Last major update issued on September 23, 2011 at 04:35 UTC.
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Annotated geomagnetic activity charts - Carrington rotation
2112 [July
2011] -
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June 27, 2011]
The geomagnetic field was quiet on September 22. Solar wind speed ranged between 344 and 412 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 150.8 (increasing 46.2 over the last solar rotation). The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.3). Three hour interval K indices: 10001012 (planetary), 11012222 (Boulder).
The background x-ray flux is at the class C1 level.
At midnight UTC the visible solar disk had 7 spotted regions (in 2K resolution SDO images).
Region 11295 [N23W62] is likely to produce further M class flares as
there's still a magnetic delta structure in the eastern part of the region.
Flares: C6.6 at 04:28, M1.1 at 10:00 (wrongly
attributed to region 11302 by SWPC), C4.0 at 20:20, C5.5 at 22:30, C4.1 at 23:56 UTC.
The region was the source of and M1.6/1N long duration event peaking at 02:00
UTC on September 23.
Region 11296 [N25W43] was quiet and stable.
Region 11299 [S20W68] decayed slowly and quietly.
Region 11301 [N20E27] was quiet. There's slight polarity intermixing to
the north of the leading penumbra.
New region 11302 [N13E76] rotated partly into view at the northeast limb
on September 21 and was numbered the next day by SWPC. Further X class flares
are possible as this is a magnetically complex region, particularly in the
trailing spot section. Flare: X1.4/2N long
duration event peaking at 11:01 UTC. The shock wave from this event was global (observed
in the corona all around the visible disk). The CME was very wide and was
observed as full halo in STEREO A and B and LASCO (asymmetrical). Due to its
origin near the northeast limb it is difficult to estimate the CME arrival time
at Earth. Proton flux levels have been increasing slowly since the event and a
proton event could start later today (possibly with contribution from events in
region 11295 as well)
Spotted regions not numbered by NOAA/SWPC:
[S1223] emerged in the southeast quadrant on September 20. Location at
midnight: S16E06
[S1227] emerged in the northwest quadrant on September 21. Location at
midnight: N12W33
September 20-21: No obviously Earth directed CMEs observed.
September 22: An unusually large and wide CME was observed after the X1.4
event in region 11302. While it is rare that limb events cause geomagnetic
storming, this CME could when it arrives, probably on September 25.
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 23-24. A CME arrival is possible on September 25 and could cause unsettled to minor storming.
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 | |||||
11295 | 2011.09.11 2011.09.12 |
19 | 33 | N22W62 | 0350 | EKC | EAC | beta-gamma-delta | ||
11296 | 2011.09.12 2011.09.13 |
1 | 1 | N26W44 | 0010 | AXX | AXX | |||
11299 | 2011.09.14 2011.09.16 |
2 | 3 | S19W64 | 0010 | BXO | BXO | location: S20W68 | ||
11298 | 2011.09.14 | N16W61 | ||||||||
11301 | 2011.09.17 2011.09.18 |
12 | 33 | N19E29 | 0120 | ESO | DSO | beta-gamma area: 0080 |
||
S1222 | 2011.09.20 | N22W03 | plage | |||||||
S1223 | 2011.09.20 | 4 | S16E06 | 0010 | BXO | |||||
S1224 | 2011.09.20 | N10W02 | plage | |||||||
S1225 | 2011.09.21 | S15E29 | plage | |||||||
11302 | 2011.09.21 2011.09.22 |
2 | 30 | N11E74 | 0480 | EKI | EHC | beta-gamma-delta location: N13E76 area: 0950 |
||
S1227 | 2011.09.21 | 1 | N12W33 | 0000 | AXX | |||||
S1228 | 2011.09.21 | S17W05 | plage | |||||||
S1229 | 2011.09.21 | S08W18 | plage | |||||||
Total spot count: | 36 | 105 | ||||||||
Sunspot number: | 86 | 175 | (total spot count + 10 * number of spotted regions) | |||||||
Classification adjusted SN: | 61 | 125 | (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): | 51 | 58 | 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 | 128.3 (1) | 80.6 (2A) / 109.9 (2B) | (56.7 predicted, +2.3) | (10.78) |
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.