Solar Terrestrial Activity Report

Last major update issued on October 14, 2011 at 04:50 UTC.

[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 13. Solar wind speed ranged between 332 and 370 km/s.

Solar flux measured at 23h UTC on 2.8 GHz was 137.6 (decreasing 5.5 over the last solar rotation). The planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.1). Three hour interval K indices: 12021221 (planetary), 22111211 (Boulder).

The background x-ray flux is at the class B4 level.

At midnight UTC the visible solar disk had 11 spotted regions (in 2K resolution SDO images).

Region 11309 [N23W76] was quiet and stable.
Region 11312 [N23W42] was quiet and stable.
Region 11313 [S14W37] decayed slowly and was mostly quiet. Flare: C1.0 at 09:46 UTC.
Region 11314 [N27E22] added several small spots. There's a small chance of a major flare. Flare: C1.2/1F at 07:11 UTC.
Region 11315 [N21W32] added a few small spots.
Region 11316 [S12E30] appears to be maturing and was quiet.
Region 11317 [S27E42] was quiet and stable.
Region 11318 [N21W18] developed slowly and quietly.
Region 11319 [N11E29] developed slowly and was close to an EAI classification at midnight. Flares: C2.0 at 00:31, C1.3 at 03:05, C2.0 at 18:50 UTC.
New region 11320  [S22W36] emerged in the southwest quadrant.

Spotted regions not reported by NOAA/SWPC:
[S1251] reemerged with a couple of spots as it rotated to the southwest limb. Location at midnight: S21W80

Coronal mass ejections (CMEs)

October 11-13: 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 fair. Propagation on long distance northeast-southwest paths is poor.

Forecast

The geomagnetic field is expected to be quiet on October 14. Quiet to active with a chance of minor storm intervals is possible on October 15-16 due to effects from CH479.

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 N23W75 0070 HSX HSX

 

S1251 2011.10.03   2 S21W80 0000   AXX   poor limb image quality
11312 2011.10.03
2011.10.04
1 3 N23W42 0190 HSX CHO

area: 0320

11313 2011.10.04
2011.10.05
10 14 S14W38 0110 CSO CSO  
S1255 2011.10.06     S14W65           plage
S1257 2011.10.07     N11W06           plage
S1258 2011.10.07     S26W56           plage
11314 2011.10.08
2011.10.09
3 15 N27E21 0300 CKO CHO

area: 0400

11315 2011.10.09
2011.10.10
3 9 N19W31 0010 BXO BXO

location: N21W32

S1264 2011.10.09     N33W35           plage
11317 2011.10.10
2011.10.11
1 1 S27E41 0070 HSX HSX  
11316 2011.10.10
2011.10.11
10 19 S12E28 0310 DKI DHC

area: 0500

11319 2011.10.10
2011.10.12
11 23 N10E29 0080 CSO DAI beta-gamma

area: 0150

S1268 2011.10.10     N18E29            
S1269 2011.10.10     N18W48           plage
11318 2011.10.11
2011.10.12
4 6 N20W18 0050 DSO DSO  
S1271 2011.10.12     N07E12         plage
11320 2011.10.13 3 8 S22W39 0010 BXO BXO    
Total spot count: 47 101  
Sunspot number: 147 211  (total spot count + 10 * number of spotted regions)
Classification adjusted SN: 97 156  (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): 88 70  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
2011.10 128.3 (1) 42.8 (2A) / 102.2 (2B) (61.8 predicted, +1.5) (7.99)

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.