Solar Terrestrial Activity Report

Activity chart

Last major update issued on July 9, 2012 at 06:45 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)] [Cycle 24 progress NEW]
[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 July 1, 2012)]

[POES auroral activity level since October 2009 - updated July 2, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to minor storm on July 8. Solar wind speed at SOHO ranged between 395 and 541 km/s. The total field of the interplanetary magnetic field strengthened significantly after 08:30 UTC. Bz was mostly northwards until 22h UTC, then swung moderately southwards causing a active to minor storm conditions at the end of the day. The source of this disturbance is likely a CME, perhaps the one associated with the X1 flare on July 6.

Solar flux measured at 20h UTC on 2.8 GHz was 177.7 (increasing 43.8 over the last solar rotation). The Potsdam WDC planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.5). Three hour interval K indices: 22232225 (planetary), 23232323 (Boulder).

The background x-ray flux is at the class C3 level.

At midnight UTC the visible solar disk had 12 spotted active regions (in 2K resolution SDO images).

Region 11515 [S17W79] rotated partly out of view, however, the largest penumbra split into smaller penumbrae with none of the visible penumbra exceeding 2.5 degrees latitudinal extent. The region continued to produce lots of C and M flares and could produce another major event while at or just behind the southwest limb. Flares: C6.6 at 04:19, C5.9 at 05:34, M1.3 at 05:46, C6.8/1F at 06:25, M1.1/1F at 09:53, C6.9 at 10:30, C5.4 at 10:50, M1.4/1F at 12:10, C6.7 at 14:43, major M6.9/1N at 16:32 UTC.
Region 11518 [N09E13] decayed slowly and quietly.
Region 11519 [S16E23] was quiet and stable.
Region 11520 [S17E48] is a large and compact region with a huge main penumbra. There's a significant magnetic delta structure in the central part of this penumbra. A major flare is possible. Flares: C6.1 at 13:02, C8.8 at 17:43, C6.6 at 19:24 UTC

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1776
[S16E38] developed quickly and could produce minor M class flares.
S1777 [S12E45] was quiet and stable.
S1781 [S16E28] developed slowly with polarity intermixing. Flare: C9.2 at 18:03 UTC.
S1782 [S21E35] developed slowly and quietly.
S1783 [N15E37] was quiet and stable.
S1785 [S25E18] added a few tiny spots.
New region S1786 [S20W51] emerged to the west of AR S1780.
New region S1787 [S20E05] emerged with a tiny spot.

Coronal mass ejections (CMEs)

July 6: While the core CME associated with the X1 event in AR 11515 will not reach Earth, a flank impact is likely on July 9.
July 7-8
: 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 coronal hole (CH522] in the northern hemisphere was in an Earth facing position on July 6-7. 

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 minor storm on July 9-10 due to CME and coronal hole effects. Quiet to active is likely on July 11.

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
11513 2012.06.25
2012.06.26
3     N17W89 0180 HSX     rotated out of view
11515 2012.06.26
2012.06.27
32 19 12 S17W76 0550 EKI EAC

location: S17W79

11516 2012.06.27
2012.06.29
      N20W79           plage

location: N14W78

11517 2012.06.30
2012.07.01
      N19W67          
S1769 2012.07.01       N17W47           plage
11518 2012.07.03
2012.07.04
3 12 5 N10E12 0030 DSO BXO location: N09E13

area: 0010

11519 2012.07.04 1 6 2 S15E22 0080 HSX CSO  
S1774 2012.07.04       S26E25           plage
11520 2012.07.05
2012.07.06
23 62 26 S15E43 1070 FHC EKC beta-gamma-delta

location: S17E48

area: 1600

S1776 2012.07.05   35 19 S16E38 0140   DAI  
S1777 2012.07.05   2 1 S12E45 0100   HSX  
S1778 2012.07.05       S28W52           plage
S1779 2012.07.05       N15W36           plage
S1780 2012.07.06       S21W46         plage
S1781 2012.07.07   10 5 S16E28 0040   DRO beta-gamma
S1782 2012.07.07   9 4 S21E35 0030   CRO  
S1783 2012.07.07   2   N13E37 0000   AXX  
S1784 2012.07.07       N25W10         plage
S1785 2012.07.07   7 2 S25E18 0000   AXX  
S1786 2012.07.08   1 1 S20W51 0000   AXX    
S1787 2012.07.08   1   S20E05 0000   AXX    
Total spot count: 62 165 77  
Sunspot number: 112 285 177  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 97 201 113  (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): 67 100 97 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
 
2011.04 112.6 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 63.4 (+2.3) 3.78
2012.01 132.5 58.3 (65.0 projected, +1.6) 7.15
2012.02 106.5 33.1 (66.5 projected, +1.5) 8.81
2012.03 114.7 64.2 (67.2 projected, +0.7) 16.08
2012.04 113.0 55.2 (66.5 projected, -0.7) 10.10
2012.05 121.5 69.0 (64.8 projected, -1.7) 7.06
2012.06 119.6 64.5 (64.0 projected, -0.8) 10.08
2012.07 151.7 (1) 34.2 (2A) / 132.4 (2B) (65.0 projected, +1.0) (15.78)

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.