P(論文) In recent years (at least since 1978) a possible definition of a geoelectric index has been frequently discussed. This index, derived from experimental data, should give a useful description of the electrical state of the atmosphere to be referred to when dealing with various related studies. A likely variable to be used is the electrical potential of the upper atmosphere relative to the ground, and much discussion is about how to record it continuously. Another part of the discussion is about the importance of having such an index available in analogy with, for example, the geomagnetic index Kp. It is argued that more than one index will be desirable.