Last major update issued on March 26, 2011 at 06:05 UTC. Minor update posted at 13:10 UTC.
[Solar and geomagnetic data - last month (updated
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[Solar cycles 21-24 (last update March 2, 2011)]
[Solar cycles 1-20]
[Graphical comparison of cycles 21, 22, 23 and 24 (last update March 2, 2011)]
[Graphical comparison of cycles 10, 12, 13, 14, 16 and 24 (last update March 2, 2011)]
[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
[Archived reports since January 2003 (last update March 1, 2011)]
[POES auroral activity level charts since October
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Annotated geomagnetic activity charts - Carrington rotation 2106 [Jan.-Feb.2011] - 2107 [Feb.-March 2011] NEW
The geomagnetic field was quiet on March 25. Solar wind speed ranged between 395-470 km/s.
Solar flux measured at 20h UTC on 2.8 GHz was 112.6 (increasing 22.4 over the last solar rotation). The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 3.4). Three hour interval K indices: 00012111 (planetary), 00112211 (Boulder).
The background x-ray flux is at the class B5 level.
At midnight UTC the visible solar disk had 7 spotted regions.
Region 11176 displayed some fragmentation of the largest penumbra,
otherwise no major changes were observed. M class flares are possible.
Flares: C1.0 at 00:42, C1.0 at 01:01, C1.0
at 17:12 and M1.0 at 23:22 UTC. The latter event was associated with weak type
II and IV radio sweeps.
Region 11177 was quiet and stable.
Region 11178 developed and has many spots in a small area. C flares are possible
Region 11179 decayed slowly and quietly.
New region 11180 rotated into view at the northeast limb on March 24 and was numbered by NOAA/SWPC the following day.
New region 11181 rotated into view at the southeast limb on March 24 and received a NOAA/SWPC number the next day.
Spotted regions not numbered by NOAA/SWPC:
[S920] emerged in the southeast quadrant on March 25. Location at midnight: S24E55
Minor update added at 13:10 UTC on March 26: New region S921 is rotating into view at the northeast limb while region S919 has reemerged with a spot. Region 11178 is developing quickly and currently has a DAI classification. Region 11176 has begun developing tiny spots in the large trailing plage area, the region currently spans more than 25 degrees longitudinally. The latest high resolution STAR CHARMAP image.
March 23 and 25: No obviously Earth directed CMEs were observed in LASCO
and STEREO imagery.
March 24: A small partial halo CME was observed in association with an M1 flare in region 11176.
Compare today's report to the situation one solar rotation ago: 28 days ago 27 days ago 26 days ago
No obvious coronal holes are currently in or near Earth facing positions.
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 fair. Propagation on long distance northeast-southwest paths is poor to fair.
The geomagnetic field is expected to be quiet on March 26-27. On March 28 there's a chance of unsettled and active intervals if the CME observed on March 24 reaches Earth.
|Coronal holes (1)||Coronal mass ejections (2)||M and X class flares (3)|
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
|1||1||S25E69||0010||HSX||HRX||formerly region S917|
|1||1||N26E66||0030||HSX||HSX||formerly region S918
|Total spot count:||44||84|
|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)|
|2009.12||76.7||10.8||8.3 (+0.7)||1.41 / 1.92|
|2010.01||81.1||13.2||9.3 (+1.0)||2.93 / 3.07|
|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||16.8 (+0.4)||6.31 / 5.15|
|2010.08||79.2||19.6||17.4 (+0.6)||8.49 / 7.77|
|2010.09||81.1||25.2||(19.1 predicted, +1.7)||5.33 / 5.45|
|2010.10||81.6||23.5||(21.7 predicted, +2.6)||6.07 / 6.27|
|2010.11||82.5||21.6||(24.5 predicted, +2.8)||4.80 / 5.50|
|2010.12||84.2||14.5||(26.9 predicted, +2.4)||3.41 / 4.35|
|2011.01||83.6||19.1||(29.0 predicted, +2.1)||4.32|
|2011.02||94.6||29.4||(31.1 predicted, +2.1)||5.41|
|2011.03||114.7 (1)||61.3 (2A) / 76.0 (2B)||(33.0 predicted, +1.9)||(8.93)|
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.