Using ForeCAT to constrain the initial parameters of the 2010 August 14 CME in the low corona.

Abstract:

Forecasting a CME's Altered Trajectory (ForeCAT) is a model of the trajectory of coronal mass ejections (CMEs) (Kay et al. (2013, 2015)). ForeCAT models a CME as a torus, calculates magnetic pressure and tension forces and drag at grid points along the CME, and integrates these forces to calculate a complete trajectory. To do so, ForeCAT must assume models of CME mass and size evolution. Kay et al. (2015b) demonstrated that when approximating CME mass as constant and using observed angular widths to determine CME size evolution, ForeCAT successfully replicates the observed trajectory of the 2008 December 12 CME. Here, we use ForeCAT to replicate the observed trajectory of the 2010 August 14 CME assuming constant mass and constant angular width. We also find that ForeCAT can reproduce the observed trajectory when we assume an increasing mass with distance as the CME propagates, and when assuming a changing angular width. Under each of these assumptions, we calculate the reduced chi-squared between simulated and observed latitudes to constrain CME parameters such as drag coefficient, initial latitude and longitude, and initial speed of the CME. With this exploration we show that ForeCAT can constrain tightly the initial parameters of the CME in the low corona.