Electricity of the convective atmospheric boundary layer: Field observations and numerical simulation

The electric state of the middle-latitude convective atmospheric boundary layer (ABL) is investigated during a point in time when it is not disturbed by clouds, precipitation, mist, or industrial aerosols. A numerical model is developed that estimates the electroaerodynamic state of the convective ABL. The model is parameterized using results of field observations and laboratory experiments. According to the model, vertical profiles of atmospheric electric field strength, space charge density, electric conductivity, and atmospheric electric current density are calculated in the horizontally homogeneous approximation with a high space-time resolution.     

Radon volumetric activity and ion production in the undisturbed lower atmosphere: Ground-based observations and numerical modeling

The results of in situ ground-based observations of radon volumetric activity carried out at the Borok Geophysical Observatory of Schmidt Institute of Physics of the Earth of the Russian Academy of Sciences (58°04′ N; 38°14′ E) are presented. Modeling the characteristic diurnal variation in the ion production rate in the undisturbed midlatitude lower atmosphere above land is carried out. The Lagrangian stochastic model of turbulent transport is developed in application to determining the vertical profiles of radon activity for 222Rn and 220Rn isotopes and their radioactive decay products. The results calculated by the Lagrangian stochastic model are matched with the analytical solution for the free atmosphere. Based on the model, the estimate is obtained for the rate of radon outflow from the convective boundary layer to the free clear sky atmosphere. The implications of temperature stratification of the atmosphere for the vertical distribution of the ion production rate at the different radon emission rate are explored.     

Electric State of the Near-Surface Atmosphere according to the Results of Tethered Balloon Observations

The electric state of the near-surface atmosphere up to a height of 400 m is investigated using a tethered balloon with a measuring platform and a ground-based information-measuring complex of the Borok middle-latitude geophysical observatory. For the first time, measurements were taken simultaneously for vertical profiles of the atmospheric electric field, polar electrical conductivities, size distribution of aerosol particles, and the volume activity of radon, which have allowed estimating the average values and variability of the space charge density and conduction current in the atmosphere. The height dependence of the electric potential with respect to the Earth’s surface and electrical resistance of the near-surface atmospheric column under different conditions of the temperature stratification is studied.

     

Formation of electrically active layers in the atmosphere with temperature inversion

The dynamics of the electric field in the planetary boundary layer (PBL) is thoroughly studied from in situ observations of the aeroelectric field and the height profiles of the wind-velocity components in the conditions of temperature inversion and incipient convection. It is established that the formation of a layer with temperature inversion is accompanied by a positive trend in the intensity of the aeroelectric field and by the generation of short-period aeroelectric pulsations. The transfer of a spatially nonuniform space charge and the formation of electrically active layers in PBL are studied by numerical modeling. The response of the electric field to the motion of the space charges simulating the coherent structures of electrogasdynamical turbulence is investigated for the vicinity of the observation point. The key parameters of the model distributions of the space charge are analyzed. The linear dimensions of the model structures range from 20 to 500 m, and the density of the transported charge varies from 0.1 to 1 nC/m³. The layer containing the model structures is located at a height of 60–300 m. It is shown that the spatial distribution and the transfer of the space charge form the dynamical component of the aeroelectric field in the surface layer. The short-period aeroelectric pulsations are induced by the transfer of the spatially heterogeneous space charge in PBL, while the positive trend is due to the accumulation of the space charge below the inversion layer. When the inversion was recorded by a sodar, the intensity of the field at the onset of the convection increased at a rate of 100 V/(m h) on average.     

Global and Regional Electricity Components in Undisturbed Midlatitude Lower Atmosphere

The physical mechanisms determining the variability of the vertical profiles of electrical conductivity, space charge density, and electric field in the undisturbed midlatitude lower atmosphere are discussed. The influence of the global and local mesoscale processes on the variability of electrical conductivity and the main component of the atmospheric electric field is estimated. The sunrise effect is studied, estimates are obtained for the charge accumulation rate in the column of the lower atmosphere and the corresponding growth rate of the field strength close to the ground. It is shown that the increase in the average charge density is mainly due to the breakdown of the stable stratification of the atmospheric boundary layer and transformation of the vertical profile of electrical conductivity following the convective mixing of a radon and its daughter products.