Solar Terrestrial Activity Report

Last major update issued on November 3, 2011 at 05:15 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update November 1, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update November 1, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update November 1, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update November 2, 2011)]

[POES auroral activity level since October 2009 - updated November 2, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2114 [August-September 2011] - 2115 [September-October 2011] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to active on November 2. Solar wind speed ranged between 342 and 457 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 153.6 (increasing 29.7 over the last solar rotation). The planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 11.4). Three hour interval K indices: 33243212 (planetary), 23343311 (Boulder).

The background x-ray flux is at the class C1 level.

At midnight UTC the visible solar disk had 9 spotted regions (in 2K resolution SDO images).

Region 11330 [N06W80] rotated quietly to the northwest limb.
Region 11332 [N32W41] was quiet and stable.
Region 11334 [N13W18] decayed slowly and quietly.
Region 11335 [N18W08] decayed slowly and could soon become spotless.
Region 11336 [N13E27] decayed slowly and quietly.
Region 11337 [N18E38] was quiet and lost a few spots.
Region 11338 [S13E56] was quiet and stable.
Region 11339 [N19E72] rotated fully into view. This is a compact region with a very high flare potential. X class flares are possible, even X10+ events. The region has a significant magnetic delta structure in the central part and several small deltas elsewhere. Flares: C5.1 at 02:52, C2.2 at 06:50, C3.4 at 08:43, C3.2 at 10:48, C1.6 at 12:23, C2.7 at 15:56, C7.8 at 17:21, M4.3 at 22:01 UTC

Spotted regions not reported by NOAA/SWPC:
[S1304] emerged in the northeast quadrant on October 31. Location at midnight: N22W20

Coronal mass ejections (CMEs)

October 31 - November 2: No obviously Earth directed CMEs observed.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A small coronal hole (CH482) in the northern hemisphere was in an Earth facing position on October 31-November 1. A small coronal hole (CH484) in the northern hemisphere will rotate into an Earth facing position on November 3.

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.

Propagation

Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor. Propagation on long distance northeast-southwest paths is fair to good.

Forecast

The geomagnetic field is expected to be quiet to unsettled on November 3-6, mostly due to weak coronal hole effects.

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 green.
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.

Active solar regions

(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
detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
11330 2011.10.21
2011.10.22
2 6 N05W82 0210 CSO CHO

location: N06W80

area: 0320

11333 2011.10.23
2011.10.27
3   N10W71 0010 BXO       spotless

location: N16W67

SWPC has moved the region southwards to include the trailing spots of 11330

11332 2011.10.23
2011.10.24
1 1 N30W40 0010 AXX HRX location: N32W41
S1296 2011.10.27     N17W42           plage
11335 2011.10.28
2011.10.31
5 1 N17W11 0010 BXO AXX  
S1299 2011.10.28     N16W49           plage
11336 2011.10.29
2011.10.31
5 5 N12E26 0030 DRO CRO  
11334 2011.10.29
2011.10.30
6 6 N11W17 0080 CSO CSO location: N13W18
11337 2011.10.30
2011.10.31
3 6 N17E38 0010 BXO CRO  
11338 2011.10.31
2011.11.01
5 22 S14E54 0230 DAO DHO location: S13E56

area: 0350

S1304 2011.10.31   1 N22W20 0000   AXX  
11339 2011.11.01 4 34 N18E63 0560 DKC FKC area: ~2000

location: N19E72

Total spot count: 34 82  
Sunspot number: 124 172  (total spot count + 10 * number of spotted regions)
Classification adjusted SN: 62 126  (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): 74 77  k * (sunspot number). k = 0.6 for SWPC. k = 0.45 (changed from 0.33 on Nov.1) for STAR SDO

Monthly solar cycle data

Month Average measured solar flux International sunspot number (SIDC) Smoothed sunspot number Average ap
(3)
2008.07 65.7 (SF minimum) 0.5 2.8 (-0.4)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
3.25
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 41.8 (+4.9) 9.71 / 8.83
2011.05 95.8 41.6 (47.4 predicted, +5.6) 9.18 / 8.94
2011.06 95.8 37.0 (52.5 predicted, +5.1) 8.96 / 8.06
2011.07 94.2 43.9 (58.2 predicted, +5.7) 9.14 / 8.16
2011.08 101.7 50.6 (63.7 predicted, +5.5) 8.16 / 7.26
2011.09 133.8 78.0 (67.0 predicted, +3.3) 12.80 / 12.27
2011.10 137.3 88.0 (70.5 predicted, +3.5) 7.52
2011.11  146.1 (1) 8.42 (2A) / 126.5 (2B) (74.9 predicted, +4.4) (16.31)

1) Running average based on the daily 20:00 UTC observed solar flux value at 2800 MHz.
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.