资源环境科技发展态势分析平台

Electric fields and currents of the global electric circuit have been measured at different locations and time periods around the globe, but a long-term analysis from a regional array of electric field mills has never been performed. Kennedy Space Center (KSC) in Florida has an array of over 30 electric field mills that have been continuously operating and archiving data for over 18 years. KSC is also instrumented with many meteorological towers. With this initial statistical analysis of a long-term data set four unique observations are reported that encompass global as well as local effects. To quantitatively describe the effects, a model to determine near-surface electric fields, incorporating space charge, and conductivity perturbations is developed. Statistical autonomous grouping of the mills using the spatial array demonstrates a greater than 50 V/m spatial variation from coastal to inland mills caused by wind-advected space charge generated near the coast. A temporal analysis identified a strong, globally generated, diurnal signature, but only a weak annual signal is found. A realistic limit on conductivity reductions within clouds is estimated by analyzing overhead cloud cover in relation to near-surface electric field strengths. The estimated in-cloud conductivity reduction of approximately 1/3 is similar to observations but appreciably less than values estimated from microphysical cloud estimates. Finally, an enhancement in the electric field at sunrise is statistically well correlated with low wind speeds and high relative humidities. This paper provides a statistical description of local environmental effects on near-surface electric fields by which to base future studies.