Last major update issued on August 6, 2011 at 06:20 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 to very severe storm on August 5. Solar wind speed ranged between 358 and 693 km/s. The August 2 CME which was observed arriving at SOHO at 21:11 UTC on August 4, caused a weak disturbance early in the day. At 17:22 UTC ACE observed another solar wind shock, most likely the arrival of the CME observed on August 3. At 18:32 UTC SOHO observed a much stronger solar wind shock, likely the arrival of the large and fast CME observed early on August 4. The interplanetary magnetic field was strongly to very strongly southwards following the arrival of the last CME causing severe geomagnetic storming.
Solar flux measured at 20h UTC on 2.8 GHz was 109.4 (increasing 23.8 over the last solar rotation). The planetary A index was 49 (STAR Ap - based on the mean of three hour interval ap indices: 49.4). Three hour interval K indices: 32001287 (planetary), 32011257 (Boulder).
The background x-ray flux is at the class B3 level.
At midnight UTC the visible solar disk had 5 spotted regions.
Region 11261 decayed further, still with no penumbra on the positive
Flares: C1.0 at 10:30, C1.4 at 19:45
Region 11263 did not display any major changes and remains capable of producing a major flare. Flare: C1.8 at 17:47 UTC
Region 11266 decayed and could become spotless today.
New region 11267 emerged in the southeast quadrant on August 4 and was numbered the next day by SWPC. The region developed slowly and could produce further C class flares. Flare: C1.3 at 06:07 UTC
Spotted regions not numbered by NOAA/SWPC:
[S1155] emerged in the northeast quadrant on August 5. Location at midnight: N18E48
August 3: A full halo CME was observed in LASCO and STEREO images
following the M6 event in region 11261 at 13:48 UTC.
August 4: A full halo CME was observed in LASCO images after the M9 event in region 11261 at 03:57 UTC.
August 5: 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 trans equatorial coronal hole (CH469) was Earth facing position on August 4-5, CH469 decayed significantly on August 5.
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 very poor. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be unsettled to major storm on August 6 due to CME effects. A high speed stream from CH469 could cause unsettled and active intervals on August 7-8.
|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
|11260||2011.07.24||1||N19W92||0180||HSX||rotated out of view|
formerly region S1153
|S1154||2011.08.04||N17W24||merged with region 11263|
|Total spot count:||44||60|
|Sunspot number:||94||110||(raw spot count + 10 * number of spotted regions)|
|Classification adjusted SN:||64||83||(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):||56||36||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||118.4 (1)||15.1 (2A) / 93.8 (2B)||(54.8 predicted, +4.2)||(13.71)|
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.