Mid-latitude atmospheric boundary layer electricity: A study by using a tethered balloon platform

In this study, we used a tethered balloon equipped with an instrumented platform to examine the altitude distribution of principal quantities of the lowest atmospheric region of the global electric circuit (GEC), radon volumetric activity, and aerosol particles concentration. Altitude soundings covered approximately 0.5 km of the lowest atmosphere and were accompanied by simultaneous ground-based measurements. This method of spaced observations allowed us to analyze the spatial and temporal changes in electrical quantities of the atmospheric boundary layer (ABL) more deeply than was possible before. Using successive balloon ascents and descents as well as holding the platform at certain heights, long-lived space charge layers were discovered and the rate of change of charge in atmospheric columns of various thickness was estimated. A charge density of small ions was determined to be enclosed in a range from -20 pC m(-3) to 30 pC m(-3) reaching the highest values with rare exceptions directly at the earth's surface. It was found that the electric field vertical profiles tend a decrease during the day most pronounced in the lower 100 m. Similar behavior is also demonstrated by radon and aerosol particle concentration profiles. Based on the results of soundings, columnar electrical resistance, electric potential, and electromotive force acting in the ABL in fair-weather conditions are quantified. These estimates show the significant contribution of the ABL to the GEC, which must be taken into account when considering it.