Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 3, 2012 at 07:05 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 2, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to active on June 2. Solar wind speed at SOHO ranged between 326 and 375 km/s. The interplanetary magnetic field swung moderately southwards between 15 and 22:30 UTC causing unsettled to active geomagnetic conditions.

Solar flux measured at 20h UTC on 2.8 GHz was 129.1 (increasing 11.5 over the last solar rotation). The Potsdam WDC planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 10.5). Three hour interval K indices: 11122334 (planetary), 11222323 (Boulder).

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

At midnight UTC the visible solar disk had 14 spotted active regions (in 2K resolution SDO images).

Region 11490 [S13W65] decayed slowly and quietly.
Region 11492 [S13W37] decayed slowly and quietly.
Region 11493 [N14E36] matured and produced the only interesting event of the day, a C1.5 flare at 04:31 UTC. This event was associated with a small CME off the east limb and was visible in both LASCO and STEREO imagery.
Region 11494 [S17E46] was quiet and stable.
Region 11495 [S16W05] decayed slowly and quietly.
Region 11496 [N15E47] developed slowly and quietly.
Region 11497 [S23E22] developed further and could produce at least C flares.
Region 11498 [N07E57] decayed slowly and quietly.

Spotted active regions not numbered by NOAA/SWPC:
S1696
[S27W70] developed slowly and quietly.
S1703 [N10E38] matured and was quiet. SWPC includes this in AR 11493.
S1704 [N13E61] decayed slowly and quietly.
New region S1705 [S18E70] emerged near the southeast limb with a single spot.
New region S1706 [N08W07] emerged with a single spot near CH520.
New region S1707 [N16W35] emerged with a tiny spot.

Coronal mass ejections (CMEs)

May 31 - June 2: 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

A large recurrent trans equatorial coronal hole (CH520) will be in an Earth facing position on June 1-4.

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 3. Unsettled to minor storm conditions are likely on June 4-6 due to effects from CH520.

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
11490 2012.05.23
2012.05.24
2 3 3 S13W65 0070 DSO CSO

 

11492 2012.05.24
2012.05.25
2 9 4 S13W37 0020 DSO DRO

 

S1682 2012.05.25       S22W40         plage
S1690 2012.05.26       S07W44           plage
S1691 2012.05.26       S26W51           plage
11495 2012.05.27
2012.05.31
5 9 3 S14E20 0100 DSO CRO

location: S16W05

area: 0020

Hard to make sense of SWPC data for ARs 11494 and 11495. Obvious errors are redlined

S1693 2012.05.28       S20W18         plage
S1694 2012.05.28       N09W33           plage
S1696 2012.05.29   6 2 S27W70 0020   CRO  
11494 2012.05.30
2012.05.31
3 5 3 S14E20 0100 DSO CSO area: 0180

location: S17E46

11493 2012.05.30
2012.05.31
8 12 7 N15E35 0140 DSO DSO beta-gamma

area: 0280

11496 2012.05.30
2012.06.01
6 11 7 N16E47 0100 DAI DAI

 

11497 2012.05.30
2012.06.01
5 19 10 S21E21 0060 DSO DAI

area: 0250

location: S23E22

11498 2012.05.31
2012.06.01
2 5 3 N08E55 0060 DSO CAO location: N07E57
S1702 2012.05.31       S27W19           plage
S1703 2012.06.01   10 6 N10E38 0050   DRO  
S1704 2012.06.01   13 6 N13E61 0040   CRO  
S1705 2012.06.02   1 1 S18E70 0010   HRX    
S1706 2012.06.02   1 1 N08W07 0000   AXX    
S1707 2012.06.02   1   N16W35 0000   AXX    
Total spot count: 33 105 56  
Sunspot number: 113 245 186  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 73 153 104  (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 86 102 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
2012.06 128.9 (1) 8.8 (2A) / 132.0 (2B) (73.9 projected, +0.7) (8.25)

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.