Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 9, 2012 at 05:30 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 minor storm on August 8. Solar wind speed at SOHO ranged between 321 and 431 km/s under the influence of weak CME effects.

Solar flux measured at 20h UTC on 2.8 GHz was 133.3 (decreasing 32.1 over the last solar rotation). The Potsdam WDC planetary A index was 11 (STAR Ap - based on the mean of three hour interval ap indices: 10.9). Three hour interval K indices: 52221212 (planetary), 41312311 (Boulder).

The background x-ray flux is at the class B7 level.

At midnight UTC the visible solar disk had 11 spotted active regions (in 2K resolution SDO images).

Region 11535 [N19W56] decayed slowly and quietly.
Region 11537 [N12W29] was quiet and stable.
Region 11538 [S23W35] was quiet and stable.
Region 11539 [S20W15] gained a few spots and was quiet.
Region 11540 [S26W08] decayed slightly and was quiet.
Region 11541 [S17W03] was quiet and stable.
Region 11542 [S14E51] has polarity intermixing and is likely to produce further low level C class flares. A minor M class flare is possible.
Region 11543 [N20E59] displayed little change and remained quiet.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1842
[N17W43] developed slowly and quietly.
New region S1849 [S10E10] emerged with a few spots.
New region S1850 [S31E07] emerged quickly and has many spots. If the region develops further minor M class flares will become possible.

Coronal mass ejections (CMEs)

August 6-8: 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 small trans equatorial coronal hole (CH526) was in an Earth facing position on August 7. CH536 nearly closed on August 8 due to coronal expansion following a filament eruption in the suthwest quadrant. A coronal hole (CH527) in the southern hemisphere will likely rotate into an Earth facing position on August 9-10.  A coronal hole (CH528) in the northern hemisphere could rotate into an Earth facing position on August 10-11.

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 9. Quiet to active conditions are possible on August 10-11 (due to effects from CH526) and on August 12-14 (due to effects from CH527 and CH528).

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
11535 2012.07.29
2012.07.30
2 3 2 N18W54 0070 CSO CSO

area: 0140

location: N19W56

11537 2012.07.31 1 3 1 N12W30 0050 HSX HSX  
11538 2012.07.31 2 9 2 S23W35 0100 DSO DSO beta-gamma

area: 0200

11539 2012.08.01
2012.08.02
2 10 2 S22W20 0020 CSO CRO

location: S20W15

S1837 2012.08.01       N27W59           plage
11541 2012.08.02
2012.08.03
  10 4 S17W04 0000   BXO  
11540 2012.08.02
2012.08.03
9 20 11 S26W09 0090 DAI CAI

 

S1840 2012.08.02       N09W50           plage
S1842 2012.08.03   3 1 N17W43 0010   CRO  
S1843 2012.08.05       N10W08         plage
S1844 2012.08.05       N30W17           plage
S1845 2012.08.05       N23W47           plage
11542 2012.08.06 9 19 11 S14E50 0160 DAI DSI beta-gamma

area: 0300

11543 2012.08.06
2012.08.07
4 11 6 N21E58 0230 DAO DHO area: 0400
S1847 2012.08.07       S05W11         plage
S1848 2012.08.07       S12W20         plage
S1849 2012.08.08   4 2 S10E10 0010   BXO    
S1850 2012.08.08   18 11 S31E07 0060   DRI    
Total spot count: 29 110 53  
Sunspot number: 99 220 163  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 64 154 97  (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): 59 77 90 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
2012.08 135.5 (1) 30.8 (2A) / 119.3 (2B) (68.6 projected, +2.6) (8.88)

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.