engleski

Comparison between Linear and Quadratic Drag Models for ICME Propagation

In this paper, we have examined a recent issue what kinds of drag form (linear or quadratic drag) is proper for interplanetary coronal mass ejections (ICMEs). For this work, we have examined well-observed LASCO CMEs associated with DH Type II bursts satisfying the following conditions: (1) the CMEs speeds are larger than 600 km/s, (2) their longitudes are larger than 60 degrees, (3) the numbers of their LASCO data points are larger than 6, and (4) their accelerations are smaller than -1 m/s2. We find that their accelerations (Log a) in the LASCO field of view has a very good quadratic relationship with the CME relative speeds Log (Vcme-400) with the correlation coefficient of R=0.83, supporting the quadratic drag force. Another test has been made by applying two drag models to two well-observed STEREO/SECCHI events. As a result, we found that (1) while two speed profiles are well fitted by the quadratic drag model, one speed profile can not be fitted by the linear model ; (2) while the physical parameters for the quadratic model are well consistent with observations, the kinematic viscosity for the linear model should be four orders larger than its observed value. From this study, we conclude that the quadratic drag model for ICME propagation should be proper than the linear drag model.

Coronal mass ejections

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