Last major update issued on October 24, 2011 at 04:20 UTC. Minor update posted at 19:05 UTC
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The geomagnetic field was quiet on October 23. Solar wind speed ranged between 270 and 345 km/s. A low speed stream associated with CH480 became the dominant solar wind factor late in the day.
Solar flux measured at 20h UTC on 2.8 GHz was 155.5 (increasing 7.3 over the last solar rotation). The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.1). Three hour interval K indices: 00011121 (planetary), 01111211 (Boulder).
The background x-ray flux is at the class B6 level.
At midnight UTC the visible solar disk had 10 spotted regions (in 2K resolution SDO images).
Region 11324 [N12E01] has many small spots and some polarity
intermixing. C flares are likely with a chance of a minor M class flare.
Flare: C2.5 at 11:47 UTC
Region 11325 [N15E28] was quiet and stable.
Region 11326 [N15W76] decayed slowly and quietly.
Region 11327 [S21W27] lost spots and regained penumbra on the leader
spots.
Region 11328 [N15W16] was quiet and stable.
Region 11330 [N08E57] was quiet and has M class flaring potential.
New region 11331 [N09W60] emerged in the northwest quadrant on October 22
and got an SWPC number the next day.
Spotted regions not reported by NOAA/SWPC:
[S1292] emerged just north of region 11330 on October 23. Location at midnight:
N15E65
[S1293] rotated partly into view at the northeast limb on October 23.
Location at midnight: N31E87
[S1294] emerged in the northeast quadrant on October 23. Location at
midnight: N27E23
Minor update added at 19:05 UTC on October 24: A strong solar wind shock was observed at ACE near 17:50 UTC, the arrival of the CME observed early on October 22. Minor to severe geomagnetic storming is possible for the end of today and the first half of October 25.
October 21 and 23: No obviously Earth directed CMEs observed.
October 22: A full halo CME was observed after a large filament eruption
in the northwest quadrant early in the day.
Coronal hole history (since late October
2002)
Compare today's report to the situation one solar rotation ago:
28 days ago
27 days ago
26 days ago
A small coronal hole (CH480) in the northern hemisphere was in an Earth facing position on October 19-20.
The above coronal hole map is based on a new method where coronal holes are detected automatically. The method may need some fine tuning, however, it has significant advantages over detecting coronal holes manually. The main improvement is the ability to detect coronal holes at and just beyond the solar limbs. Early results using this method for SDO images over a span of several weeks indicate a good match between coronal holes observed over the visible disk and their extent and position at the east and west limbs. Note that the polar coronal holes are easily detected using the new method, the extent and intensity of both holes are consistent with other data sources.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to unsettled on October 24 due to weak coronal hole effects. On October 25 the CME observed on October 22 could arrive and cause unsettled to active conditions with a chance of minor storm intervals until October 26.
Coronal holes (1) | Coronal mass ejections (2) | M and X class flares (3) |
1) Effects from a coronal hole could reach Earth within the
next 5 days. When the high speed stream has arrived the color changes to
green.
2) Effects from a CME are likely to be observed at Earth within 96 hours.
3) There is a possibility of either M or X class flares within the next 48
hours.
Green: 0-20% probability, Yellow: 20-60% probability, Red: 60-100% probability.
(Click on image for higher resolution image) Compare to the previous day's image
When available the active region map has a coronal hole polarity overlay where red (pink) is negative and blue (blue-green) is positive.
Data for all numbered solar regions according to the Solar Region Summary provided by NOAA/SWPC. Comments are my own, as is the STAR spot count (spots observed at or inside a few hours before midnight) and data for regions not numbered by SWPC or where SWPC has observed no spots. SWPC active region numbers in the table below and in the active region map above are the historic SWPC/USAF numbers.
