Statistical analysis of spatial and temporal variations in atmospheric electric fields from a regional array of field mills

Abstract

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.

Revisiting the long-term decreasing trend of atmospheric electric potential gradient measured at Nagycenk, Hungary, Central Europe

“…Regarding the last period, a similar decreasing trend in the PG has been reported based on the data of an array of field mills at the Kennedy Space Center (KSC, Florida, USA) (Lucas et al, 2017). The magnitude of the decrease between 2003 and 2009 is very alike at all three (NCK, KSC, andŚwider) locations (see Fig.…”

“…The PG reduction that is revealed in the corrected NCK data series after 1997 is present both in theŚwider measurements (after 2000) and in the PG data recorded by an array of field mills at the Kennedy Space Center in Florida, USA (Lucas et al, 2017). Coherent observations in three well separated stations suggest that this is a globally present trend.…”

“…The magnitude of the decrease between 2003 and 2009 is very alike at all three (NCK, KSC, andŚwider) locations (see Fig. 7 in (Lucas et al, 2017)). The fact that this decreasing 270 13 https://doi.org/10.5194/angeo-2021-7 Preprint.…”

An Array of Low‐Cost, High‐Speed, Autonomous Electric Field Mills for Thunderstorm Research

“…Originally, the near-surface GEC signal was researched over the oceans where the planetary boundary layer is relatively free of pollution, where the diurnal variation is known as the Carnegie curve after one of the geophysical survey vessel that first measured it (Harrison, 2012). Local perturbations to the GEC signal, especially within the boundary layer, have been discussed and documented (e.g., Anisimov et al, 2017;Lucas et al, 2017;Markson, 2007) In the presence of electrified clouds, the near-surface electric field is strongly influenced by the cloud's charge regions and lightning neutralization of charges, with fields that can easily increase from a few kV/m to tens of kV/m. EFM measurements of the local electric field can therefore be used to infer the charge distributions dynamically within thunderclouds and provide a better understanding of thundercloud electrification (e.g., Jacobson & Krider, 1976;Koshak & Krider, 1989;1994;Maier & Krider, 1986;Murphy et al, 1996).…”

“…Originally, the near‐surface GEC signal was researched over the oceans where the planetary boundary layer is relatively free of pollution, where the diurnal variation is known as the Carnegie curve after one of the geophysical survey vessel that first measured it (Harrison, 2012). Local perturbations to the GEC signal, especially within the boundary layer, have been discussed and documented (e.g., Anisimov et al, 2017; Lucas et al, 2017; Markson, 2007)…”