The Use of Geophysical Data in Studies of the Historical Solar-Terrestrial Environment

Recent studies of the solar-terrestrial environment for the past 500 years have necessitated the use of a variety of historical databases: nitrates in ice cores, knowledge of large volcanic eruptions, sunspot numbers, mid-latitude aurora and geomagnetic records. The nitrate data are being used to identify large solar proton fluence events. The volcanic record helps to provide time markers for the ice core. The records of major geomagnetic storms and mid-latitude aurora have been used for additional identification. We also know that the Earth’s magnetic field is evolving with a present rapid decrease in magnitude. In addition the wandering magnetic pole must be considered in ascertaining what was “mid latitude” in historic times versus “mid latitude” in 2000. We illustrate how these databases are being used in recent studies of historic solar proton events.