This paper, using the dataset of BBFs （bursty bulk flows） observed by two Cluster satellites C1 and C4, studies the difference between onset times of BBFs observed by C1 and C4. It is found that the onset time diffe...This paper, using the dataset of BBFs （bursty bulk flows） observed by two Cluster satellites C1 and C4, studies the difference between onset times of BBFs observed by C1 and C4. It is found that the onset time differences of most of BBFs observed by Cl and C4 are smaller than 60 s. The average onset time difference of BBFs of CI and C4 is 68.5 s. The probabilities of onset time difference of BBFs of C1 and C4 larger than 30, 60, 90 and 120 s are respectively 55%, 35%, 27% and 23%. The largest onset time difference of BBFs of C1 and C4 decreases with the increase of earthward component of maximum velocities of BBFs. The onset time difference of BBFs of C1 and C4 results from the velocity inhomogeneity inside the flow channel of BBF, which may be produced in propagation path and/or in source region of BBFs. Such a wide range of onset time difference of BBFs suggests that the velocity inhomogeneity inside the flow channel of BBF is various. These results are very important to the current study of substorm research based on THEMIS data because they indicate that it is impossible to determine the onset time of BBF with a single satellite.展开更多
利用尺度不变特征点的提取方法提取特征点,并对SIFT方法提取出的特征点用最近邻算法进行配准,在搜索最近邻特征点和次近邻特征点时使用了在K-D树搜索算法基础上进行改进的搜索算法BBF(Best Bin First)算法.实验证明该算法具有配准精度高...利用尺度不变特征点的提取方法提取特征点,并对SIFT方法提取出的特征点用最近邻算法进行配准,在搜索最近邻特征点和次近邻特征点时使用了在K-D树搜索算法基础上进行改进的搜索算法BBF(Best Bin First)算法.实验证明该算法具有配准精度高,鲁棒性好的特点.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 40931054 and 41174141)National Basic Research Program of China ("973" Program) (Grant No. 2011CB811404)
文摘This paper, using the dataset of BBFs （bursty bulk flows） observed by two Cluster satellites C1 and C4, studies the difference between onset times of BBFs observed by C1 and C4. It is found that the onset time differences of most of BBFs observed by Cl and C4 are smaller than 60 s. The average onset time difference of BBFs of CI and C4 is 68.5 s. The probabilities of onset time difference of BBFs of C1 and C4 larger than 30, 60, 90 and 120 s are respectively 55%, 35%, 27% and 23%. The largest onset time difference of BBFs of C1 and C4 decreases with the increase of earthward component of maximum velocities of BBFs. The onset time difference of BBFs of C1 and C4 results from the velocity inhomogeneity inside the flow channel of BBF, which may be produced in propagation path and/or in source region of BBFs. Such a wide range of onset time difference of BBFs suggests that the velocity inhomogeneity inside the flow channel of BBF is various. These results are very important to the current study of substorm research based on THEMIS data because they indicate that it is impossible to determine the onset time of BBF with a single satellite.
