Measurements of global current density and electric field in urban environment

Results of continuous and simultaneous measurements of global current density (flowing between ionosphere and the earth) and electric field intensity (in the vicinity of the earth surface) are presented. The results were obtained in a measuring system placed 20 m above ground level. Using the continuity equation, the conductive and displacement components of current density (as well as conductivity of the atmosphere) were determined. It was found that the displacement part of the total current is much smaller in comparison to the conduction one. Analysis of measurement showed a high coincidence of the electric field derivative with the time course of the global current. Temporal courses of conductivity indicate the presence of space charge and suggests the continuity equation is supplemented with a space charge component. The calculated average value of the short-period (10 min long) current density was found to be on the level of 2-3 pA m−2 (average conductivity of the order of 15-20 fS m−1). At the same time period the average value of field intensity was on the level of 150-300 V m−1.