Last major update issued on March 29, 2011 at 04:20 UTC.
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[Solar cycles 21-24 (last update March 2, 2011)]
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[Historical solar and geomagnetic data charts 1954-2006 (last update April 5, 2007)]
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[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 28. Solar wind speed ranged between 321-370 km/s.
Solar flux estimated at 20h UTC on 2.8 GHz was 119 (increasing 8.5 over the last solar rotation). The planetary A index was 3 (STAR Ap - based on the mean of three hour interval ap indices: 2.6). Three hour interval K indices: 10001111 (planetary), 10001111 (Boulder).
The background x-ray flux is at the class B4 level.
At midnight UTC the visible solar disk had 7 spotted regions.
Region 11176 decayed further and only has penumbra on leading polarity
spots. The spots in the region extend longitudinally over 27 degrees, however,
there is only penumbra at one end of the region. None of the penumbrae are
large. Magnetically there's only minor polarity intermixing and as such the
region is not very complex. Additionally opposite polarity spots occur at quite
a distance from each other. Classifying this region is difficult. An FSI
classification is possible as the penumbrae are spread out over more than 15
degrees, however, CSI is more accurate from a polarity perspective and when
considering the lack of trailing polarity penumbrae.
Flare: C1.4 at 11:39 UTC.
Region 11177 was quiet and stable.
Region 11178 decayed slowly and was quiet.
Region 11180 was quiet and stable.
Region 11181 was quiet and stable.
Region 11183 was quiet. The region has minor polarity intermixing. An M class flare is possible.
Spotted regions not numbered by NOAA/SWPC:
[S920] reemerged on March 27. Location at midnight: S27E18.
March 26-28: 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
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 to good. Propagation on long distance northeast-southwest paths is poor.
The geomagnetic field is expected to be quiet on March 29-31.
|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
|Total spot count:||43||98|
|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||115.0 (1)||72.2 (2A) / 79.9 (2B)||(33.0 predicted, +1.9)||(8.19)|
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.