Last major update issued on July 29, 2011 at 04:30 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2110 [May-June 2011] - 2111 [June-July 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was quiet on July 28. Solar wind speed ranged between 283 and 357 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 107.3 (increasing 19.7 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: 12000012 (planetary), 12001222 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight UTC the visible solar disk had 8 spotted regions.
Region 11260 developed slowly and could produce M class flares. The
magnetic delta structure weakened.
Flares: C2.5 at 00:26, C5.2 at 02:25, C1.6 at 05:08, C1.9 at 07:05,
C2.7 at 07:57, C1.5 at 10:59, C5.3/1N at 12:12, C4.1 at 15:27, C2.4 at 16:50,
C3.5 at 20:37 UTC.
Region 11261 is a compact region capable of producing M class flares. There's minor polarity intermixing. Flare: C1.6 at 18:15 UTC
Region 11262 decayed and was quiet.
New region 11263 rotated into view at the northeast limb on July 27 and was numbered by SWPC the next day. The region is compact and has minor polarity intermixing. An M class flare is possible.
New region 11264 emerged in the southeast quadrant on July 27 and got an SWPC number the next day. Slow decay was observed on July 28.
Spotted regions not numbered by NOAA/SWPC:
[S1127] reemerged on July 27. Location at midnight: N05W33
[S1141] emerged in the northeast quadrant on July 27. Location at midnight: N16E00
[S1145] emerged in the northwest quadrant on July 28 at the southern edge of CH468. Location at midnight: N30W20
July 26-28: No obviously earth directed CMEs were observed.
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 well defined recurrent coronal hole (CH468) in the northern hemisphere was in an Earth facing position on July 26-27. CH468 may be too far to the north to cause a geomagnetic disturbance. A poorly defined trans equatorial coronal hole was Earth facing on July 26-27.
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.
The geomagnetic field is expected to be mostly quiet on July 29-31. If the stream from CH468 arrives there will likely be some unsettled and active intervals.
|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
|4||3||S31E50||0010||BXO||BXO||formerly region S1138
formerly region S1143
|Total spot count:||34||86|
|Sunspot number:||84||166||(raw spot count + 10 * number of spotted regions)|
|Classification adjusted SN:||59||111||(Sum of raw spot count + classification adjustment for each AR. Classification adjustment: X=0, R=3, A/S=5, H/K=10)|
|Relative sunspot number (Wolf number):||50||55||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)|
|2010.04||75.9||8.0||14.0 (+1.7)||10.22 / 10.24|
|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||(30.6 predicted, +1.8)||4.32 / 5.51|
|2011.02||94.6||29.4||(32.6 predicted, +2.0)||5.41 / 6.44|
|2011.03||115.0||56.2||(35.2 predicted, +2.6)||7.79 / 8.18|
|2011.04||112.6||54.4||(38.1 predicted, +2.9)||9.71 / 8.83|
|2011.05||95.8||41.6||(41.4 predicted, +3.3)||9.18 / 8.94|
|2011.06||95.8||37.0||(45.2 predicted, +3.8)||8.96|
|2011.07||92.0 (1)||56.8 (2A) / 62.9 (2B)||(49.4 predicted, +4.1)||(9.05)|
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.