Electromagnetic Response Functions from Interrupted and Noisy Data

General methods for constructing reliable electromagnetic response functions from interrupted and noisy recordings of the naturally occurring electromagnetic variations are described. The aim is to be able to effectively utilize the 11 years of hourly mean electric and magnetic data (1932-42) from Tucson, Arizona, despite the many gaps and large extraneous values. This long-time series is extremely useful in helping one to focus on techniques that yield stable and reproducible response functions. The ultimate goal is to obtain accurate response functions in order to construct reliable earth electrical conductivity models and to determine the ocean fluid-induced part of the electromagnetic field. The Tucson electric field data is found to have diurnal and semidiurnal tidal frequencies most likely of oceanographic origin and a 6 d-1 peak of unknown origin.