Toward a comprehensive global electric circuit model: Atmospheric conductivity and its variability in CESM1(WACCM) model simulations

Citation:Jánský, J., and V. P. Pasko (2014), Charge balance and ionospheric potential dynamics in time-dependent global electric circuit model, J. Geophys. Res. Space Physics, 119, 10,184-10,203, doi:10.1002 An implicit time stepping is used to avoid a strict dielectric relaxation time step condition, and boundary conditions for Poisson's equation are implemented to allow accurate description of time evolution of the ionospheric potential. The concept of impulse response of GEC is introduced that allows effective representation of complex time dynamics of various physical quantities in the circuit using model results obtained for instantaneous deposition of a point charge. The more complex problems are then reconstructed using convolution and linearity principles. For a point charge instantaneously deposited at a typical thundercloud altitude the impulse response of the charge density shows induction of the same value and polarity charge at the ionospheric boundary, while charge of the same value but opposite sign is moving down logarithmically with time and neutralizes the source point charge on time scale corresponding to the dielectric relaxation time at altitude of the source point charge. The ionospheric potential is modified immediately with input of the source point charge based on free space solution of Poisson's equation. Then the ionospheric potential relaxes. It is shown that during formation of two main charge centers of the thundercloud, typically represented by a current dipole, the ionospheric potential can be determined from the difference of time integrals of two ionospheric potential impulse responses corresponding to charge locations at the opposite ends of the current dipole. For latitude-and longitude-independent conductivity model, the total charge on the Earth is exactly zero at all times. During cloud-to-ground lightning discharge, the ionospheric potential changes instantaneously by a value proportional to the charge moment change produced by lightning and then relaxes to zero. For a typical charge moment change of 35 C km and lightning frequency 10 s −1 , the ionospheric potential changes by 9.3 kV; this value agrees well with the results presented by Rycroft et al. (2007) and Rycroft and Odzimek (2010).

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“…This equality is verified numerically as the global resistance of the atmosphere is R a =234.9Ω and from equation we get

M_{IE}^{IR} (0)

=−234.2Ω. These values are also consistent with those recently published [ Baumgaertner et al , ]. Therefore, both models give consistent results.…”

Section: Resultssupporting

confidence: 91%

Charge balance and ionospheric potential dynamics in time‐dependent global electric circuit model

Jánský

Pasko

2014

JGR Space Physics

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“…A number of models of atmospheric electricity focus on the role of the conductivity distribution in the global circuit (Makino and Ogawa 1985;Tinsley and Zhou 2006;Zhou and Tinsley 2010;Baumgaertner et al 2013). It is a well-known fact that the conductivity of the air increases nearly exponentially with altitude, and that is why many models deal with a universal exponential vertical profile of the conductivity.…”

Section: Introductionmentioning

confidence: 99%

Influence of Large-Scale Conductivity Inhomogeneities in the Atmosphere on the Global Electric Circuit

Slyunyaev

Mareev

Калинин

et al. 2014

Journal of the Atmospheric Sciences

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Theoretical estimation of the influence of large-scale conductivity inhomogeneities on the global electric circuit and, in particular, on the ionospheric potential is considered. A well-posed formulation of this problem is presented, on the basis of which an approximate method is developed so as to take account of large-scale conductivity inhomogeneities. Under certain restrictions imposed on the distributions of the conductivity and the external current density, explicit approximate formulas for the ionospheric potential are derived. The approximation developed is shown to be equivalent to that of classical models of atmospheric electricity in which the atmosphere is divided into two or more columns and is replaced by a simple equivalent electric circuit. The effect of conductivity inhomogeneities located inside and outside thunderclouds is discussed and, in particular, it is demonstrated that taking account of the conductivity reduction inside thunderclouds leads to a substantial increase in the ionospheric potential. The results following from the approximate theory are compared with those obtained from direct numerical simulations. It is found that the suggested approximation qualitatively accounts for the dependence of the ionospheric potential on the parameters of the conductivity distribution, although the relative error may be significant, especially in the case of a substantial reduction in the conductivity inside thunderclouds.

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“…It can be an analytic function or a discrete data set output from a different numerical model, such as the Whole Atmosphere Community Climate Model (WACCM; for further details about how the conductivity is computed see Baumgaertner et al, 2013Baumgaertner et al, , 2014. In the latter case, the conductivity is interpolated to the node distribution used in this paper.…”

Section: Conductivitymentioning

confidence: 99%

A 3-D RBF-FD solver for modeling the atmospheric global electric circuit with topography (GEC-RBFFD v1.0)

et al. 2015

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Abstract. A numerical model based on radial basis functiongenerated finite differences (RBF-FD) is developed for simulating the global electric circuit (GEC) within the Earth's atmosphere, represented by a 3-D variable coefficient linear elliptic partial differential equation (PDE) in a spherically shaped volume with the lower boundary being the Earth's topography and the upper boundary a sphere at 60 km. To our knowledge, this is (1) the first numerical model of the GEC to combine the Earth's topography with directly approximating the differential operators in 3-D space and, related to this, (2) the first RBF-FD method to use irregular 3-D stencils for discretization to handle the topography. It benefits from the mesh-free nature of RBF-FD, which is especially suitable for modeling high-dimensional problems with irregular boundaries. The RBF-FD elliptic solver proposed here makes no limiting assumptions on the spatial variability of the coefficients in the PDE (i.e., the conductivity profile), the right hand side forcing term of the PDE (i.e., distribution of current sources) or the geometry of the lower boundary.

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Toward a comprehensive global electric circuit model: Atmospheric conductivity and its variability in CESM1(WACCM) model simulations

Cited by 45 publications

References 91 publications

Charge balance and ionospheric potential dynamics in time‐dependent global electric circuit model

Charge balance and ionospheric potential dynamics in time‐dependent global electric circuit model

Influence of Large-Scale Conductivity Inhomogeneities in the Atmosphere on the Global Electric Circuit

A 3-D RBF-FD solver for modeling the atmospheric global electric circuit with topography (GEC-RBFFD v1.0)

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