Midlatitude geomagnetic pulsations during the March 7, 1970, solar eclipse

Three-axis (H, D, Z) measurements of the earth's magnetic field were made at Crawford Hill, New Jersey (∼97% visual obscuration), during the March 7, 1970, solar eclipse. Any hope of detecting an eclipse-associated ionospheric effect by observing a decrease in H or an over-all change in D was eliminated by the occurrence of a disturbed geomagnetic period. Dynamic power spectral analysis was performed on 13 magnetic field pulsations observed in the period range 0.85–6.0 min prior to and during the eclipse. The results of these analyses indicate that there were no significant changes in the orientation of the major axis of the H-D ellipse during the period of the eclipse. This lack of a consistent change would appear to be compatible with the small E layer ionization changes measured during the eclipse period.