[1] We have compared the prediction capability of two types of Sun-Earth connection models: (1) ensemble of physics-based shock propagation models (STOA, STOA-2, ISPM, and HAFv.2) and (2) empirical CME propagation (CME-ICME and CME-IP shock) models. For this purpose, we have selected 38 near-simultaneous pairs of coronal mass ejections (CMEs) and metric type II radio bursts. By applying the adopted models to these events, we have estimated the time difference between predicted and observed arrivals of interplanetary (IP) shocks and ICMEs at the Earth or L1. The mean absolute error of the shock arrival time (SAT) within an adopted window of ±24 hours is 9.8 hours for the ensemble of shock propagation models, 9.2 hours for the CME-IP shock model, and 11.6 hours for the CME-ICME model. It is also found that the success rate for all models is about 80% for the same window. The results imply that the adopted models are comparable in their prediction of the arrival times of IP shocks and interplanetary CMEs (ICMEs). The usefulness of these models is also discussed in terms of real-time forecasts, underlying physics, and identification of IP shocks and ICMEs at the Earth.

[1] We examine a possibility that metric type II solar radio bursts are all caused by coronal mass ejection (CME) generated shocks. For this we consider 129 type II flare events from February 1997 to October 2000 and examine their associations with SOHO/LASCO CMEs according to their temporal and spatial closeness using SOHO/EIT and GOES data. We then carefully inspected 26 CME-less events to examine if there are CME-related features in LASCO and EIT images. In addition we examined 28 limb type II CME events to compare the kinematics of coronal shocks with those of the CME fronts. Under the assumption that the observed type IIs are all generated by CME-related shocks, we determine the formation heights of the CME-associated type IIs using LASCO CME speeds and type II onset times. From these studies, we have found (1) a large fraction (81%) of the type II bursts have temporal and spatial association with CMEs, and the association increases as their source position approaches to the limb; (2) most of the events without the association are related with weak flares and/or disk events; (3) most of the events are super-Alfvenic with a mean speed of 900 km s À1 ; (4) the front heights of all CMEs except for a few events are in the range of 1 to 3 solar radii, which are consistent with the type II formation heights; (4) the onset time difference (CME-type II) of all events are within about ±1 hour, mostly À30 min to 10 min; (5) the CME speeds have a possible correlation (r = 0.6) with coronal shock speeds, when two outliers are excluded. Considering a possibility that some outliers could result from some effects such as the coronal shock generation at CME flanks and CME accelerations, our results show that most of the type II bursts can be explained by the CME origin.