Solar Terrestrial Activity Report

Last major update issued on June 2, 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 1, 2011]
Annotated geomagnetic activity charts - Carrington rotation 2108 [March-April 2011] - 2109 [April-May 2011]
[Solar polar fields vs solar cycles - updated May 26, 2011] NEW

Recent activity

The geomagnetic field was quiet to unsettled on June 1. Solar wind speed ranged between 448 and 616 km/s under the diminishing influence of a high speed stream from CH451.

Solar flux measured at 20h UTC on 2.8 GHz was 113.6 (increasing 8.7 over the last solar rotation). The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 11.9). Three hour interval K indices: 31312333 (planetary), 31422312 (Boulder).

The background x-ray flux is at the class B4 level.

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

Region 11225 was quiet and stable.
Region 11226 decayed slowly and still has minor polarity intermixing. Further C flares are likely. Flares: C1.6 at 16:16, C2.9 at 16:31, C4.1/1F long duration event peaking at 17:08 UTC. The latter event was associated with a filament eruption to the north of the region and a CME.
Region 11227 was quiet and stable.
Region 11228 has minor polarity intermixing. Flare: C2.6 at 02:53 UTC
Region 11229 decayed slowly and was quiet.
Region 11230 was quiet and stable.
New region 11231 rotated partly into view at the northeast limb on May 31 and was numbered the next day by NOAA/SWPC.

Spotted regions not numbered by NOAA/SWPC:
[S1043] emerged in the northeast quadrant on June 1. Location at midnight: N09E62
[S1044] was split off from region 11227 on June 1. Location at midnight: S19E25
[S1045] emerged with a tiny spot in the southwest quadrant on June 1. Location at midnight: S22W13

Coronal mass ejections (CMEs)

May 30-31: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
June 1: An apparently Earth directed CME was observed after the C4 event in and to the north of region 11226.

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

The southernmost extension of a large coronal hole (CH452) in the northern hemisphere was in an Earth facing position on May 30-31.

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 June 2-3 due to effects from CH452. The CME observed on June 1 could arrive on June 4 and cause unsettled to minor storm conditions.

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
11223 2011.05.21
2011.05.26
    S17W64           plage
S1026 2011.05.25     N10W47           plage
11225 2011.05.25
2011.05.27
1 5 N16W09 0020 HSX CRO location: N17W04
11224 2011.05.26
2011.05.27
    N21W82         plage
11226 2011.05.27 15 35 S22E14 0150 CSI CSI beta-gamma
S1033 2011.05.28     S18W17           plage
11228 2011.05.28
2011.05.29
6 18 N17E31 0090 CSO CSO

beta-gamma

11227 2011.05.28
2011.05.29
7 11 S19E26 0100 DSO CSO

location: S22E33

S1037 2011.05.28     N00W50           plage
S1038 2011.05.28     N30W45           plage
11229 2011.05.29
2011.05.30
5 7 N16E10 0030 BXO CRO  
11230 2011.05.30
2011.05.31
2 6 N19E44 0010 BXO BXO

 

11231 2011.05.31
2011.06.01
1 2 N09E68 0040 HSX CSO formerly region S1042

location: N08E73

S1043 2011.06.01   6 N09E62 0010   BXO    
S1044 2011.06.01   6 S19E25 0030   CSO   split off from 11227
S1045 2011.06.01   1 S22W13 0000   AXX    
Total spot count: 37 97  
Sunspot number: 107 197  

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
2011.06 113.6 (1) 3.6 (2A) / 107 (2B) (47.4 predicted, +3.7) (11.88)

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.