Multi-station synthesis of early twentieth century surface atmospheric electricity measurements for upper tropospheric properties

摘要

The vertical columnar current density in the global atmospheric electricalcircuit depends on the local columnar resistance. A simple model for thecolumnar resistance is suggested, which separates the local boundary layercomponent from the upper troposphere cosmic ray component, and calculatesthe boundary layer component from a surface measurement of air conductivity.This theory is shown to provide reasonable agreement with observations. Oneapplication of the simple columnar model theory is to provide a basis forthe synthesis of surface atmospheric electrical measurements madesimultaneously at several European sites. Assuming the ionospheric potentialto be common above all the sites, the theoretical air-earth current densitypresent in the absence of a boundary layer columnar resistance can be foundby extrapolation. This is denoted the free troposphere limit air-earthcurrent density, J₀. Using early surface data from 1909 when noionospheric potential data are available for corroboration, J₀ is foundto be ~6 pA m−2, although this is subject to uncertainties in thedata and limitations in the theory. Later (1966–1971) European balloon andsurface data give J₀=2.4 pA m−2.