Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 1, 2012 at 06:10 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 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 unsettled to minor storm on June 30. Solar wind speed at SOHO ranged between 363 and 724 km/s under the influence of a high speed stream from CH521.

Solar flux measured at 20h UTC on 2.8 GHz was 124.0 (decreasing 5.4 over the last solar rotation). The Potsdam WDC planetary A index was 28 (STAR Ap - based on the mean of three hour interval ap indices: 28.1). Three hour interval K indices: 34455444 (planetary), 33443434 (Boulder).

The background x-ray flux is at the class B5 level.

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

Region 11512 [S15W29] decayed slowly and quietly.
Region 11513 [N15E17] simplified after the 2 M flares with no traces of a magnetic delta structure remaining. Flares: M1.0 at 12:50, M1.6 at 18:32 UTC.
Region 11514 [S15E17] produced a couple of C flares while decaying. There's still minor polarity intermixing.
Region 11515 [S17E32] developed further with a nearly continuous penumbral area from the easternmost to the westernmost spots. While the region was mostly quiet and only has minor polarity intermixing, there is potential to produce a major flare.
Region 11516 [N13E31] decayed slowly and quietly.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
New region S1766 [N18E40] emerged quickly and has grown further in size and spot count early on July 1. C flares are possible.
New region S1767 [N18E23] was numbered with the leader spot split off from AR 11513 and a tiny trailing spot emerging.
New region S1768 [N15W18] emerged with a tiny spot.

Coronal mass ejections (CMEs)

June 28-30: 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 28 - 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 very poor. Propagation on long distance northeast-southwest paths is fair to good.

Forecast

The geomagnetic field is expected to be unsettled to minor storm on July 1-2, quiet to active on July 3 and quiet to unsettled on July 4-5 under the influence of a high speed stream from CH521.

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       N20W36           plage
11512 2012.06.24
2012.06.25
9 7 5 S16W29 0180 DSO DSO

 

S1751 2012.06.24       S13W49           plage
S1753 2012.06.25       S27E02           plage
S1754 2012.06.25       S18W39           plage
11513 2012.06.25
2012.06.26
4 11 7 N17E17 0120 DSO CSO beta-gamma

area: 0200

location: N15E17

 

11514 2012.06.26
2012.06.27
11 16 7 S15E15 0070 DSI DRI beta-gamma

area: 0030

location: S15E17

11515 2012.06.26
2012.06.27
10 40 25 S16E30 0380 EKC EKC beta-gamma

area: 0850

location: S17E32

S1758 2012.06.26       N14W28           plage
S1759 2012.06.26       N19W42           plage
S1760 2012.06.26       N06W44           plage
11516 2012.06.27
2012.06.29
6 14 8 N14E27 0060 DSO DRI location: N13E31
S1762 2012.06.27       N03W01           plage
S1764 2012.06.29       N20W36         plage
S1765 2012.06.29       S28E09         plage
S1766 2012.06.30   7 5 N18E40 0020   CRO    
S1767 2012.06.30   2 1 N18E23 0010   CRO    
S1768 2012.06.30   1   N15W18 0000   AXX    
Total spot count: 40 98 58  
Sunspot number: 90 178 128  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 70 130 90  (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): 54 62 70 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) 7.06
2012.06 119.6 (1) 88.2 (2A/2B) (73.9 projected, +0.7) (12.58)

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.