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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.

Analysis of smoke blanketing of European Russia (ER) in summer 2016 is presented. The results of the analysis indicate that the cause of the smoky atmosphere over ER was long-range transport of smoke from wildfires in Siberia. The aerosol optical thickness at a wavelength of 550 nm over ER in late July reached 3. The features of circulation in the troposphere over northern Eurasia in July 2016, with an anomalous east transfer of combustion products in the troposphere over thousands of kilometers, which is opposite to the westerly transfer prevailing in the mid-latitudes, are discussed. A comparison of variations in the probability distribution functions of the aerosol optical thickness is performed for ER and Siberia for the summer periods in different years with massive wildfires.

Quasi-horizontal trajectories of salting sand grains were found using high-speed video-recording in the desertified territory of the Astrakhan region. The sizes and displacement velocities of the saltating sand grains were determined. A piecewise logarithmic approximation of the wind profile in a quasi-stationary wind–sand flow is suggested, which is consistent with the data of observations and modeling. It was established that, in the regime of stationary saltation, the wind profile in the lower saltation layer of the wind–sand flow depends only slightly on the wind profile variations in the upper saltation layer. The vertical profiles of the horizontal wind component gradient in a quasi-stationary wind–sand flow were calculated and plotted. It was shown using high-speed video recording of the trajectory of a sand grain with an approximate diameter of 95 μm that the weightlessness condition in the desertified territory of the Astrakhan region in a stationary wind–sand flow is satisfied at a height of approximately 0.15 mm. The electric parameters of a wind–sand flow, which can provide for compensation of the force of gravity by the electric force, were estimated. In particular, if the specific charge of a sand grain is 100 μC/kg, the force of gravity applied to the sand grain can be compensated by the electric force if the vertical component of the electric field in a wind–sand flow reaches approximately 100 kV/m. It was shown that the quasi-horizontal transport of sand grains in the lower millimeter saltation layer observed in the desertified territory can be explained by the joint action of the aerodynamic drag, the force of gravity, the Saffman force, the lift force, and the electric force.

It is shown that the absorption capacity of smoke aerosol during mass forest and forest–peat fires is determined to a considerable degree by light absorbing organic compounds or brown carbon. According to the data from the AERONET global network of stations [1], the absorption spectra of smoke aerosol vary significantly if airborne particulate matter is contained in brown carbon. It is established that in several cases, the absorption spectra of smoke aerosol are approximated with satisfactory accuracy by exponents. It is shown that the finely dispersed (submicron) fraction of the smoke aerosol makes a major contribution to its optical characteristics in the 0.44–1.02 μm spectral region. Strong variation in the single scattering albedo is discovered in the presence of brown carbon in the smoke aerosol. It is shown that the optical characteristics of coarsely dispersed and finely dispersed fractions of smoke aerosol differ considerably.

Based on monitoring data from AERONET stations, variations in the optical and microphysical characteristics of dust aerosol during a large-scale dust haze over the Middle East in spring 2022 are analyzed. It is shown that the coarse fraction of dust aerosol with a mode radius from 1.70 to 2.95 µm dominates the particle size distribution. The imaginary part of the refractive index of the aerosol substance reaches 0.042, and the single-scattering albedo varies from 0.70 to 0.99. Selective absorption of dust aerosol is found at a wavelength of 675 nm, which is associated with the presence of the mineral goethite in the dust aerosol particles. The selective absorption at a wavelength of 440 nm induced by hematite is relatively insignificant in the examined dust haze: the imaginary part of the refractive index reaches approximately 0.005, and the single-scattering albedo varies from 0.90 to 0.99. Regional hotspots of dust aerosol emission are identified.

According to interferometric data of radio waves from GPS satellites, which are received in Moscow region on the stations of the Moscow Navigation-Geodesic Support Network and the International Geophysical Survey (IGS) network, traveling ionospheric disturbances are detected moving from the Moscow megapolis and forming a ring around it. The empirical velocity distribution functions of this movement, the observed duration, and the direction of propagation of these disturbances are presented. It is shown that the observed traveling ionospheric disturbances may be due to the urban heat island effect.

