Last major update issued on October 22, 2011 at 05:45 UTC. Minor update posted at 17:40 UTC.
[Solar and geomagnetic data - last month (updated
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update October 1, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update October 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update October 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update October 1, 2011)]
[POES auroral activity level since October
2009 - updated October 12, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2113 [July-August 2011] - 2114 [August-September 2011]
[Solar polar fields vs solar cycles - updated June 27, 2011]
The geomagnetic field was quiet on October 21. Solar wind speed ranged between 298 and 412 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 167.8 (decreasing 0.9 over the last solar rotation). The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 4.6). Three hour interval K indices: 22111121 (planetary), 13101221 (Boulder).
The background x-ray flux is at the class C1 level.
At midnight UTC the visible solar disk had 14 spotted regions (in 2K resolution SDO images).
Region 11314 [N28W82] rotated quietly to the northwest limb.
Region 11317 [S26W63] was quiet and stable.
Region 11319 [N10W80] decayed and rotated to the northwest limb. Flares: C1.5 at 13:44, C2.7 at 17:04 UTC
Region 11321 [S14W29] decayed slowly and quietly.
Region 11323 [N24W00] was quiet and stable.
Region 11324 [N13E28] has many small spots, however, some loss of penumbral area and a decrease in polarity intermixing has caused the region to become less active. Flare: C2.4 at 08:57 UTC
Region 11325 [N16E57] was quiet and stable.
Region 11326 [N17W48] decayed slowly and quietly.
Region 11327 [S19W02] developed slowly and could produce C flares.
Region 11328 [N19E08] was quiet and stable.
New region 11329 [S30W41] emerged in the southwest quadrant on October 20 and was numbered the next day by SWPC.
Spotted regions not reported by NOAA/SWPC:
[S1281] emerged in the southwest quadrant on October 19. Location at midnight: S18W84
[S1286] rotated into view at the northeast limb on October 21. Location at midnight: N07E81
[S1287] emerged in the northwest quadrant near the center of the solar disk on October 21. Location at midnight: N02W08
An M1.3 flare was recorded at 13:00 UTC, its source was probably region 11318 behind the northwest limb.
A large filament eruption was observed early on October 22 in the northwest quadrant. Although most of the ejected material is directed northwards, some of it could be heading towards Earth. If that's the case the CME will likely arrive on October 25.
Minor update posted at 17:40 UTC on October 22: After many relatively quiet days on the Sun, today has been a totally different story. The large filament eruption mentioned earlier today produced a full halo CME which is likely to impact Earth on October 25. Then region 11314 at the northwest limb produced a very long duration M1.3 event peaking at 11:10 UTC. This event was similar to the spectacular events produced by the same region when it was on the solar backside about 15-20 days ago and cause a big northwards moving wave and a large and bright CME. The CME is partial halo and has a slight chance of causing a flank impact in 4-5 days. Proton flux levels have increased slowly since the eruption and may reach event levels later today or sometime tomorrow.
October 19-21: No obviously Earth directed CMEs observed.
October 22: The CME observed early in the day could be partially Earth directed.
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 small coronal hole (CH480) in the northern hemisphere was in an Earth facing position on October 19-20.
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 fair.
The geomagnetic field is expected to be quiet to unsettled on October 22-24 due to weak coronal hole effects. On October 25 the CME observed on October 22 could arrive and cause unsettled to minor storm conditions.
|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:||74||138|
|Sunspot number:||184||278||(total spot count + 10 * number of spotted regions)|
|Classification adjusted SN:||132||199||(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):||110||92||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)|
|2010.07||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||36.9 (+3.5)||7.79 / 8.18|
|2011.04||112.6||54.4||(41.1 predicted, +4.2)||9.71 / 8.83|
|2011.05||95.8||41.6||(45.2 predicted, +4.1)||9.18 / 8.94|
|2011.06||95.8||37.0||(49.2 predicted, +4.0)||8.96|
|2011.07||94.2||43.9||(53.1 predicted, +3.9)||9.14|
|2011.08||101.7||50.6||(57.2 predicted, +4.1)||8.16|
|2011.09||133.8||78.0||(60.3 predicted, +3.1)||12.80|
|2011.10||136.5 (1)||83.6 (2A) / 123.4 (2B)||(61.8 predicted, +1.5)||(6.97)|
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.