Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 19, 2012 at 03:55 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 19, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to major storm on June 18. Solar wind speed at SOHO ranged between 427 and 577 km/s under the influence of CME effects.

Solar flux measured at 20h UTC on 2.8 GHz was 118.0 (decreasing 3.3 over the last solar rotation). The Potsdam WDC planetary A index was 22 (STAR Ap - based on the mean of three hour interval ap indices: 22.4). Three hour interval K indices: 56432221 (planetary), 45322212 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight UTC the visible solar disk had 7 spotted active regions (in 2K resolution SDO images).

Region 11504 [S17W52] decayed slowly and was mostly quiet.
Region 11506 [N10W43] was quiet and stable.
Region 11507 [S27W74] decayed quickly and quietly.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1732
[S17E16] developed slowly and quietly.
New region S1738 [N16E20] emerged with tiny spots.
New region S1739 [N11W01] emerged with tiny spots.
New region S1740 [S20E07] emerged to the southwest of S1732.

Solar flux could drop below 100 when AR 11504 rotates over the west limb in a few days' time. No large regions are visible in STEREO backside images for longitudes that will rotate into view over the next few days. Most backsided bright areas are in the southern hemisphere.

Coronal mass ejections (CMEs)

June 15-17: No obvious 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

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.

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 quit to unsettled on June 19 and quiet on June 20-21.

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
11507 2012.06.07
2012.06.10
5 6 4 S25W77 0080 CSO CAO location: S27W74
11504 2012.06.08
2012.06.09
7 12 7 S17W52 0690 EKC EHC

 

11505 2012.06.09 1     S13W52 0010 AXX     spotless
11506 2012.06.09
2012.06.10
2 10 1 N13W41 0010 CRO CRO

location: N10W43

11509 2012.06.10
2012.06.15
      S17W72         plage
11508 2012.06.13 1     S28W70 0030 HRX       part of AR 11507
S1729 2012.06.13       N17W38           plage
S1732 2012.06.16   3 1 S17E16 0010   CRO  
S1733 2012.06.16       N14W14           plage
S1734 2012.06.16       N23W54           plage
S1735 2012.06.16       S41W29           plage
S1737 2012.06.17       S15W40         plage
S1738 2012.06.18   2 1 N16E20 0000   AXX    
S1739 2012.06.18   2 1 N11W01 0000   AXX    
S1740 2012.06.18   1   S20E07 0000   AXX    
Total spot count: 16 36 15  
Sunspot number: 66 106 75  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 42 57 36  (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): 40 37 41 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
2012.06 131.9 (1) 70.3 (2A) / 117.1 (2B) (73.9 projected, +0.7) (15.51)

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.