Solar Terrestrial Activity Report

Activity chart

Last major update issued on June 7, 2012 at 05:10 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 6. Solar wind speed at SOHO ranged between 590 and 775 km/s under the influence of a high speed stream from CH520.

Solar flux measured at 18h UTC on 2.8 GHz was 132.7 (increasing 2.0 over the last solar rotation, the measurement at 20h UTC was flare enhanced). The Potsdam WDC planetary A index was 19 (STAR Ap - based on the mean of three hour interval ap indices: 18.8). Three hour interval K indices: 44233343 (planetary), 34233443 (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 11492 [S14W83] developed as it rotated to the west limb.
Region 11493 [N15W22] was quiet and stable.
Region 11494 [S16W05] developed early in the day, however, the magnetic delta structure disappeared after the M class event. Flare: M2.1/1B at 20:06 UTC. This event was associated with both type II and IV radio sweeps. A CME was observed in both LASCO and STEREO imagery. While most of the ejected material has a southward direction, parts of the CME appear to be heading towards earth.
Region 11496 [N17W08] decayed slowly and quietly.
Region 11497 [S21W31] decayed slowly and quietly.
Region 11498 [N08E04] developed in the northern part and decayed in the southern section.
Region 11499 [N16E07] developed slightly with an increase in polarity intermixing due to the negative polarity area emerging centrally in the eastern half of this extensive region.
Region 11502 [S16E13] was quiet and stable.
Region 11503 [N10W55] decayed slowly and quietly.

Spotted active regions not numbered by NOAA/SWPC:
S1703
[N13W14] lost penumbral area and remained quiet.
S1709 [N13E37] was quiet and stable.
S1711 [S19W86] was quiet and stable.
New region S1713 [N11E34] emerged with a single spot.
New region S1714 [N27W49] emerged near the northern limit of CH520.

Coronal mass ejections (CMEs)

June 4: No obviously Earth directed CMEs were observed in LASCO or STEREO imagery.
June 5: A filament eruption near AR 11493 and close to the central meridian was observed beginning at 19:30 UTC. A small CME was observed at 20:39 UTC in STEREO-A.
June 6: A partial halo CME associated with an M2 flare in AR 11494 was observed from 20:39 UTC in LASCO images. This CME could reach Earth on June 9.

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) was 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 good.

Forecast

The geomagnetic field is expected to be quiet to unsettled on June 7-8 due to effects from CH520, occasional active intervals are possible. There's a slight chance of weak effects from the CME observed on June 5 late on June 8 or early on June 9. The CME observed on June 6 could reach Earth on June 9 and cause unsettled to active conditions with a chance of minor storming.

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
11492 2012.05.24
2012.05.25
  1 1 S18W87 0060   HSX

location: S14W83

note that SWPC data is for AR S1711 as they lost track of AR 11492

11495 2012.05.27
2012.05.31
      S15W60         plage
11494 2012.05.30
2012.05.31
8 28 10 S18W06 0160 CSO DHI beta-gamma

area: 0280

11493 2012.05.30
2012.05.31
11 10 6 N14W18 0130 ESI DSO

beta-gamma

location: N15W22

11496 2012.05.30
2012.06.01
1 6 2 N16W10 0020 HAX CSO

 

11497 2012.05.30
2012.06.01
7 17 9 S22W31 0230 DAO DAO

 

11498 2012.05.31
2012.06.01
7 18 11 N06E01 0020 CAO DRI location: N08E04
S1703 2012.06.01   20 8 N13W14 0070   DRI SWPC thinks this is part of AR 11493
11499 2012.06.01
2012.06.03
14 48 22 N15E05 0020 BXI DRI  
11502 2012.06.02
2012.06.04
1 1 1 S17E12 0000 AXX AXX  
11500 2012.06.02
2012.06.04
      N09W63         plage
11501 2012.06.04       N07W15           plage
S1709 2012.06.04       N13E24         plage
11503 2012.06.04
2012.06.05
2 3 1 N09W55 0000 AXX AXX  
S1711 2012.06.04   2 1 S19W86 0020   HRX  
S1712 2012.06.05       N01W83         plage
S1713 2012.06.06   1 1 N11E34 0000   AXX    
S1714 2012.06.06   2 2 N27W49 0000   BXO    
Total spot count: 51 157 75  
Sunspot number: 131 287 205  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 76 199 117  (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): 79 100 113 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
2012.06 131.1 (1) 27.9 (2A) / 139.5 (2B) (73.9 projected, +0.7) (16.56)

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.