3:45 PM - 4:00 PM
[PEM16-02] Validation of initial Parameter dependence of CME Propagation and its Time of Arrival at Earth in SUSANOO-CME
Keywords:Solar wind, CME, Space weather, MHD simulation
Coronal mass ejections (CMEs) are known as eruptive solar plasma ejections and primary sources of magnetospheric disturbances on the Earth. Once strong southward magnetic fields arrive at the Earth accompanied with interplanetary CMEs (ICMEs), various disruptions of social infrastructures could be caused. In recent years, it has been demanded urgently to predict the arrival of interplanetary space disturbances at the Earth in advance. Global heliospheric magnetohydrodynamics (MHD) simulation models have been developed and improved to predict the time of arrival (ToA) of ICMEs to the Earth accurately. However, the ToA predicted by such models have uncertainties because of the accuracies of their initial parameters determined by observations. Especially, for the models that reproduce the flux-lope structures similar to the observed CMEs, it is suggested that the initial parameters related to magnetic field structure have significant influences on the ToA.
The purpose of this study is quantifying the contribution of magnetic parameters in the MHD models to the ToA. SUSANOO-CME is a heliospheric MHD model that reproduces the magnetic structure of CMEs by spheromak. In this study, we investigated the relationship between the magnetic flux within the spheromak and the predicted ToA by ensemble simulations using SUSANOO-CME for the first time.
We performed a large number of ensemble simulations also for various combinations of initial velocity, angular width, radial width of spheromak, and velocities of solar wind, in addition to magnetic flux. We calculated the duration that each simulated CME can reach at the Earth. As a result, we found qualitative varieties in propagation characteristics of CMEs depending on the combinations of the magnetic flux and other initial parameters. We also found that the magnetic flux parameter characteristics of the ToA differ depending on the velocities of the background solar wind.
In current observations, magnetic flux included in the CME is difficult to determine directly by remote sensing. This study focuses on a method to estimate magnetic flux included in CMEs indirectly obtained by statistical observation studies. The correlations between the soft X-ray peak flux during flares and photospheric magnetic flux lying below flare-ribbons or coronal dimming regions are reported by several studies. Utilizing these correlations, we estimated the uncertainty of the predicted ToA caused by the estimation errors of the magnetic flux based on observations for the first time. The results suggest that the uncertainty of the ToA caused by the errors of the magnetic flux parameters determined by the correlation between soft X-ray peak flux during flares and photospheric magnetic flux under the flare-ribbon region is approximately 19~48 hours. This implies that the uncertainty of magnetic flux estimated by current observations can cause significant deviations for the forecast results.
We also introduce parameter diagrams which indicate relationships for the predicted duration time of CMEs and initial conditions of each simulation for the first time. These results could be an effective tool to reduce the simulation time in the real-time forecast.
The purpose of this study is quantifying the contribution of magnetic parameters in the MHD models to the ToA. SUSANOO-CME is a heliospheric MHD model that reproduces the magnetic structure of CMEs by spheromak. In this study, we investigated the relationship between the magnetic flux within the spheromak and the predicted ToA by ensemble simulations using SUSANOO-CME for the first time.
We performed a large number of ensemble simulations also for various combinations of initial velocity, angular width, radial width of spheromak, and velocities of solar wind, in addition to magnetic flux. We calculated the duration that each simulated CME can reach at the Earth. As a result, we found qualitative varieties in propagation characteristics of CMEs depending on the combinations of the magnetic flux and other initial parameters. We also found that the magnetic flux parameter characteristics of the ToA differ depending on the velocities of the background solar wind.
In current observations, magnetic flux included in the CME is difficult to determine directly by remote sensing. This study focuses on a method to estimate magnetic flux included in CMEs indirectly obtained by statistical observation studies. The correlations between the soft X-ray peak flux during flares and photospheric magnetic flux lying below flare-ribbons or coronal dimming regions are reported by several studies. Utilizing these correlations, we estimated the uncertainty of the predicted ToA caused by the estimation errors of the magnetic flux based on observations for the first time. The results suggest that the uncertainty of the ToA caused by the errors of the magnetic flux parameters determined by the correlation between soft X-ray peak flux during flares and photospheric magnetic flux under the flare-ribbon region is approximately 19~48 hours. This implies that the uncertainty of magnetic flux estimated by current observations can cause significant deviations for the forecast results.
We also introduce parameter diagrams which indicate relationships for the predicted duration time of CMEs and initial conditions of each simulation for the first time. These results could be an effective tool to reduce the simulation time in the real-time forecast.