High-time resolution of the low-latitude asymmetric disturbance in the geomagnetic field.

The low-latitude asymmetric disturbance field is investigated by means of a Fourier harmonic analysis performed on 2.5-min interspaced values of magnetic records from eight stations, in lieu of the hourly values used in Crooker and Siscoe's (1971) study. The major advantage of the higher time resolution is that substorm activity, which has a time scale of 1-2 hr, can be studied in detail. Data covering four active periods in 1965 and five active periods in 1967 are used.