Russian studies of atmospheric electricity in 2011–2014

This review contains the most significant results of Russian studies in the field of atmospheric electricity in 2011–2014. It is part of the Russian National Report on Meteorology and Atmospheric Sciences to the International Association of Meteorology and Atmospheric Sciences (IAMAS). The report was presented and approved at the XXVI General Assembly of the International Union of Geodesy and Geophysics (IUGG).¹ The review is followed by a list of the main published works on the studies of atmospheric electricity of Russian scientists in 2011–2014.     

The Correlation of Temperature,Stratus Cloudiness,and Electric Field Strength in the Atmosphere

Doklady Earth Sciences - This paper presents the results of observations and processing of experimental data on long-term (2012–2018) continuous electric field measurements and compares them...     

Anomalous Decimeter Radio Noise from the Region of the Atmospheric Front: I. Characteristics of the Detected Radio Noise and Meteorological Parameters of the Frontal Cloudiness

An extraordinary experimental fact is presented and analyzed, namely, a rather intense broadband radio noise detected during the passage of an atmospheric front through the field of view of UHF antennas. Local atmospheric properties and possible sources of the extraordinary noise, including the thermal noise from cloudiness and extra-atmospheric sources, are considered. A conclusion is made about the presence of an additional nonthermal source of radio noise in the frontal cloudiness. According to the proposed hypothesis, these are multiple electric microdicharges on hydrometeors in the convective cloud.     

Anomalous Decimeter Radio Noise from the Region of the Atmospheric Front: II. On the Nonthermal Mechanism of UHF Noise

The intensity and spectrum of nonthermal radiation from a cloud of oppositely charged drops as a possible explanation for the anomalous UHF radio noise originating from frontal clouds have been considered. It has been shown that the noise intensity is determined by the dimensions of charged particles and the particle electrification rate, which must equal 0.1–0.3 C/s km³. The radiation spectrum in the UHF range strongly depends on the resistance of microdischarge channels between drops. The frequency dependence of the radiation agrees with experimental data if R ≤ 377 Ω, i.e., if oscillations of the discharge current appear.     

Simulation of the impact of thunderstorm activity on atmospheric gas composition

A chemistry-climate model of the lower and middle atmosphere has been used to estimate the sensitivity of the atmospheric gas composition to the rate of thunderstorm production of nitrogen oxides at upper tropospheric and lower stratospheric altitudes. The impact that nitrogen oxides produced by lightning have on the atmospheric gas composition is treated as a subgrid-scale process and included in the model parametrically. The natural uncertainty in the global production rate of nitrogen oxides in lightning flashes was specified within limits from 2 to 20 Tg N/year. Results of the model experiments have shown that, due to the variability of thunderstorm-produced nitrogen oxides, their concentration in the upper troposphere and lower stratosphere can vary by a factor of 2 or 3, which, given the influence of nitrogen oxides on ozone and other gases, creates the potential for a strong perturbation of the atmospheric gas composition and thermal regime. Model calculations have shown the strong sensitivity of ozone and the OH hydroxyl to the amount of lightning nitrogen oxides at different atmospheric altitudes. These calculations demonstrate the importance of nitrogen oxides of thunderstorm origin for the balance of atmospheric odd ozone and gases linked to it, such as ozone and hydroxyl radicals. Our results demonstrate that one important task is to raise the accuracy of estimates of the rate of nitrogen oxide production by lightning discharges and to use physical parametrizations that take into account the local lightning effects and feedbacks arising in this case rather than climatological data in models of the gas composition and general circulation of the atmosphere.     

Simulating indirect effects that thunderstorm activity has on atmospheric temperature

A coupled chemistry-climate model of both lower and middle atmospheres is used to study variations in the temperature of the atmosphere when its chemical composition is disturbed due to thunderstorm activity, which results in variations in its local heating and cooling and in atmospheric heat and mass transfer. The results of model calculations showed that, due to variations in the lightning production of nitrogen oxides and resulting variations in the concentrations of atmospheric gases, the temperature varies mostly in the lower and middle stratospheres over both tropical and polar regions. On average, over a period of several decades, this effect quantitatively amounts to a few tenths of a degree; however, it can reach a few degrees at heights of the lower stratosphere over Polar regions. The level of the statistical significance of estimates exceeds 0.95 almost within all height ranges for the global lightning production (exceeding 6 TgN/year).     

Lifetime of the thunderstorm electric energy in the global atmospheric circuit and thunderstorm energy characteristics

The lifetime of electric energy in the atmosphere is introduced and investigated as is the total electric energy of the atmosphere related to the total mean rate of electric energy dissipation. This lifetime, as determined from general estimations and convenient analytical expressions, turns out to be very small – from about 10 to about 100 s, depending on the assumptions on the control parameters of principal sources in the global electric circuit. In particular the energy lifetime is less than the relaxation time of the “global condenser” and field relaxation time near the ground surface. It is explained by the high dissipative rate of the electric energy in the atmosphere, taking into account that the regions mainly contributing to the total energy and its dissipative rate are connected to the altitudes of active parts of electrified (thunderstorm) clouds in the atmosphere with exponentially increasing conductivity.     

Russian Studies of Atmospheric Electricity in 2015–2018

Izvestiya, Atmospheric and Oceanic Physics - The most significant results of Russian studies in the field of atmospheric electricity in 2015–2018 are reviewed. The review is a part of the...     

On the Contribution of Turbulence to the Electrification of Thunderclouds

The contribution of turbulence to the electrification of thunderstorm clouds is considered for the first time using a model of the large-scale electric field generation in a weakly conducting media containing two fractions of colliding hydrometeors. The calculation results are compared with experimental data. It has been found that scenarios of electric-field generation and growth are significantly different for inductive and noninductive charging mechanisms. The range of thundercloud parameters (of conductivity and particle radii) for which the electric field grows exponentially in the case of inductive charging has been found. In the case of noninductive charging, it has been shown that the electric field strength grows linearly in time due to intensive fluctuations of the electric charge. The linear growth of the electric field can be a significant factor when approaching the threshold of the discharge initiation.     

Generating electric-discharge layers in mesoscale convective systems

A system of quasi-hydrodynamic equations for the electric field, charges, and concentrations of cloud particles and light aeroions in stratified regions of mesoscale convective systems is proposed and analyzed numerically in a one-dimensional approximation. The important role of Debye-charge layers, which are caused by light ions, is established. It is shown that, under certain aerodynamic conditions, both noninductive and inductive melting-related charging of particles may cause a narrow intense positive-charge layer to form near the zero-temperature isotherm; the altitude at which the vertical velocity component changes sign with respect to the height of the zero-temperature isotherm is of particular importance. When consideration is taken for an inductive charging mechanism and the real structure of the rising flow’s velocity, the distributions of charges and field strength (with a peak of about 100 kV/m), which describe the profiles observed in experiments, form in about 30 min. Taking into account the polarization of melting aggregates and water drops in an electric field when aeroions attach to them causes the rate of generating electric-charge layers to reduce. Thus, the solutions obtained in this study describe the structure and dynamics of spatially separated regions of electric charges in the stratified region and offer a satisfactory explanation for the experimental data. The results are important for explaining the abnormally high lightning activity of mesoscale convective systems, their role in initiating charges in the middle atmosphere, and maintaining the quasi-stationary state of the global electric circuit.