By mail-
NBS Radio Station WWV
2000 East County RD 58
Fort Collins, CO 80524
In addition, minutes 45-50 have no audio tones so that storm forecasts from WWVH can be heard.
On the 18th minute of each hour, information reguarding ionispherical conditions are reported. Here is some information on how these can be classified and what they mean.
1.) Solar activity is classified as:
Very Low- Usually only quiet regions on the solar disk and no more than five of these; fewer than ten class-C subflares without centimetric radio burst of SID observed or expected.
Low- Usually more than five but less than ten quiet regions on the solar disk; fewer than ten class-C subflares without centimetric radio bursts of SID observed or expected.
Moderate- Eruptive regions on the solar disk; fewer than five class M-X-ray events with centimetric radio bursts of SID observed or expected.
High- Active regions on the solar disk; several class-M X-ray events with centimetric radio bursts and strong SID; and/or one or two importance= 2 chromospheric flares or class X X-ray events observed or expected.
Very High- Region capable of producing protons on the sun; one or more chromospheric falres of importance-2 or greater; with outstanding centimetric radio bursts (500 flux units or greater), Class X X-ray bursts, and major SID observed or expected.
2.) The geomagnetic field is classified as:
Quiet- A <= 7, usually no K-indices> 2
3.) The geomagnetic storms are classified as:
Minor- 30 <= A <50, K-indices mostly 4 or 5
4.) Solar Flares-
Class C- any sorry X-ray burst with a peak flux at 1-8 angstroms of less than 1 microwatt PSM
5.) Major Solar-
Flare- a flare of optical importance (must be at least 2B bright) with a centimetric outburst of 500 flux units or more; or an X-ray event optical flare Ha flare.
6.) Satellite Level-
Proton Event- a proton enhancement detected by Earth orbiting satellites with measured particle flux of at least 10 protons per square centimeter per second per sterdian of at least 10 million electroncolts.
7.) Polar Cap-
Absorption- proton-included absorption at lease 2 dB as measured by a 30 MHz riometer within the polar cap
Propagation Forecasts-
Unsettled- 7 3
Active- 15 <= A <30 a few K-indices of 4>
Major- A > 50, some K-indices 6 or greater. Sudden commencements indicated by beginning time to nearest minute. Gradual commencement indicated by beginning time to nearest hour.
Class M- a solar burst with a peak flux at 1-8 angstroms, greater than or equal to 10 but less than 100 microwatts PSM
Class X- a solar X-ray burst with a peak flux at 1-8 angstroms, greater than or equal to 100 mircrowatts PSM
Proton Flare- Protons by satellite detectors (or polar cap absorption by riometer) have been observed in time associated with Ha flare.
Stratwarm- reports of stratpheric warnings in the high latitude regions of winter/hemisphere of the Earth associated with gross distortions of the normal circulation associated with the winter season.
Further information reguarding radio station WWV and atmospheric reports can be obtianed from the Nation Oceanic and Atmospheric Administration and the Space Environment Services Center.
R43, Boulder, CO 80303 or by phone at (303) 499-8129
The radio propagation forecasts on WWV were discontinued on September 30, 1976. Some of the information previously contained in these forecasts is now included in the Geophysical Alert announcements at 18 minutes after each hour. However, neither NBS nor the Space Environment Services Center which sponsors the Geophysical Alerts radio propagation predictions, nor do they maintain a literature file on the subject. Users interested in further reading material on the effect of solar and geophysical activity on should consult the latest edition of the Amateur Radio Handbook, published by the American Radio Relay League. ...73 DE Jamie, KG2JI
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