Modeling Contributions of Continents and Oceans to the Diurnal Variation of the Global Electric Circuit

Abstract

Contributions of different land and ocean regions to the diurnal variation of the global electric circuit are simulated using the Weather Research and Forecasting model by estimating the ionospheric potential produced by thunderstorms and electrified shower clouds in each grid column. The model predicts that contributions from land regions have maxima at about 14:00–18:00 local time (LT), whereas contributions from oceans have maxima at about 2:00–6:00 LT, and different ocean regions show nearly the same relative diurnal variation. It is remarkable that contributions from ocean regions with many islands (Maritime Continent and Middle America) have maxima at both 14:00–18:00 and 2:00–6:00 LT.

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

“…The IP variation obtained from equation with the basic parameterizations of all factors is shown in Figure a (adapted from Slyunyaev et al, ). The IP is shown as a fraction of the mean; if we assume that in and require that the mean IP be equal to 240 kV, we need to choose nA m , which looks rather realistic.…”

“…(a) Simulated diurnal variation of the IP with the basic parameterization of all factors (A, blue). Adapted from Slyunyaev et al (). (b) Simulated IP variation (A, blue) and the classical Carnegie curve after Harrison () (B, red).…”

“…(b) Simulated IP variation (A, blue) and the classical Carnegie curve after Harrison () (B, red). Adapted from Slyunyaev et al (). (c)–(f) Comparison of the simulated diurnal variations of the IP corresponding to different seasons (A, blue) with the corresponding fits to the Carnegie data given by Harrison () (B, red) and Burns et al () (C, green).…”

“…Figure b, also taken from Slyunyaev et al (), compares the simulated IP variation with the classical Carnegie curve. More precisely, we use the four‐term harmonic fit obtained by Harrison () for the data of Cruise VII of the Carnegie ship, published by Torreson et al ().…”

“…It is usually thought that the shape of the Carnegie curve is primarily determined by continents, as thunderstorm activity over them has a noticeable diurnal variation, reaching its maximum around 16:00 local time; at the same time the contribution of oceans has a less pronounced variation (e.g., Mach et al, , Figure 14), although, according to simulations, they also have their own diurnal cycle with a maximum between 2:00 and 6:00 local time (Slyunyaev et al, , Figure 3). Figure compares contributions of different land and ocean regions to the IP simulated using equation with the basic parameterization (technically we just restrict the summation in to the grid columns pertaining to each particular region).…”