Mathematics – Logic
Scientific paper
Dec 2003
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2003agufmsh22b..03m&link_type=abstract
American Geophysical Union, Fall Meeting 2003, abstract #SH22B-03
Mathematics
Logic
7507 Chromosphere, 7509 Corona, 7513 Coronal Mass Ejections, 7519 Flares, 7531 Prominence Eruptions
Scientific paper
Solar filament disappearance (Disparition Brusque: DB) is often accompanied by a great magnetic activities such as flares and transient shock waves on and near the solar surface as well as enormous disturbances in interplanetary space due to the associated coronal mass ejection (CMEs). Thus, DBs are of great interest not only to solar physics research, but also to space science, and solar-terrestrial study. Since it is impossible to measure the velocity field of DBs with ordinal observations in the Hα line center alone, most previous studies have focused on the morphological signatures of DBs. In order to obtain the physical characteristics of DBs and relate them to other active phenomena, much effort is put into the calculation of their three-dimensional (3-D) velocity fields. Using the Hα line center, blue and red wing (Hα +/- 0.8 Å ) images obtained by the Flare Monitoring Telescope (FMT) at Hida Observatory, Kyoto University, and based on the Beckers' cloud model, we developed a new method to obtain the line-of-sight velocity of disappearing solar filaments. The line-of-sight velocity is obtained (i) by calculating the Hα line profile of the filament, and (ii) by measuring the Doppler shift which best fits the observed temporal variations of contrasts of the filament. The tangential velocity is obtained by tracing the motions of internal structures on successive images, and both line-of-sight and tangential velocities are combined to yield the 3-D velcoty field of DBs. In this method, corrections for the effective filter bandwidths of the instrument, stray light and Doppler brightening effect, are performed. Using the 3-D velocity field of DBs, we also developed a method to judge whether the DB was ejected into interplanetary space (eruptive) or remained in the corona (quasi-eruptive). The type of DBs are compared with the type of the associated coronal activites such as arcade formations observed in soft X-rays and EUV, CMEs and we conclude that the calculation of the three dimensional vector trajectories of disappearing filaments with our method can enhance the quality of space weather forecast and improve its accuracy.
Kurokawa Hiroki
Morimoto Takahiro
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