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摘要
Substorm research largely depends on the precise definition and the timing accuracy of the substorm onset used in various observations. At present, the substorms are studied mainly in two ways. One is the case study or statistical study by selecting substorm events from auroral images via visual inspection; and the other is examining, manually or automatically, some physical indices, such as the auroral electrojet (AE) index, SuperMAG electrojet (SME) index, Pi2, and positive bays. In this paper, we propose to automatically identify auroral substorm onset time from global Ultraviolet Imager (UVI) images. We first transformed the original UVI images into the MLT-MLAT rectangular coordinate system, and the bright bulge was determined with the spatial fuzzy c-means method. The proposed technique was tested using Polar UVI observations acquired from three months of the winter season in 1996-1997. The identified onset results were compared with the available manual statistical report made by Liou (J. Geophys. Res., 2010, 115: A12219), and the missed substorms and the extra identified events were analyzed in detail. The proposed method can easily provide the substorm candidates from massive UVI images for researchers to further explore the nature of auroral substorm.
- 出版日期2013-5
- 单位西安电子科技大学; 中国极地研究中心
