Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 15, 2012 at 05:00 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update June 2, 2012)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update June 2, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update June 2, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update May 3, 2012)]

[POES auroral activity level since October 2009 - updated June 10, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was very quiet on June 14. Solar wind speed at SOHO ranged between 305 and 405 km/s.

Solar flux measured at 23h UTC on 2.8 GHz was 140.4 (increasing 8.2 over the last solar rotation, the measurements at 17 and 20h UTC were enhanced because of the very long duration event in AR 11504). The Potsdam WDC planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 3.8). Three hour interval K indices: 11111111 (planetary), 11121111 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight UTC the visible solar disk had 6 spotted active regions (in 2K resolution SDO images).

Region 11504 [S17E02] developed and became more complex with multiple magnetic delta structures forming along the inversion line in the southeastern part of the region. A major flare is possible. Flares (above the C5 level): C5.0/1F at 11:12, very long duration M1.9/1N event peaking at 14:35 UTC. The latter event was associated with a symmetrical full halo CME.
Region 11505 [S11W01] developed and moved closer to AR 11504. If this development continues the two regions could merge within a couple of days. The two regions could interact to cause larger flares.
Region 11506 [N10E11] added some small spots and was otherwise quiet and stable.
Region 11507 [S28W22] merged with AR 11508 (reversing the premature decision to split them the previous day). The region is developing and could soon become a compact region. There's polarity intermixing and a chance of an M class flare.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
[S28W08] developed slightly and was quiet.
S1726 [S17W02] developed slowly and quietly.

Coronal mass ejections (CMEs)

June 12: A filament eruption began slowly to the northwest of AR 11507 at 14h UTC and later on expanded to include filaments across most of the southern hemisphere. A CME was observed over the eastern limb in STEREO-A images starting at 17:54 UTC and over the west limb in STEREO-B images.
June 13: A partial halo CME was observed after the M1.2 LDE in AR 11504. This CME could reach Earth on June 16.
June 14: A large symmetrical full halo CME was associated with the M1.9 LDE in AR 11504. This CME could reach Earth during the latter half of June 16.

Coronal holes

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

No obvious coronal holes are currently in or near potentially geoeffective positions. 

Coronal hole map

The above coronal hole map is based on a method where coronal holes are detected automatically. While the method may need some fine tuning, 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 this method, the extent and intensity of both CHs 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 fair. Propagation on long distance northeast-southwest paths is poor.


The geomagnetic field is expected to be quiet most of June 15. The CME observed on June 12 could arrive during the latter half of June 15 and cause unsettled to active conditions. The CME observed on June 13 could reach Earth on June 16 and cause unsettled to active conditions. The June 14 CME could reach Earth during the latter half of June 16 and cause active to severe storm conditions.

Coronal holes (1) Coronal mass ejection (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
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlay
2K 1K
11507 2012.06.07
15 53 28 S25W24 0080 DAO EAI

SWPC considers this to be two regions

location: S28W22

area: 0350

11504 2012.06.08
20 57 21 S16E01 0570 EKC EHC


area: 0950

location: S17E02

11505 2012.06.09 10 24 14 S10W02 0050 DAO DAC location: S11W01

area: 0170

S1719 2012.06.09   3   S28W08 0010   BXO  
11506 2012.06.09
7 22 11 N11E11 0070 CSO CSO

location: N10E11

S1721 2012.06.09       N11W21           plage
S1723 2012.06.09       S31W33           plage
S1726 2012.06.10   4 2 S16W16 0010   HRX  
S1727 2012.06.10       N10W58           plage
11508 2012.06.13 12     S28W20 0070 DSI      
S1729 2012.06.13       N17E14         plage
S1730 2012.06.13       N20W11         plage
S1731 2012.06.13       S15W33         plage
Total spot count: 64 163 76  
Sunspot number: 114 223 136  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 94 191 104  (Sum of total spot count + classification weighting for each AR. Classification weighting: X=0, R=3, A/S=5, H/K=10)
Relative sunspot number (Wolf number): 68 78 75 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 (changed from 0.45 on March 1, 2011) for STAR SDO 2K, k = 0.55 for STAR SDO 1K

Monthly solar cycle data

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)  
2008.12 69.2 0.8 1.7 (-)
sunspot minimum
2011.03 115.0 56.2 36.9 (+3.5) 8.18
2011.04 112.6 54.4 41.8 (+4.9) 8.83
2011.05 95.8 41.6 47.6 (+5.8) 8.94
2011.06 95.8 37.0 53.2 (+5.6) 8.06
2011.07 94.2 43.9 57.2 (+4.0) 8.16
2011.08 101.7 50.6 59.0 (+1.8) 7.26
2011.09 133.8 78.0 59.5 (+0.5) 12.27
2011.10 137.3 88.0 59.9 (+0.4) 8.28
2011.11 153.5 96.7 61.1 (+1.2) 5.55
2011.12 141.3 73.0 (64.3 projected, +3.2) 3.78
2012.01 132.5 58.3 (68.0 projected, +3.7) 7.15
2012.02 106.5 33.1 (71.3 projected, +3.3) 8.81
2012.03 114.7 64.2 (73.0 projected, +1.7) 16.08
2012.04 113.0 55.2 (73.2 projected, +0.2) 10.10
2012.05 121.5 69.0 (73.2 projected, +0.0) 8.75
2012.06 132.4 (1) 57.4 (2A) / 123.1 (2B) (73.9 projected, +0.7) (12.40)

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 quicklook and definitive Potsdam WDC ap indices. Values in red are based on the definitive international Potsdam WDC 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.