The influence of anisotropic wind velocity and temperature inhomogeneities on the attenuation of infrasound field intensity with increasing distance from a point source and on its altitude distribution is studied. The field is calculated as a function of receiver height and horizontal distance from the source using method of the pseudo-differential parabolic equation for the atmosphere with model realizations of anisotropic effective sound speed fluctuations. These realizations are obtained from the nonlinear shaping model for the gravity wave perturbations which produces the fluctuations with both the vertical and horizontal spectra consistent with the observed spectra. When propagating in the stratospheric and thermospheric wave guides the multiple scattering of infrasound field from the anisotropic fluctuations results in certain vertical wave number spectra and probability density functions of infrasound intensity fluctuations in the stratospheric (altitudes 30–40 km) and mesospheric layers (50–70 km). The statistical characteristics of the intensity fluctuations as a function of distance from the source (up to 2200 km) were studied. The same characteristics were obtained for the infrasound field scattered from the inhomogeneities whose vertical profile was retrieved from the infrasound signals from surface explosions detected in the shadow zone.

The results of studying the influence of internal gravity waves (IGWs) on the spatiotemporal variability of atmospheric pressure and wind velocity in the lower troposphere using a triangular network of three microbarographs and an antihail acoustic cannon installed in Talin (Armenia) are presented. By coherent analysis of pressure fluctuations measured at different points, IGWs generated by thunderstorm fronts about 5–6 h before the passage of the fronts over the network of microbarographs have been detected. The regularities of changes in phase speeds and propagation directions of IGWs as thunderstorm precursors with time are studied. The possibility of IGW monitoring in the troposphere by measuring temporal fluctuations of the travel time of acoustic pulses along the ray-paths connecting the antihail cannon with spatially separated acoustic receivers has been demonstrated. Vertical profiles of wind velocity fluctuations in certain layers of the lower troposphere up to a height of 800 m have been retrieved from the shapes and travel times of acoustic pulses having a shock front and scattered by anisotropic fluctuations of wind velocity and temperature in the stably stratified lower troposphere. Owing to the high vertical resolution (on the order of 1 m) of the method of pulsed acoustic sounding of the lower troposphere used here, the vertical spectra of anisotropic fluctuations of wind velocity in the range of short vertical scales, from one to tens of meters, are obtained for the first time and theoretically interpreted.

The paper deals with studying the influence of air pressure fluctuations on the health of patients. Since August 2008, the Obukhov Institute of Atmospheric Physics of Russian Academy of Sciences and the Central Clinical Hospital of the Russian Academy of Sciences (CCH RAS) observed air pressure fluctuations with a simultaneous registration of patients who were urgently hospitalized to the CCH RAS and classified as weather-sensitive. Weather-sensitive patients included patients diagnosed with myocardial infarction, angina, hypertension, extrasystole, stroke, and cerebrovascular disease. The data on 6078 patients over a four-year period (January 1, 2009-November 31, 2012) were processed. The results have shown an increase in the cases of patients' hospitalization with an enhancement of the external effects of air pressure.

A model of atmospheric pressure signal propagation from the eruption of the Hunga–Tonga—Hunga–Haʻapai volcano (hereafter abbreviated as Tonga) is proposed. The model is used to explain some peculiarities in the changes in the wave form of the observed signal with increasing distance from the volcano. The model is based on the solution of the linearized Korteweg de Vries (KDV) equation, which describes the change in the wave form of the Lamb wave as a function of distance from the source. We compare the observed and model signals obtained as a superposition of the Lamb wave and the acoustic modes calculated for three infrasound stations (IS22, IS24, and IS30). The energy of the volcanic eruption is estimated from the pressure amplitude and characteristic duration of the signal recorded at one of the infrasound stations closest to the volcano (IS24).

A model of propagation of an atmospheric pressure signal from the eruption of the Hunga Tonga−Hunga Haʻapai volcano is proposed. This model is used to explain some patterns in the change in the form of the observed signal with an increase in the distance from the volcano. It is based on the solution of the linearized Korteweg–de Vries (KdV) equation, which describes the change in the Lamb wave form as a function of the distance from a source. We compare the observed and model signals obtained as a superposition of the Lamb wave and acoustic modes calculated for three infrasound stations (IS22, IS24, and IS30). The energy of the volcanic eruption is estimated using the fluctuation amplitude of the atmospheric pressure and the characteristic duration of the signal recorded at the infrasound stations closest to the volcano.

