obtained in the model depending on the surface type indicate the importance of taking into account the surface type in the schemes for calculating turbulent flows.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):579-591
579-591
POTENTIAL VORTICITY AND HELICITY DYNAMICS OF CONVECTIVE STORMS
Resumo
Using the example of a catastrophic convective storm that occurred in Moscow and the region on June 20, 2024, a study was done on the evolution of the potential vorticity and helicity based on information from a global hydrodynamic model and then a nonhydrostatic mesoscale model. Comparison of model data with weather radar information showed that a synoptic-scale tropospheric potential vorticity anomaly can serve as an indicator of the existence of convection. However, to specify the time and place of occurrence and development of active convection, a study based on information from a mesoscale nonhydrostatic model is necessary. If convection exists, mesoscale potential vorticity in the troposphere in the baroclinic zone are horizontally oriented dipoles of positive and negative anomalies. The integral helicity (0–3 km) in the zone of active fronts also has a dipole structure, and a comparison of the integral helicity with an objective frontal analysis showed that negative helicity is present in the zone of cold fronts, and positive helicity is present in the zone of warm fronts. In the zone of active convection, near the convective updraft flow, the structure of helicity calculated from the vertical component of vorticity is vortex dipoles – cyclonically and anticyclonically directed vortices, and in this zone, the same dipoles are formed in the structure of the mesoscale potential vorticity. Considering the occurrence of positive feedback between the mesoscale potential vorticity and helicity in the baroclinic zone, it is suggested to use the product of the gradient of the integral helicity in the layer from 0 to 3 km and the gradient of the mesoscale potential vortex in the middle troposphere to determine the zones of occurrence of dangerous convective phenomena – thunderstorms, squalls, heavy precipitation.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):592-602
592-602
REGIMES AND TRANSITIONS OF HYDRODYNAMIC FLOWS IN A ROTATING ANNULAR CHANNEL (NUMERICAL EXPERIMENTS)
Resumo
Numerical experiments study the possibility of the existence of different regimes of barotropic circulation in rotating closed annular channels, when the external influence increases for some time and then returns to its previous value while maintaining other flow parameters unchanged. The regimes differ both in the number of vortices in the flow or their location, and in the speed of transfer through the channel. It is also possible to return to a regime that is practically without difference from the original one after restoring the values of the parameters that determine the flow.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):603-618
603-618
FREQUENCY SPECTRA AND SURFACE WAVE HEIGHT DISTRIBUTIONS BASED ON THE MEASUREMENTS OF SAKHALIN ISLAND
Resumo
Spectral characteristics of long-term measurements of surface sea waves off the coast of Sakhalin Island by bottom pressure stations are analyzed. The shapes of frequency spectra in the wind wave range demonstrate great diversity and variability. The frequency of sea state conditions are determined in terms of the parameters of the frequency spectrum width and wave nonlinearity taking into account the change in the dimensionless parameter of depth at the measurement point. A significant decrease in the probability of high waves with increasing spectrum width, as well as with an increase in the ratio of the characteristic wave amplitude to depth or with an increase in the Ursell parameter is shown. The result is most clearly manifested when estimating the spectrum width through the Goda parameter.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):619-632
619-632
DYNAMIC REGIME OF THE MIDDLE ATMOSPHERE DURING THE MINOR SUDDEN STRATOSPHERIC WARMING DEVELOPMENT IN WINTER 2014–2015: WAVE PROCESSES AND JET STREAMS
Resumo
A study of the dynamic regime of the middle atmosphere in the 2014–2015 winter season was carried out using reanalysis data. The variability of the atmosphere as a whole this winter was due to the development of sudden stratospheric warming (SSW). Despite the fact that this SSW is classified as minor, it has had a significant impact on the temperature regime, circulation and chemical composition of the middle atmosphere. The main attention is paid to the study of wave activity variations of stationary planetary waves (SPW) and processes caused by wave activity before, during and after the SSW, as well as the sensitivity of upper-tropospheric jet streams (JS) to stratospheric and mesospheric processes. The method of perturbed potential enstrophy analysis is used to study wave activity and wave processes. It is shown that variations in wave activity