Toward a Realistic Representation of Global Electric Circuit Generators in Models of Atmospheric Dynamics

Abstract

The diurnal variation of the global electric circuit (GEC) is simulated using the Weather Research and Forecasting model by estimating contributions of grid columns to the ionospheric potential (IP). A parameterization based on cutting off the grid columns with shallow convection and estimating the area covered by GEC generators (electrified clouds) in each column from the amount of precipitation yields the IP variation of the same shape as the classical Carnegie curve with a correlation coefficient of 0.97, although with a smaller peak‐to‐peak amplitude (18% against 34% of the mean) and maxima and minima shifted by 1–2 hr. It is shown that omission in the IP parameterization of either convective activity or the area covered by electrified clouds (estimated using the calculated precipitation) would result in poor similarity between the modeled IP variation and the classical Carnegie curve. The results of simulation show the best agreement with the Carnegie data during Northern Hemisphere winters; the shape of the simulated diurnal variation of the IP substantially changes throughout the year owing to the decrease of South America's contribution and the increase of Southern Asia's contribution in summer. The discrepancies between the results of modeling and the results of observations are probably caused by the limited ability of large‐scale models to differentiate between electrified and nonelectrified clouds. Further improvement of the parameterization of the IP in models of atmospheric dynamics requires using finer grids, which should allow computing microphysical characteristics of clouds and estimating source currents more accurately.

Electric Field Measurements in the Antarctic Reveal Patterns Related to the El Niño—Southern Oscillation

“…In order to shed further light on the results of measurements, it is useful to recall that the GEC is maintained by global electrified clouds, which implies that its variation can also be simulated on the basis of modeling the atmospheric dynamics (Mareev & Volodin, 2014). More precisely, grid cell contributions to the IP can be parameterized in terms of convection and precipitation (Ilin et al., 2020; Slyunyaev et al., 2019), which makes it possible not only to determine the total IP (perhaps the most fundamental measure of the GEC intensity) but also to decompose it as a sum of regional constituents, which may reveal the mechanisms behind the variation of the GEC (Slyunyaev et al., 2021b).…”

“…Figures 1e and 1f quantify the similarity between the results of measurements and the results of modeling, demonstrating that 2-h differences between the relative PG values and 2-h differences between the relative IP values behave similarly (a time shift of about 1-2 h between the variations of measured and modeled differences during 6:00-16:00 UTC is apparently related to shortcomings of simulations, which are inevitable on large-scale grids, where microphysical characteristics of clouds are not available and one cannot faithfully separate electrified clouds from nonelectrified ones; see Ilin et al, 2020).…”

“…To calculate the IP and regional contributions to it, we used the parameterization suggested by Slyunyaev et al (2019) on the basis of an earlier idea of Mareev and Volodin (2014); a detailed discussion of this parameterization can be found in Ilin et al (2020). The formula expressing the IP in terms of climate variables is included in Supporting Information S1 for this article, while here we just mention that the two most important features of this parameterization are (i) cutting off the grid columns with weak convective activity on the basis of convective available potential energy and (ii) estimating the area covered by electrified clouds (i.e., the generators of the GEC) in each column from the amount of precipitation.…”

“…Although such simulations with weather and climate models are known to generally underestimate the peak-to-peak amplitude of the diurnal variation of GEC parameters, they yield satisfactory results during Northern Hemisphere winters (see Ilin et al, 2020), which are most important for the ENSO. For this study, we calculated the total IP and regional contributions to it for the same October-February periods of 2006-2016, using the WRF model (Powers et al, 2017;Skamarock et al, 2019) and meteorological reanalysis data for the simulation of the atmospheric dynamics.…”

Radon Variability as a Result of Interaction with the Environment

“…The Global Electric Circuit (GEC) exists due to two major processes: creating the potential difference of nearly 250 kV between the ionosphere at altitude ~80 km and ground surface created by the global thunderstorm activity [78] and the existence of air conductivity which provides the fair weather vertical current from the ionosphere to the Earth's surface due to air ionization by external sources (galactic cosmic rays, solar proton events, magnetospheric electrons and protons, and solar electromagnetic emission) and an internal source, i.e., natural ground radioactivity, where radon plays the major role [14,79]. Modified from [7].…”