Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 10, 2012 at 06:55 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 quiet to unsettled on June 9. Solar wind speed at SOHO ranged between 441 and 569 km/s. Solar wind speed increased after 16h UTC and a weak disturbance caused unsettled conditions for the remainder of the day and an increase in solar wind speed to near 500 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 128.3 (decreasing 2.2 over the last solar rotation). The Potsdam WDC planetary A index was 9 (STAR Ap - based on the mean of three hour interval ap indices: 9.0). Three hour interval K indices: 23222133 (planetary), 22212233 (Boulder).

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

At midnight UTC the visible solar disk had 13 spotted active regions (in 2K resolution SDO images).

Region 11493 [N15W65] decayed slowly and quietly.
Region 11494 [S17W45] decayed slowly and quietly.
Region 11497 [S22W73] decayed quickly and was quiet.
Region 11499 [N16W33] developed quickly in the central section as new flux emerged. While spots disappeared in other parts of the region the new spots have significant polarity intermixing. The region produced a number of small C flares, however, if the current rate of development is maintained, M class flares will become likely.
Region 11502 [S16W26] reemerged with a couple of tiny spots.
New region 11504 [S17E68] rotated into view at the southeast limb on June 8 and was numbered by SWPC the following day. The region has a weak magnetic delta structure in the trailing spot section. Flares: M1.9 at 11:32 (incorrectly attributed to AR 11499 by SWPC), M1.8 at 16:53 UTC
New region 11505 [S09E66] emerged with a few spots.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1715
[S26E43] developed slowly and quietly.
New region S1719 [S24E54] emerged with a few spots.
New region S1720 [N11E79] rotated into view. C flares are possible.
New region S1721 [N10E46] emerged with small spots in the northeast quadrant.
New region S1722 [S17W08] emerged with small spots.
New region S1723 [S27E29] emerged with tiny spots.

Coronal mass ejections (CMEs)

June 7-9: No obviously Earth directed CMEs were observed in LASCO or 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

No obvious coronal holes are currently in or near obviously 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.

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 poor to fair.

Forecast

The geomagnetic field is expected to be quiet to unsettled on June 10 and quiet on June 11-12.

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
11494 2012.05.30
2012.05.31
1 8 4 S17W45 0090 HKX CSO

area: 0220

11493 2012.05.30
2012.05.31
1 1 1 N15W66 0050 HAX HSX

area: 0160

11496 2012.05.30
2012.06.01
1     N16W48 0010 AXX      

merged with AR 11499

11497 2012.05.30
2012.06.01
6 5 3 S22W69 0080 CAO CRO

area: 0030

location: S22W73

11498 2012.05.31
2012.06.01
      N07W37         plage
S1703 2012.06.01       N13W54           plage
11499 2012.06.01
2012.06.03
7 44 20 N16W31 0060 CAO FRI beta-gamma
11502 2012.06.02
2012.06.04
  2   S17W30 0000   AXX   location: S16W26
11501 2012.06.04       N07W60           plage
S1709 2012.06.04       N13W15           plage
S1713 2012.06.06       N11W07           plage
S1715 2012.06.07   6 3 S26E43 0010   CRO  
11504 2012.06.08
2012.06.09
6 8 6 S17E67 0060 CAO DAO beta-gamma-delta

area: 0160

S1717 2012.06.08       S15W10         plage
S1718 2012.06.08       N34W16         plage
11505 2012.06.09 1 4 2 S09E63 0030 AXX DAO   location: S09E66
S1719 2012.06.09   4 1 S24E54 0010   BXO    
S1720 2012.06.09   3 2 N11E79 0080   DAO    
S1721 2012.06.09   2 1 N10E46 0000   AXX    
S1722 2012.06.09   2 2 S17W08 0010   BXO    
S1723 2012.06.09   2   S27E29 0000   AXX    
Total spot count: 23 91 45  
Sunspot number: 93 221 155  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 53 125 79  (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): 56 77 85 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
2012.06 129.7 (1) 37.3 (2A) / 124.2 (2B) (73.9 projected, +0.7) (13.89)

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.