An Application of the Stereoscopic Self-Similar-Expansion Model to the Determination of CME-Driven Shock Parameters

TL;DR

This study applies the stereoscopic self-similar-expansion model to CME observations to estimate shock parameters and validate them against in-situ measurements, demonstrating the model's predictive capability.

Contribution

The paper demonstrates that CME-driven shock parameters can be inferred from stereoscopic observations using the SSSEM and validated with in-situ data, enhancing space weather prediction methods.

Findings

Good agreement between model-derived and in-situ shock parameters

Optimal fit with SSSEM half width of 40 degrees and uniform deceleration

Shock parameters can be estimated from time-elongation plots for space weather forecasting

Abstract

We present an application of the stereoscopic self-similar-expansion model (SSSEM) to Solar Terrestrial Relations Observatory (STEREO)/Sun-Earth Connection Coronal and Heliospheric Investigation (SECCHI) observations of the 03 April 2010 CME and its associated shock. The aim is to verify whether CME-driven shock parameters can be inferred from the analysis of j-maps. For this purpose we use the SSSEM to derive the CME and the shock kinematics. Arrival times and speeds, inferred assuming either propagation at constant speed or with uniform deceleration, show good agreement with Advanced Composition Explorer (ACE) measurements. The shock standoff distance $[\Delta]$, the density compression $[\frac{\rho_d}{\rho_u}]$ and the Mach number $[M]$ are calculated combining the results obtained for the CME and shock kinematics with models for the shock location. Their values are extrapolated to $\textrm{L}_1$ and compared to in-situ data. The in-situ standoff distance is obtained from ACE solar-wind measurements, and the Mach number and compression ratio are provided by the Harvard-Smithsonian Center for Astrophysics interplanetary shock database. They are $\frac{\rho_d}{\rho_u} =2.84$ and $M = 2.2$. The best fit to observations is obtained when the SSSEM half width $\lambda = 40 \deg$ and the CME and shock propagate with uniform deceleration. In this case we find $\Delta = 23 \textrm{R}_{\odot}$, $\frac{\rho_d}{\rho_u} =2.61$, and $M = 2.93$. The study shows that CME-driven shock parameters can be estimated from the analysis of time-elongation plots and can be used to predict their in-situ values.