Comparison of Dst forecast models for intense geomagnetic storms

We have compared six Dst forecast models using 63 intense geomagnetic storms (Dst ≤ -100 nT) that occurred from 1998 to 2006. For comparison, we estimated linear correlation coefficients and RMS errors between the observed Dst data and the predicted Dst during the geomagnetic storm period as well as the difference of the value of minimum Dst (ΔDst_min) and the difference in the absolute value of Dst minimum time (Δt_Dst) between the observed and the predicted. As a result, we found that the model by Temerin and Li (2002, 2006) gives the best prediction for all parameters when all 63 events are considered. The model gives the average values: the linear correlation coefficient of 0.94, the RMS error of 14.8 nT, the ΔDst _min of 7.7 nT, and the absolute value of t_Dst of 1.5 hour. For further comparison, we classified the storm events into two groups according to the magnitude of Dst. We found that the model of Temerin and Lee (2002, 2006) is better than the other models for the events having -100 ≤ Dst < -200 nT, and three recent models (the model of Wang et al. (2003), the model of Temerin and Li (2002, 2006), and the model of Boynton et al. (2011b)) are better than the other three models for the events having Dst ≤-200 nT.