Last major update issued on May 12, 2011 at 03:50 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2107 [Feb.-March 2011] - 2108 [March-April 2011]
The geomagnetic field was quiet to unsettled on May 11. Solar wind speed ranged between 341 and 414 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 94.1 (decreasing 24.6 over the last solar rotation). The planetary A index was 6 (STAR Ap - based on the mean of three hour interval ap indices: 5.5). Three hour interval K indices: 13101111 (planetary), 13111211 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight UTC the visible solar disk had 5 spotted regions.
Region 11204 decayed slowly and will rotate over the northwest limb
Region 11207 decayed slowly and quietly.
Region 11208 decayed slowly and was quiet.
Region 11210 decayed slowly and quietly.
Spotted regions not numbered by NOAA/SWPC:
[S1000] emerged in the southwest quadrant on May 11. Location at midnight: S20W42
May 9: A large, wide and fast partial halo CME was observed following
a long duration C5.4 event at the northeast limb in the evening. There's a
slight chance of a flank impact from this CME on May 13.
May 10: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
May 11: A filament eruption to the west of region 11207 early in the day was associated with a partial halo CME. Weak effects from this CME could reach Earth on May 14 or 15.
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 trans equatorial coronal hole (CH448) was in an Earth facing position on May 11-12.
The darkest areas on the solar disk are likely coronal holes.
Long distance low and medium frequency (below 2 MHz) propagation along paths north of due west over high and upper middle latitudes is poor to fair. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on May 12-14 becoming quiet to active on May 15-16 due to effects from CH448. There's a chance of unsettled intervals on May 13 and 14 due to possible flank CME effects.
|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
|11203||2011.04.28||1||N18W92||0060||HSX||rotated out of view|
|1||S13E46||0010||AXX||formerly region S999
|Total spot count:||24||24|
|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||(26.9 predicted, +3.7)||4.80 / 5.50|
|2010.12||84.2||14.4||(30.1 predicted, +3.2)||3.41 / 4.35|
|2011.01||83.6||19.1||(33.1 predicted, +3.0)||4.32 / 5.51|
|2011.02||94.6||29.4||(35.6 predicted, +2.5)||5.41 / 6.44|
|2011.03||115.0||56.2||(37.9 predicted, +2.3)||7.79|
|2011.04||112.6||54.4||(40.8 predicted, +2.9)||9.71|
|2011.05||103.3 (1)||25.1 (2A) / 70.8 (2B)||(44.1 predicted, +3.3)||(8.35)|
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.