Solar Terrestrial Activity Report

Last major update issued on July 10, 2011 at 06:20 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 8, 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 active on July 9. Solar wind speed ranged between 335 and 485 km/s under the influence of a high speed stream from CH463.

Solar flux measured at 20h UTC on 2.8 GHz was 85.6 (increasing 1.0 over the last solar rotation). The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.1). Three hour interval K indices: 34121324 (planetary), 34222324 (Boulder).

The background x-ray flux is at the class B1 level.

At midnight UTC the visible solar disk had 7 spotted regions.

Region 11245 was quiet and stable.
Region 11246 decayed slowly and quietly.
Region 11247 was mostly quiet. While the region appears to have mixed polarities, the alignment of the polarity fields suggest that region 11247 is two separate regions.
New region 11249 emerged in the southeastern quadrant on July 7 and was numbered 2 days later by SWPC.

Spotted regions not numbered by NOAA/SWPC:
[S1101] reemerged on July 9 with a single tiny spot. Location at midnight: S14E10
[S1105] emerged in the northeast quadrant on July 9. Location at midnight: N15E10
[S1106] emerged in the northwest quadrant on July 9. Location at midnight: N02W50

Coronal mass ejections (CMEs)

July 7-8: No obviously earth directed CMEs were observed.
July 9: A long duration B4 event peaking near 01h UTC was associated with a filament eruption to the east of region 11247. A CME was observed and there's a fair chance this CME will reach Earth on July 12.

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 coronal hole (CH463) in the northern hemisphere was Earth facing on July 5-6. A recurrent coronal hole (CH464)  in the southern hemisphere was Earth facing on July 7-8. A trans equatorial coronal hole (CH465) will likely become Earth facing on July 10.

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.

Forecast

The geomagnetic field is expected to be quiet to active on July 10-11 due to high speed streams from CH463 and CH464. A weak CME could reach Earth on July 12 and cause a few unsettled and active intervals. A disturbance associated with CH465 may cause quiet to active conditions on July 13-14.

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
11243 2011.06.27
2011.06.28
    N15W87          
S1090 2011.06.29     N15W55           plage
11246 2011.07.02
2011.07.08
1 1 N15W62 0000 AXX AXX location: N14W60
11247 2011.07.03
2011.07.08
8 20 S18W02 0040 CAO CAI

location: S20W00

area: 0050

S1097 2011.07.05     N01W16           plage
S1098 2011.07.05     N03W26           plage
S1099 2011.07.05     S23W25           plage
S1100 2011.07.05     S35W35           plage
S1101 2011.07.06     S16E07           plage
11245 2011.07.06
2011.07.07
4 5 N15E31 0030 CAO CSO

location: N14E33

11248 2011.07.06
2011.07.08
    N20E39         plage
11249 2011.07.07
2011.07.09
2 3 S16E25 0000 AXX BXO formerly region S1104

location: S18E26

S1105 2011.07.09   1 N15E10 0000   AXX    
S1106 2011.07.09   1 N02W50 0000   AXX    
Total spot count: 15 31  
Sunspot number: 55 101  

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 85.6 (1) 13.5 (2A) / 46.6 (2B) (49.4 predicted, +4.1) (9.69)

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.