Understanding shock dynamics in the inner heliosphere with modeling and Type II radio data: The 2010‐04‐03 event

Abstract

The 2010 April 03 solar event was studied using observations from STEREO SECCHI, SOHO LASCO, and Wind kilometric Type II data (kmTII) combined with WSA-Cone-ENLIL model simulations performed at the Community Coordinated Modeling Center (CCMC). In particular, we identified the origin of the coronal mass ejection (CME) using STEREO EUVI and SOHO EIT images. A flux-rope model was fit to the SECCHI A and B, and LASCO images to determine the CME's direction, size, and actual speed. J-maps from STEREO COR2/HI-1/HI-2 and simulations from CCMC were used to study the formation and evolution of the shock in the inner heliosphere. In addition, we also studied the time-distance profile of the shock propagation from kmTII radio burst observations. The J-maps together with in-situ data from the Wind spacecraft provided an opportunity to validate the simulation results and the kmTII prediction. Here we report on a comparison of two methods of predicting interplanetary shock arrival time: the ENLIL model and the kmTII method; and investigate whether or not using the ENLIL model density improves the kmTII prediction. We found that the ENLIL model predicted the kinematics of shock evolution well. The shock arrival times (SAT) and linear-fit shock velocities in the ENLIL model agreed well with those measurements in the J-maps along both the CME leading edge and the Sun-Earth line. The ENLIL model also reproduced most of the large scale structures of the shock propagation and gave the SAT prediction at Earth with an error of ~1+/- 7 hours. The kmTII method predicted the SAT at Earth with an error of ~15 hours when using n0 = 4.16 cm3, the ENLIL model plasma density near Earth; but it improved to 2 hours when using n0 = 6.64 cm3, the model density near the CME leading edge at 1 AU.