Volume 42, Nº 10 (2023)

В рамках стохастического подхода выполнен анализ особенностей резонансной и аномальной структур спектров ассоциативной ионизации (АИ) для случая дипольно-дипольного взаимодействия ридберговских атомов. Использование такого подхода позволяет количественно описать реакцию АИ с образованием положительно заряженного молекулярного иона. Обнаружено, что эффективность несимметричных процессов ионизации для оже-переходов может на порядки превышать эффективность симметричных. Обсуждена важная роль этого явления для развития современных квантовых прикладных исследований и представлений о процессах ионизации, протекающих в ионосфере. Полученные результаты могут быть использованы для решения ряда принципиальных проблем физики плазмы ионосферы. Особенно это касается эффекта “временной задержки” сигналов глобальных навигационных спутниковых систем (ГНСС), что, в свою очередь, существенно влияет на устойчивость работы ГНСС и дистанционное зондирование поверхности Земли.

Halogenated acids are of anthropogenic and natural origin and play an important role in atmospheric processes. The global distribution and high stability of halogenated acids is concerning because they are toxic, accumulate in surface waters, and pose a threat to humans and the ecosystem. Knowledge of the reaction mechanism of halogenated acids in the gas phase makes it possible to explain and control many important processes occurring in the atmosphere and during combustion. In this paper, we experimentally study the reactions of atomic fluorine with monochloroacetic, dichloroacetic, trichloroacetic, trifluoroacetic, and pentafluoropropionic acids at a pressure of 1 Torr. The experiments are carried out using a flow reactor connected to a mass spectrometer with a modulated beam. The rate constants of these reactions at room temperature are determined by the method of competing reactions (MCR) using the available published data. It is shown that in this series the fastest reaction is F + CH2ClCOOH. In addition, the temperature dependences of the rate constants are obtained for F + CF3COOH and F + C2F5COOH reactions in the ranges of 258–343 and 262–343 K, respectively.

The results of measuring the integral and temporal spectral characteristics of shock-heated air are presented. The experiments are carried out on a modified two-sections SST-M shock tube of the Institute of Mechanics, Moscow State University in shock wave velocities ranging from 7.8 to 10.7 km/s and initial pressures in the low-pressure chamber of 0.125 and 0.25 Torr. The radiation wavelength range 115–195 nm, corresponding to the vacuum ultraviolet (VUV) spectral region, in which the main contribution to the radiation is made by the atomic lines of nitrogen and oxygen, is studied. The obtained radiation spectrograms are analyzed. The measurement data are compared with the available experimental data of other authors.

The method for determining of the temperature of the lower thermosphere developed and improved by us based on long-term measurements of the parameters of the ionosphere and the neutral atmosphere is described in detail. The requirements for carrying out measurements by the method based on resonant scattering of probe radio waves by artificial periodic inhomogeneities of the ionospheric plasma are formulated, and the basic requirements for recording signals scattered by inhomogeneities and data processing are substantiated. It is shown that the limit of the determining of the temperature in altitude is limited by the level of the turbopause and the upper limit is the determined of by the condition for the fulfillment of thermal equilibrium. Examples of altitude-time temperature variations at altitudes of 90–130 km are given. The new data obtained as a result of experiments on the SURA facility (56.15° N, 46.11° E) in September 2021 are presented. The altitude and time resolutions of the order of 1 km and 15 s, respectively, make it possible to study both fast and slow processes in the lower thermosphere. A large temperature variability at altitudes of 90–130 km during the day and from day-to-day due to the propagation of atmospheric waves with periods ranging from 5–10 min to several hours is demonstrated. The features of smoothing the altitude profile over time and the influence of the use of real and model electron density profiles on temperature, as well as the influence of the sporadic E layer, atmospheric turbulence, and other natural factors, are discussed. The temperature profiles are compared with the MSIS-E-90 model and satellite measurement data.

The generation of acoustic-gravity waves by meteorological heat sources in the troposphere and the propagation of these waves to the heights of the upper atmosphere are studied theoretically. Equations that describe separately the generation and propagation of acoustic and gravity waves by a local heat source are derived. The heat source of the waves is divided into partial sources of gravity and acoustic waves (AWs). The power of these partial sources is estimated and it is shown that the power of the sources differs by about a factor of two, regardless of the shape, size, and frequency of the heat source. It is shown that in the case of heat sources of the waves, the generation of gravity waves cannot occur without the corresponding generation of AWs: these waves are generated only in pairs. The splitting of the problem of waves from a heat source into problems of waves from gravity and acoustic sources is illustrated by the direct modeling of these waves. The application of the obtained results to the problem of parametrization of acoustic-gravity waves in general circulation and climate models is discussed.

The ultraviolet (UV)-C range ensures high noise immunity and the possibility of operating equipment in the troposphere during the daytime, since the ozone layer of the atmosphere almost completely absorbs the UV-C radiation from the Sun. One of the main advantages of this range in comparison with the visible, infrared, and even radio range is the weak scattering of ultraviolet on aerosol particles of dust, snow, hail, water droplets, fog, and rain. In this paper, we propose a method for determining the optical thickness of the atmosphere during the propagation of UV-C radiation along an inclined path over the sea. Accounting for the inhomogeneity of the path of propagation of UV-C radiation is ensured by introducing in the model the dependence of the extinction coefficient and the optical thickness of the atmosphere on altitude. The validity of the proposed model is confirmed by the data of a full-scale experiment conducted over the Black Sea. The extinction coefficient of the atmosphere above the sea surface, as well as its aerosol and molecular components, is determined based on the experimental data.