Last major update issued on August 27, 2011 at 05:15 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2111 [June-July 2011] - 2112 [July 2011] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was quiet on August 26. Solar wind speed ranged between 346 and 425 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 104.6 (decreasing 8.1 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: 10011121 (planetary), 00011212 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight UTC the visible solar disk had 10 spotted regions (in 2K resolution SDO images).
Region 11271 decayed further losing both spots and penumbral area.
Flares: C1.0 at 03:34, C2.3 at 13:13 UTC
Region 11274 was quiet and stable.
Region 11275 developed slowly and quietly.
Region 11277 was quiet and stable.
Region 11278 decayed slowly and was quiet.
Region 11279 added several small spots and was quiet.
New region 11280 emerged in the northeast quadrant on August 24 and was numbered by SWPC two days later.
Spotted regions not numbered by NOAA/SWPC:
[S1182] emerged in the southeast quadrant on August 25. Location at midnight: S19W05
[S1183] emerged in the northwest quadrant on August 26. Location at midnight: N23W58
August 24-26: No obviously Earth directed CMEs were observed in LASCO or STEREO imagery.
Coronal hole history (since late October
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
A recurrent coronal hole (CH473) in the northern hemisphere was in an Earth facing position on August 24-25.
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 fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet initially on August 27. A high speed stream from CH473 could arrive during the latter half of the day and cause quiet to active conditions until August 28. On August 29 mostly quiet conditions are likely.
|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
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
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with polarity overlay
|11276||2011.08.23||N20E07||region should be deleted, spot was the trailing spot of region 11274|
|11280||2011.08.24||3||9||N17E24||0030||CRO||DRO||formerly region S1181|
|Total spot count:||16||44|
|Sunspot number:||76||144||(total spot count + 10 * number of spotted regions)|
|Classification adjusted SN:||44||65||(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):||46||48||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
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|2010.05||73.8||8.7||15.5 (+1.5)||9.18 / 8.15|
|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||(33.6 predicted, +2.6)||5.41 / 6.44|
|2011.03||115.0||56.2||(36.6 predicted, +3.0)||7.79 / 8.18|
|2011.04||112.6||54.4||(39.4 predicted, +2.8)||9.71 / 8.83|
|2011.05||95.8||41.6||(42.7 predicted, +3.3)||9.18 / 8.94|
|2011.06||95.8||37.0||(46.5 predicted, +3.8)||8.96|
|2011.07||94.2||43.9||(50.6 predicted, +4.1)||9.14|
|2011.08||101.4 (1)||52.7 (2A) / 62.8 (2B)||(54.8 predicted, +4.2)||(8.72)|
1) Running average based on the daily 20:00 UTC observed solar flux value at
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.