High Resolution Geomagnetic Data

Digital Data

• SPIDR - 1-minute and hourly data values on-line
• 1-minute Values (Selected data and plots for STEP)
• Worldwide Observatory Hourly Values

Magnetic Indices

There are numerous indices of magnetic activity. The International Association of Geomagnetism and Aeronomy (IAGA) offically recognizes magnetic indices aa, Am, Kp, Dst, and AE. More information about the IAGA indices is available from ISGI - International Services for Geomagnetic Indices (off-site).

• AA* Index (Major magnetic storms list)
• Auroral Electrojet Index (AE) (High resolution and hourly data)
• Ap* Index (Major magnetic storms list)
• Disturbance Storm-Time (Dst) Index
• Proposed Est and Ist Indices
• Kp and Ap indices
• Geomagnetic Indices Bulletin

More information about magnetic indices is available from:

• GFZ Potsdam (off-site)
• WDC Geomagnetism, Kyoto
• WDC Geomagnetism, Copenhagen (off-site)
• Observatory de l'Ebro (off-site)

FTP Access

• to aa indices, k indices, pc index
• to Sudden Commencements

NGDC has a brief description of the Earth's magnetic field.