Solar Terrestrial Activity Report

Last major update issued on July 13, 2011 at 05:00 UTC. Minor update posted at 19:05 UTC.

[Solar and geomagnetic data - last month (updated daily)]
[Solar wind and electron fluence charts (updated daily)
[Solar cycles 21-24 (last update July 2, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update July 2, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update July 2, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update July 2, 2011)]

[POES auroral activity level charts since October 2009 - updated July 11, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2110 [May-June 2011] - 2111 [June-July 2011] NEW
[Solar polar fields vs solar cycles - updated June 27, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on July 12. Solar wind speed ranged between 627 and 774 km/s under the influence of a high speed stream from CH464.

Solar flux measured at 20h UTC on 2.8 GHz was 91.7 (decreasing 9.8 over the last solar rotation). The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 7.9). Three hour interval K indices: 33012222 (planetary), 33122321 (Boulder).

The background x-ray flux is at the class B2 level.

At midnight UTC the visible solar disk had 10 spotted regions.

Region 11245 decayed slowly and quietly.
Region 11247 decayed further. Flare: C1.9 at 14:49 UTC
Region 11249 decayed slowly and quietly.
Region 11250 was quiet and stable.
Region 11251 was quiet and stable.

Spotted regions not numbered by NOAA/SWPC:
[S1108] emerged in the northeast quadrant on July 10. Location at midnight: N21E07
[S1112] emerged in the northeast quadrant on July 11. Location at midnight: N08E36
[S1113] rotated into view at the northeast limb on July 12. Location at midnight: N17E73
[S1114] rotated into view at the northeast limb on July 12. Location at midnight: N25E84
[S1115] emerged in the northeast quadrant on July 12. Location at midnight: N16E22

Minor update added at 19:05 UTC: As you can see in the latest high resolution STAR CHARMAP, several new regions have become visible today while regions 11249 and 11247 could become spotless before midnight UTC.

Coronal mass ejections (CMEs)

July 10 and 12: No obviously earth directed CMEs were observed.
July 11
: A small CME was observed after a C2.6 flare in region 11249. The CME could reach Earth late on July 13.

Coronal holes

Coronal hole history (since late October 2002)
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago

A recurrent coronal hole (CH464)  in the southern hemisphere was Earth facing on July 7-8. A trans equatorial coronal hole (CH465) was Earth facing on July 10-11. A large trans equatorial coronal hole (CH466) will likely become Earth facing on July 16-17.

The above coronal hole map is based on a new method where coronal holes are detected automatically. The method may need some fine tuning, however, 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 the new method, the extent and intensity of both holes 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 active on July 13-14. A high speed stream from CH465 will likely arrive during the first half of July 13 while a weak CME impact is possible late in the day or early on July 14. Quiet to unsettled is likely on July 15.

Coronal holes (1) Coronal mass ejections (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 polarity overlay
Comment
SWPC STAR SDO SWPC STAR Current Previous
11247 2011.07.03
2011.07.08
4 5 S18W40 0030 CAO CRO

location: S20W39

area: 0010

S1097 2011.07.05     N01W55           plage
S1101 2011.07.06     S14W31         plage
11245 2011.07.06
2011.07.07
1 2 N15W08 0010 AXX AXX

location: N13W08

11248 2011.07.06
2011.07.08
    N20W03           plage
11249 2011.07.07
2011.07.09
2 5 S16W14 0020 CRO BXO

location: S18W16

area: 0010

S1105 2011.07.09     N15W31           plage
11250 2011.07.10 4 14 S27E18 0140 DSO DSO location: S28E20
11251 2011.07.10
2011.07.11
1 1 N16E57 0100 HSX HSX

 

S1108 2011.07.10   1 N21E07 0000   AXX  
S1109 2011.07.10     N23W03           plage
S1110 2011.07.10     S28E06           plage
S1111 2011.07.10     S06W27           plage
S1112 2011.07.11   3 N08E36 0000   AXX  
S1113 2011.07.12   3 N17E73 0000   AXX    
S1114 2011.07.12   3 N25E84 0010   BXO    
S1115 2011.07.12   1 N16E22 0000   AXX    
Total spot count: 12 38  
Sunspot number: 62 138  

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
3.25
2010.04 75.9 8.0 14.0 (+1.7) 10.22 / 10.24
2010.05 73.8 8.7 15.5 (+1.5) 9.18 / 8.15
2010.06 72.5 13.6 16.4 (+0.9) 8.17 / 6.85
2010.07 79.8 16.1 16.7 (+0.3) 6.31 / 5.15
2010.08 79.2 19.6 17.4 (+0.7) 8.49 / 7.77
2010.09 81.1 25.2 19.6 (+2.2) 5.33 / 5.45
2010.10 81.6 23.5 23.2 (+3.6) 6.07 / 6.27
2010.11 82.5 21.5 26.5 (+3.3) 4.80 / 5.50
2010.12 84.2 14.4 28.8 (+2.3) 3.41 / 4.35
2011.01 83.6 19.1 (30.6 predicted, +1.8) 4.32 / 5.51
2011.02 94.6 29.4 (32.6 predicted, +2.0) 5.41 / 6.44
2011.03 115.0 56.2 (35.2 predicted, +2.6) 7.79 / 8.18
2011.04 112.6 54.4 (38.1 predicted, +2.9) 9.71 / 8.83
2011.05 95.8 41.6 (41.4 predicted, +3.3) 9.18 / 8.94
2011.06 95.8 37.0 (45.2 predicted, +3.8) 8.96
2011.07 86.9 (1) 20.0 (2A) / 51.7 (2B) (49.4 predicted, +4.1) (10.02)

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 preliminary daily SWPC ap indices. Values in red are based on the official NGDC 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.