Space Weather Model Validations Using dBH/dt at High and Mid-Latitude Magnetometer Locations

As part to the model validation efforts performed at the Community Coordinated Modeling Center (CCMC), a Research-to-Operation (R2O) modeling challenge was started in 2010 to investigate the performance of first-principles and statistical models of the magnetosphere-ionosphere system to predict magnetic disturbances that can trigger geomagnetically induced currents. These models have to be able to run in real-time on a small-sized computer cluster in order to be able to support space weather operations. The outputs of the models are the horizontal magnetic perturbations ("delta-BH") at a given list of magnetometer stations that cover the high, middle and low latitudes. The "R2O challenge" is a continuation of the 2008 GEM challenge and involves the Space Weather Modeling Framework (SWMF), the OpenGGCM and the Lyon Fedder Mobarry (LFM) models of the global magnetosphere-ionosphere system and the Weimer and Weigel delta-BH specification models. These 5 models have been run for 6 events of at least a day's length that include 2 strong storms, 3 intermediate sized storms and one weak event. We compared model outputs with 12 magnetometers that were selected for the original 2008 GEM challenge. In this paper we describe the calculation of the delta-BH values for the magnetosphere-ionosphere models that include currents in the ionosphere, field-aligned currents and the magnetosphere portions of the simulations. To validate the calculations performed at CCMC we compared our results to delta-BH computed during run-time by the Space Weather Modeling Framework (SWMF) model. We present the role and intensity of the contributions to the delta-BH signal coming from the three current systems. The evaluation of the model results is based on an event-based metric using counts of how often the observed or modeled time derivative of delta-BH ("dBH/dt") exceeds a threshold at least once in each of the time windows that cover the storm events. The resulting contingency table (number of hits, false alarms, misses and predicted non-events) for each threshold value and window length is converted to a single skill, such as the Heidke Skill Score that will be used to select models for space weather operations.