Last major update issued on October 26, 2011 at 03:25 UTC.
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October 1, 2011)]
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(last update April 5, 2007)]
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Annotated geomagnetic activity charts - Carrington rotation
2113 [July-August
2011] -
2114 [August-September 2011]
[Solar polar fields vs solar cycles - updated
June 27, 2011]
The geomagnetic field was quiet to major storm on October 25. Solar wind speed ranged between 430 and 681 km/s. The disturbance that began on October 24 peaked between 23h on Oct.24 and 02h UTC on Oct.25 when the 3-hour planetary A index reached 132.
Solar flux measured at 20h UTC on 2.8 GHz was 138.8 (increasing 5.4 over the last solar rotation). The planetary A index was 33 (STAR Ap - based on the mean of three hour interval ap indices: 33.3). Three hour interval K indices: 66533221 (planetary), 55543222 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight UTC the visible solar disk had 8 spotted regions (in 2K resolution SDO images).
Region 11324 [N12W23] decayed further and was quiet.
Region 11325 [N16W00] decayed slowly and quietly.
Region 11327 [S22W52] was quiet and stable.
Region 11330 [N07E30] was mostly quiet and has M class flaring potential.
Flare: C1.7 at 20:19 UTC
Region 11331 [N08W86] developed further as it rotated to the northwest
limb.
Region 11332 [N31E62] was quiet and stable.
Spotted regions not reported by NOAA/SWPC:
[S1292] emerged just north of region 11330 on October 23. Location at midnight:
N15E40
[S1295] emerged in the southeast quadrant on October 25. Location at
midnight: S21E23
October 23-25: No obviously Earth directed CMEs observed.
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 coronal hole (CH481) in the southern hemisphere will be in an Earth facing position on October 25-26.
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. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet to unsettled on October 26-27. A high speed stream from CH481 could cause quiet to active conditions on October 28-29.
| 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 | |||||
| 11323 | 2011.10.16 2011.10.17 |
N25W53 | plage |
|||||||
| 11324 | 2011.10.17 | 30 | 25 | N12W26 | 0140 | EAI | BXI |
 |
 |
area: 0020 |
| 11327 | 2011.10.17 2011.10.20 |
4 | 6 | S21W54 | 0080 | CSO | DSO |
 |
 |
location: S22W52 |
| 11325 | 2011.10.19 | 11 | 21 | N15E03 | 0100 | DSO | CSO |
 |
 |
area: 0050 location: N16W00 |
| 11328 | 2011.10.20 | N17W48 |
 |
|||||||
| S1283 | 2011.10.20 | S06W50 | plage | |||||||
| 11330 | 2011.10.21 2011.10.22 |
12 | 18 | N08E31 | 0450 | EHO | EHO |
 |
 |
area: 0750 |
| S1288 | 2011.10.22 | S15W31 | plage | |||||||
| S1289 | 2011.10.22 | N20W22 | plage | |||||||
| S1290 | 2011.10.22 | N17W34 | plage | |||||||
| 11331 | 2011.10.22 2011.10.23 |
3 | 3 | N08W86 | 0030 | CRO | DAO |
 |
 |
area: 0080 |
| S1292 | 2011.10.23 | 2 | N15E40 | 0000 | BXO |
 |
 |
|||
| 11332 | 2011.10.23 2011.10.24 |
1 | 1 | N31E62 | 0060 | HSX | HSX |
 |
 |
|
| S1294 | 2011.10.23 | N27W03 | plage | |||||||
| S1295 | 2011.10.25 | 1 | S21E23 | 0000 | AXX |
 |
||||
| Total spot count: | 61 | 77 | ||||||||
| Sunspot number: | 121 | 157 | (total spot count + 10 * number of spotted regions) | |||||||
| Classification adjusted SN: | 94 | 107 | (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): | 73 | 52 | 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 | 138.8 (1) | 100.1 (2A) / 124.1 (2B) | (61.8 predicted, +1.5) | (8.35) |
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.
