Last major update issued on June 21, 2011 at 04:40 UTC. Minor update posted at 13:55 UTC.
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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]
The geomagnetic field was quiet to unsettled on June 20. Solar wind speed ranged between 374 and 440 km/s under the influence of a low speed stream associated with CH458.
Solar flux measured at 20h UTC on 2.8 GHz was 96.4 (increasing 14.7 over the last solar rotation). The planetary A index was 7 (STAR Ap - based on the mean of three hour interval ap indices: 7.3). Three hour interval K indices: 22312212 (planetary), 22312222 (Boulder).
The background x-ray flux is at the class B2 level.
At midnight UTC the visible solar disk had 5 spotted regions.
Region 11236 decayed losing quite a few small spots. If the current
development continues the trailing spots will be without penumbra by the end of
the day. The region produced a long duration C7 event peaking at 03:20 UTC on
June 21. A large CME was associated with this event.
Region 11237 was quiet and stable.
New region 11239 emerged in the northeast quadrant on June 17 and was numbered by NOAA/SWPC 3 days later. Slow development was observed on June 20.
New region 11240 emerged in the southeast quadrant on June 20.
Spotted regions not numbered by NOAA/SWPC:
[S1075] emerged in the northeast quadrant on June 20. Location at midnight: N36E14
Minor update added at 13:55 UTC on June 21: The C7.7 LDE today triggered a filament eruption to the north of region 11236 and caused a large part of the corona between 11236 and CH457 to disappear. The resulting full halo CME is very close to being aimed straight at Earth.
June 18 and 20: No obviously earth directed CMEs were observed.
June 19: A partial halo CME was observed by LASCO beginning at 16:36 UTC following an event in region 11237. A flank impact is possible from this CME on June 22 or 23.
June 21: A halo CME was observed after a C7 LDE in region 11236. Although most of the core of the CME was observed over the northern limbs, Earth appears to be in the path of the southern part of the core. The CME will likely reach Earth on June 23 or 24 and could cause a major geomagnetic disturbance.
Coronal hole history (since late October
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 was Earth facing on June 19-20. A coronal hole (CH459) in the northern hemisphere will be Earth facing on June 23.
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.
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.
The geomagnetic field is expected to be quiet to unsettled on June 21 due to weak effects from CH458. Quiet to unsettled is possible on June 22 due to weak effects from the CME observed on June 19. 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. The CME observed early on June 21 could reach Earth on June 23 or 24 and cause unsettled to major 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
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.
(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
|Spot count||Location at midnight||Area||Classification||SDO / HMI 4K continuum
image with polarity overlay
|S16W87||rotated out of view|
|5||8||N18E13||0010||BXO||BXO||formerly region S1070
|Total spot count:||13||43|
|Month||Average measured solar flux||International sunspot number (SIDC)||Smoothed sunspot number||Average ap
|2008.07||65.7 (SF minimum)||0.5||2.8 (-0.4)|
|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||97.9 (1)||41.3 (2A) / 62.0 (2B)||(47.4 predicted, +3.7)||(9.42)|
1) Running average based on the daily 20:00 UTC observed solar flux value at
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.