Solar Terrestrial Activity Report

Last major update issued on June 20, 2011 at 04:40 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 17, 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 on June 19. Solar wind speed ranged between 366 and 490 km/s. A low speed stream associated with CH458 began to influence the field early on June 20.

Solar flux measured at 20h UTC on 2.8 GHz was 99.1 (increasing 15.0 over the last solar rotation). The planetary A index was 4 (STAR Ap - based on the mean of three hour interval ap indices: 4.0). Three hour interval K indices: 10111111 (planetary), 10212222 (Boulder).

The background x-ray flux is at the class B2 level.

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

Region 11234 decayed with only small spots remaining. The region will rotate over the southwest limb today. Flare: C4.7 at 15:22 UTC
Region 11236 has minor polarity intermixing with spots spread out over a large area latitudinally and longitudinally.
Region 11237 decayed early in the day and was spotless a few hours, then new tiny spots emerged. Flare: long duration C1.5 event peaking at 16:37 UTC. This event was associated with a CME observed off the east limb.
New region 11238 emerged in the southeast quadrant on June 18 and was numbered the next day by NOAA/SPWC. The region decayed slowly on June 19.

Spotted regions not numbered by NOAA/SWPC:
[S1070] emerged in the northeast quadrant on June 17. Location at midnight: N16E42
[S1073] emerged in the southeast quadrant near the equator on June 19. The region has reversed polarities. Location at midnight: S05E43
[S1074] emerged in the southwest quadrant on June 19. Location at midnight: S16W10

Coronal mass ejections (CMEs)

June 17-19: 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 recurrent coronal hole (CH457) in the southern hemisphere will be Earth facing on June 19-20. A coronal hole (CH458) in the southern hemisphere was Earth facing on June 16.

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 20 due to weak effects from CH458. Quiet conditions are likely on June  21. Late on June 22 or early on June 23 a high speed stream from CH457 will likely reach Earth and cause unsettled to minor storm conditions until June 24.

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
11234 2011.06.08
2011.06.09
 4 5 S16W74 0960 DSO BXO   area: 0020
11236 2011.06.13
2011.06.14
11 35 N16E06 0200 ESI EHO location: N17E05

area: 0330

beta-gamma

S1063 2011.06.13     N33W41           plage
S1064 2011.06.13     S22W35         plage
S1068 2011.06.15     S30W40           plage
11237 2011.06.16
2011.06.17
  4 S15E39 0000   BXO location: S16E43
S1070 2011.06.17   2 N16E26 0000   AXX  
11238 2011.06.18
2011.06.19
2 1 S17E11 0010 AXX AXX formerly region S1071
S1072 2011.06.18     S18W03         plage
S1073 2011.06.19   2 S05E43 0000   BXO    
S1074 2011.06.19   2 S16W10 0010   BXO    
Total spot count: 17 51  
Sunspot number: 47 121  

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 98.0 (1) 39.9 (2A) / 62.9 (2B) (47.4 predicted, +3.7) (9.54)

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.