Date: December 13, 2024
Average Daily Sunspot Number: 104.4
Weekly Commentary on the Sun, the Magnetosphere, and the Earth's Ionosphere for December 12, 2024 from OK1HH:
"The high solar activity in October this year suggests that this may have been the peak of an 11-year cycle. This is not to say that solar activity will not continue to rise. On the contrary, it may well be that the first maximum of the cycle took place in October and that we can look forward to a second maximum. This could take place in 2025 or 2026 at the latest, but it will be followed by a decline.
"Solar activity in November was lower and December's is even lower. The expected geomagnetic disturbance, predicted for November 29, did not take place because the CME did not affect the Earth. However, the almost daily occurrence of moderate solar flares continued and a large flare occurred. It happened on December 8 at around 0906 UT. However, even after this eruption, no major geomagnetic disturbance followed, and the changes in ionospheric shortwave propagation were rather random."
Solar Activity in December
- Sun's Activity: The Sun is quieter in December, with no large sunspot groups in its photosphere.
-
Active Regions: The only major active regions are south of the solar equator, with an area about half of those seen in November.
- AR3917: The active area is slowly expanding, increasing the likelihood of a larger flare.
Earth's Ionosphere
-
Free Electrons: Increased concentrations of solar-origin free electrons have repeatedly affected the ionosphere in recent days.
- Effects: Slight rise in Maximum Usable Frequency (MUF), more pronounced scattering and attenuation in the ionosphere, negatively impacting longer shortwave bands.
Meteor Activity
-
Geminids Meteor Shower: More meteors are arriving at Earth, peaking around December 14.
- Sporadic E Layer: Increased frequency of sporadic E layer occurrences.
- Propagation: More frequent propagation through ionospheric waveguides, beneficial for QRP enthusiasts.
Predicted Solar Flux
| Date Range | Solar Flux |
|---|---|
| December 13 – 15, 2024 | 165 |
| December 16 – 17, 2024 | 160 & 165 |
| December 18 – 19, 2024 | 160 |
| December 20 – 22, 2024 | 175, 185, 190 |
| December 23 – 24, 2024 | 185 |
| December 25 – 26, 2024 | 180 |
| December 30, 2024 – January 2, 2025 | 180 |
Predicted Planetary A Index
| Date Range | A Index |
|---|---|
| January 13 – 14, 2025 | 5 |
| January 15 – 16, 2025 | 8 |
| January 17 – 20, 2025 | 5 |
| January 29, 2025 | 8 |
Important Links
- Flare Blasts South Africa: https://bit.ly/3Do6nJJ
- STCE Newsletter Online Version: STCE Newsletter
- STCE Newsletter PDF Version: Download PDF
Contact Information
Send your tips, reports, observations, questions, and comments to k7ra@rrl.net. When reporting observations, don't forget to specify the mode you were operating.
Additional Resources
- Shortwave Radio Propagation Information:
- Explanation of Bulletin Numbers: The Sun, the Earth, the Ionosphere
- Propagation Bulletins Archive: W1AW Bulletins Archive
- Propagation Tutorials: K9LA Tutorials
- Understanding Solar Indices (QST September 2002): Read Here
- ARRL Bulletins Subscription Instructions: Manage Subscriptions
Sunspot and Flux Data (December 5 – 11, 2024)
-
Sunspot Numbers: 101, 103, 91, 103, 94, 125, 114
Mean: 104.4 -
10.7 cm Flux: 174.6, 177.5, 182.5, 177.7, 172.5, 171.9, 160.5
Mean: 170.9 -
Estimated Planetary A Indices: 4, 8, 11, 7, 6, 13, 7
Mean: 8 -
Middle Latitude A Index: 3, 6, 9, 6, 6, 6, 10, 5
Mean: 7.3
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