Last major update issued on May 17, 2011 at 04:50 UTC.
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Annotated geomagnetic activity charts - Carrington rotation 2108 [March-April 2011] - 2109 [April-May 2011] NEW
The geomagnetic field was quiet to active on May 16. Solar wind speed ranged between 424 and 674 km/s. Early in the day a high speed stream from CH448 was the dominant solar wind source, then after about 07 UTC a high speed stream from CH449 caused a significant increase in solar wind speed.
Solar flux measured at 20h UTC on 2.8 GHz was 92.2 (decreasing 18.7 over the last solar rotation). The planetary A index was 12 (STAR Ap - based on the mean of three hour interval ap indices: 12.5). Three hour interval K indices: 22334323 (planetary), 22333222 (Boulder).
The background x-ray flux is at the class B1 level.
At midnight UTC the visible solar disk had 8 spotted regions.
Region 11208 decayed quietly.
Region 11214 lost several small spots but could produce C flares.
New region 11216 rotated into view at the southeast limb on May 15 and was numbered the next day by NOAA/SWPC..
Spotted regions not numbered by NOAA/SWPC:
[S1008] emerged with tiny spots in an old plage area in the northeast quadrant on May 14. Location at midnight: N17W01
[S1011] emerged in the northeast quadrant on May 15. Location at midnight: N08E31
[S1013] emerged in the southeast quadrant on May 15, just to the east region 11214. Location at midnight: S25W05
[S1014] emerged with a single tiny spot in the southeast quadrant on May 16. Location at midnight: S32E37
[S1015] emerged in the northwest quadrant on May 16. Location at midnight: N12W23
May 14-16: No obviously Earth directed CMEs were observed in LASCO and STEREO imagery.
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
An extension (CH449) of the southern polar coronal hole was Earth facing on May 14-15.
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. Propagation on long distance northeast-southwest paths is fair.
The geomagnetic field is expected to be quiet to unsettled on May 17-18 due to a high speed stream from CH449. Quiet conditions are likely on May 19-20
|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
rotated out of view
|1||1||S14E66||0090||HSX||HSX||formerly region S1009|
|Total spot count:||23||41|
|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||99.9 (1)||32.8 (2A) / 63.6 (2B)||(44.1 predicted, +3.3)||(7.91)|
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.