International Service of Geomagnetic Indices

The International Service of Geomagnetic Indices (ISGI) is in charge of the elaboration and dissemination of geomagnetic indices, and of tables of remarkable magnetic events, based on the report of magnetic observatories distributed all over the planet, with the help of ISGI Collaborating Institutes. The interaction between the solar wind, including plasma and interplanetary magnetic field, and the Earth's magnetosphere results in a transfer of energy and particles inside the magnetosphere. Solar wind characteristics are highly variable, and they have actually a direct influence on the shape and size of the magnetosphere, on the amount of transferred energy, and on the way this energy is dissipated. It is clear that the great diversity of sources of magnetic variations give rise to a great complexity in ground magnetic signatures. Geomagnetic indices aim at describing the geomagnetic activity or some of its components. Each geomagnetic index is related to different phenomena occurring in the magnetosphere, ionosphere and deep in the Earth in its own unique way. The location of a measurement, the timing of the measurement and the way the index is calculated all affect the type of phenomenon the index relates to. The IAGA endorsed geomagnetic indices and lists of remarkable geomagnetic events constitute unique temporal and spatial coverage data series homogeneous since middle of 19th century.

国际地磁指数服务（ISGI）负责地磁指数的编制与传播，以及显著磁事件表格的发布，这些工作基于遍布全球的磁观测站的报告，并在ISGI协作机构的协助下进行。太阳风（包括等离子体和星际磁场）与地球磁层的相互作用导致磁层内部能量和粒子的转移。太阳风特性高度多变，并直接影响到磁层的形状与大小、能量转移的量级以及能量耗散的方式。显而易见，磁变源的多样性导致了地面磁特征的高度复杂性。地磁指数旨在描述地磁活动或其某些组成部分。每个地磁指数都以其独特的方式与磁层、电离层以及地球深部发生的不同现象相关联。测量的位置、测量的时间以及指数的计算方式都会影响该指数所关联的现象类型。国际地磁与大气电联合会（IAGA）认可的地磁指数和显著地磁事件列表构成了具有独特时空覆盖的数据系列，这一系列自19世纪中叶以来一直保持同质性。