Solar Terrestrial Activity Report

Last major update issued on June 25, 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 20, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2109 [April-May 2011] - 2110 [May-June 2011]
[Solar polar fields vs solar cycles - updated June 11, 2011]

Recent activity

The geomagnetic field was quiet to unsettled on June 24. Solar wind speed ranged between 558 and 675 km/s under the influence of a high speed stream from CH457.

Solar flux measured at 20h UTC on 2.8 GHz was 96.2 (decreasing 4.3 over the last solar rotation). The planetary A index was 10 (STAR Ap - based on the mean of three hour interval ap indices: 10.3). Three hour interval K indices: 32222233 (planetary), 33332233 (Boulder).

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

At midnight UTC the visible solar disk had 6 spotted regions.

Region 11236 was mostly quiet. There's minor polarity intermixing and several small spots have formed near the inversion line to the east of the main spot.
Region 11237 lost the spot in the northern part of the region and gained a couple of tiny spots in the southern section.
Region 11239 was quiet and stable.
Region 11240 was quiet and gained several tiny spots.
New region 11241 emerged in the northeast quadrant on June 22 and was noticed by NOAA/SWPC 2 days later.

Spotted regions not numbered by NOAA/SWPC:
[S1083] emerged in the northeast quadrant on June 24. Location at midnight: N25E26

Coronal mass ejections (CMEs)

June 22-24: 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 coronal hole (CH459) in the northern hemisphere was Earth facing on June 23. A recurrent coronal hole (CH460) in the northern hemisphere will likely rotate into an Earth facing position on June 27-28.

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 unsettled on June 25. Some unsettled and active intervals are possible on June 26-27 due to effects from CH459.

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
11236 2011.06.13
2011.06.14
4 13 N17W61 0180 CSO CHO

area: 0260

location: N16W64

11237 2011.06.16
2011.06.17
  2 S18W29 0000   AXX location: S22W22
11239 2011.06.17
2011.06.20
1 3 N17W44 0000 AXX BXO

 

S1073 2011.06.19     S05W22           plage
11240 2011.06.20 9 16 S19W12 0050 CRO CRO location: S20W12
S1075 2011.06.20     N36W37           plage
S1076 2011.06.21     S09W03          

plage

11241 2011.06.22
2011.06.24
8 20 N19W08 0050 DRO BXI formerly region S1077

location: N18W05

S1078 2011.06.22     S47W38          

plage

S1079 2011.06.23     N08E37         plage
S1080 2011.06.23     S24W34         plage
S1081 2011.06.23     N18W55         plage
S1082 2011.06.23     N23W21         plage
S1083 2011.06.24   3 N25E26 0000   BXO    
Total spot count: 22 57  
Sunspot number: 62 117  

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 97.4 (1) 48.3 (2A) / 60.4 (2B) (47.4 predicted, +3.7) (9.92)

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.