The HandyMan's Guide to Solar/Geomagnetic Conditions

by Paul Harden, NA5N





Geomagnetic Indices and Conditions

Kp Index Ap Index Geomagnetic Field Conditions HF Noise Aurora 0 0 - 2 Very Quiet S1 - S2 None 1 3 - 5 Quiet S1 - S2 Very Low 2 6 - 9 Quiet S1 - S2 Very Low 3 12 - 18 Unsettled S2 - S3 Low 4 22 - 32 Active S3 - S4 Moderate 5 39 - 56 Minor Storm S4 - S6 High 6 67 - 94 Major Storm S6 - S9 Very High 7 111 - 154 SEVERE Storm S9+ Very High 8 179 - 236 SEVERE Storm BLACKOUT Extreme 9 300 - 400 EXTREMELY SEVERE BLACKOUT Extreme

Terms Kp Index Planetary K-Index, averaged over the past three hours and tends to be a measure of current conditions. Ap Index Planetary A-Index, 24-hour average and represents overall geomegnetic field conditions for the UTC day. HF Noise Approximate "S-Meter" noise level below 10Mhz. Aurora Approximate level of auroral activity.

"High" conditions usually extends to Latitude 45 degrees

"Very High" conditions usually extends to about Letitude 35 degrees

SOLAR WIND averages 350-450 km/sec and density less than 10 p/cm^3 greater than 500 km/sec or high density can trigger geomagnetic activity.

SHOCK WAVE from a solar flare or Coronal Mass Ejection (CME) arrives at the Earth about 55 hours after the solar event.





SOLAR FLARE CLASSIFICATIONS Flare Class Type of Flare HF Radio Effects Resulting Geomagnetic Storm A Very Small None None B Small None None C Moderate * Low Absorptons * Active to Minor M Large * High absorption * Minor to Major X Extreme * Possible Blackout * Major to Severe





Sunspot/Active Region Classifications



Sunspot Class Description of the Active Region Potential for Flare Activity Alpha Unorganized, unipolar magnetic fields Little threat, but watched for growth. Beta Bipolar magnetic fields between sunspots C class flares and posssible large M class. Delta Strong, compact bipolar fields between spots High potential for M or X class major flare, Major Flare Alert issued.

This was contributed by Paul Harden, NA5N

National Radio Astronomy Observatory

VLA/VLBA Radio Telescopes

Socorro, New Mexico

Email Paul at [email protected]

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