Last major update issued on July 30, 2011 at 06:50 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 29. Solar wind speed ranged between 276 and 349 km/s. A weak disturbance was observed beginning at ACE near 13h UTC. Only a minor increase in geomagnetic activity was observed for the remainder of the day. The source of the disturbance is uncertain and may have been a low speed coronal hole stream.
Solar flux measured at 20h UTC on 2.8 GHz was 111.7 (increasing 26.1 over the last solar rotation). The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.3). Three hour interval K indices: 11002221 (planetary), 11003211 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight UTC the visible solar disk had 6 spotted regions.
Region 11260 appeared to be maturing as the leading penumbra became
large and symmetrical. Decay was observed elsewhere in the region. Polarities
are still mixed and there's a weak magnetic delta structure in the southeastern
part of the main penumbra. Although the region was much quieter than on the
previous day, M class flares are still possible.
Flares: C4.1 at 01:06, C1.1 at 05:33 UTC.
Region 11261 developed with many new spots emerging and a magnetic delta structure forming. Further M class flares are possible. Flares: C2.3 at 00:39, C1.0 at 02:24, C1.2 at 03:48, C1.1 at 04:35, C1.1 at 06:20, C1.4 at 08:07, C1.1 at 08:37, C3.9 at 12:17, C6.3/1F at 16:40, C3.2 at 18:02 UTC. The region was the source of a major, impulsive M9.3 flare at 02:09 on July 30. No CME was observed after the event.
Region 11263 did not change significantly and remains capable of producing an M class flare. Flare: C1.3 at 13:51 UTC
Spotted regions not numbered by NOAA/SWPC:
[S1141] emerged in the northeastern quadrant on July 27. Location at midnight: N18W27
[S1146] emerged in the southeastern quadrant on July 29. Location at midnight: S22E17
[S1147] emerged in the southwestern quadrant on July 29. Location at midnight: S24W17
July 27-29: 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 30 - August 1. If the stream from CH468 arrives there will likely be some unsettled and active intervals on July 30-31.
|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
|Total spot count:||48||99|
|Sunspot number:||88||159||(raw spot count + 10 * number of spotted regions)|
|Classification adjusted SN:||68||124||(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):||53||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
|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||92.7 (1)||59.6 (2A) / 63.8 (2B)||(49.4 predicted, +4.1)||(8.92)|
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.