Last major update issued on September 22, 2011 at 04:45 UTC. Minor update posted at 14:55 UTC
[Solar and geomagnetic data - last month (updated
daily)]
[Solar wind and electron fluence charts (updated
daily)
[Solar cycles 21-24 (last update
September 1, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last
update September 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and
24 (last update September 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006
(last update April 5, 2007)]
[Archived reports since January 2003 (last update
September 1, 2011)]
[POES auroral activity level since October
2009 - updated September 21, 2011]
Annotated geomagnetic activity charts - Carrington rotation
2112 [July
2011] -
2113 [July-August
2011]
[Solar polar fields vs solar cycles - updated
June 27, 2011]
The geomagnetic field was quiet on September 21. Solar wind speed ranged between 331 and 370 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 144.2 (increasing 40.0 over the last solar rotation). The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.9). Three hour interval K indices: 01112222 (planetary), 11212212 (Boulder).
The background x-ray flux is at the class C1 level.
At midnight UTC the visible solar disk had 13 spotted regions (in 2K resolution SDO images).
Region 11295 [N23W49] developed a magnetic delta structure in the
northern part of the main penumbra. An M class flare is possible.
Flares: C1.9 at 07:41, C2.6 at 14:23, C2.7
at 14:38, C2.8 at 15:26, C2.0 at 20:36 UTC
Region 11296 [N25W30] decayed quickly and quietly.
Region 11298 [N16W41] decayed and could soon become spotless.
Region 11299 [S20W55] was quiet and stable.
Region 11300 [N24W86] rotated quietly to the northwest limb.
Region 11301 [N20E40] decayed slowly. Further C flares are possible. Flare:
C3.9/2F at 11:24UTC.
Spotted regions not numbered by NOAA/SWPC:
[S1222] emerged in the northeast quadrant on September 20. Location at
midnight: N22E10
[S1223] emerged in the southeast quadrant on September 20. Location at
midnight: S17E21
[S1225] emerged in the southeast quadrant on September 21. Location at midnight:
S15E42
[S1226] rotated partly into view at the northeast limb on September 21.
This region is hot and could produce a major flare, maybe even an X class flare.
Location at midnight: N11E85. Flare: M1.8 at
12:23 (wrongly attributed to region 11301 by SWPC)
[S1227] emerged in the northwest quadrant on September 21. Location at
midnight: N12W21
[S1228] emerged in the southeast quadrant on September 21. Location at
midnight: S17E08
[S1229] emerged in the southwest quadrant on September 21. Location at
midnight: S08W05
Minor update added at 14:55 UTC on September 22: Region 11302 (formerly S1226) produced a major long duration X1.4/2N event peaking at 11:01 UTC. An impressive full halo CME was observed in both STEREO-A and B. The CME was extremely wide and became full halo even in LASCO images. A flank impact from this CME is possible on September 25. As more of the region has rotated into view it appears to have the largest area of any sunspot group so far in cycle 24.
September 19-21: 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
An extension of the southern polar coronal hole rotated across the central meridian on September 21 and is likely too far to the south to cause geomagnetic effects. Another coronal hole in the northern hemisphere will likely rotate into an Earth facing position on September 23 and is probably too far to the north to become geoeffective.
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 mostly quiet on September 22-24.
| 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 | |||||
| 11292 | 2011.09.11 | N10W73 | plage | |||||||
| 11295 | 2011.09.11 2011.09.12 |
26 | 48 | N22W47 | 0380 | EHC | DKC |
 |
 |
beta-gamma-delta |
| 11296 | 2011.09.12 2011.09.13 |
4 | 2 | N26W29 | 0020 | CRO | HRX |
 |
 |
|
| 11299 | 2011.09.14 2011.09.16 |
4 | 8 | S20W53 | 0020 | CRO | CRO |
 |
 |
|
| 11298 | 2011.09.14 | 2 | 1 | N16W47 | 0010 | BXO | AXX |
 |
 |
location: N16W41 area: 0000 |
| 11300 | 2011.09.16 2011.09.18 |
2 | 1 | N24W86 | 0030 | CSO | HSX |
 |
 |
|
| 11301 | 2011.09.17 2011.09.18 |
10 | 24 | N20E41 | 0210 | ESO | DSO |
 |
 |
beta-gamma area: 0110 |
| S1222 | 2011.09.20 | 5 | N22E10 | 0000 | AXX |
 |
 |
|||
| S1223 | 2011.09.20 | 4 | S17E21 | 0010 | BXO |
 |
 |
|||
| S1224 | 2011.09.20 | N10E11 |
 |
plage | ||||||
| S1225 | 2011.09.21 | 1 | S15E42 | 0000 | AXX |
 |
||||
| S1226 | 2011.09.21 | 3 | N11E85 | 0500 | CKO |
 |
||||
| S1227 | 2011.09.21 | 1 | N12W21 | 0000 | AXX |
 |
||||
| S1228 | 2011.09.21 | 3 | S17E08 | 0000 | BXO |
 |
||||
| S1229 | 2011.09.21 | 1 | S08W05 | 0000 | AXX |
 |
||||
| Total spot count: | 48 | 102 | ||||||||
| Sunspot number: | 108 | 232 | (total spot count + 10 * number of spotted regions) | |||||||
| Classification adjusted SN: | 74 | 136 | (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): | 65 | 77 | 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 |
| 2010.06 | 72.5 | 13.6 | 16.4 (+0.9) | 8.17 / 6.85 |
| 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 | (36.2 predicted, +2.8) | 7.79 / 8.18 |
| 2011.04 | 112.6 | 54.4 | (39.1 predicted, +2.9) | 9.71 / 8.83 |
| 2011.05 | 95.8 | 41.6 | (42.4 predicted, +3.3) | 9.18 / 8.94 |
| 2011.06 | 95.8 | 37.0 | (46.1 predicted, +3.7) | 8.96 |
| 2011.07 | 94.2 | 43.9 | (50.3 predicted, +4.2) | 9.14 |
| 2011.08 | 101.7 | 50.6 | (54.4 predicted, +4.1) | 8.16 |
| 2011.09 | 127.2 (1) | 77.7 (2A) / 111.0 (2B) | (56.7 predicted, +2.3) | (11.14) |
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.
