Identifying Critical Input Parameters for Accurate Drag-Based Coronal Mass Ejection Arrival Time Predictions

Coronal mass ejections (CMEs) tend to cause the strongest geomagnetic storms so a major focus of space weather research has been predicting the arrival time of CMEs. Most arrival time models fall into two categories: (1) drag-based models that integrate the drag force between a simplified CME structure and the background solar wind and (2) full magnetohydrodynamic (MHD) models. Drag-based models tend to be much more computationally efficient than MHD models, allowing for ensemble studies or large parameter space explorations. While the errors have improved since the earliest modeled arrival times, currently both types of model have difficulty achieving average absolute errors less than about 10 hours. Here we use a drag-based model, ANTEATR (Another Type of Ensemble Arrival Time Results, Kay & Gopalswamy 2018), to explore the sensitivity of arrival times to input parameters. We consider CMEs of different scales from small, slow, and low mass to large, fast, and high mass. For each scale CME we perform ensembles varying the input parameters to reflect our observational uncertainty in each value. We determine which parameters are the most critical to know precisely for accurate arrival time predictions and how they change with CME scale. Finally, we show that the sensitivities derived from ANEATR results are representative of those of other drag-based models.