The influence of wind velocity and temperature stratification in the upper stratosphere on the waveform of the infrasound signal received at a distance of 2398 km from the epicenter of the powerful explosion in Beirut that occurred on August 4, 2020 is studied using ray trace and pseudo-differential parabolic equation (PDPE) methods. Given a high temporal variability of the wind velocity in the stratopause predicted by the European Centre for Medium-Range Weather Forecasts model, it is assumed that within the stratopause layer, the increase in effective sound speed with increasing height is very small, on the order of 1 m/s. When modeling propagation of the signal from the explosion, the presence of a fine-scale layered structure of wind velocity and temperature in the real atmosphere was also taken into account. Accounting for the scattering of infrasound by strongly anisotropic (layered) inhomogeneities of the effective sound speed allowed us to explain the appearance of "fast" stratospheric arrivals, their time durations, the time period between successive arrivals (about 110 s), and the waveform of the entire observed signal.

The results of study of temporal variations of the characteristics of infrasound and internal gravity waves (amplitudes, coherences, grazing angles, azimuths and horizontal phase speeds) detected during a passage of warm and cold fronts through the networks of microbarometers installed in the Moscow region and Armenia (city Talin) are presented. Infrasound radiated during periods of weather changes is an almost continuous background against which infrasound monitoring of explosions in the atmosphere is carried out. The significant differences were observed in the characteristics of infrasound from warm and cold fronts. Such differences must be taken into account when detecting infrasound precursors of atmospheric storms. A possible aerodynamic mechanism for the generation of infrasound caused by the turbulent air flow around the geometric irregularities of the surface of meteorological front is proposed.

The waveform of the infrasound signal received at a distance of 2398 km (infrasound station IS48) from the epicenter of the powerful explosion in Beirut, which occurred on August 4, 2020, is analyzed and modeled by using ray trace and pseudo-differential parabolic equation (PDPE) methods. Given a high temporal variability of the effective sound speed in the stratopause predicted by the European ECMWF model, we assumed that within the stratopause layer the increase in effective sound speed with increasing height is very small, on the order of 1 m/s. We also took into account the fine-scale layered structure of wind velocity and temperature in the real atmosphere, which is not taken into account in the ECMWF model. Accounting for the scattering of infrasound by strongly anisotropic (layered) inhomogeneities of the effective sound speed by using the PDPE wave method allowed us to explain for the first time the appearance of “fast” stratospheric arrivals, their time durations, time period between successive arrivals (about 110 s) and the waveform of the entire observed signal. [This work was supported by the Russian Science Foundation, Grant No 21-17-00021.]

The results of study of the parameters of infrasound waves (amplitudes, coherences, grazing angles, azimuths, and horizontal phase speeds) detected during a passage of warm and cold fronts through the networks of microbarometers in Moscow region are presented. The observed effect of internal gravity waves on the coherence and phase speed of infrasound from meteorological fronts is analyzed. The differences found in the time dependences of the parameters of infrasound from warm and cold fronts that must be taken into account when detecting infrasound precursors of atmospheric storms are discussed. A possible mechanism for the generation of infrasound by the turbulent airstream flowing around the geometric irregularities of the meteorological front is proposed. [This work was supported by the Russian Science Foundation, Grant No. 21-17-00021.]

The results of study of temporal variations of the characteristics of infrasound (amplitudes, coherences, grazing angles, azimuths and horizontal phase speeds) detected during a passage of warm and cold fronts through the networks of microbarometers in the Moscow region are presented. .Infrasound radiated during periods of weather changes is an almost continuous background against which infrasound monitoring of explosions in the atmosphere is carried out. The significant differences observed in the characteristics of infrasound from warm and cold fronts are found. Such differences must be taken into account when detecting infrasound precursors of atmospheric storms. A possible aerodynamic mechanism for the generation of infrasound caused by the turbulent air flow around the geometric irregularities of the surface of meteorological front is proposed. [Work supported by RSF Grant No. 21-17-00021.]

We present characteristics (waveform, coherence, phase speed, and propagation directions) of Lamb waves from 2022 Hunga Tonga volcano eruption detected by the network of microbarographs in the Moscow region. The pressure waves were detected both on the day of the volcano eruption (January 15 UTC) and after the time interval during which they circled the entire globe after the first detection and returned to the receiving point (on January 17 UTC). This made it possible to study the change in the waveform and duration of the Lamb wave depending on the distance from the volcanic eruption site and the influence of stratification of wind speed and atmospheric temperature on the signal waveform. [This work was supported by the Russian Science Foundation, Grant No. 21-17-0002.]

