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Study of CME transit speeds for the event of 07-NOV-2004 |
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| Authors: | JL Culhane S Pohjolainen L van Driel-Gesztelyi PK Manoharan HA Elliott |
| Institution: | aMullard Space Science Laboratory, University College London, Holmbury St Mary, Dorking, Surrey RH5 6NT, UK bTuorla Observatory/VISPA, University of Turku, Finland cKonkoly Observatory of the Hungarian Academy of Sciences, Budapest, Hungary dObservatoire de Paris, LESIA, Meudon, France eRadio Astronomy Centre, Tata Institute of Fundamental Research, India fSouthwest Research Institute, San Antonio, TX, USA |
| Abstract: | Several methods for CME speed estimation are discussed. These include velocity derivation based on the frequency drifts observed in metric and decametric radio wave data using a range of coronal density models. Coronagraph height–time plots allow measurement of plane-of-sky and expansion speeds. These in turn can enable propagation speeds to be derived from a range of empirical relations. Simple geometric e.g., cone, models can provide propagation velocity estimates for suitable halo or partial halo events. Interplanetary scintillation observations allow speed estimates at large distances from the Sun detecting in particular the deceleration of the faster CMEs. Related interplanetary shocks and the arrival times and speeds of the associated magnetic clouds at Earth can also be considered. We discuss the application of some of these methods to the transit to Earth of a complex CME that originated earlier than 16:54 U.T. on 07-NOV-2004. The difficulties in making velocity estimates from radio observations, particularly under disturbed coronal conditions, are highlighted. |
| Keywords: | CME Speed Earth |
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