Ensemble modeling to predict space weather impacts on the North American power grid

Errors in space weather predictions typically arise through inaccurate specification of initial conditions or boundary conditions, as well as model uncertainties that arise because the model only approximates the system it simulates. As part of a large, interdisciplinary project studying the impacts of extreme space weather events on power grid infrastructure we have recently developed a method to assess the effect of uncertainties in solar wind driving on the predictions from a modeling framework. We used the Space Weather Modeling Framework, coupling a global magnetohydrodynamic code with an ionospheric electrodynamics solver and an inner magnetosphere code, to simulate the geospace response to solar wind driving. Applying our perturbed input ensemble method also allows us to examine the uncertainty in predicted field quantities such as ground magnetic perturbations. Combining the spatiotemporal predictions of magnetic perturbations with a ground conductivity model we estimate geoelectric field. We then use the multiple realizations of geoelectric field to drive a model of the North American power transmission system, predicting geomagnetically induced currents and transformer heating across the power grid. We then examine the variability in system response to the different realizations of the same simulated event to begin to quantify the uncertainty.