地磁活动的InterHourly-Variability（IHV）指数及其在推导太阳风速度长期变化中的应用
The InterHourly-Variability (IHV) Index of Geomagnetic Activity and its Use in Deriving the Long-term Variation of Solar Wind Speed
摘要：
我们描述了地磁活动的时间变率（IHV）指数的推导。地磁要素的IHV指数是从每小时值中机械地导出的，每小时值是以当地午夜为中心的7小时间隔内相邻小时之间的无符号差异之和。该指数是分别得出的站在两个半球内的六个经度部门只使用当地夜间。它是一个长期的指标。现有的数据允许该指数的推导可以追溯到19世纪。在一个27天的Bartels旋转的时间尺度上，IHV平均校正地磁纬度小于55度的台站与中纬度范围指数密切相关。假设aa指数的恒定校准，我们发现，1957年之前观察到的aa的年度值是2.9 nT太小相比，从IHV使用基于1980年至2004年的回归常数计算的值。我们将这种差异解释为1957年之前aa指数的校准是错误的。ap索引没有这样的问题。IHV的旋转平均值与太阳风参数（BV ^2）也有很强的相关性。在一年的时间尺度上，结合IHV指数和最近开发的日间变率（IDV）指数（给出B），可以确定1890年至今的太阳风速度V。在120年的时间序列中，年平均太阳风速度从1902年的303 km/s的最低值到2003年的545 km/s的最高值。用B和V分别从IDV和IHV计算出的BV乘积的年值与从1926年以来极冠H分量日变化幅度和零星的BV乘积的年值在数量上一致（完全独立）。
英文摘要：
We describe the derivation of the InterHourly Variability (IHV) index of geomagnetic activity. The IHV-index for a geomagnetic element is mechanically derived from hourly values as the sum of the unsigned differences between adjacent hours over a seven-hour interval centered on local midnight. The index is derived separately for stations in both hemispheres within six longitude sectors using only local night hours. It is intended as a long-term index. Available data allows derivation of the index back well into the 19th century. On a time scale of a 27-day Bartels rotation, IHV averages for stations with corrected geomagnetic latitude less than 55 degrees are strongly correlated with midlatitude range indices. Assuming a constant calibration of the aa-index we find that observed yearly values of aa before the year 1957 are 2.9 nT too small compared to values calculated from IHV using the regression constants based on 1980-2004. We interpret this discrepancy as an indication that the calibration of the aa index is in error before 1957. There is no such problem with the ap index. Rotation averages of IHV are also strongly correlated with solar wind parameters (BV^2). On a time scale of a year combining the IHV-index and the recently-developed Inter-Diurnal Variability (IDV) index (giving B) allows determination of solar wind speed, V, from 1890-present. Over the ~120-year series, the yearly mean solar wind speed varied from a low of 303 km/s in 1902 to a high value of 545 km/s in 2003. The calculated yearly values of the product BV using B and V separately derived from IDV and IHV agree quantitatively with (completely independent) BV derived from the amplitude of the diurnal variation of the H component in the polar caps since 1926 and sporadically beyond.
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