Solar Terrestrial Activity Report

Last major update issued on June 16, 2011 at 04:20 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 14, 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 15. Solar wind speed ranged between 476 and 555 km/s under the influence of a high speed stream from CH455.

Solar flux measured at 20h UTC on 2.8 GHz was 101.5 (increasing 17.1 over the last solar rotation). The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.1). Three hour interval K indices: 22222213 (planetary), 22222222 (Boulder).

The background x-ray flux is at the class B3 level.

At midnight UTC the visible solar disk had 4 spotted regions.

Region 11234 developed slowly and could produce further C flares. Flare: C3.2/1F at 14:32 UTC.
Region 11236 displayed only minor activity and remains capable of producing occasional M class flares. Flare: C2.6 at 11:50 UTC.

Spotted regions not numbered by NOAA/SWPC:
[S1064] emerged in the southeast quadrant on June 13 in a large plage field. The spot observed on June 13 and 14 disappeared on June 15 with another one emerging much further east in the same plage area. Location at midnight: S18E32
[S1068] emerged in the southeast quadrant on June 15. Location at midnight: S30E12

Coronal mass ejections (CMEs)

June 13 and 15: No obviously earth directed CMEs were observed.
June 14: A partial halo CME was observed in LASCO images beginning at 06:02 UTC after a prominence eruption in the southeast quadrant. There's a chance of weak effects from this CME on June 17/18.

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 (CH456) in the northern hemisphere near the equator was Earth facing on June 13. A recurrent trans equatorial coronal hole (CH457) will likely become Earth facing on June 20-21.

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 unsettled on June 16-18 due to effects from CH456 and possible CME effects June 17/18.

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
S1052 2011.06.07     N11W46           plage
11234 2011.06.08
2011.06.09
 17 31 S15W22 0100 DAI DAI   area: 0200
11235 2011.06.10
2011.06.11
    N14W29         plage
S1057 2011.06.10     S23W32           plage
S1060 2011.06.11     N22W26         plage
S1061 2011.06.12     S02W23           plage
11236 2011.06.13
2011.06.14
11 24 N17E58 0350 EHI EHI  
S1063 2011.06.13     N33E11           plage
S1064 2011.06.13   1 S18E32 0000   AXX  
S1065 2011.06.13     N17W13           plage
S1066 2011.06.13     N44W36           plage
S1067 2011.06.14     N50E01           plage
S1068 2011.06.15   4 S30E12 0000   AXX    
Total spot count: 28 60  
Sunspot number: 48 100  

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 97.0 (1) 31.8 (2A) / 63.7 (2B) (47.4 predicted, +3.7) (10.49)

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.