We found an oscillatory process of the Earth's pole associated with the precession motion of the Moon's orbit using numerical processing a series C01 of observational data and measurements of the Earth's pole motion over a long time interval starting from 1900. Several methods have been proposed for converting the coordinates of the Earth's pole to a system in which its motion occurs in phase with a change in the orientation of the plane of the lunar orbit in relation to the Earth's equator. The performed transformation depends only on the average parameters of the Earth's pole motion and does not explicitly depend on time. In this system, we showed that the polar radius oscillates in phase with oscillations of the inclination angle of the lunar orbit plane to the Earth's equator, and the polar angle oscillations occur in phase with the deviation along the equator of the intersection point of the lunar orbit with the equator.

The characteristics of acoustic-gravity waves (waveforms, time durations, amplitudes, azimuths and horizontal phase speeds) from the eruption of the Hunga-Tonga-Hunga-Hapai volcano detected at different infrasound stations of the Infrasound Monitoring System and at a network of low-frequency microbarographs in the Moscow region are studied. Using the correlation analysis of the signals at different locations, six arrivals of signals from the volcano, which made up to two revolutions around the Earth, were detected. The Lamb mode of acoustic gravity waves from the volcano eruption is identified and the effect of this mode on generation of tsunami waves and variation of aerosol concentration is studied. The energy released from an underwater volcano into the atmosphere is estimated from the parameters of the Lamb wave and compared with the energy released from the most powerful nuclear bomb of 58 Mt TNT.

Some results on modeling and observation of infrasound propagation in the atmosphere in a presence of mesoscale and anisotropic wind velocity and temperature fluctuations are presented. The theoretical model of infrasound scattering from anisotropic wind velocity and temperature inhomogeneities of the atmosphere is developed. With this model, the appearance of the stratospheric, mesospheric, and thermospheric arrivals of the infrasound signals in the acoustic shadow zones is explained. The analytic relation between the wave field of the scattered infrasound signal and the vertical profile of the effective sound speed fluctuations is obtained. Using this relation, the vertical profiles of the fluctuations within the upper stratosphere (25-55 km) and the lower thermosphere (105-140 km) were retrieved from the waveforms and travel times of the signals recorded in the acoustic shadow zones. The theoretical frequency spectrum of the infrasound wavefield reflected from the fine-scale layered structure of the atmosphere is obtained and compared with the spectra of the observed stratospheric arrivals.

The main characteristics (coherences, phase velocities, propagation directions, characteristic periods, and amplitudes) of wave disturbances in the field of pressure and wind speed in the troposphere caused by the solar terminator (ST) moving relative to the Earth are studied. A coherent analysis of pressure variations measured by infrasound microbarographs of the stations IS26 (Germany), IS37 (Norway), and IS43 (Russia) making a triangle with sides of about 2000 km in size is used to detect wave disturbances from the ST. With such a large triangle, it is possible to isolate acoustic-gravity waves of high coherence with ST azimuths and propagation velocities against the background of much slower internal gravity waves (IGWs) from meteorological fronts. Wind speed and atmospheric pressure fluctuations are measured with sodars and microbarographs located in the region of Moscow and forming a small triangle with side lengths from 7 to 60 km. The distributions of the number of signal arrivals over azimuths and horizontal phase speeds are obtained. An explanation is given for the presence of dominant azimuths and phase speeds of internal gravity waves in the small triangle.

Infrasound parameters (amplitudes, coherences, grazing angles, azimuths, and horizontal phase speeds) derived during the passage of warm and cold fronts through the networks of microbarometers in the cities of Dubna and Moscow are presented. The significant differences observed in the temporal variations of the parameters of infrasound from warm and cold fronts are discussed. Such differences must be taken into account when detecting infrasound precursors of atmospheric storms. A possible mechanism for the generation of infrasound by the turbulent airstream flowing around the geometric irregularities of the meteorological front is proposed. The observed effect of internal gravity waves on the parameters of infrasound and its frequency spectrum is explained.

Within the framework of the model of a viscoelastic Earth, the tidal deformations caused by its motion by inertia around the center of mass are determined. The obtained expressions for the pole tide differ from the generally accepted model in dissipative terms. These terms are determined by the speed of the pole but not by its position. The analysis of the dynamics of the Earth’s pole motion at the Chandler frequency is carried out taking into account the pole tide. It is shown that the optimal approximation of the pole tide parameters according to the generally accepted model does not lead to the optimal approximation of the parameters of the steady state pole oscillation.

On the basis of a numerical-analytical approach, the disturbed motion of the Earth’s pole is investigated. The existence of various modes of the oscillatory process is shown that affect the accuracy of predicting its position. Perturbations are found that lead to a change in the average speed of the Earth’s pole and to a change in its oscillatory mode. A method is proposed for constructing a modification of a low-parameter two-frequency model, which makes it possible to improve the accuracy of forecasting the movement of the Earth’s pole for short time intervals.