Solar Terrestrial Activity Report

Activity chart

Last major update issued on August 8, 2012 at 05:15 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 7. Solar wind speed at SOHO ranged between 354 and 417 km/s. Solar wind speed and density increased noticably from 20:36 UTC at SOHO, this marked the beginning of a disturbance which is causing active conditions early on August 8. The source of the disturbance is currently uncertain, it could be the CME observed on August 4 or a coronal hole.

Solar flux measured at 20h UTC on 2.8 GHz was 128.1 (decreasing 33.6 over the last solar rotation). The Potsdam WDC planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.3). Three hour interval K indices: 21121123 (planetary), 21232323 (Boulder).

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

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

Region 11535 [N19W43] decayed slowly and quietly.
Region 11537 [N12W16] was quiet and stable.
Region 11538 [S23W22] decayed slightly and was quiet.
Region 11539 [S21W03] decayed slowly and quietly.
Region 11540 [S26E05] gained a few spots and was mostly quiet. C flares are possible.
Region 11541 [S16E08] decayed slowly and quietly.
Region 11542 [S14E64] rotated fully into view and is a compact region which produced most of the C class flaring during the day. C and minor M class flares are possible.
New region 11543 [N20E72] rotated into view on August 6 and was numbered by SWPC the next day.

Spotted active regions not numbered or interpreted differently by NOAA/SWPC:
S1842
[N18W27] decayed slowly and quietly.
S1843 [N10E05] reemerged with a tiny spot.
New region S1847 [S05E02] emerged with a tiny spot.
New region S1848 [S12W07] emergd with a single spot.

Coronal mass ejections (CMEs)

August 5-7: 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 minor storm on August 8 and quiet to unsettled on August 9 due to CME effects. Quiet conditions are likely on August 10 becoming quiet to unsettled on August 11-12 due to effects from CH526.

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     S16W92 0180 HSX    

rotated out of view

11534 2012.07.27
2012.07.28
      N23W82           location: N18W83
11535 2012.07.29
2012.07.30
2 8 1 N19W42 0050 CSO CSO

area: 0160

11537 2012.07.31 1 1 1 N12W17 0050 HSX HSX  
11538 2012.07.31 3 13 4 S22W23 0100 DSO DSO beta-gamma

area: 0220

S1835 2012.07.31       N12W55           plage
11539 2012.08.01
2012.08.02
  6 3 S20W07 0010   CRO

location: S21W03

S1837 2012.08.01       N27W46           plage
11541 2012.08.02
2012.08.03
  7 1 S17E10 0000   BXO location: S16E08
11540 2012.08.02
2012.08.03
9 24 12 S26E04 0090 DAI DAI

area: 0130

S1840 2012.08.02       N09W37           plage
S1842 2012.08.03   2 2 N18W27 0000   AXX  
S1843 2012.08.05   1   N10E05 0000   AXX    
S1844 2012.08.05       N30W04           plage
S1845 2012.08.05       N23W34           plage
11542 2012.08.06 6 13 8 S14E62 0140 CSO DSC area: 0300
11543 2012.08.06
2012.08.07
4 7 6 N21E70 0140 CSO DHO area: 0400
S1847 2012.08.07   1 1 S05E02 0000   AXX    
S1848 2012.08.07   1 1 S12W07 0000   AXX    
Total spot count: 26 84 40  
Sunspot number: 96 204 150  (total spot count + 10 * number of spotted regions)
Weighted penumbral SN: 61 122 78  (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): 58 71 83 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
2012.08 135.9 (1) 27.6 (2A) / 122.1 (2B) (68.6 projected, +2.6) (8.59)

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.