before the development of the SSW are due to wave-wave interactions, and during and after are due to the exchange processes of SPW2 (zonal wave number 2) with the mean flow. The development of the minor SSW in January 2015 had similar characteristics to the development of the major SSW, which likely led to the observed differences in the distribution of JS frequency during the month before and after the SSW. The highest JS frequency after the SSW was noted at more southern latitudes compared to the period before the SSW across most of the North Atlantic region. It has been shown that the greatest changes in JS frequency are associated with the southward shift of the upper-level frontal zone, which is in turn triggered by the deepening of upper-level troughs due to the intrusion of cold stratospheric air into the upper troposphere.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):633-650
633-650
THE DIFFERENCE IN THE PROGNOSTIC POTENTIAL OF TROPOSPHERIC PREDICTORS OF STRATOSPHERIC SUDDEN WARMING IN DIFFERENT PHASES OF ENSO ACCORDING TO IDEALIZED NUMERICAL EXPERIMENTS
Resumo
The stratospheric dynamic and its variability play one of the key roles in the tasks of weather forecasting on a sub-seasonal scale in winter season in the Northern Hemisphere. The stratospheric influence on tropospheric dynamics is most pronounced during sudden stratospheric warming (SSW), when in many cases it is possible to trace the spread of dynamic disturbances from the stratosphere to the underlying troposphere, down to the Earth’s surface. Therefore, a more complete understanding of the formation of SSW events will assist to clarify the forecast of anomalies of synoptic activity with an advance time of 10 to 30 days. In this paper based on the data of idealized numerical modeling we analyze the differences in the characteristics of the stratospheric polar vortex (SPV), such as the intensity and frequency of the SSW at different phases of the El Niño – Southern Oscillation (ENSO). The results of the study allow to explain the mechanisms of formation of these differences and show that the predictability of SSW in El Niño conditions is higher than in La Niña conditions.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):651-660
651-660
ASSESSMENT OF STATISTICAL CHARACTERISTICS OF CLOUD LIQUID WATER PATH OVER LAND SURFACE AND WATER BODIES IN THE BALTIC SEA REGION AND THE NORTHWEST RUSSIA BASED ON SEVIRI SATELLITE INSTRUMENT DATA
Resumo
The results of remote sensing of cloud liquid water path (LWP) by the SEVIRI satellite instrument in the Baltic Sea region and northwestern Russia in 2011–2017 are analyzed. For a detailed study, characteristic geographic points in the water areas of large water bodies and on land were selected. Based on special criteria, the LWP measurement data were selected into several separate arrays, which made it possible to study both the so-called «intrinsic» properties of clouds and the properties of the cloudy/cloudless atmosphere as a whole. The main conclusions of the work were obtained for non-precipitating clouds with LWP not exceeding the threshold value of 0.4 kg · m−2. Precipitating clouds were classified as having LWP of more than 0.4 kg · m−2 and were considered separately. The statistical distributions of cloud liquid water path, as well as its interannual and seasonal variability, were analyzed. The analysis of the seasonal variation is limited to the period from February to October due to the lack of SEVIRI measurements in autumn/winter when the solar zenith angle is large. For all the considered data arrays, the obtained main statistical characteristics are presented in tabular form, which can be used for solving problems of cloud modeling, weather forecasting and climate change, as well as for composing statistical models of the cloudy atmosphere applied for training of regression and neural network algorithms for derivation of the cloud LWP from remote measurements.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):661-682
661-682
PROPAGATION OF PULSED ACOUSTIC WAVES IN THE SURFACE LAYER OF THE ATMOSPHERE. PART 1. INFLUENCE OF PHYSICOCHEMICAL CHARACTERISTICS OF THE ATMOSPHERE ON THE TRANSFORMATION OF ACOUSTIC PULSES
Resumo
An overview of the results of experimental and theoretical studies of the propagation of acoustic waves in the boundary layer of the atmosphere created by pulsed point sources of various nature is presented. The influence of molecular kinetic mechanisms of sound dispersion, thermal conductivity and viscosity, atmospheric turbulence and temperature inversion, atmospheric aerosols and wind in the surface layer of the atmosphere on the expansion of the front region and the shape change of acoustic signals propagating in it is considered. The necessity of searching for a mechanism that causes the expansion of the front region of the wave according to the law of energy similarity is shown.
Izvestiya, Atmospheric and Oceanic Physics. 2025;61(5):683-698
683-698