Solar Terrestrial Activity Report

Last major update issued on October 15, 2011 at 03:55 UTC. Updates during the next week will be irregular and maybe incomplete. On October 16 any update will be either very late or not at all.

[Solar and geomagnetic data - last month (updated daily)]
[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]

Recent activity

The geomagnetic field was quiet on October 14. Solar wind speed ranged between 334 and 407 km/s. A high speed stream associated with CH479 was observed arriving at ACE near 23:30 UTC and is causing a disturbance early on October 15.

Solar flux measured at 23h UTC on 2.8 GHz was 136.1 (decreasing 8.7 over the last solar rotation). The planetary A index was 2 (STAR Ap - based on the mean of three hour interval ap indices: 2.3). Three hour interval K indices: 00002111 (planetary), 00111110 (Boulder).

The background x-ray flux is at the class B6 level.

At midnight UTC the visible solar disk had 14 spotted regions (in 2K resolution SDO images).

Region 11309 [N23W86] rotated quietly to the northwest limb.
Region 11312 [N23W54] was quiet. A few small spots emerged and it appears that a weak magnetic delta structure has formed in the western part of the large penumbra.
Region 11313 [S14W53] decayed slowly and quietly.
Region 11314 [N28E09] added several small spots. There's a small chance of a major flare.
Region 11315 [N21W44] decayed slowly and quietly.
Region 11316 [S12E17] was mostly unchanged and has the potential to produce an M class flare.
Region 11317 [S26E30] added a few trailing spots and was mostly quiet.
Region 11318 [N21W33] decayed slowly and quietly.
Region 11319 [N11E17] developed further and has many spots with some polarity intermixing. There's a weak magnetic delta structure in a central penumbra. A minor M class flare is possible.
Region 11320  [S21W51] did not change significantly and was quiet.

Spotted regions not reported by NOAA/SWPC:
[S1268] reemerged with several tiny spots. Location at midnight: N21E12
[S1272] emerged in the northeast quadrant on October 14. The region has minor polarity intermixing. Location at midnight: N12E47
[S1273] emerged in the northeast quadrant on October 14. Location at midnight: N12E38
[S1274] emerged near the northwest limb on October 14. Location at midnight: N15W76

Coronal mass ejections (CMEs)

October 12-14: 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 trans equatorial coronal hole (CH479) was in an Earth facing position on October 12-13.

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.

Forecast

The geomagnetic field is expected to be quiet to active on October 15-16 with a chance of minor storm intervals due to effects from CH479. Quiet conditions are likely on October 18.

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
11309 2011.10.01
2011.10.02
1 1 N24W86 0060 HSX AXX

 

11312 2011.10.03
2011.10.04
1 5 N23W55 0270 HHX DKO

beta-gamma-delta

11313 2011.10.04
2011.10.05
5 5 S16W52 0080 DSO CAO  
S1257 2011.10.07     N11W19           plage
11314 2011.10.08
2011.10.09
6 15 N26E09 0280 CHO CHO

beta-gamma

area: 0400

11315 2011.10.09
2011.10.10
3 3 N20W44 0010 BXO BXO

 

S1264 2011.10.09     N33W48           plage
11317 2011.10.10
2011.10.11
1 4 S26E28 0070 HSX CSO  
11316 2011.10.10
2011.10.11
9 16 S12E15 0330 DHC DKC

area: 0450

11319 2011.10.10
2011.10.12
20 43 N09E16 0080 ESI EAI beta-gamma-delta

area: 0300

location: N11E17

S1268 2011.10.10   6 N21E12 0000   BXO    
11318 2011.10.11
2011.10.12
7 6 N20W31 0040 CSO CRO area: 0020
S1271 2011.10.12     N07W01           plage
11320 2011.10.13 4 8 S21W51 0030 CRO CRO  
S1272 2011.10.14   14 N12E47 0040   DRO   beta-gamma
S1273 2011.10.14   1 N12E38 0000   AXX    
S1274 2011.10.14   1 N15W76 0000   AXX    
Total spot count: 57 128  
Sunspot number: 157 268  (total spot count + 10 * number of spotted regions)
Classification adjusted SN: 115 182  (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): 94 88  k * (sunspot number). k = 0.6 for SWPC. k = 0.33 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 (41.1 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
2011.10 128.8 (1) 47.9 (2A) / 106.1 (2B) (61.8 predicted, +1.5) (7.58)

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.