Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value Theory
Estimating the Occurrence of Geomagnetic Activity Using the Hilbert‐Huang Transform and Extreme Value Theory
复制标题
使用希尔伯特-黄变换和极值理论估计地磁活动的发生
DOI：
10.1029/2020sw002513
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发表时间：
2020
期刊：
影响因子：
3.7
通讯作者：
S. Elvidge
中科院分区：
文献类型：
--
作者：
S. Elvidge
本文用极值理论(EVT)估计了基于AA指数的地磁活动回归水平。AA指数是最长的、连续记录的地磁数据集(从1868年到现在)。这个长达150年的数据集是极值分析的理想候选者。然而，这些数据并不像EVT所要求的那样独立和均匀分布，因为它们受到大约11年一次的太阳周期的影响。利用希尔伯特-黄变换来识别数据中的太阳周期分量，并将数据分解为太阳最大和最小时间。在这两种情况下，广义极值分布都适用于数据集。还将这些数据合并在一起，以估计总的退货时间。结果表明，数据库中最大的事件(3月)是25年一遇的事件。然而，分开考虑太阳最大和最小次数对回归时间有很大的影响。在太阳活动极小期，1989年3月事件的返回时间为130年。这表明，极端空间天气事件的发生有条件地取决于我们在太阳周期中的位置。
In this paper extreme value theory (EVT) has been used to estimate the return levels for geomagnetic activity based on the aa index. The aa index is the longest, continuously recorded, geomagnetic data set (from 1868 to present). This long, 150‐year data set is an ideal candidate for extreme value analysis. However, the data are not independent and identically distributed as required for EVT since they are impacted by the approximately 11‐year solar cycle. The Hilbert‐Huang transform has been used to identify the solar cycle component in the data, and the data have been split into solar maximum and minimum times. In these two regimes the generalized extreme value distribution has been fit to the data sets. These have also been combined for an estimate of the overall return times. The results suggest that the largest event in the database (March 1989) is a 1‐in‐25‐year event. However, considering separate solar maximum and minimum times has a large impact on the return times. During solar minimum conditions the return time of the March 1989 event is 130 years. This suggests that the occurrence of extreme space weather events is conditionally dependent on where in the solar cycle we are.
过去五个太阳周期空间天气气候的可再现方面
影响因子：
3.7
作者：
Chapman S
通讯作者：
Chapman S