Measurements of the Atmospheric Electric Current Density by a Passive Horizontal Ring Antenna in the Surface Layer: Quasi-Stationary Approximation

We consider a quasi-stationary approximation for turbulent electrical processes in the atmospheric boundary layer and their recording by a passive horizontal ring antenna acting as a collector of atmospheric electric current. On the basis of large eddy simulation, variations in electrical variables are calculated and spatial correlation functions and the spectral density of fluctuations of the atmospheric-current density components are estimated along with the response of the collector current to local turbulent perturbations of the conduction-current density and an instantaneous change in the global potential difference between the ionosphere and the Earth’s surface. Based on the simulation results, we estimate the ratio of the total vertical atmospheric electric current density and the conduction current density at the height of the antenna location, which can be used to extrapolate the results of ground-based measurements beyond the atmospheric boundary layer. The results of direct observations of the atmospheric electric current density by the collector are compared with the results of synchronous observations of the atmospheric electric field and the electrical conductivity in the surface layer. The frequency spectra of the collector-measured and calculated fluctuations of electric current have a power-law decay with increasing frequency with indices that are consistent for measurements and model calculations in the range from −1.0 to −1.5.