ARLP041 Propagation de K7VVV:
October 5, 2001

Propagation Forecast Bulletin 41 ARLP041
From Tad Cook, K7VVV
Seattle, WA October 5, 2001
To all radio amateurs

ARLP041 Propagation de K7VVV

Solar flux and sunspot numbers were lower this week. This is no surprise, because the flux had reached a new high for this solar cycle during the previous week. Average daily sunspot numbers dropped over 45 points and solar flux was down over 25 points. Indicators that did not drop were those tied to geomagnetic stability. The average daily planetary A index increased by 16 points to 29.6. The most active days were Monday through Wednesday, when the planetary A index was 50, 43 and 53. The planetary K index reached a high of 7 on Wednesday, indicating a geomagnetic storm. For higher latitudes the peak day for geomagnetic activity was Tuesday, when Alaska's College A index was 82, and the College K index reached 8.

The geomagnetic activity was caused by a series of solar wind disturbances. In addition to absorption of HF signals over high latitude paths, there were some impressive aurora displays. Check for some dramatic photos.

Current predictions project solar flux decreasing to 185 on Friday, then increasing to 190 on Saturday and 195 on Sunday and Monday. Geomagnetic indices should be quiet to unsettled. The next peak in solar flux is projected around October 22 or 23. Flux values are expected to rise above 200 after October 14 and above 250 after October 19.

September 30 ended the third quarter of 2001. Now it is time to look at quarterly averages for sunspot numbers and solar flux. The numbers begin with the first quarter of 1999 and end with the third quarter of 2001. Average daily sunspot numbers were 96.1, 147.2, 137.9, 163.1, 168.9, 190.8, 187.4, 145, 147.3, 164.8 and 170.4. Average daily solar flux was 136.7, 145, 157.6, 175.2, 180.5, 182.9, 181.9, 173.3, 164.4, 166.7 and 175.5. Even after the recent record shattering daily solar flux for the current cycle, it still appears that solar flux had a broad peak throughout the first nine months of last year. But this year the trend was up, with higher average daily numbers in each quarter for both solar flux and sunspot numbers.

The monthly averages of daily numbers over the past few months show a steady rise in activity. Average daily sunspot numbers for July, August and September were 124.6, 159.4 and 229.1, and average daily solar flux was 131.3, 163.1 and 233.8.

The 2001 Oceania DX SSB Contest is this weekend. Here are some path projections.

Sunspot numbers for September 27 through October 3 were 279, 234, 233, 230, 289, 236 and 196 with a mean of 242.4. 10.7 cm flux was 269.5, 284.5, 239.5, 235.8, 216.5, 200.9 and 191.7, with a mean of 234.1, and estimated planetary A indices were 10, 13, 21, 17, 50, 43 and 53 with a mean of 29.6.