Vol 59, No 1 (2023)

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).

Based on the observational data, statistical estimates of the relationship between different characteristics of atmospheric tornadoes were received. Statistically significant estimates of the power-law relationship of the tornado path length and path width were obtained. Specific features are noted for different ranges of path length and path width of intense atmospheric vortices. A simple model is proposed to explain the noted power-law, including the root, dependence of the tornado path length on path width.

Using the method of different scales, formulas for the hydrodynamic fields of acoustic-gravity waves (AGWs) with vertical wavelengths small compared to the scales of changes in the background temperature and wind fields are derived. These formulas are equivalent to the conventional WKB approximation, but explicitly include the vertical gradients of the background fields. The conditions for the applicability of the obtained formulas for describing the propagation of AGWs from the troposphere to the thermosphere are formulated and analyzed. The absence of singular points (critical levels) in the equations for wave modes in the analyzed height range is one of the conditions for the applicability of approximate formulas. For the wind from the empirical HWM model, singular points are often located below 200 km and are typical for internal gravity waves (IGWs), with lengths of the order of 10 km. As the wavelength increases, the number of singular points decreases. For IGWs with scales on the order of 300 km or more, there are usually no singular points. It is shown that IGWs with periods of less than 20 min propagating upward from tropospheric heights usually have one turning point in the altitude range from 100 to 130 km. The obtained formulas are useful, in particular, for parametrization of AGW effects in numerical models of atmospheric dynamics and energy.

An analysis of the acidity of precipitation is carried out by using the ChAP-1.0 (Chemistry and Aerosol Processes) atmospheric sulfur cycle scheme developed for Earth System Models of Intermediate Complexity (EMICs)These calculations are forced by monthly mean anthropogenic emissions of sulfur dioxide to the atmosphere in 1850–2000 adapted from the CMIP5 (Coupled Models Intercomparison Project, phase 5) database and by long-term means (taking into account annual variations) of meteorological variables adapted from the ERA-Interim reanalysis for 1979–2015. It was revealed that significant acidity of precipitation (minimum pH of hydrometeors) is typical for regions with high anthropogenic loading of sulfur compounds in atmosphere – Europe, southeast Asia, east North America, southern Africa, and western South America. In these regions in the last decades of the 20th century, typical precipitation values of pH amount from 2.5 to 3.5, which agrees well with the available measurements. The maximum acidity of precipitation (the minimum pH of hydrometeors, which is close to 2) due to anthropogenic sulfur are noted in the eastern Mediterranean region. Atmospheric transport leads to regions with pH < 3.5 covering almost all of Eurasia in the last decades of the 20th century. The influence of this transport is also noticeable in other midlatitudinal regions – south of North America and western South America. In general, the ChAP scheme can be used in EMICs, but after a refinement to account for the effect of various types of precipitation on the wet deposition of sulfur compounds from the atmosphere and the effects of orography on the transport of chemical species in the atmosphere

Results of measurements of NO₂ contents in vertical columns of the stratosphere and troposphere using the Ozone Monitoring Instrument aboard the EOS–Aura satellite in 2004–2020 are compared to results of ground-based measurements at stations of the Network for the Detection of Atmospheric Composition Change (NDACC), first of all, to results of measurements at the Zvenigorod Scientific Station (ZSS) of the A.M. Obukhov Institute of Atmospheric Physics Russian Academy of Sciences. The comparison of satellite data to the ZSS data is done using the both products of satellite measurements—the stratospheric and tropospheric column NO₂ contents. When comparing the data of OMI and ground-based measurements at other stations, satellite values of the NO₂ content in the stratospheric column are compared to values of the total column NO₂ content obtained in ground-based measurements. Correspondence between the results of satellite and ground-based measurements is characterized by the magnitude of the difference between them, linear correlation coefficients and regression coefficients. The difference has a noticeable seasonal variation. Correlation and regression coefficients depend significantly on the season. Characteristic patterns of correlation coefficient changes with latitude as well as features of correlation between satellite and ground-based data in the polar and middle latitudes of the southern hemisphere in spring have been revealed. For some stations, the dependence of the quantitative characteristics of the correspondence between the results of satellite and ground-based measurements on cloudiness has been revealed. Under cloudless conditions at the ZSS, a weakening of the correlation between satellite and ground-based values of the stratospheric NO₂ content and an increase in the correlation between the values of the tropospheric NO₂ content is noted. The dependence of the correspondence characteristics between the data of satellite and ground-based measurements on the level of pollution of the lower troposphere with nitrogen oxides has been revealed. The correlation between the values of the tropospheric NO₂ content in the vicinity of the ZSS under strong pollution increases, while the correlation between the values of the stratospheric NO₂ content decreases. Based on the results of the comparison of satellite and ground-based data, estimates of the upper threshold values of the tropospheric NO₂ content at different stations is obtained. The lowest values have been obtained for polar stations, and the highest value has been obtained for the ZSS which is most susceptible to anthropogenic pollution due to its proximity to the Moscow megapolis.