Global circuit variability from multiple stratospheric electrical measurements

Abstract

In this paper we have examined the vertical component of the electric field, conductivity, and the derived current density from eight superpressure balloons. Special emphasis was placed on the fair‐weather, simultaneous measurements from widely spaced constant‐altitude (26 km) balloons. The conductivity measurements were well organized by a simple ionization rate parameterization depending on the geomagnetic latitude. The variability of all the electrical parameters was found to be independent of the balloon separation. Much of the time the current density measurements were within 20%, for simultaneous flights, even though the balloons were up to 6000 km apart. Also, these simultaneous current density data show that the global current source was significantly variable on hourly and daily time scales. Finally, the use of the simultaneous current density data are discussed as a possible “geoelectric index.” Advantages and limitations of such an index are discussed.