Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 7, 2012 at 03:20 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)]
[Solar cycles 21-24 (last update August 6, 2012)] [Cycle 24 progress (last update August 2, 2012) ]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update August 6, 2012)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update August 6, 2012)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update August 5, 2012)]

[POES auroral activity level since October 2009 - updated August 5, 2012]
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on August 6. Solar wind speed at SOHO ranged between 293 and 377 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 134.1 (decreasing 39.3 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: 11.5). Three hour interval K indices: 33232323 (planetary), 23232323 (Boulder).

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

At midnight UTC the visible solar disk had 10 spotted active regions (in 2K resolution SDO images).

Region 11532 [S19W80] decayed slowly as it rotated to the southwest limb.
Region 11535 [N18W28] was quiet and stable.
Region 11537 [N12W03] was quiet and stable.
Region 11538 [S23W09] has minor polarity intermixing and could produce C flares.
Region 11539 [S20E09] added a few spots and was quiet.
Region 11540 [S26E23] lost several small spot, however, new flux emerged to the north of the largest penumbra. C flares are possible.
Region 11541 [S16E23] decayed slowly and quietly.
New region 11542 [S13E76] rotated into view at the southeast limb. This was the only region producing any activity of interest. The largest flares were C9.4 at 00:45 and M1.6 at 04:38 UTC.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1842
[N18W03] was quiet and stable.
New region S1846 [N21E82] rotated partly into view. C and minor M flares are possible.

Coronal mass ejections (CMEs)

August 5-6: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
August 4: A full halo CME was associated with a large filament eruption in the southeeast quadrant, the CME could influence Earth on August 7-9.

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 small trans equatorial coronal hole (CH536) will rotate into an Earth facing position on August 8.

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 to good.

Forecast

The geomagnetic field is expected to be quiet to unsettled on August 7. The CME from the August 4 eruption could reach Earth during the latter half of August 7 or early on August 8 and cause unsettled to minor storm conditions. Effects from CH526 are possible on August 11-12.

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
11532 2012.07.25
2012.07.26
1 1 1 S19W80 0150 HSX HHX

area: 0280

11534 2012.07.27
2012.07.28
      N23W68         location: N18W70
11535 2012.07.29
2012.07.30
4 15 4 N19W29 0080 CSO CSO

area: 0200

11536 2012.07.30       S25W66           part of AR 11532
11537 2012.07.31 1 2 1 N13W04 0040 HSX HSX area: 0090
11538 2012.07.31 5 16 6 S22W11 0130 DSO DSO beta-gamma

area: 0220

S1835 2012.07.31       N12W42           plage
11539 2012.08.01
2012.08.02
1 10 3 S23E04 0000 AXX CRO

location: S20E09

S1837 2012.08.01       N27W33           plage
11541 2012.08.02
2012.08.03
1 8 4 S17E24 0010 AXX BXO  
11540 2012.08.02
2012.08.03
13 20 10 S27E17 0100 CAI DAI

area: 0130

S1840 2012.08.02       N09W24           plage
S1842 2012.08.03   4 2 N18W14 0000   BXO  
S1843 2012.08.05       N14E23         plage
S1844 2012.08.05       N30E09         plage
S1845 2012.08.05       N23W21         plage
11542 2012.08.06 2 2 2 S13E75 0020 HAX HSX   area: 0180
S1846 2012.08.06   3 1 N21E82 0280   HHX    
Total spot count: 28 81 34  
Sunspot number: 108 181 134  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 58 129 82  (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): 65 63 74 k * (sunspot number). k = 0.6 for SWPC, k = 0.35 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)
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 65.5 (+2.1) 7.15
2012.02 106.5 33.1 (67.4 projected, +1.9) 8.81
2012.03 114.7 64.2 (68.1 projected, +0.7) 16.08
2012.04 113.0 55.2 (67.5 projected, -0.6) 10.10
2012.05 121.5 69.0 (65.8 projected, -1.7) 7.06
2012.06 119.6 64.5 (65.0 projected, -0.8) 10.08
2012.07 133.9 66.5 (66.0 projected, +1.0) 14.37
2012.08 137.2 (1) 24.5 (2A) / 126.5 (2B) (68.6 projected, +2.6) (8.92)

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.