Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 10, 2012 at 04:45 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 9. Solar wind speed at SOHO ranged between 286 and 354 km/s.

Solar flux measured at 20h UTC on 2.8 GHz was 131.2 (decreasing 16.0 over the last solar rotation). The Potsdam WDC planetary A index was 5 (STAR Ap - based on the mean of three hour interval ap indices: 5.0). Three hour interval K indices: 32111111 (planetary), 22231211 (Boulder).

The background x-ray flux is at the class B4 level.

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

Region 11535 [N19W70] decayed slowly and quietly.
Region 11537 [N12W42] decayed slowly and quietly.
Region 11538 [S23W48] was  mostly quiet and stable.
Region 11539 [S21W31] decayed slowly and quietly.
Region 11540 [S26W22] decayed slowly and quietly.
Region 11541 [S15W21] was quiet and stable.
Region 11542 [S13E37] became more complex and compact as a magnetic delta structure formed in the northeasternmost penumbra. M flares are possible. Flares: C8.4/1N at 11:47 UTC and several low level C flares.
Region 11543 [N20E46] was quiet and stable.
New region 11544 [S31W05] emerged quickly on August 8 and was numbered by SWPC the next day. The region developed further on August 9 and has polarity intermixing. A few low level C flares were recorded and further C class flaring is likely.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1842
[N17W57] decayed slowly and quietly.
New region S1851 [S15E07] emerged with a tiny spot.

Coronal mass ejections (CMEs)

August 7-9: 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 southwest quadrant. A coronal hole (CH527) in the southern hemisphere will rotate into an Earth facing position on August 9-10.  A coronal hole (CH528) in the northern hemisphere will 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 poor to fair.

Forecast

The geomagnetic field is expected to be quiet to active 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
1 1 1 N19W70 0080 HSX HSX

area: 0140

11537 2012.07.31 1 1 1 N13W42 0030 HSX HSX  
11538 2012.07.31 5 5 3 S22W47 0160 DSO DSO

 

11539 2012.08.01
2012.08.02
1 3 2 S20W29 0010 AXX BXO

location: S21W31

11541 2012.08.02
2012.08.03
  12 5 S17W18 0010   BXO  
11540 2012.08.02
2012.08.03
6 12 5 S26W21 0090 CAO DSI

 

S1842 2012.08.03   4   N17W57 0000   BXO  
S1843 2012.08.05       N10W21           plage
S1844 2012.08.05       N30W30           plage
11542 2012.08.06 14 35 17 S14E37 0190 DAI DAC beta-gamma-delta

area: 0270

11543 2012.08.06
2012.08.07
6 11 6 N21E45 0260 DHO DHO area: 0400
S1847 2012.08.07       S05W24           plage
S1848 2012.08.07       S12W33           plage
S1849 2012.08.08       S10W03         plage
11544 2012.08.08
2012.08.09
10 20 9 S30W06 0070 DAI DSI beta-gamma

location: S31W05

area: 0210

S1851 2012.08.09   1   S15E07 0000   AXX    
Total spot count: 44 105 49  
Sunspot number: 124 215 139  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 84 145 89  (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): 74 75 76 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
2012.08 135.0 (1) 34.8 (2A) / 119.8 (2B) (68.6 projected, +2.6) (8.44)

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.