According to measurements in September 2021 in a desertefied area in Astrakhan oblast, vertical turbulent heat and dust aerosol fluxes were determined as components of wind speed, air temperature, and concentration of aerosol particles in the surface layer of the atmosphere. A statistical analysis of variations in meteorological parameters and aerosol particle concentrations has been performed. The temporal variability of the horizontal and vertical components of wind speed, air temperature, and aerosol particle concentration is analyzed using spectral analysis. A comparison has been made of the empirical distribution functions of heat flux density and the temporal variability of the rate of heat uplift from the underlying surface according to synchronous measurements using Meteo-2 and Metek acoustic weather stations. Significant differences in the spatiotemporal variability of the vertical turbulent transfer of heat and dust aerosol in a desertified area have been revealed. The 30-min average values of the friction velocity, the Monin–Obukhov scale, turbulent heat fluxes (90–160 W/m 2 ), and dust aerosol (7.2–27.5 cm –2 s –1 ), as well as the heat uplift rate (14–21 cm/s) and dust aerosol (10–16 cm/s) from the underlying surface, have been determined. It is shown that the temporal variability of the dust aerosol flux density is caused by a superposition of convective “low-frequency” movements with a scale of approximately 3–15 min and “high-frequency variations with a duration of less than approximately 10 s.”

The vertical turbulent dust aerosol (DA) and heat fluxes are determined on the basis of measured fluctuations of the components of the wind speed, air temperature, and concentration of aerosol particles on a desertified territory of Astrakhan oblast during intermittent DA emission. The temporal variability of the horizontal and vertical components of the wind speed, air temperature, and concentration of aerosol particles is characterized using spectral analysis. It is shown that the intermittent DA emission is caused by low-frequency convective-related variations in the horizontal component of wind speed if the threshold saltation speed is exceeded. The significant differences in the spatiotemporal variability of vertical heat and DA flux are revealed. The 30-min average values of heat (90‒158 W/m 2 ) and DA (7.2‒27.5 cm –2 cm –1 ) fluxes, as well as the rates of heat (14‒21 cm/s) and DA (10‒16 cm/s) removal, are calculated.

Anomalous absorption of finely dispersed smoke aerosol was recorded in large-scale smoke haze during mass fires in the boreal forests of Alaska in July 2019 in the visible and near-infrared regions of the spectrum (440‒1020 nm) according to the data of monitoring of the spectral dependences in the refractive index imaginary part on the network of AERONET stations. The variations in the spectral dependences of the aerosol optical depths (extinction and absorption), as well as the size distribution function of aerosol particles, are analyzed. During the anomalous absorption, the imaginary part of the refractive index increased by a factor of 1.8‒7.2 with an increasing optical wavelength from 440 to 1020 nm, reaching a value of 0.315 for the wavelength of 1020 nm. A power approximation is proposed for the spectral dependence of the imaginary part of the refractive index with indices of power approximately from 0.7 to 2.3.

The effect of the emergence of quasi-periodic oscillations of particle (with size >50 mсm) concentrations in the saltation flow has been detected in similar arid conditions in desertified areas: (1) using high-speed video in Astrakhan region (2009); (2) by acoustic method in the Republic of Kalmykia (2021). During the field experiments were revealed characteristic low frequencies (<50 Hz), which is associated with the peculiarities of the microrelief shape. More high frequences (>50 Hz) have been observed also. The appearance of these frequencies is determined by changes in the saltation cycle in heterogeneous topography. Such processes is simulated in a numerical experiment using the OpenFoam package. There are demonstrated the characteristic frequencies of changes in the number of particles (from 10 to 200 Hz) in the saltation flow over the surface ledge of the ripple type. Numerical experiments include analysis of frequency characteristics of particle concentration changes in the flow behind the ledge. Spectral analysis of data of numerical realizations of the saltation flow at variation of boundary parameters and height of the obstacle shows that the characteristic frequency or frequencies change and are close to those observed in the experiment. Input parameters such a models can be adjusted with such analysis.