Power Spectra of Geomagnetic Fluctuations between 0.4 and 40 Hz.
Abstract
Power spectra of the fluctuations of the geomagnetic field were obtained for the frequency range of 0.4-40 Hz using an optically pumped Cesium vapor magnetometer. The spectra display a gradual decrease in slope at low frequencies with zero slope occurring between approximately 5 Hz and 15 Hz followed by a slight increase in slope. Data was collected at local midnight (0000-0200), local morning (0800-1000) and local afternoon (1600-1800). The morning and afternoon specta exhibit what is believed to be a schumann resonance peak at 8.0 Hz. A peak at 2.2 Hz and its first harmonic (4.4 Hz) were also observed, but are believed to be a man-made phenomenon or a sensor related instrumentation effect. Considerable high frequency disturbances (20-40 Hz) were observed around local midnight and are believed to be ELF 'Sferics. A comparison between a magnetically disturbed day (Fredericksburg Index of 7+) and a quiet day (Fredericksburg Index of 2+) at the same time period (0800-1000) showed a difference of 7-9 dB in power spectral density.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1979
- Accession Number
- ADA074378
Entities
People
- Frederick William Clayton
Organizations
- Naval Postgraduate School