Validation of the space weather modeling framework using ground‐based magnetometers

Abstract

[1] Geomagnetically induced currents (GICs) can disrupt power grid operations, causing significant interference for many people; therefore, predictions of ground-based magnetic perturbations and their time derivatives are quite important. This study quantifies how well the University of Michigan's Global MHD code predicts approximately 150 ground-based magnetometer traces for a number of storm-time intervals. It is found that in order to accurately represent the magnetic perturbation, Biot-Savart integrals over the entire hemisphere are needed, especially when calculating the vertical component. The 4 May 1998 storm is examined in detail. The code compares well with some stations, quantified by a normalized root mean squared error and cross correlation, while missing even the general trends for other stations. When multiple magnetometer station perturbations are averaged together, the model does an adequate job in the north and vertical components but reverses the trends in the eastward component. The code does significantly better when comparing an AL-like index but does not have as strong a variation as the actual data. Comparison of dB/dt in a wide window rather than simultaneously shows better model performance in capturing events but worse in yielding false alarms. It is further found that the MHD code models the magnetic perturbations better in the summer hemisphere than in the winter hemisphere.Citation: Yu, Y., and A. J. Ridley (2008), Validation of the space weather modeling framework using ground-based magnetometers, Space Weather, 6, S05002,

Numerical considerations in simulating the global magnetosphere

“…This means that BATSRUS is a useful tool when studying different regimes within the solar system. As this study shows, and other validation studies have shown, BAT-SRUS is capable of accurately modeling the magnetospheric dynamics (e.g., Wang et al, 2008b;Yu and Ridley, 2008;Taktakishvili et al, 2007;Wang et al, 2008a;Welling and Ridley, 2010a;Yu et al, 2010). Further, BATSRUS is versatile enough that it can be used to simulate the magnetosphere under a wide variety of user needs (i.e., resolution, run-time, etc.…”

“…Figure 12 shows the most relevant solar wind and IMF inputs into the MHD code that were used as a time-dependent upstream boundary condition on the MHD simulation as it ran. The studies by Yu and Ridley (2008); Wang et al (2008b) and Welling and Ridley (2010a) show many validation results of this time period that demonstrate how the code compares against other data sets not shown here.…”

The response of the magnetosphere-ionosphere system to a sudden dynamic pressure enhancement under southward IMF conditions

“…Ground magnetic field perturbations are calculated from Hall currents over the entire hemisphere by Biot-Savart integral, using the technique described by Yu and Ridley (2008). Figure 4 shows the ground perturbations at various magnetic local times and latitudes.…”

Reducing numerical diffusion in magnetospheric simulations

“…The simulated Dst index is calculated by the global magnetosphere model as the average value of the B z component of the magnetic field taken over a spherical surface at R = 3.0 R e . The simulated Dst index neglects the effect of currents inside 3 R e , but it still provides a reasonable approximation for the global magnetic perturbation (see Yu and Ridley [2008] for a detailed discussion). Finally, the in situ magnetic field values are obtained by interpolating the magnetic field from the global magnetosphere grid to the position of the satellite as it moves along its trajectory.…”