A compact finite difference model for the global electric circuit

Erik Lehto
Numerical Analysis Group
Department of Mathematics
Royal Institute of Technology (KTH)


Electrical linkages within Earth's lower atmosphere are typically considered in terms of a global electric circuit (GEC), in which thunderstorms are driving an upward current from Earth's surface to the ionosphere, a highly conductive layer at an altitude of about 80 km, and the circuit is closed by a small downward current in the fair weather region. This downward current varies considerably with space and time due to variations in atmospheric conductivity, which in turn is affected by atmospheric chemistry, aerosols, solar radiation and other processes. The global electric circuit may influence, for example, cloud formation, global temperature change, and pressure within weather systems, and these effects are not taken into account in current climate simulations.

Constructing a numerical model for the global electric circuit is a challenging task, with obstacles such as topography, anisotropy, variable coefficients, singular sources, and boundary coupling to overcome. In this seminar, I will present initial work and results on a high-order compact finite difference model that is under development at the National Center for Atmospheric Research (NCAR) in Boulder, CO. The venture forms a part of the ECCWES project, which is an interdisciplinary collaboration between University of Colorado, Penn State University and NCAR.