Active region | Date numbered detected |
Spot count | Location at midnight | Area | Classification | SDO / HMI 4K continuum image with polarity overlay |
Comment | |||
---|---|---|---|---|---|---|---|---|---|---|
SWPC | STAR SDO | SWPC | STAR | Current | Previous | |||||
11321 | 2011.10.14 2011.10.15 |
S16W62 | plage | |||||||
11323 | 2011.10.16 2011.10.17 |
N25W25 | plage |
|||||||
11324 | 2011.10.17 | 26 | 61 | N12W00 | 0150 | EAI | FSI | beta-gamma | ||
11327 | 2011.10.17 2011.10.20 |
11 | 13 | S21W29 | 0130 | DAO | DAO | area: 0200 | ||
S1280 | 2011.10.17 | S15W38 | plage | |||||||
11325 | 2011.10.19 | 8 | 21 | N15E29 | 0180 | DAO | CAO |
|
||
11326 | 2011.10.20 | 3 | N16W76 | 0010 | BXO | |||||
11328 | 2011.10.20 | 5 | N17W20 | 0000 | AXX | location: N15W16 | ||||
11329 | 2011.10.20 2011.10.21 |
S29W69 | plage | |||||||
S1283 | 2011.10.20 | S06W24 | plage | |||||||
11330 | 2011.10.21 2011.10.22 |
5 | 14 | N08E60 | 0210 | EAO | EHO | location: N08E57 area: 0750 |
||
S1287 | 2011.10.21 | N02W34 | plage | |||||||
S1288 | 2011.10.22 | S15W05 | plage | |||||||
S1289 | 2011.10.22 | N20E04 | plage | |||||||
S1290 | 2011.10.22 | N17W08 | plage | |||||||
11331 | 2011.10.22 2011.10.23 |
2 | 3 | N11W60 | 0010 | BXO | CRO | |||
S1292 | 2011.10.23 | 1 | N15E65 | 0000 | AXX | |||||
S1293 | 2011.10.23 | 1 | N31E87 | 0080 | HSX | |||||
S1294 | 2011.10.23 | 1 | N27E23 | 0000 | AXX | |||||
Total spot count: | 52 | 123 | ||||||||
Sunspot number: | 102 | 223 | (total spot count + 10 * number of spotted regions) | |||||||
Classification adjusted SN: | 72 | 156 | (Sum of total spot count + classification adjustment for each AR. Classification adjustment: X=0, R=3, A/S=5, H/K=10) | |||||||
Relative sunspot number (Wolf number): | 61 | 74 | k * (sunspot number). k = 0.6 for SWPC. k = 0.33 for STAR SDO |
Month | Average measured solar flux | International sunspot number (SIDC) | Smoothed sunspot number | Average ap (3) |
---|---|---|---|---|
2008.07 | 65.7 (SF minimum) | 0.5 | 2.8 (-0.4) | |
2008.12 | 69.2 | 0.8 | 1.7 (-) sunspot minimum |
3.25 |
2010.07 | 79.8 | 16.1 | 16.7 (+0.3) | 6.31 / 5.15 |
2010.08 | 79.2 | 19.6 | 17.4 (+0.7) | 8.49 / 7.77 |
2010.09 | 81.1 | 25.2 | 19.6 (+2.2) | 5.33 / 5.45 |
2010.10 | 81.6 | 23.5 | 23.2 (+3.6) | 6.07 / 6.27 |
2010.11 | 82.5 | 21.5 | 26.5 (+3.3) | 4.80 / 5.50 |
2010.12 | 84.2 | 14.4 | 28.8 (+2.3) | 3.41 / 4.35 |
2011.01 | 83.6 | 19.1 | 31.0 (+2.2) | 4.32 / 5.51 |
2011.02 | 94.6 | 29.4 | 33.4 (+2.4) | 5.41 / 6.44 |
2011.03 | 115.0 | 56.2 | 36.9 (+3.5) | 7.79 / 8.18 |
2011.04 | 112.6 | 54.4 | (41.1 predicted, +4.2) | 9.71 / 8.83 |
2011.05 | 95.8 | 41.6 | (45.2 predicted, +4.1) | 9.18 / 8.94 |
2011.06 | 95.8 | 37.0 | (49.2 predicted, +4.0) | 8.96 |
2011.07 | 94.2 | 43.9 | (53.1 predicted, +3.9) | 9.14 |
2011.08 | 101.7 | 50.6 | (57.2 predicted, +4.1) | 8.16 |
2011.09 | 133.8 | 78.0 | (60.3 predicted, +3.1) | 12.80 |
2011.10 | 138.5 (1) | 92.2 (2A) / 124.2 (2B) | (61.8 predicted, +1.5) | (6.62) |
1) Running average based on the daily 20:00 UTC observed solar flux value at
2800 MHz.
2A) Current impact on the monthly sunspot number based on the Boulder
(NOAA/SWPC) sunspot number (accumulated daily sunspots / month days). The
official SIDC international sunspot number is typically 30-50% lower. 2B) Month
average to date.
3) Running average based on the preliminary daily SWPC ap indices.
Values in red are based on the official NGDC
ap indices.
This report has been prepared by Jan Alvestad. It is based on analysis of data from whatever sources are available at the time the report is prepared. All time references are to the UTC day. Comments and suggestions are always welcome.
SDO images are courtesy of NASA/SDO and the AIA, EVE, and HMI science teams.