Solar Terrestrial Activity Report

Last major update issued on June 11, 2011 at 05:25 UTC.

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

[POES auroral activity level charts since October 2009 - updated June 11, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2109 [April-May 2011] - 2110 [May-June 2011] NEW
[Solar polar fields vs solar cycles - updated June 11, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on June 10. Solar wind speed ranged between 358 and 522 km/s. A weak solar wind shock was observed at SOHO at 08:11 UTC, the arrival of the CME observed on June 7.

Solar flux measured at 20h UTC on 2.8 GHz was 86.7 (decreasing 4.7 over the last solar rotation). The planetary A index was 8 (STAR Ap - based on the mean of three hour interval ap indices: 8.0). Three hour interval K indices: 20132123 (planetary), 30232223 (Boulder).

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

At midnight UTC the visible solar disk had 5 spotted regions.

Region 11232 decayed slowly and quietly.
Region 11234 developed slowly and was quiet.

Spotted regions not numbered by NOAA/SWPC:
[S1056] emerged in the northeast quadrant on June 10. Location at midnight: N13E40
[S1057] emerged in the southeast quadrant on June 10. Location at midnight: S23E33
[S1058] emerged in the northwest quadrant on June 10. Location at midnight: N19W29

Region 11226 produced a flare from behind the southwest limb: C2.9 at 17:51 UTC.

Coronal mass ejections (CMEs)

June 8-10: No obviously earth directed CMEs were observed.

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 small coronal hole (CH454) in the northern hemisphere was in an Earth facing position early on June 9. An elongated coronal hole (CH455) in the southern hemisphere was Earth facing on June 10-11.

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 minor storm on June 11 due to CME effects. On June 12 there's a chance of a few unsettled intervals due to effects from CH454. On June 13-14 a high speed stream from CH455 could cause some unsettled and active intervals.

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
11227 2011.05.28
2011.05.29
1   S20W88 0010 AXX    

rotated out of view

11230 2011.05.30
2011.05.31
    N20W78          

location: N22W69

plage

11232 2011.05.31
2011.06.01
1 6 N09W46 0020 HRX BXO

location: N10W43 

11231 2011.06.01
2011.06.02
    N09W64          

location: N08W60

plage

S1046 2011.06.03     N18W56         plage
S1047 2011.06.04     S26W26           plage
S1048 2011.06.06     N22W23            plage
S1049 2011.06.06     S17W32           plage
S1052 2011.06.07     N11E19           plage 
11234 2011.06.08
2011.06.09
 3 11 S16E43 0010 BXO BXO   location: S17E46
S1054 2011.06.08     N29W54           plage
S1055 2011.06.09     S35W18         plage
S1056 2011.06.10   4 N13E40 0000   BXO    
S1057 2011.06.10   1 S23E33 0000   AXX    
S1058 2011.06.10   1 N19W29 0000   AXX    
Total spot count: 5 23  
Sunspot number: 35 73  

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
2010.02 84.7 18.8 10.6 (+1.3) 4.15 / 4.61
2010.03 83.4 15.4 12.3 (+1.7) 4.58 / 4.65
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 (29.4 predicted, +2.9) 3.41 / 4.35
2011.01 83.6 19.1 (32.6 predicted, +3.2) 4.32 / 5.51
2011.02 94.6 29.4 (35.2 predicted, +2.6) 5.41 / 6.44
2011.03 115.0 56.2 (37.5 predicted, +2.3) 7.79
2011.04 112.6 54.4 (40.4 predicted, +2.9) 9.71
2011.05 95.8 41.6 (43.7 predicted, +3.3) 9.18
2011.06 99.9 (1) 26.3 (2A) / 79.0 (2B) (47.4 predicted, +3.7) (11.5)

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.