Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 30, 2012 at 06:40 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 June 24, 2012)]

[POES auroral activity level since October 2009 - updated June 19, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on June 29. Solar wind speed at SOHO ranged between 353 and 438 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 117.4 (decreasing 11.7 over the last solar rotation). The Potsdam WDC planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 6.0). Three hour interval K indices: 11111123 (planetary), 11112213 (Boulder).

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

At midnight UTC the visible solar disk had 8 spotted active regions (in 2K resolution SDO images).

Region 11512 [S15W16] decayed slowly and was mostly quiet. Minor polarity intermixing is present.
Region 11513 [N16E33] lost some spots, however, a magnetic delta structure formed in the western part of the largest penumbra. Further M class flaring is possible. Flares: C6.7 at 01:25, M2.2/1B at 09:19 UTC as well as a few C flares below the C5 level.
Region 11514 [S15E30] added a few spots and was quiet. There's minor polarity intermixing.
Region 11515 [S17E45] developed into a compact region capable of producing M class flares. Flares: C4.6 at 04:14, C6.2 at 06:47 UTC
New region 11516 [N14E45] emerged on June 27 and got the attention of SWPC two days later. The region developed slowly on June 29.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1763
[N07W60] developed slowly and quietly.
New region S1764 [N20W23] emerged with a tiny spot.
New region S1765 [S28E22] emerged with tiny spots.

Coronal mass ejections (CMEs)

June 27-29: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.

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

A large recurrent trans equatorial coronal hole (CH521) will rotate into an Earth facing position on June 29 - July 1. 

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.

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 June 30. A high speed stream from CH521 could cause unsettled to minor storm conditions on July 1-3.

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
detected
Spot count Location at midnight Area Classification SDO / HMI 4K continuum
image with magnetic polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
2K 1K
S1745 2012.06.21       N20W23           plage
S1747 2012.06.22       S32W47         plage
11512 2012.06.24
2012.06.25
16 21 8 S16W16 0290 DKI ESO beta-gamma

area: 0260

S1751 2012.06.24       S13W36           plage
S1753 2012.06.25       S27E15           plage
S1754 2012.06.25       S18W26         plage
11513 2012.06.25
2012.06.26
8 14 6 N17E30 0100 DSO DSO beta-gamma-delta

area: 0180

location: N16E33

 

11514 2012.06.26
2012.06.27
11 29 14 S15E42 0060 DAO DRI beta-gamma

area: 0080

location: S17E45

11515 2012.06.26
2012.06.27
8 20 11 S17E43 0310 DKC EKC beta-gamma

area: 0550

location: S17E45

S1758 2012.06.26       N14W15           plage
S1759 2012.06.26       N19W29           plage
S1760 2012.06.26       N06W31         plage
11516 2012.06.27
2012.06.29
4 15 7 N13E43 0030 DRO DAO location: N14E45

area: 0090

S1762 2012.06.27       N03E12           plage
S1763 2012.06.28   3 2 N07W60 0010   BXO  
S1764 2012.06.29   1   N20W23 0000   AXX    
S1765 2012.06.29   2 1 S28E22 0000   AXX    
Total spot count: 47 105 49  
Sunspot number: 97 185 119  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 80 133 77  (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): 58 65 65 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
(3)
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
2012.06 119.5 (1) 85.2 (2A) / 88.1 (2B) (73.9 projected, +0.7) (12.04)

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.